CN1778760A - High-strength ceramic composite material gel injection molding blank and its forming method - Google Patents

Abstract

A gel injection moulding body with high strength ceramic composite materials and its formation are disclosed. The gel injection moulding body consists of organic monomer, cross-linking agent, dispenser, initiator, catalyst and ceramic composite powders 55vol% with iron-aluminium intermetallic compound and alumina with mass proportion=(10-30): (90-70). It is prepared by dispersing the composite powders into solution containing organic monomer and cross-linking agent, forming it into ceramic slurry with high solid-phase volume fraction, pouring it into form mould, obtaining composite powder concentrated slurry with high solid-phase volume content>55% and low viscosity<1000mPa.s, organic polymerization reacting at 60-80DEG C, solidification forming, drying, degreasing, and sintering to obtain ceramic composite material products with complex shape, large size and high precision.

Description

High-strength ceramic composite material gel injection molding blank and its forming method

technical field

The invention relates to the improvement of the ceramic composite material, especially the high-strength ceramic composite material gel injection mold body and its forming method, that is, the gel injection molding technology of the intermetallic compound/alumina ceramic composite material. It belongs to the technical field of synthesis and preparation of inorganic materials

Background technique

At present, in the preparation process of high-tech ceramics, the molding methods used are mainly divided into two categories: dry method and wet method. In order to broaden the application range of ceramic materials, practical applications increasingly require ceramic products to be prepared into various complex shapes, and wet forming can mostly achieve this goal. However, there are some problems in the traditional wet forming technology. For example, the grouting molding is realized by the gypsum model absorbing water, which easily causes the density of the green body to be distributed in a gradient, and the shrinkage is inconsistent during drying. The product is easily deformed, and the strength of the green body is low. Easily damaged. Hot die-casting or injection molding needs to add about 20% (mass fraction) of wax or organic polymer, which leads to difficulty in subsequent wax removal or degreasing, and reduces the strength of the green body during the process of wax removal or degreasing, which is prone to defects or even It collapses, so it is not suitable for the preparation of complex shapes and large-sized products.

Gel casting method (gelcasting) overcomes most of the shortcomings of slip casting, hot die casting and injection molding, and is especially suitable for the preparation of complex shapes and large-sized ceramic products, and has high reliability, good product quality, and production Low cost and many other advantages. This method combines the traditional ceramic grouting molding technology with the polymer chemistry theory well. Gel injection molding uses less organic matter, is easy to degrease, and has high strength and can be machined, so it has a broader application prospect. At present, gel injection molding is mostly used for the preparation of pure ceramic products, and has not been used for the preparation of intermetallic compound-ceramic composite materials.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a new high-strength ceramic composite material gel injection molded body and its forming method, that is, a new forming technology of iron-aluminum intermetallic compound/alumina ceramic composite material.

The purpose of the present invention is achieved by the following technical solutions, developed a high-strength ceramic composite material gel injection molded body, which includes: organic monomers accounting for less than 5% of the weight of the body, a crosslinking agent, Dispersants, initiators and catalysts; also include ceramic composite powder accounting for more than 55% of the body volume. The ceramic composite powder is composed of iron-aluminum intermetallic compound and alumina, wherein the mass ratio between the iron-aluminum intermetallic compound and alumina is (10-30): (90-70), the ceramic composite The average particle size of the powder is 1-10 μm.

The ceramic composite powder is also composed of titanium-aluminum intermetallic compound and alumina, wherein the mass ratio between titanium-aluminum intermetallic compound and alumina is (5-30):(95-70).

The ceramic composite powder is also composed of nickel-aluminum intermetallic compound and alumina, wherein the mass ratio between nickel-aluminum intermetallic compound and alumina is (5-40):(95-60).

