CN118307293A

CN118307293A - A kind of talc-clay system talc daily-use porcelain and its preparation method

Info

Publication number: CN118307293A
Application number: CN202410474680.4A
Authority: CN
Inventors: 李鑫浩; 胡其国; 马岚; 邱辉辉; 胡澄清; 曹志敏; 吴可
Original assignee: Jiangxi Ceramic And Art Institute
Current assignee: Jiangxi Ceramic And Art Institute
Priority date: 2024-04-19
Filing date: 2024-04-19
Publication date: 2024-07-09

Abstract

The present invention relates to the technical field of daily-use ceramics, and specifically discloses a talc-clay system talc daily-use porcelain and a preparation method thereof. The present invention comprises the following preparation raw materials: calcined talc and clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talc. The present invention conducts theoretical research on the mechanism of the narrow firing range of traditional talc porcelain. On the basis of the mechanism research, the present invention proposes a calcined talc-clay system for the first time, uses potassium carbonate as a flux, and the flux is added in advance when calcining talc, dissolves clay and its decomposition products before the _SiO2 -MS _- _M2A2S ternary low eutectic reaction, reduces the total liquid phase amount generated in the system, significantly improves the sintering temperature range and clay dosage of talc porcelain, ensures the forming performance, and compares the talc daily-use porcelain of a certain factory with a light transmittance increased by 21.5%, a whiteness increased by 10.9%, and a flexural strength increased by 10%, fundamentally solving the contradiction between the forming performance and the sintering performance in the production of talc porcelain, and is conducive to the green development of talc daily-use porcelain.

Description

Talc-clay system talcum-like domestic porcelain and preparation method thereof

Technical Field

The invention relates to the technical field of daily-use ceramic, in particular to a talcum-clay system sliding stone daily-use ceramic and a preparation method thereof.

Background

The magnesia porcelain is porcelain with aluminosilicate containing MgO as main crystal phase. The main crystal phases are classified into enstatite porcelain (steatite porcelain), cordierite, spinel porcelain and forsterite porcelain. Talc porcelain is a magnesia porcelain using talc as a main raw material, and is mainly used for high-frequency electric porcelain at the earliest. The main points of the papers are that the sintering range of the carbide ceramic is only about 20 ℃, but in the solving method, the feldspar with the content of about 6-7% is added, so that a certain sintering temperature range can be widened, but the electric property and the mechanical strength of the carbide ceramic can be greatly reduced by the content of alkali metal oxide in the feldspar, so that the carbide ceramic can be strictly controlled and can be used only when large ceramic parts with low requirements on the property are manufactured. Talc porcelain developed by Zibo silicate institute and the like is put into production in 1977, a new composition system is developed in the field of daily porcelain, and the result gives rise to three prizes of national technology invention in 1983, which is the first invention prize of China ceramic industry. Compared with the traditional long stone porcelain, sericite porcelain and bone porcelain, the talcum porcelain has the advantages of high strength, good thermal stability and light transmittance and the like, and is popular with consumers. However, the daily porcelain with talcum quality is produced always with the problems of difficult forming, narrow sintering temperature range and easy deformation at high temperature, and the problems of difficult forming, narrow sintering temperature range and the like are overcome by adopting bentonite with reduced clay content in the prior industry, however, the whiteness and other performances of the talcum porcelain are obviously reduced. The existing formulation composition points of the talcum porcelain are all near the composition points initially determined by the silicate research institute of the catalpa, and a large number of experiments prove that the clay consumption is 15 percent, and the clay consumption in the talcum porcelain can not exceed 15 percent if the addition of the clay in the talcum porcelain is not considered to be more than 15 percent, and other measures can be taken to improve the plasticity of the pug and not increase the clay consumption if the shaping requirement is not met. The amount of the fixed clay is 15% (the content of alumina in the formula is 7.06%), the proportion of feldspar to the calcined talc in the formula is changed, when the calcined talc is 73% and the feldspar is 12%, the sintering temperature is 1280-1320 ℃, and the use of bentonite and an organic plasticizer is required to increase the plasticity because the amount of the clay is limited to about 15 wt%, so that the whiteness of the product is reduced. Even after bentonite and plasticizer are used, the technological conditions for plastic forming of the talcum daily porcelain are still harsh. The sintering performance of talcum porcelain production is poor, and slight errors in the production process can lead to low product quality and fault tolerance and a large amount of ceramic wastes.

In the prior art, the majority of documents for researching the talcum-based daily porcelain consider that the increase of the clay consumption not only leads the whiteness of the porcelain blank to be influenced, but also leads the firing temperature range to be narrowed, the thermal stability to be reduced, li Xiaosheng and the like, and the free amorphous SiO ₂ is the cause of thickening of talcum porcelain slurry when the talcum is calcined in papers. The proposed solution is that raw talcum is crushed, mixed with 2wt.% of feldspar and 0.1wt.% of barium carbonate and then calcined together, the dosage of the feldspar is reduced during batching, the dosage of clay is increased, and the mud forming performance is further improved. The process method of talcum porcelain can solve the problem of slurry thickening without greatly increasing the cost, and can also slightly increase the consumption of clay, but the process method is still traditional potassium feldspar in terms of solvent selection, the potassium feldspar can generate more liquid phase, and the process method has strong dissolving capacity for the original enstatite, so the adding amount cannot be too much, and the aim is mainly to solve the problem of slurry thickening. At present, the theoretical research of the smooth porcelain is relatively few, and the sintering temperature range is widened mostly by adding feldspar, but the effect is limited, and the value of the sintering temperature range is not measured by adopting a standard high-temperature microscope test method. Jiang Weihui et al in the "Talc-feldspar-Kaolin" system, increased the amount of Kaolin to above 25% and added 2-5% alumina to ensure that the ceramic body is in both cordierite and orthoenstatite phases, and that the amount of cordierite is greater than that of orthoenstatite, a cordierite-orthoenstatite ceramic. The patent publication number is CN101717248B, the name is a medium-low temperature sintered daily talcum porcelain and a production method thereof, and the patent publication formula comprises the following components in percentage by weight: 50-55% of talcum, 25-30% of kaolin, 15-20% of feldspar, 2-5% of alumina and metatalcum: metakaolin= (1.9-2.6): 1, the firing temperature range is as follows: 1180-1230 ℃. The reason why the firing range of the talcum porcelain is narrowed is pointed out that the formulation composition of the talcum porcelain is close to the lowest eutectic point composition of the original enstatite-cordierite-tridymite ternary system, when the temperature is lower than the lowest eutectic point temperature, no liquid phase is generated in a blank, a large amount of liquid phase appears from the temperature to the lowest eutectic point temperature, and the liquid phase quantity is rapidly increased along with the temperature rise, so that the porcelain blank is excessively fired and deformed, the firing range of the talcum porcelain is narrow, and the firing temperature range is only about 20 ℃. According to the patent, by introducing enough feldspar raw materials, the sintering temperature of a green body is greatly reduced; on the other hand, the green body is sintered in advance at the temperature which is greatly lower than the eutectic point, which is favorable for expanding the sintering range of the green body, and the increase of the using amount of the feldspar can lead the green body to generate a large amount of liquid phase at about 1200 ℃ to promote the sintering of the green body. However, the ceramic body is formed by two crystal phases of cordierite and enstatite, and the cordierite is more than the enstatite, so that the ceramic body is a cordierite-enstatite ceramic.

