CN1135457A

CN1135457A - Method for preparation of titanium carbide micropowder by using self-spreading high-temp. synthesizing chemical-reacting furnace

Info

Publication number: CN1135457A
Application number: CN 96116213
Authority: CN
Inventors: 汪华林; 吴东棣; 李海林; 马玉录; 魏学安
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 1996-01-12
Filing date: 1996-01-12
Publication date: 1996-11-13

Abstract

The preparation method of titanium carbide fine powder includes the following steps: firstly the intermediate compound TiC 0.5+0.5C mixture is die-formed, and placed in the (Ti+C) mixture, then is placed in a self-spreading high-temp. synthesis-chemical reacting furnace at normal temp. and pressure under the protection of argon shield, then ignited and burned to make the outer layer of (Ti+C) mixture quick react and produce the TiC product with grain size of 20-80 micra, and at the same time the reaction heat produced by its outer layer material is used to make the internal layer material (TiC0.5+0.5C) mixture quick react to produce the TiC product whose grain size is less than 10 micra.

Description

Method for preparing titanium carbide micropowder by self-propagating high-temperature synthesis-chemical reaction furnace

The invention relates to a solid-phase synthesis method of refractory compounds.

Titanium carbide powder is widely known to have a series of advantages of high hardness, high melting point, high elastic modulus, low thermal conductivity and the like, and is one of high-grade abrasives widely used in industrial departments. The traditional synthesis process comprises the following steps: the mixture of titanium or titanium dioxide and carbon is placed in a vacuum graphite tube furnace and then carbonized by heating to about 2250 ℃. The main disadvantages of this method are: not only has complex device, long reaction time and high energy consumption, but also obtains the titanium carbide with low carbon content and poor product purity. The self-propagating high-temperature titanium carbide synthesis process developed in recent years can overcome the defects, the production cost can be reduced to 30-45% of the original cost, but the granularity of the product is too coarse, usually 90-100 mu m, the requirement that the granularity of commercial titanium carbide is less than or equal to 10 mu m cannot be met, and the competitiveness of the self-propagating high-temperature titanium carbide synthesis process is greatly reduced. In 1991, a self-propagating high-temperature synthesis-hot pressing method is disclosed by Russian academy of sciences structure macro-dynamics research, titanium carbide powder with the particle size of 3-20 μm is successfully synthesized under the condition of 100MPa of pressure, but the process device is complex, so that no industrial production is seen.

In 1988, U.S. munir.z.a. proposed chemical furnace technology (chemical Oven) which placed a weakly exothermic reaction mixture inside a strongly exothermic reaction mixture and utilized the heat released by the strongly exothermic reaction of the latter to induce the synthesis reaction of the former. And successfully prepared to give B₄C、Al₄C₃、MoSi₂And WC. However, the products of the outer layer of the chemical furnace and the products of the inner layer of the chemical furnace which are highly exothermic are not the same chemical formula system, so that the products of the outer layer of the chemical furnace pollute the reaction products of the inner layer. In addition, the product particle size is also large due to the low cooling rate, which also limits the industrial application of the process.

The purpose of the invention is as follows: it is intended to overcome the above-mentioned disadvantages of the prior art and to provide a self-propagating high-temperature synthesis-chemical reaction furnace method. Because the products in the inner layer and the outer layer of the reaction furnace are systems with the same chemical formula, and the instantaneous temperature of the reaction system can reach about 2730 ℃, the reaction can be finished within minutes (generally 1-2 minutes), and micro powder (generally 2-8 μm) with the particle size less than or equal to 10 μm can be obtained.