A molding method of the high-strength ceramic composite material gel injection molded body. Described method steps are as follows:

(1) Preparation of premixed solution: add mass/volume ratio to organic monomer and crosslinking agent of 18～35% in the deionized water of constant volume, the mass ratio between this organic monomer and crosslinking agent is (10～ 120): 1;

(2) Add ceramic composite powder: add ceramic composite powder to the premixed solution in step (1), the amount of the composite powder added is (40-80) according to the volume ratio of the premixed solution: (60-20) The ratio is added to make a slurry;

(3) add dispersant: add 3～8% dispersant in (2) step slurry;

(4) adjust the pH value: adjust the pH value of the (3) step slurry at 8 to 11 with ammonia water;

(5) Ball mill slurry: ball mill the slurry prepared in step (4) for 8 to 12 hours to obtain a composite powder thick slurry with a solid phase volume content > 55% and a viscosity < 1000mPa·s;

(6) Add initiator and catalyst: keep the temperature of the slurry in step (5) between 0 and 40°C, add 0.01 to 2% of initiator and 0 to 2% of catalyst, stir evenly, and then add the slurry The material is vacuum stirred and defoamed to make a ceramic slurry;

(7) Grouting molding: inject the ceramic slurry in step (6) into the molding mold, and solidify the ceramic slurry in the mold into a molding body at a temperature of 60-80°C;

(8) Drying the molding body: drying the cured molding body at 50-80°C to obtain the gel injection molding body; the dried gel injection molding body can also be made according to the specific product Machining is required.

(9) Put the machined green body in a kiln to degrease, and then sinter after degreasing to make a ceramic composite product.

The organic monomer is acrylamide (AM), or methacrylamide, or ethylene oxide.

The cross-linking agent is N, N'-methylenebisacrylamide (MBAM), or ethylene glycol coordinated with ethylene oxide.

The dispersant is an ammonia solution of polymethacrylic acid (PMAA), or an ammonia solution of polyacrylic acid, or an aqueous solution of sodium polyacrylate.

The initiator is ammonium persulfate aqueous solution or hydrogen peroxide solution.

The catalyst is N, N, N', N'-tetramethylethylenediamine (TEMDE).

The beneficial effect of the present invention lies in that the ceramic composite powder composed of iron-aluminum intermetallic compound and alumina is selected to account for more than 55% of the body volume. The iron-aluminum intermetallic compound contains two compounds, Fe ₃ Al and FeAl; the powder is prepared by a process of mechanical alloying and calcination at 750° C. for 1 hour. The mass ratio between the iron-aluminum intermetallic compound and the alumina in the ceramic composite powder is (10-30):(90-70). Or it is a ceramic composite powder composed of titanium-aluminum intermetallic compound and alumina that accounts for more than 55% of the body volume; the mass ratio between the titanium-aluminum intermetallic compound and alumina in the ceramic composite powder is ( 5-30): (95-70). Or it is a ceramic composite powder composed of nickel-aluminum intermetallic compound and alumina that accounts for more than 55% of the body volume; the mass ratio between the nickel-aluminum intermetallic compound and alumina in the ceramic composite powder is ( 5-40): (95-60). All ceramic composite powders have a particle size of 1-10 μm. These ceramic composite powders are dispersed in organic monomers: acrylamide (AM), or methacrylamide, or ethylene oxide, and crosslinking agents: N, N'-methylenebisacrylamide (MBAM), Or in the solution of ethylene glycol combined with ethylene oxide, a suspension with a high solid phase volume fraction is formed. When the suspension is in the mould, the in-situ network polymerization of the macromolecules makes the composite powder particles combine together, so that the organic monomer solution becomes a low-viscosity carrier for the composite powder, and then through the action of the crosslinking agent, the The slurry forms a gel of polymer. Since 3-8% polymethacrylate ammonia (PMAA) is added as a dispersant in the slurry; the pH value of the slurry is adjusted to 8-11 with ammonia water; the prepared slurry is ball-milled for 8-40 hours, and then Keep the temperature of the slurry at 0-40°C, add 0.01-2% initiator and 0-2% catalyst, stir evenly, then vacuum stir the slurry to remove foam, and obtain a high solid phase Composite powder thick slurry with volume content > 55% and low viscosity <1000mPa·s; these are the keys to the gel injection molding process.

Detailed ways

Example

Add 20% (wt) organic monomer and crosslinking agent in deionized water, the ratio of organic monomer and crosslinking agent is 24: 1, make premix liquid; The inter-compound powder and the α-alumina powder of the same particle size are evenly mixed to form a composite powder. The iron-aluminum intermetallic compound powder accounts for about 10% to 30% of the total powder mass, and is added to the premixed liquid to form a slurry. The volume fraction of the composite powder in the slurry is 55%; add 3% ammonia solution of polymethacrylic acid with a concentration of 5% to the slurry, adjust the pH value of the slurry to about 10 with ammonia water, and ball mill for 12 hours; When the temperature of the slurry is below 40°C, add 0.1% ammonium persulfate aqueous solution with a concentration of 5%, and continue ball milling for 10 minutes; pour out the slurry from the ball mill, put it in a vacuum chamber for vacuuming and degassing, and the vacuum degree is 400mmHg, Hold for 2 minutes; take out the slurry from the vacuum chamber, pour it into a molding mold, and put it in a water bath at 80°C to solidify and form it. After demoulding, dry and degrease, then fire at 1550-1650°C and keep warm for 1 hour. Finally, a dense iron-aluminum intermetallic compound/alumina ceramic composite product is obtained. See Table 1 for other formulations and main process conditions of the molding materials of the gel-casting blank.