Talc porcelain has the characteristics of high whiteness, high transparency and high strength mainly because the phase composition is a enstatite phase and a glass phase. This is because fewer phase types reduce mismatch and interface scattering between the object phases, thereby improving the flexural strength and transmittance of the sample, and the enstatite phase has a high white characteristic. The compositions of the formulations initially established by the industrial employed Zibo silicate institute, although the phase compositions of the products are the enstatite phase and the vitreous phase, have the problems of difficult formation, narrow sintering temperature range, high-temperature and easy deformation, reduced whiteness and the like. Therefore, a new manufacturing method of talcum porcelain is developed, the phase composition of the talcum porcelain is original enstatite phase and glass phase, the advantages of high whiteness, high transparency and high strength of the talcum porcelain are maintained, the clay consumption and the firing temperature range can be improved, and the contradiction problem between the forming property and the sintering property is fundamentally solved.

Disclosure of Invention

The invention aims at overcoming the defects in the prior art and provides a talcum-clay system-burned talcum-based household porcelain.

The second purpose of the invention is to provide a preparation method of talcum-clay system-burned smooth household porcelain aiming at the defects in the prior art.

In order to achieve the first object, the invention adopts the following technical scheme:

A talcum-clay system talcum-like domestic porcelain comprises the following preparation raw materials: burning talcum and clay; the calcined talc comprises the following preparation raw materials: potassium carbonate, raw talc.

In the talcum-clay system talcum-based domestic porcelain, the preparation method preferably comprises the following preparation raw materials: 70-80 parts of calcined talc and 20-30 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4-4.8:100.

In the talcum-clay system talcum domestic porcelain, the talcum-clay system talcum domestic porcelain is preferably prepared from the following raw materials in parts by weight: 75 parts of calcined talc and 25 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4:100.

In the talcum-clay system talcum domestic porcelain, the talcum-clay system talcum domestic porcelain is preferably prepared from the following raw materials in parts by weight: 80 parts of calcined talc and 20 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4.8:100.

In the talcum-clay system talcum domestic porcelain, the talcum-clay system talcum domestic porcelain is preferably prepared from the following raw materials in parts by weight: 70 parts of calcined talc and 30 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4.4:100.

In the above talc-clay system talc-based household porcelain, preferably, the preparation method comprises the steps of: mixing raw talcum and potassium carbonate, and calcining at 1300-1340 ℃ to obtain calcined talcum; mixing the calcined talc and clay, shaping, heating to sintering temperature, and cooling.

In the talcum-clay system talcum domestic porcelain, the main crystal phase in the porcelain body is the enstatite.

Compared with the scheme that the main crystal phase prepared by adding feldspar to widen the sintering temperature range in the prior art is two crystal phases of cordierite and enstatite, under the condition that the content of iron and titanium in the formula is equivalent, the main crystal phase of the talcum ceramic of the talcum-clay system is the enstatite, and the whiteness of the product is obviously improved.

In order to achieve the second purpose, the invention adopts the following technical scheme:

The preparation method of the talcum-clay system talcum-based household porcelain comprises the following steps:

Step (1): taking raw materials according to a proportion;

Step (2): mixing raw talcum and potassium carbonate, and calcining to obtain calcined talcum;

step (3): mixing and shaping the calcined talc and clay, heating to sintering temperature, and cooling.

In the preparation method of the talcum-clay system talcum domestic porcelain, the calcination temperature in the step (2) is preferably 1300-1340 ℃.

In the preparation method of the talcum-clay system talcum-based domestic porcelain, the preferable method is that the temperature is kept for 0-80min after the sintering temperature is reached in the step (3); more preferably, the temperature is maintained for 20 to 60 minutes after the sintering temperature is reached in the step (3).

In the preparation method of the talcum-clay system talcum domestic porcelain, the preparation method preferably comprises the following steps:

Step (1): taking raw materials according to a proportion;

step (2): mixing raw talcum and potassium carbonate, and calcining at 1300-1340 ℃ to obtain calcined talcum;

step (3): mixing and shaping the calcined talc and clay, heating to sintering temperature at 4-6deg.C/min, maintaining the temperature for 0-80min, and cooling.

Aiming at the problem of narrow sintering range of the traditional talcum porcelain of a calcined talcum-clay-feldspar system, the invention carries out theoretical explanation by combining phase diagram theoretical research after a large number of experiments, test analysis and repeated correction, and the main mechanism is divided into three stages: in the first stage, at about 1200 ℃, quartz, mullite and potassium feldspar undergo eutectic reaction, and part of recalcitrant spodumene is dissolved in the generated liquid phase; the second stage is about 1260 ℃, the enstatite is re-precipitated again, the liquid phase quantity is kept within a certain range, cordierite begins to appear along with the temperature rise, and the content of the cordierite determines the content of the liquid phase quantity in the third stage; finally, a eutectic reaction of quartz-orthoenstatite-cordierite (SiO ₂-MS-M₂A₂S₅) occurs at 1355 ℃ forming a large amount of liquid phase.

Based on the research of the mechanism, attempts are made to prepare talcum porcelain by adopting a talcum-clay-frit (small amount) system, and the action mechanism is as follows: alkali metal or alkaline earth metal frit is used as a solvent, and clay and decomposition products thereof are dissolved before the ternary eutectic reaction of SiO2-MS-M2A2S by using the frit, so that the ternary eutectic reaction of SiO ₂ -MS-M2A2S is avoided, the total liquid phase quantity generated in a system is further reduced, and the sintering temperature range of talcum porcelain and the clay consumption are improved. Firstly, exploring a scheme of taking alkali metal potassium, sodium and different alkaline earth metal frits as solvents, and examining the influence of the alkali metal potassium, sodium and different alkaline earth metal frits as solvents on the sintering range of talcum porcelain, wherein when the alkali metal oxide is K ₂ O and the dosage is 40.8g, the sintering temperature range is 50 ℃; none of the samples with the alkali metal oxide Na ₂ O had a broad sintering temperature range; when different alkaline earth metal oxides (basic magnesium carbonate, calcium carbonate, zinc oxide, strontium carbonate, barium carbonate) are introduced into the flux, all samples are deformed when reaching the sintering temperature point, and the shrinkage of the samples is inconsistent in the sintering process. The influence of the formulation of potassium frit as solvent on the performance of talcum porcelain in different firing regimes is further examined. In the potassium frit, the sample with the temperature rising rate of 10 ℃/min has a higher sintering temperature range, while the sample with the temperature rising rate of 5 ℃/min is deformed in the severe shrinkage process, namely, the sample is burned just before reaching the sintering temperature, and the sintering temperature range is not provided. And opening a furnace door in the sintering process to observe the generation of sample defects, wherein the flux is the defect that the sample is concave in the middle when naturally cooled in a kiln after the potassium frit sample reaches the highest sintering temperature at the heating rate of 10 ℃/min. That is, the potassium frit solution has a wide sintering temperature range at a heating rate of 10 deg.c/min, but the sample has a defect of dishing in the middle at this heating rate.

In order to make the sample with K ₂ O as alkali metal oxide in flux have better application property, a new calcined talcum-clay system is explored, i.e. potassium carbonate is added all while calcining talcum, and no potassium frit is prepared. The specific method is that the added flux is calcined into talcum powder together with raw talcum, the talcum powder and clay are mixed and proportioned, and then ball-milled, sieved, formed and sintered.

In the new talc-clay system, the influence of the calcination temperature of raw talc on the sintering temperature range is explored, the sintering is facilitated when the calcination temperature is 1200 ℃, the calcination temperature is further improved to 1320-1360 ℃, and the sintering temperature range is wider only at 1320 ℃.

