CN1300359C - Compact titanium carbon silicide-titanium diboride composite block material and producing process thereof - Google Patents

Abstract

The invention is a dense titanium silicide carbon-titanium diboride composite bulk material and a preparation method thereof. The raw material composition and composition range of the material are as follows: Ti powder, Si powder, TiC powder, _TiB2 and aluminum powder are used as raw materials, and the molar ratio of the five raw materials is n(Ti):n(Si):n(TiC): n(TiB ₂ ):n(Al)=1:(0.85-1.15):2:(0.15-0.6):(0.04-0.12). The preparation of the material includes the following steps: Weigh Ti powder, Si powder, TiC powder, _TiB2 and aluminum powder according to the process requirements, mix them evenly, place them in a graphite mold, and sinter in an argon environment in a hot pressing sintering system . The sintering step is: raising the temperature to 1100-1250° C. at a rate of 60-180° C./min, keeping the temperature for 30-120 minutes, and the pressure at 20-80 MPa. The process of the invention is simple, and the product performance is excellent.

Description

Preparation method of dense titanium silicide carbon-titanium diboride composite bulk material

technical field

The invention relates to the field of building materials, in particular to a method for preparing a dense titanium silicide carbon-titanium diboride composite block material.

Background technique

Titanium silicide carbon (Ti ₃ SiC ₂ ) is a new layered ternary compound discovered in the 1990s. It has many advantages of both metals and ceramics, such as excellent electrical and thermal conductivity, machinability, good damage resistance, high melting point, high modulus, high strength and low density, etc. This is a new type of structural/functional material that can be widely used in high-tech fields such as electronic information, new energy, and aerospace. But the difficulty of preparing Ti ₃ SiC ₂ has limited its research and application. Document (1) used TiH ₂ , Si and graphite as raw materials to synthesize Ti ₃ SiC ₂ by chemical reaction at 2000°C. Literature (2, 3) used SiCl ₄ , TiCl ₄ , CCl ₄ , H ₂ and TiCl ₄ , SiCl ₄ , CH ₄ , and H ₂ as raw materials respectively, and prepared Ti ₃ SiC ₂ thin films by vapor deposition. Document (4) uses Ti, Si and carbon black as raw materials to synthesize Ti ₃ SiC ₂ by self-propagating high-temperature reaction, and there are a large number of impurity phases in the reaction product. Literature (5) used Ti, Si and carbon black as raw materials to prepare Ti ₃ SiC ₂ bulk material by arc melting method and post-annealing treatment, but the reaction product has high impurity content and the reaction temperature is not easy to control accurately. Document (6) adopts the hot isostatic pressing process to prepare dense single-phase Ti ₃ SiC ₂ bulk materials with Ti, SiC and graphite as raw materials, but the preparation process is quite complicated. Document (7) used Ti, Si and graphite as raw materials, and added 4% NaF as reaction aid, and prepared Ti ₃ SiC ₂ bulk material by hot pressing process, and the product contained a large amount of TiC. Document (8) adopts a new process of spark plasma sintering (SPS), using Ti, Si and TiC as raw materials, and obtains a Ti ₃ SiC ₂ bulk material with a purity of 98%. However, the hardness of Ti ₃ SiC ₂ is low (3-5GPa), and its resistance to nitric acid is poor, which greatly limits its use as structural and functional materials.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a dense titanium silicide carbon-titanium diboride composite bulk material. The obtained product has both the advantages of titanium silicide and titanium diboride, thereby overcoming the problems in the prior art.

The technical solution adopted by the present invention to solve its technical problems is:

A method for preparing a dense titanium silicide carbon-titanium diboride composite block material, the steps comprising:

1) Weigh Ti powder, Si powder, TiC powder, TiB ₂ and aluminum powder, and the molar ratio of the five raw materials is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al )=1:(0.85~1.15):2:(0.15~0.6):(0.04~0.12).

2) Mix the weighed raw material powders evenly, place them in a graphite mold, and sinter in an argon atmosphere in a hot-press sintering system.

3) The sintering step is: raising the temperature to 1100-1250° C. at a rate of 60-180° C./min, keeping the temperature for 30-120 minutes, and applying a pressure of 20-80 MPa.

Titanium diboride (TiB ₂ ) is a kind of high melting point (2790°C), high hardness (34GPa), corrosion resistance, oxidation resistance, and good electrical and thermal conductivity. It is used in high-temperature structural materials, wear-resistant It has broad application prospects in corrosion resistance and electrical materials, and more importantly, its crystal _{structure is the same as that of Ti 3 SiC 2} , both of which are hexagonal layered structures with similar thermal expansion coefficients _{. 2} particles will help to improve the properties of Ti ₃ SiC ₂ materials and obtain composite materials with both advantages.

The essence of the invention is to add TiB ₂ particles with different volume ratios on the basis of preparing Ti ₃ SiC ₂ material by using a hot-press reaction. Due to the low melting point of Al, at a lower temperature, Al will melt and form an Al-Si liquid phase alloy with Si, which promotes the reaction synthesis and increases the density of Ti ₃ SiC ₂ -TiB ₂ , by the Archimedes method It is measured that the density of the Ti ₃ SiC ₂ -TiB ₂ bulk material reaches 99%.

The innovation of the present invention lies in the addition of a small amount of aluminum to suppress the formation of Ti-Si compounds, and at the same time, replacing elemental powders Ti and C with TiC in the original powder can reduce the content of TiC in the reaction product. The whole preparation process uses simple raw materials, fully utilizes the advantages of in-situ reaction and the characteristics of hot pressing sintering process, and synthesizes Ti ₃ SiC ₂ -TiB ₂ bulk material with excellent performance.