Table 1:

Those skilled in the art will understand that within the protection scope of the present invention, modifications, additions and substitutions are all possible to the above embodiments, and none of them exceed the protection scope of the present invention.

Claims (9)

1. A high-strength ceramic composite material gel injection molded body, which includes: an organic monomer accounting for less than 5% of the mass of the body, a crosslinking agent, a dispersant, an initiator and a catalyst; The ceramic composite powder whose volume is more than 55% of the green body is characterized in that: the ceramic composite powder is composed of iron-aluminum intermetallic compound and alumina, wherein the iron-aluminum intermetallic compound and alumina The mass ratio is (10-30):(90-70), and the average particle size of the ceramic composite powder is 1-10 μm. 2. The high-strength ceramic composite material gel-casting body according to claim 1, characterized in that: the ceramic composite powder is composed of titanium-aluminum intermetallic compound and alumina, wherein titanium-aluminum metal The mass ratio between the inter-compound and alumina is (5-30): (95-70). 3. The high-strength ceramic composite material gel injection molded body according to claim 1, characterized in that: said ceramic composite powder is still composed of nickel-aluminum intermetallic compound and alumina, wherein nickel-aluminum metal The mass ratio between the inter-compound and alumina is (5-40): (95-60). 4. A method for forming a high-strength ceramic composite material gel injection molded body as claimed in claim 1, characterized in that: the steps of the method are as follows: (1) Preparation of premixed solution: add mass/volume ratio to organic monomer and crosslinking agent of 18～35% in the deionized water of constant volume, the mass ratio between this organic monomer and crosslinking agent is (10～ 120): 1; (2) Add ceramic composite powder: add ceramic composite powder to the premixed solution in step (1), the amount of the composite powder added is (40-80) according to the volume ratio of the premixed solution: (60-20) The ratio is added to make a slurry; (3) add dispersant: add 3～8% dispersant in (2) step slurry; (4) adjust the pH value: adjust the pH value of the (3) step slurry at 8 to 11 with ammonia water; (5) Ball mill slurry: ball mill the slurry prepared in step (4) for 8 to 12 hours to obtain a composite powder thick slurry with a solid phase volume content > 55% and a viscosity < 1000mPa·s; (6) Add initiator and catalyst: keep the temperature of the slurry in step (5) between 0 and 40°C, add 0.01 to 2% of initiator and 0 to 2% of catalyst, stir evenly, and then add the slurry The material is vacuum stirred and defoamed to make a ceramic slurry; (7) Grouting molding: inject the ceramic slurry in step (6) into the molding mold, and solidify the ceramic slurry in the mold into a molding body at a temperature of 60-80°C; (8) Drying the molded body: drying the cured molded body at 50-80° C. to obtain the gel injection molded body. 5. The molding method of the high-strength ceramic composite material gel casting body according to claim 4, characterized in that: the organic monomer is acrylamide, or methacrylamide, or ethylene oxide. 6. The molding method of the high-strength ceramic composite material gel casting body according to claim 4, characterized in that: the crosslinking agent is N, N'-methylenebisacrylamide, or combined with epoxy Ethylene glycol complexed with ethane. 7. The molding method of the high-strength ceramic composite material gel casting body according to claim 4, characterized in that: the dispersant is an ammonia solution of polymethacrylic acid, or an ammonia solution of polyacrylamine, or Sodium polyacrylate aqueous solution. 8. The molding method of the high-strength ceramic composite material gel casting body according to claim 4, characterized in that: the initiator is ammonium persulfate aqueous solution or hydrogen peroxide solution. 9. The molding method of high-strength ceramic composite material gel casting body according to claim 4, characterized in that: the catalyst is N, N, N', N'-tetramethylethylenediamine.