In the new talcum-clay burning system, the influence of the heat preservation time on the performance of the sample is explored, the light transmittance of the sample is gradually increased along with the increase of the heat preservation time, and the change trend of the whiteness and the flexural strength of the sample is firstly increased and then decreased.

In the new burnt talcum-clay system, after the clay dosage is increased to 30%, the light transmittance of the sample is gradually increased along with the increase of the potassium carbonate dosage, the whiteness and the flexural strength are both in a decreasing trend, and when the added amount of the potassium carbonate is 4.4 wt%, the sample has better light transmittance, flexural strength and whiteness.

The invention applies a burnt talcum-clay system for the first time, breaks through the condition that the clay dosage is about 15% given at the beginning of the research and development of talcum-quality daily-use porcelain in the study of the Zibo silicate on the basis of comprehensively improving the performance of talcum-quality daily-use porcelain samples in certain factories, and can rather take other measures to improve the plasticity of pugs without increasing the clay dosage if the forming requirement cannot be met. By the demonstration of' the clay consumption is improved to 25-30 wt%, so that bentonite can be omitted, and the problem of low whiteness of the conventional plastic shaped talcum domestic porcelain is solved. Compared with a daily-use talc ceramic sample in a certain factory, the whiteness is improved by 14%, the forming performance and sintering performance related to the existing harsh production process are improved, the sintering temperature range is further widened, the transmittance is improved by 21.5%, the whiteness is improved by 10.9%, and the flexural strength is improved by 10%. The contradiction between the forming property and the sintering property in the production of talcum porcelain is fundamentally solved, and the green development of talcum daily-use porcelain is facilitated.

The novel calcined talcum-clay system skillfully utilizes amorphous SiO ₂ generated by decomposing calcined talcum, K ₂CO₃ is added to form a flux component during calcining, and less flux can be used for dissolving more alumina components, so that the use efficiency of the flux is improved, the process flow is further reduced compared with a frit system, and the production cost for preparing talcum porcelain is reduced.

Drawings

FIG. 1 shows the composition range of the talc ceramic.

FIG. 2 is a graph showing the change in flexural strength at various temperatures.

FIG. 3 is a graph of a method for broadening the sintering temperature range of talc ceramic with increased clay usage.

FIG. 4 is a plot of projected area change in a high temperature microscope for samples 4-1#, 4-2# and 4-3#. And (b) is (a) enlarging the rectangular inner area.

FIG. 5 is a photograph of a high temperature microscopic analysis of a sample No. 4-1. (a) 25 ℃; (b) 1200 ℃; (c) 1310 ℃.

FIG. 6 is a photograph of a high temperature microscopic analysis of a sample No. 4-2. (a) 1324 ℃; (b) 1370 ℃; (c) 1380 ℃.

FIG. 7 is a photograph of a high temperature microscope analysis of a sample No. 4-3. (a) 1340 ℃; (b) 1390 ℃; (c) 1400 ℃.

FIG. 8 is a plot of projected area change in a high temperature microscope for sample 5-1 and sample 5-2.

FIG. 9 is a photograph of the 5-1# sample and the 5-2# sample in a high temperature microscope when the sintering temperature point is reached. (a) 10deg.C/min; (b) 5 ℃/min.

FIG. 10a is a flow chart of a process for preparing a calcined talc-clay system.

FIG. 10b is a plot of projected area change in a high temperature microscope for samples 5-13.

FIG. 11 is a photograph of a high temperature microscope analysis of samples 5-13. (a) 24 ℃; (b) 1118 ℃; (c) 1348 ℃.

FIG. 12 shows the projected area profiles of samples 5-14#, 5-15#, 5-16# and 5-13# in a high temperature microscope. And (b) is (a) a rectangular inner region.

FIG. 13 is a photograph of a high temperature microscope analysis of samples 5-14. Wherein (a) 1390 ℃; (b) 1400 ℃.

FIG. 14 is a photograph of a high temperature microscope analysis of samples 5-15. Wherein (a) 1378 ℃; (b) 1388 ℃.

FIG. 15 is a photograph of a high temperature microscope analysis of samples 5-16. Wherein (a) 1362 ℃; (b) 1372 ℃.

FIG. 16 is a graph showing the ultraviolet-visible light transmittance spectrum and transmittance change of samples 5-17#, 5-18# and 5-19#.

FIG. 17 is a graph showing the whiteness change and flexural strength change of samples 5-17#, 5-18# and 5-19#.

FIG. 18 shows XRD patterns of samples 5-19 after firing.

FIG. 19 is a graph comparing the performance of samples 5-19 with that of a mill's talc daily porcelain.

FIG. 20 shows the projected area curves for samples 5-20#, 5-21#, 5-22#, 5-23# and 5-14# in a high temperature microscope. And (b) is (a) enlarging the rectangular inner area.

FIG. 21 is a photograph of a high temperature microscope analysis of samples 5-20.

FIG. 22 is a photograph of a high temperature microscope analysis of samples 5-21.

FIG. 23 is a photograph of a high temperature microscope analysis of samples 5-22.

FIG. 24 is a photograph of a high temperature microscope analysis of sample No. 5-23.

FIG. 25 is a graph showing changes in UV-visible light transmission spectra and transmittance of samples 5-20#, 5-21# and 5-22#.

FIG. 26 is a graph showing the whiteness change and flexural strength change of samples 5-20#, 5-21# and 5-22#.

FIG. 27 shows XRD patterns of samples 5-21 after firing.

Detailed Description

The application is further described below in conjunction with the detailed description. It is to be understood that these examples are illustrative of the present application and are not intended to limit the scope of the present application. Further, it is understood that various changes and modifications of the present application may be made by those skilled in the art after reading the description of the present application, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.

Raw materials

The raw materials mainly comprise mineral raw materials such as talcum powder, water-washed kaolin, potassium feldspar and the like, and chemical raw materials such as potassium carbonate, sodium carbonate, lithium carbonate, basic magnesium carbonate, calcium carbonate, calcined zinc oxide, strontium carbonate, barium carbonate and the like, wherein the chemical raw materials adopt analytical grade, and the potassium carbonate, the sodium carbonate and the lithium carbonate are all purchased from national pharmaceutical group chemical reagent limited companies. The chemical composition of the mineral raw materials used in the search experiments 1-2, examples 1-4 and comparative example 1 was as follows.

The chemical composition of the mineral raw materials is as follows.

TABLE 1 chemical composition of mineral raw materials

Testing and characterization

(1) Sintering temperature range determination

The method is mainly based on a high-temperature microscope method in QB/T1547-2016 ceramic material sintering temperature range test method, wherein the experimental principle is that the sintering temperature range is determined according to the projection area change of a sample in the heating process, the temperature of the sample when the projection shrinkage reaches the maximum value is the lower limit T _L, the temperature before the sample is subjected to overburning expansion or softening shrinkage is the upper limit T _h, and the sintering temperature range of the sample is T _L～T_h.

For determining the sintering temperature range of the talcum porcelain, the volume expansion phenomenon caused by precipitation of the raw fire and the overburning expansion phenomenon caused by precipitation of the raw fire during the talcum porcelain are distinguished. Junction temperature is defined as: the refractory material or ceramic green body is sintered to a temperature at which pores are minimized, shrinkage is large, the product is most dense, the performance is most excellent, or the ceramic green body is in a solid and aggregated state. Three conditions for determining the sample sintering temperature range are summarized according to this definition: (1) The sample is required to reach a densification state, and the judgment standard of the daily porcelain is that the water absorption rate of the sample is less than 0.5%; (2) The sample does not have defects in the sintering temperature range, and mainly refers to deformation or irregular morphology of the sample; (3) The properties of the sample in the sintering temperature range, such as flexural strength, thermal stability and the like, are not greatly reduced.