Description of drawings

The accompanying drawing is the X-ray diffraction pattern of the Ti ₃ SiC ₂ /TiB ₂ sample sintered by hot pressing process. Compared with the standard JCPDS card formulated by the Joint Committee on Powder Diffraction Standards, the standard card number of Ti ₃ SiC ₂ is 740310, and the standard card number of TiB ₂ is 70275. It can be known that only Ti ₃ SiC ₂ and TiB ₂ are in the synthesized composite materials. one substance, and no other substance is produced.

Detailed ways

The present invention will be further described below in conjunction with the embodiments and accompanying drawings.

The invention relates to a dense titanium silicide carbon-titanium diboride composite block material. The raw material composition and composition range are as follows: Ti powder, Si powder, TiC powder, TiB ₂ and aluminum powder are used as raw materials, and the moles of five raw materials The ratio is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al)=1:(0.85-1.15):2:(0.15-0.6):(0.04-0.12).

The method for preparing dense titanium silicide carbon-titanium diboride composite block material of the present invention comprises the following steps:

1) Weigh Ti powder, Si powder, TiC powder, TiB ₂ and aluminum powder, and the molar ratio of the five raw materials is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al )=1:(0.85~1.15):2:(0.15~0.6):(0.04~0.12).

2) Mix the weighed raw material powders evenly, place them in a graphite mold, and sinter in an argon atmosphere in a hot-press sintering system.

3) The sintering step is: raising the temperature to 1100-1250° C. at a rate of 60-180° C./min, keeping the temperature for 30-120 minutes, and the pressure at 20-80 MPa.

Example 1

The molar ratio of raw material powder is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al)=1:0.85:2:0.15:0.04; mix well and put into graphite mold , Sintered in a hot press sintering system under argon protection. The heating rate is 80°C/min, the sintering temperature is 1100°C, the pressure is 30MPa, and the temperature is kept for 60 minutes. The bulk material has a density of 99% and a Ti ₃ SiC ₂ content of 90%. Measured on the INSTRON-1195 million mechanical testing machine: the compressive strength of the material is ≥750MPa, the three-point bending strength σ _b is ≥470MPa, and the K _IC is ≥8MPa·m ^1/2 .

Example 2

The molar ratio of raw material powder is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al)=1:1.15:2:0.6:0.12; mix well and put into graphite mold , Sintering is carried out in a vacuum system of spark plasma sintering. The heating rate is 80°C/min, the sintering temperature is 1250°C, the pressure is 60MPa, and the temperature is kept for 120 minutes. The bulk material has a density of 99.5% and a Ti ₃ SiC ₂ content of 88%. Measured on the INSTRON-1195 million mechanical testing machine, the compressive strength of the material is ≥750MPa, the three-point bending strength σ _b ≥470MPa, and the K _IC ≥8MPa·m ^1/2 .

Example 3

The molar ratio of raw material powder is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al)=1:1.0:2:0.4:0.08; mix well and put into graphite mold , Sintering is carried out in a vacuum system of spark plasma sintering. The heating rate is 80°C/min, the sintering temperature is 1250°C, the pressure is 60MPa, and the temperature is kept for 120 minutes. The bulk material has a density of 99.5% and a Ti ₃ SiC ₂ content of 88%. Measured on the INSTRON-1195 million mechanical testing machine, the compressive strength of the material is ≥750MPa, the three-point bending strength σ _b ≥470MPa, and the K _IC ≥8MPa·m ^1/2 .

References for this patent:

[1] Jeitschko W, and Nowotny H. Die Kristallstructur von Ti ₃ SiC ₂ -Ein NeuerKomplxcarbid-Typ. Monatsh. Fur Chem., 1967, 98: 329-37

[2] Nickl J J, Schweitzer K K, Luxenberg P.Gasphasenabscheidung im Systeme Ti-C-Si, J Less Common Metals,, 1972, 26: 283

[3] Racault C, Langlais F, Bernard C. On the Chemical Vapor Deposition of _{Ti 3} SiC ₂ from TiCl ₄ -SiCl ₄ -CH ₄ -H ₂ Gas Mixtures: Part II an experimental approach, J.Mater.Sci., 1994 ,29:5023

[4] Pampuch R, Lis J, Stobierski L, et al. Solid Combustion Synthesis of Ti ₃ SiC ₂ , J Eur Ceram Soc, 1989, 5: 283

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Claims (3)

1. a preparation method of dense titanium silicide carbon-titanium diboride composite block material, is characterized in that comprising the following steps: 1) Weigh Ti powder, Si powder, TiC powder, TiB ₂ and aluminum powder, and the molar ratio of the five raw materials is n(Ti):n(Si):n(TiC):n(TiB ₂ ):n(Al )=1:(0.85～1.15):2:(0.15～0.6):(0.04～0.12), 2) Mix the weighed raw material powders evenly, place them in graphite molds, and sinter them under the argon atmosphere in the hot pressing sintering system, 3) The sintering step is: raising the temperature to 1100-1250° C. at a rate of 60-180° C./min, keeping the temperature for 30-120 minutes, and the pressure at 20-80 MPa. 2. the preparation method of dense titanium silicide carbon-titanium diboride composite bulk material according to claim 1 is characterized in that: the molar ratio n (Ti) of five kinds of raw materials: n (Si): n (TiC) :n(TiB ₂ ):n(Al)=1:0.85:2:0.15:0.04. 3. the preparation method of dense titanium silicide carbon-titanium diboride composite block material according to claim 1, is characterized in that: the molar ratio n (Ti) of five kinds of raw materials: n (Si): n (TiC) :n(TiB ₂ ):n(Al)=1:1.15:2:0.6:0.12.