The sintering temperature range of the sample was measured using an EM301 high temperature microscope manufactured by Hesse corporation, germany, and the upper limit of the test temperature was 1550 ℃. Sample preparation: grinding, sieving with 200 mesh sieve, and making into cylindrical sample with phi 2mm×2 mm.

(2) Determination of plasticity index

The plasticity index is measured by adopting a ball pressing method, and the instrument is an SKY-45 type plasticity instrument manufactured by Jingdezhen electric porcelain company.

(3) X-ray diffraction analysis

Samples were subjected to phase analysis using a D8X-ray powder diffractometer manufactured by Bruker, germany. The test conditions were: radiation of Cu-K alpha and wavelength of rayThe tube voltage is 40KV, the tube current is 40Ma, the scanning range is 2θ=10-70 degrees, the scanning step width is 0.02 degrees, and the testing rate is 5 steps/s.

(4) Thermal analysis (DTA/DSC)

The samples were subjected to differential thermal-thermogravimetric analysis using a synchronous thermal analyzer STA449C manufactured by the company Netzsch GmbH, germany, and tested for the effect of the samples during heating. The test temperature is in the range of room temperature to 1450 ℃, the test atmosphere is argon, and the reference substance is high-purity alumina.

(5) Scanning Electron Microscope (SEM) and energy spectrum (EDS) analysis

The microstructure and morphology of the samples were analyzed by using a SU-8010 type field emission scanning electron microscope (field of Japan Litshi). The X-ray micro-differentiation analysis adopts a SU-8010 scanning electron microscope. The test conditions were as follows: acceleration voltage: 5kV, resolution: 1.0-1.3 nm, and is equipped with IXRF Model-550 i type electric refrigeration energy spectrometer.

Sample preparation: taking a flat section on a sample, corroding the sample for 30s by using HF with the concentration of 5v percent, ultrasonically cleaning the sample by using deionized water for 10min,

(6) Fourier infrared spectroscopy (FT-IR) analysis

Samples were subjected to infrared spectroscopy using a Nicolet5700 fourier infrared spectrometer for thermoelectric analysis in the united states. 1mg of the powder sample was weighed, mixed with pure KBr (sample: KBr=1:150, mass ratio) and pressed into tablets for infrared spectroscopic testing. The scanning wave number range is 4000-400 cm ^-1, and the resolution is 0.4cm ^-1.

(7) Determination of flexural Strength of Material

The WDW-20 microcomputer controlled universal tester is used for testing, the span is 20mm, and the test method adopted by the bending resistance instrument is a three-point bending method. The sample is processed into a test strip with the length of 35mm multiplied by 6mm, the surface is polished, and the long edges of the test strip are chamfered at 45 degrees so as to eliminate stress defects generated by processing on the surface and edges of the sample. The sample is placed on a sample table of a universal testing machine, the center of the sample is aligned with a pressure head, the pressure head is slowly lowered at a loading speed of 0.2mm/min until the sample breaks, and a maximum loading load value P is recorded. Then the width b and thickness h of the wet oxygen are measured, and the flexural strength is calculated according to the formula.

(8) Transmittance test

The talc ceramic samples were processed into round flakes of Φ40mm, and then both sides of the samples were ground using 150 mesh, 600 mesh and 2000 mesh water-abrasive papers in order, and then polished to a mirror surface of 1mm in thickness using MgO powder. The polished samples were tested for transmittance using a Lambda850 uv-vis spectrophotometer from platinum-elmer, usa, light source wavelength range: 175-900 nm.

(9) Whiteness test

The whiteness of the talc ceramic sample was measured using a WSD-2A whiteness meter manufactured by Shanghai's instruments, inc.

(10) Thermal stability test

According to GB/T3298-2009 method for testing thermal shock resistance of daily ceramic ware, test samples are required to be 5 products which are the same in batch, the same in specification and ware type, and have no defects such as breakage, cracks and the like. Setting the heating furnace to be at a test temperature, placing the sample into the heating furnace after the heating furnace reaches the set temperature, and preserving the heat for 30min after the temperature of the heating furnace rises to the set temperature. After the completion of the incubation, the sample was put into water at 20.+ -. 2 ℃ for 15 seconds and kept in water for 10 minutes. The water surface is 2cm higher than the sample, and the temperature of the water temperature is increased by not more than 4 ℃. After the holding is finished, the sample is taken out, the sample is observed for cracks by using a dyeing solution, and the sample is subjected to repeated inspection after standing for 24 hours.

Exploring experiment 1 explores the mechanism of narrow firing range of traditional talcum porcelain

At present, the industry generally adopts the reduction of the clay content to improve the sintering property, but the reduction of the clay content can deteriorate the forming property, and the whiteness of the product is seriously influenced by using bentonite in order to meet the process requirement of plasticity. This results in a low quality product rate in the production of talc porcelain, which wastes a lot of resources and energy. Secondly, bentonite is used for improving the plasticity, so that the whiteness of the product is greatly reduced, and the performance requirement of the high-grade daily porcelain cannot be met. This clearly does not correspond to the idea of an economical operation to achieve green development. The sintering of steatite porcelain belongs to liquid phase sintering, and the liquid phase quantity has a decisive effect on the sintering performance of the steatite porcelain.

Phase diagram analysis is an ideal method for quantitatively characterizing the physicochemical reaction in the sintering process, however, the ternary formulation of the talcum porcelain belongs to a K ₂O-MgO-A1₂O₃-SiO₂ quaternary system, and no research results of related phase diagrams can be referred in the prior literature. The inventors designed different formulation compositions by using the main crystal phase formed by the talcum porcelain in the illustrative mineral composition, and explored the physicochemical reaction of the talcum porcelain in the sintering process by combining different hypothesis methods by using phase diagrams. On the basis of determining the phase diagram using method, liquid phase amounts of different temperature points of each sample are calculated to analyze the sintering property change of the sample. The physical and chemical reactions in the sintering process of the traditional smooth household porcelain are further corrected through the test analysis of DTA and XRD at different temperatures. On the basis, a mechanism that the sintering temperature range of the traditional talcum-based daily porcelain is narrow when the clay consumption is large is analyzed.

As shown in fig. 1, points a and b are selected within the composition range of the enstatite porcelain, and points f and g are selected within the composition range of the enstatite-cordierite porcelain. To investigate the sample performance impact of clay amounts in the formulation composition, discrete distribution of ingredient composition points c and e were selected from top to bottom in the middle region of their composition range as clay amounts increased. In the prior literature, the feldspar consumption of the talcum-based daily porcelain formula is more than 10wt.%, and d points with the feldspar consumption less than 10wt.% are selected for researching the effect of the feldspar in sintering. The formulation composition of the composition points is shown in Table 2.

TABLE 2 formulation composition at composition points

The test results are shown in Table 3, and the plasticity index of the sample is gradually increased with the increase of the clay dosage. Only samples 3-1# with a clay level of 13wt.% had a broad sintering temperature range. The principal crystalline phase composition is lower in flexural strength for samples 3-6# containing a cordierite phase than for samples having only enstatite as the principal crystalline phase. The whiteness of the 3-6# sample with the clay consumption of 30wt.% is 73%, and the whiteness of the 3-7# sample with the clay consumption of 35wt.% is 72%, namely, the problem that the whiteness of the existing shapable talcum daily porcelain is low cannot be solved by simply increasing the clay content. The original enstatite-cordierite ceramic also exhibits a decay in flexural strength with temperature. During the experiment, it was also found that the 3-7# sample, which had a main crystal phase composition of enstatite and cordierite, exhibited significant volume expansion due to sample overburning, but the sample was not denatured at a temperature rise rate of 5 ℃/min in the range of 1220 ℃ -1280 ℃.

Table 3 test results for each sample

"-" Indicates that the sample has no detectable sintering temperature range and thus some properties of the sample cannot be tested.

Flexural strength tests are carried out on 3-7# and 3-1# samples within the range of morphology rules, and experimental results are shown in figure 2. It can be seen that the flexural strength of the 3-7# sample gradually decreases with increasing firing temperature, indicating that the apparent volume expansion of the 3-7# sample during firing has a great effect on the flexural strength of the sample. The effect of firing temperature on the flexural strength of the sample in the sintering temperature range was compared with that of sample # 3-1, whose main crystal phase is enstatite, and the experimental result is shown in fig. 2b. It can be seen from fig. 2b that the firing temperature has little effect on the flexural strength of the 3-1# sample, further illustrating that the flexural strength of the 3-7# sample decreases with increasing firing temperature because the sample undergoes significant volume expansion with increasing temperature.

From the above analysis, it is found that simply increasing the clay amount in the ternary formulation of clay-calcined talc-potassium feldspar does not solve the problem of low whiteness of the conventional shapable talc daily porcelain, and also has the problem of reduced flexural strength. When the clay is used in a large amount, all samples do not have a wide sintering temperature range.

Subsequently, the composition points of each formulation were expressed by chemical composition representation, the calcium oxide, potassium oxide, sodium oxide and iron oxide components were converted into magnesium oxide and aluminum oxide according to the calculation coefficients, and the liquid phase amounts of each sample were calculated using the ternary system phase diagram of MgO-A1 ₂O₃-SiO₂, which was found that in the case where it was assumed that the chemical compositions of the formulations all participated in the phase change reaction in the ternary system phase diagram of MgO-A1 ₂O₃-SiO₂, And (3) putting the composition points of each sample into a MgO-A1 ₂O3-SiO₂ ternary system phase diagram, wherein the primary crystal region where part of the samples are located conflicts with the actual primary crystal region. Further correcting the chemical composition representation method of the formula, assuming that the potassium feldspar does not participate in the phase change reaction in the MgO-A1 ₂O₃-SiO₂ ternary system phase diagram, listing the potassium feldspar independently, only calculating the contents of A1 ₂O₃、SiO₂ and MgO in the calcined talc and clay in the formula, converting the chemical composition in each sample, then putting into the MgO-A1 ₂O₃-SiO₂ ternary system phase diagram, The calculated composition points were found to be on the boundary between the enstatite and the quartz primary crystal region, indicating that the theoretical assumption was correct. Then taking the fact that potassium feldspar is not melted singly but generates a ternary eutectic reaction with quartz and clay in a K ₂O-A1₂O₃-SiO₂ system to generate a liquid phase, further assuming that each dosing point firstly generates a phase change reaction in a K ₂O-A1₂O₃-SiO₂ ternary system phase diagram, the rest solid phase generates a phase change reaction in a MgO-A1 ₂O₃-SiO₂ ternary system phase diagram, The K ₂O-MgO-A1₂O₃-SiO₂ quaternary system was broken down into the K ₂O-A1₂O₃-SiO₂ ternary system (denoted as the A system) and the MgO-A1 ₂O₃-SiO₂ ternary system (denoted as the B system) and their interactions. The system A generates solid-liquid phase change reaction at a lower temperature, and the rest solid phase generates solid-liquid phase change reaction at a higher temperature in the system B. Therefore, in the ternary formulation of potassium feldspar-calcined talcum-clay, the liquid phase quantity generated by the eutectic reaction of potassium feldspar-quartz-mullite at 985 ℃ can be calculated according to a K ₂O-A1₂O₃-SiO₂ phase diagram, and the liquid phase quantity generated by the ternary eutectic reaction of SiO ₂-MS-M₂A₂S₅ at 1355 ℃ can be calculated in a MgO-A1 ₂O₃-SiO₂ ternary system phase diagram after the solid phase is left. after the composition of each formulation was converted, the amount of liquid phase L1 generated at 985 ℃ was calculated from the a-system phase diagram, the amount of liquid phase L2 generated at 1355 ℃ was calculated from the B-system phase diagram, and the total liquid phase tl=l1+l2 was calculated. The results are shown in the following table.

Table 4 chemical composition of the remaining solid phase of each formulation and total liquid phase amount in the system at 1355℃

The chemical compositions of the samples in Table 4 were put into a ternary system phase diagram of MgO-A1 ₂O₃-SiO₂, and it was found that the primary crystal region in which each composition point falls was substantially identical to the actual primary crystal region. So far, according to the analysis result of the phase diagram, the phase change reaction occurs in two systems at two temperatures in the ternary formulation of the calcined talc-clay-potassium feldspar.

In the K ₂O-A1₂O₃-SiO₂ system at 985℃:

In the MgO-A1 ₂O₃-SiO₂ system at 1355 ℃):

According to theory: talc porcelain matrices are fully sintered at 35% liquid phase but deformed at 45% liquid phase (Hu Zhijiang et al, basic courses of inorganic materials science, 2004:197). According to the calculated liquid phase quantity of the phase diagram, the liquid phase quantity L1 generated by the eutectic reaction at 985 ℃ is not more than 35% of each sample, namely, each sample cannot be sintered at a lower temperature. The total liquid phase amount T.L after eutectic reaction at 1355 ℃ is similar to the upper limit 45% of the liquid phase amount required by sintering when the clay is used for the 3-1# sample with the amount of 13%, and the liquid phase amount exceeds 45% when the clay is used for the 3-2# sample with the amount of 15%. When the clay consumption in the samples is more than or equal to 15, all the samples soften and collapse after 1355 ℃. And then verifying the result of phase diagram analysis by using the sintering temperature obtained by experiment, testing by using a high-temperature microscope at the heating rate of 10 ℃/min to obtain a projection area change curve and an analysis photo of the sample in the high-temperature microscope, and finding that the projection shrinkage of the sample with the temperature of 1343 ℃ of the sample with the temperature of T1 to be 3 ℃ reaches the maximum value, and the lower limit temperature is 1343 ℃. The curve starts to drop at a T2 temperature of 1389 ℃, and when the sample is burnt at 1400 ℃ in combination with the analytical photograph, the sintering temperature of the 3-1# sample is determined to be from 1343 ℃ to 1389 ℃ and the sintering temperature range is 46 ℃. The test results of all samples are shown in Table 3. XRD analysis of the samples at different temperature points shows that after the solid-liquid phase transformation reaction of the A system occurs at a lower temperature, part of the enstatite of the B system is dissolved, but the enstatite can be separated out of the liquid phase again before the solid-liquid phase transformation reaction of the B system occurs, and the initial substantial reduction temperature of the enstatite, quartz and cristobalite phases is about 1200 ℃, which is the temperature at which the Al-Si spinel is decomposed into mullite, as is known from DTA analysis of the samples. Therefore, the temperature of the eutectic reaction in the K ₂O-A1₂O₃-SiO₂ system is about 1200 ℃. Therefore, the reaction after correcting the physicochemical reaction in the firing process of the traditional smooth household porcelain is further carried out by the test analysis of DTA and XRD at different temperatures as follows:

In the K ₂O-A1₂O₃-SiO₂ system around 1200 ℃):

Interaction of the K ₂O-A1₂O₃-SiO₂ System with the MgO-A1 ₂O₃-SiO₂ System:

About 1200 deg.c: L1+MgO.SiO ₂ (enstatite) →L3

About 1260 ℃). L3→L1+MgO.SiO ₂ (original enstatite)

In the MgO-A1 ₂O₃-SiO₂ system at 1355 ℃):

The traditional mechanism of the narrow firing range of talcum porcelain is mainly divided into three stages: in the first stage, quartz, mullite and potassium feldspar have eutectic reaction at about 1200 ℃, and part of recalcitrant spodumene is dissolved in the generated liquid phase; the second stage is to re-precipitate the enstatite at about 1260 ℃ to keep the liquid phase amount within a certain range, and the cordierite begins to appear along with the temperature rise, so that the cordierite content determines the liquid phase amount content in the third stage; finally, as the temperature increases to 1355 ℃ the eutectic reaction of quartz, orthoenstatite and cordierite occurs, forming a large amount of liquid phase.

Exploration experiment 2 preparation of a sliding stone household porcelain with alkali metal potassium, sodium and different alkaline earth metal frits as solvents

According to the research results of the exploration experiment: when the clay is used in a large amount, the softening and collapse of the sample is caused by a large amount of liquid phase quantity generated by the ternary eutectic reaction of cordierite, enstatite and quartz in the SiO ₂-MS-M₂A₂S₅ system at 1355 ℃. Therefore, when the clay amount is increased, the talcum porcelain has a good sintering temperature range, and the generation of liquid phase quantity in the matrix during the sintering process is strictly controlled. The eutectic reaction of the solid phase of another system is not participated in as long as the phase is changed from solid phase to liquid phase. Based on this, it is proposed to assume: as long as the aluminum-containing solid phase enters the liquid phase before the SiO ₂-MS-M₂A₂S₅ ternary eutectic reaction, namely before the cordierite is generated, the cordierite which determines the liquid phase quantity generated by the SiO ₂-MS-M₂A₂S₅ ternary eutectic reaction disappears, the SiO ₂-MS-M₂A₂S₅ ternary eutectic reaction does not occur, That results in a considerable reduction of the total liquid volume at the eutectic temperature point. When the amount of liquid phase produced at the time of eutectic reaction corresponds to the formulation composition, 25g was found to be from clay and 26.2g was found to be from MgSiO ₃. The total liquid phase amount of the system can be greatly reduced by allowing the clay to independently enter the liquid phase to reduce the ternary eutectic reaction of SiO ₂-MS-M₂A₂S₅. In the research experiment, the clay in which the potassium feldspar is dissolved by the K ₂O-A1₂O₃-SiO₂ system and the decomposition products thereof are very limited, so that a solvent with stronger dissolving capacity needs to be searched for to replace the potassium feldspar, thereby further widening the firing range of the talcum porcelain. According to the above theory, the solvent needs to meet the following conditions simultaneously: ① Can dissolve clay before SiO ₂-MS-M₂A₂S₅ ternary eutectic reaction; ② The ternary eutectic reaction of SiO ₂-MS-M₂A₂S₅ is reduced, and the liquid phase quantity is controlled between 35% and 45%; ③ The clay and its decomposition products are dissolved as much as possible, while the dissolution of MgSiO ₃ is as little as possible; ④ The solvent is used in a small amount. The method of widening the sintering temperature range of the talc ceramic with increased clay usage is shown in fig. 3.

(One) Effect of different frit formulations on Talc porcelain firing Range

Table 5 different alkali metal flux formulation compositions (wt.%)

Table 6 different alkaline earth flux formulations (wt.%) were added

The sample sintering temperature range was tested with alkali and alkaline earth metals. F4-1# to F4-15# are made into a frit by the following specific method: mixing the raw materials in the formula, ball milling for 15-25 minutes in a rapid ball mill, burning in a frit furnace at 1250-1300 ℃, quenching in water, collecting fragments, and finally grinding into 200-mesh powder through a rapid prototyping ball. When burning talc, 5wt.% (compared to the amount of raw talc) of frit was added, which was present in the calcined talc when dosed, and the added 5wt.% of frit was in an amount of 3.4wt.% calculated to the total formulation. 3wt.% of the frit was then blended with calcined talc and clay according to the following table.

Table 7 composition of the sample formulations (wt.%)

High temperature microscopic test analysis was performed on each sample at a rate of 10 ℃/min. As shown in fig. 4 to 7, the projection shrinkage of the sample No. 4-1 at the temperature of T1, 1310 ℃ reaches the maximum value, which means that the sample has been sintered, but the appearance of the sample is irregular, and comparing the high temperature micrograph of the sample at 1200 ℃, it can be seen that the sample No. 4-1 deforms during the severe shrinkage from 1200 ℃ to 1310 ℃, so that the sample No. 4-1 has been burnt just before the temperature of sintering is reached. The sintering temperature of the sample No. 4-2 is 1324-1370 ℃ and 46 ℃. The sintering temperature of the 4-3# sample ranges from 1340 ℃ to 1390 ℃ and is 50 ℃. Only the 4-2# sample and the 4-3# sample had a wider sintering temperature range, the sintering temperature range of the samples gradually increased as the amount of K ₂ O in the flux increased, and the temperature at which the samples began to sinter gradually increased. As the amount of K ₂ O in the flux increases, the less the Al ₂O₃ -containing crystal phase in the system is during the ternary eutectic reaction of SiO ₂-MS-M₂A₂S₅, the less the amount of liquid phase is generated, thereby avoiding that the amount of liquid phase generated with the increase of temperature exceeds the upper limit allowed by the sintering of the talc ceramic, and the sintering temperature range of the sample is gradually increased. Since the smaller the total liquid phase amount in the sample, the higher the temperature of the sample is to reach the liquid phase amount required for sintering the talcum porcelain, the temperature at which the sample starts to sinter gradually increases with the increase of the content of K ₂ O in the flux.

High-temperature microscopic test analysis is carried out on the 4-4# to 4-6# samples, and the sintering temperature of the 4-4# samples is 1319 ℃ to 1340 ℃ which is 21 ℃. The sintering temperature of the sample No. 4-5 is 1337-1342 ℃ and 5 ℃. The sintering temperature of the sample No. 4-6 is 1308-1312 deg.C, 4 deg.C. From XRD pattern and DTA curve analysis of the samples, it was found that the flux in the 4-6 samples had nearly completely dissolved the clay and its decomposition products at 1000℃, and as the temperature continued to rise, the alumina-containing crystalline phase in the liquid phase re-precipitated. None of the samples of the flux where the alkali oxide was Na ₂ O had a broad sintering temperature range.

High temperature microscopic analysis was performed on sample # 4-10, from 1078 ℃ to 1325 ℃, and the sample was deformed during shrinkage, so that sample # 4-10 had burned when the sintering temperature point was reached. The reason for this analysis is that the mixed alkali effect weakens the ability of the flux to dissolve the clay when the sample reaches the sintering temperature point, and Al ₂O₃ and SiO ₂ begin to enter the liquid phase in large amounts when the sample approaches the sintering temperature.

Al ₂O₃ of a sample of which the flux is potassium frit enters a liquid phase under the condition that alkali metal ions meet charge balance, and Al ₂O₃ in the sample only enters a small part of the liquid phase at 600-1250 ℃, and most of Al ₂O₃ enters the liquid phase under the action of Mg ²⁺. However, when the sintered state reaches 1350 ℃, mg ²⁺ precipitates as enstatite, and Al ₂O₃ can remain balanced with k+ in the liquid phase. Thus Mg ²⁺ acts as an intermediate medium, with a liquid phase content of 37.4wt.% at 1350 ℃.

High temperature microscopy was performed on samples 4-11#, 4-12#, 4-13#, 4-14#, and 4-15#, at a rate of 10 ℃/min, with deformation during the severe shrinkage of the 4-11# sample from 1099 ℃ to the sintering temperature, deformation during the severe shrinkage of the 4-12# sample from 1223 ℃ to the sintering temperature, deformation during the severe shrinkage of the 4-13# sample from 1171 ℃ to the sintering temperature, deformation during the severe shrinkage of the 4-14# sample from 1172 ℃ to the sintering temperature, and deformation during the severe shrinkage of the 4-15# sample from 1086 ℃ to the sintering temperature. After 18.3wt.% of the different alkaline earth oxides were introduced into the flux, all samples had deformed by the time the sintering temperature point was reached and the samples had not shrunk uniformly during sintering. After the alkaline earth oxide is added, the flux of all samples has reduced dissolution capacity for clay, which is caused by the alkali pressing effect of the melt. Alkaline earth metal oxides, when added to an alkali-containing melt, tend to reduce the ability of the melt to migrate ions. The reason is that the higher charge and larger radius of the alkaline earth metal oxide prevent the migration path of alkali metal ions.

(II) Effect of temperature increase Rate on Performance

The F4-3# flux formula is prepared into a frit (the preparation method of the frit is unchanged), and the frit is ground into 200-mesh powder through a rapid prototyping ball. When calcined, 5wt.% (compared to the amount of raw talc) of frit was added, the added 5wt.% of frit being present in the calcined talc when dosed, the amount of frit added being 3.4wt.% in the total formulation. The 3wt.% frit was then blended with talc and clay according to the following table to compare the effect of different ramp rates on performance.

TABLE 8 experiment of the influence of the heating rate on the Performance

As is evident from the foregoing, the sintering temperature of the 5-1# (4-3 # potassium carbonate) sample was in the range of 1340℃to 1390℃and 50 ℃. And (3) carrying out high-temperature microscopic test on the No. 5-2 sample to determine the sintering temperature range. As shown in fig. 8 and 9, the projection shrinkage of the sample No. 5-2 in the high temperature microscope reached a maximum at a temperature of 1340 ℃ of T1, but the morphology was irregular at this temperature, indicating that the sample No. 5-2 had deformed during the severe shrinkage, i.e., the sample had been burned as soon as it reached the sintering temperature, and the sample No. 5-2 had no sintering temperature range.

The generation of sample defects is observed by opening the furnace door in the sintering process, and the 5-1# sample has defects in the natural cooling process in the kiln. For the sheet type sample, the specimen showed a phenomenon of dishing in the middle. And after the flux is potassium frit sample reaches the highest firing temperature at the heating rate of 10 ℃/min, the sample has a middle concave defect when naturally cooled in a kiln. This is due to the fact that the temperature rise rate is too fast, the sample is not sufficiently uniform in reaction at high temperature, and this defect is caused by the difference in thermal expansion coefficient during cooling. Therefore, among the solutions for preparing talc porcelain with alkali metal potassium, sodium and different alkaline earth metal frits, the potassium-only frit solution has a wide sintering temperature range at a temperature rising rate of 10 ℃/min, but the sample has a defect of dishing in the middle under the temperature rising condition.

EXAMPLE 1 preparation of Talc porcelain Using a calcined Talc-Clay System with Potassium carbonate as flux

In order to make the sample with K ₂ O as alkali metal oxide in flux have better application property, according to the element characteristic of K ⁺, a new calcined talcum-clay system is adopted, i.e. potassium carbonate is added all the time when talcum is calcined, and no potassium clinker is prepared. The new talcum-clay system firstly reduces the process flow, and secondly, the prior process introduces a certain amount of SiO ₂ and Al ₂O₃ when preparing the frit, which limits the upper limit of the using amount of clay, and the adopted new system reduces the introduced amount of SiO ₂ and Al ₂O₃. The specific preparation method is shown in figure 10a, the added flux is calcined into the calcined talcum together with the raw talcum, the calcined talcum is mixed with the clay for proportioning, and then ball milling, sieving, molding and sintering are carried out.

Table 9 formulation of samples with flux potassium carbonate under novel process conditions

The sample 5-13# was subjected to high temperature microscopic test at a temperature rising rate of 5 c/min to determine the sintering temperature range, and as a result, as shown in fig. 10b and 11, the projection shrinkage of the sample 5-13# reached a maximum value at a temperature of 1350 c at which the sample had been sintered. From FIG. 11, the morphology of sample # 5-13 was irregular at 1350℃indicating that the sample had been deformed during severe shrinkage. From the slope change of the curve, it is found that the addition of the flux in advance during calcination of the talc is advantageous for sintering of the sample of the alkali metal oxide K ₂ O in the flux.

Influence of calcination temperature on sintering temperature range of sample of potassium carbonate as flux

High temperature microscopy was performed on samples 5-14#, 5-15# and 5-16# at a ramp rate of 5 ℃/min to determine the sintering temperature range for each sample. The experimental results are shown in FIGS. 12-15. The sintering temperature of the No. 5-14 sample is 1348-1394 ℃ and 46 ℃. The sintering temperature of the sample No. 5-15 is 1351-1378 ℃ and 27 ℃. The sintering temperature of the No. 5-16 sample is 1339-1362 ℃ and 23 ℃. The sample also had a phenomenon of toppling to one side with an increase in temperature, so a suitable calcination temperature was 1320 ℃.

TABLE 10 experiment of different calcination temperatures of raw Talc

(II) Effect of incubation time on sample Performance with flux Potassium carbonate

Samples 5-17#, 5-18# and 5-19# were incubated for different periods of time as shown in the following table and tested and the results are shown in figures 16-18. It can be seen that the light transmittance of the sample gradually increases with increasing incubation time; with the increase of the heat preservation time, the change trend of the whiteness and the flexural strength of the sample is firstly increased and then decreased. The light transmittance performance is prioritized, and when the heat preservation time is 60min, the whiteness and the flexural strength of the sample are not greatly reduced, but the light transmittance is obviously improved, so the heat preservation time of the sample with the flux of 25wt.% of potassium carbonate clay is selected to be 60min. It can be seen from fig. 18 that the 5-19# sample had only enstatite in the crystalline phase. The phase composition of the talcum daily fine porcelain is the requirements of the enstatite and the glass phase from the aspects of structure and performance.

TABLE 11 influence of incubation time on sample Performance under New Process

(III) comparison of optimal Performance of samples with flux of Potassium carbonate and samples of Talc daily porcelain from certain factories

Next, the 5-19# sample with the best performance of the flux being potassium carbonate is compared with the sample with the best performance of the existing talc daily porcelain body sold in a certain factory. As shown in FIG. 19, the 5-19# sample with potassium carbonate as flux has 21.5% higher transmittance, 10.9% higher whiteness and 10% higher flexural strength than the daily porcelain sample of talc quality of a certain factory.

(IV) experiment for increasing Talc porcelain Clay usage

High temperature microscopy was performed on samples 5-20#, 5-21#, 5-22# and 5-23# at a ramp rate of 5 ℃/min, and the sintering temperature ranges for each formulation were first determined. The experimental results are shown in fig. 20 and 21, fig. 22, fig. 23, and fig. 24. The sintering temperature range of 5 # to 20# is 1318 ℃ to 1363 ℃ which is 45 ℃. The sintering temperature range of 5-21# is 1313 ℃ to 1370 ℃ and 57 ℃. The sintering temperature range of 5-22# is 1318-1364 ℃ and 46 ℃. The temperature of the sample T1 of 5-23# reaches 1313 ℃ to reach a sintering temperature point, and the morphology of the sample is irregular, which indicates that the sample is deformed in the process of violent shrinkage, and the sample of 5-23# does not have a wider sintering temperature range.

Table 12 experiment of the amount of potassium carbonate added when calcining talc with clay in an amount of 30wt.%

The properties of samples 5-20#, 5-21# and 5-22# were examined. As can be seen from fig. 25, the light transmittance of the sample gradually increased with the increase in the amount of potassium carbonate. As can be seen from fig. 26, both the whiteness and flexural strength of the sample tended to decrease with increasing amounts of potassium carbonate. Considering the three properties together, when the amount of potassium carbonate is 4.4wt.%, the sample has superior transmittance and flexural strength and better whiteness. As can be seen from fig. 27, the crystal phase composition after firing of the sample No. 5 to 21 is also only the enstatite, and the predetermined phase composition is achieved. Comparing the 5-21# sample with the optimal performance when the clay is used for 30wt.% with the 5-11# sample with the optimal performance of the talcum daily porcelain body of a certain factory, the sintering temperature range is widened by 12 ℃, the plasticity index is improved by 35%, the whiteness is improved by 14%, and the flexural strength is improved by 6%.

Example 2

The talcum-clay system talcum-like domestic porcelain comprises the following preparation raw materials in parts by weight: 75 parts of calcined talc and 25 parts of clay, wherein the calcined talc comprises raw talc and potassium carbonate according to a mass ratio of 100:4, mixing and calcining at 1320 ℃.

Grinding the mixed raw materials, sieving with a 200-mesh sieve, aging, molding, placing in an electric furnace, heating at 5 ℃/min, maintaining the temperature for 60min after reaching the highest sintering temperature, and cooling to room temperature along with the furnace. The prepared sample is subjected to performance test: the sintering temperature is 1348-1394 ℃, the transmittance is 16.4%, the whiteness is 77.3%, the flexural strength is 128MPa, and the thermal stability is 200 ℃ to room temperature without cracking after heat exchange. The sample has no concave-convex defect. XRD test results showed that the main crystal phase of the sample was orthoenstatite.

Example 3

The talcum-clay system talcum-like domestic porcelain comprises the following preparation raw materials in parts by weight: 80 parts of calcined talc and 20 parts of clay, wherein the calcined talc comprises raw talc and potassium carbonate according to a mass ratio of 100:4.8, and calcining at 1300 ℃.

Grinding the mixed raw materials, sieving with a 200-mesh sieve, aging, molding, placing in an electric furnace, heating at 6 ℃/min, maintaining the temperature for 40min after reaching the highest sintering temperature, and cooling to room temperature along with the furnace. The prepared sample is subjected to performance test: the sintering temperature is 1351-1395 ℃, the transmittance is 15.3%, the whiteness is 78.2, the flexural strength is 122.3MPa, and the thermal stability is 210 ℃ to room temperature, and the heat exchange is carried out once without cracking. The sample has no concave-convex defect. XRD test results showed that the main crystal phase of the sample was orthoenstatite.

Example 4

The talcum-clay system talcum-like domestic porcelain comprises the following preparation raw materials in parts by weight: 70 parts of calcined talc and 30 parts of clay, wherein the calcined talc consists of raw talc and potassium carbonate according to the mass ratio of 100:4.4, and calcining at 1340 ℃.

Grinding the mixed raw materials, sieving with a 200-mesh sieve, aging, molding, placing in an electric furnace, heating at 4 ℃/min, maintaining the temperature for 80min after reaching the highest sintering temperature, and cooling to room temperature along with the furnace. The prepared sample is subjected to performance test: the sintering temperature is 1313-1370 ℃, the transmittance is 13.5%, the whiteness is 79.7, the flexural strength is 123.1MPa, and the thermal stability is 200 ℃ to room temperature, and the heat exchange is carried out once without cracking. The sample has no concave-convex defect. XRD test results showed that the main crystal phase of the sample was orthoenstatite.

Comparative example 1

The talcum-clay system talcum-like domestic porcelain comprises the following preparation raw materials in parts by weight: 75 parts of calcined talc and 25 parts of clay, wherein the calcined talc comprises raw talc and potassium carbonate according to a mass ratio of 100:2, and calcining at 1320 ℃.

Grinding the mixed raw materials, sieving with a 200-mesh sieve, aging, molding, placing in an electric furnace, heating at 5 ℃/min, maintaining the temperature for 60min after reaching the highest sintering temperature, and cooling to room temperature along with the furnace. The prepared sample is subjected to performance test: sintering temperature range 1372-1393 ℃.

Example 5

The chemical composition of the mineral raw materials used in this example is as follows.

TABLE 13 chemical composition of mineral raw materials

Grinding the mixed raw materials, sieving with a 200-mesh sieve, aging, molding, placing in an electric furnace, heating at 5 ℃/min, maintaining the temperature for 60min after reaching the highest sintering temperature, and cooling to room temperature along with the furnace. The prepared sample is subjected to performance test: the sintering temperature is 1349-1396 ℃, the transmittance is 16.2%, the whiteness is 86.1%, the flexural strength is 128.23MPa, and the thermal stability is 210 ℃ to room temperature without cracking after heat exchange. The sample has no concave-convex defect. XRD test results showed that the main crystal phase of the sample was orthoenstatite.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the method of the present invention, which modifications and additions are also to be considered as within the scope of the present invention.

Claims

1. The talcum-clay system talcum-like domestic porcelain is characterized by comprising the following preparation raw materials: burning talcum and clay; the calcined talc comprises the following preparation raw materials: potassium carbonate, raw talc.

2. The talc-clay system talc-clay household porcelain according to claim 1, comprising the following preparation raw materials: 70-80 parts of calcined talc and 20-30 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4-4.8:100.

3. The talc-clay system talc-based household porcelain according to claim 1, wherein the talc-clay system talc-based household porcelain is prepared from the following raw materials in parts by weight: 75 parts of calcined talc and 25 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4:100.

4. The talc-clay system talc-based household porcelain according to claim 1, wherein the talc-clay system talc-based household porcelain is prepared from the following raw materials in parts by weight: 80 parts of calcined talc and 20 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4.8:100.

5. The talc-clay system talc-based household porcelain according to claim 1, wherein the talc-clay system talc-based household porcelain is prepared from the following raw materials in parts by weight: 70 parts of calcined talc and 30 parts of clay; the calcined talc comprises the following preparation raw materials: potassium carbonate and raw talcum, wherein the mass ratio of the potassium carbonate to the raw talcum is 4.4:100.

6. The talc-clay system talc-based household porcelain according to claim 1, wherein the preparation method comprises the steps of: mixing raw talcum and potassium carbonate, and calcining at 1300-1340 ℃ to obtain calcined talcum; mixing the calcined talc and clay, shaping, heating to sintering temperature, and cooling.

7. The method for preparing the talc-clay system-fired smooth household porcelain according to any one of claims 1 to 6, which is characterized by comprising the following steps:

Step (1): taking raw materials according to a proportion;

8. The method for producing a talc-clay system talc-based household porcelain according to claim 7 wherein the calcining temperature in step (2) is 1300 to 1340 ℃.

9. The method for producing a talc-clay system talc ceramic for daily use according to claim 8, wherein the temperature is maintained for 0 to 80 minutes after the sintering temperature is reached in the step (3), and the ceramic is naturally cooled in a furnace or is taken out and cooled outside the furnace.

10. The method for preparing the talc-clay system talc-based household porcelain according to claim 9, comprising the steps of:

Step (1): taking raw materials according to a proportion;