The idea of the invention is as follows: based on a large amount of experimental research, the inventor improves the existing chemical furnace technology according to the superfine requirements of the titanium carbide grinding material in the industrial department, and provides an idea of preparing titanium carbide micropowder by a self-propagating high-temperature synthesis-chemical reaction furnace method, which mainly comprises two contents: firstly, the self-propagating heightIntermediate compound TiC prepared in a warm synthesis furnace_0.5( ) Then (TiC)_0.5+0.5C) mixture is placed in the interior of (Ti + C) mixture, i.e. the outer layer material in self-propagating high-temp. synthesis-chemical reaction furnace is (Ti + C), and the inner layer material is (TiC)_0.5+0.5C), using self-propagating high-temperature synthesis process of outer layer (Ti + C) mixture as chemical reaction furnace, when outer layer material is ignitedThen, the high temperature generated by the chemical reaction of (Ti + C) of the outer layer makes (TiC) of the inner layer_0.5+0.5C) to produce TiC. The final product of the outer layer of the chemical reaction furnace is TiC, the product of the inner layer of the chemical reaction furnace is also TiC, and the difference between the final product of the outer layer of the chemical reaction furnace and the final product of the inner layer of the chemical reaction furnace is that the grain size of the TiC of the outer layer is between 20 and 80 mu m, and the grain size of the TiC of the inner layer is between 2 and 8 mu m (which can be observed by an electron.

The invention is also realized by the following steps: firstly, TiC obtained from a self-propagating high-temperature synthesis furnace_0.5After the micro powder and 0.5C are fully mixed, the mixture is formed by compression moulding, then the mixture is placed in the inner layer of a self-propagating high-temperature synthesis-chemical reaction furnace, the mixture of (Ti + C) and the mixture of (Ti + C) can also be formed into blocks by compression moulding is used as the outer layer of the self-propagating high-temperature synthesis-chemical reaction furnace, then under the protection of argon gas at normal temperature and normal pressure, the material of the outer layer is ignited for self-propagating high-temperature chemical reaction, the mixture of the outer layer Ti + C quickly generates TiC_0.5+0.5C) to produce TiC powder rapidly under the action of high temperature of the chemical reaction heat of the outer layer. The granularity of the outer layer product is 20-80 mu m, the granularity of the inner layer product is 2-8 mu m, and the outer layer product and the inner layer product can be respectively used as abrasive materials for different industrial purposes. Of the inner layer (TiC)_0.5+0.5C) is necessary for the compression molding, which aims to facilitate the separation and obtain TiC fine powder with uniform particle size.

The invention will be further elucidated with reference to the drawings and examples, which do not limit the scope of the invention.

FIG. 1 is a schematic diagram of TiC preparation by self-propagating high-temperature synthesis-chemical reaction furnace method

Wherein: 1-electric heating wire or electric arc igniter.

2-furnace housing.

3-outer layer (Ti + C) system.

4-inner core is die-pressed to form a block (TiC)_0.5+0.5C) system.

In the device shown in FIG. 1, the outer layer is used for generating amorphous TiC products with the granularity of 20-80 μm, and the inner layer is used for generating TiC products with the appearance of a three-branch spindle shape and the granularity of 2-8 μm.

FIG. 2 Synthesis of TiC at high temperature with self-propagating_0.5Schematic diagram of

Wherein: 1-electric heating wire or electric arc igniter.

2-furnace housing.

3- (Ti +0.5C) system.

The intermediate compound TiC is obtained in an apparatus as shown in FIG. 2_0.5。

Examples

Firstly, fully mixing 48 g of Ti powder (300 meshes) and 6 g of graphite powder (500 meshes), placing the mixture in a self-propagating high-temperature synthesis furnace shown in figure 2, igniting and burning the mixture under the protection of argon at normal temperature and normal pressure, and rapidly synthesizing TiC within 1-2 minutes_0.5An intermediate compound;

then grinding into micropowder TiC_0.527 g and 3 g of graphite powder (500 meshes) are fully mixed, pressed into blocks or columns, placed in a mixture of 48 g of Ti powder (300 meshes) and 12 g of graphite powder, then placed in a self-propagating high-temperature synthesis-chemical reaction furnace shown in figure 1, under the protection of argon gas at normal temperature and normal pressure, an outer layer material is ignited by an electric heating wire or an electric arc, and the outer layer material can be changed into a TiC product with the granularity of 20-80 mu m within 1-2 minutes, and the inner layer material is changed into a TiC product with the granularity of 2-8 mu m. Observation by an electron microscope: the TiC product on the outer layer is amorphous, and the TiC product on the inner layer is in a three-spindle crystalline state, so that the TiC product is a high-quality high-strength superfine wear-resistant material.

It is clear that the concept and method according to the inventionAlso, B of good quality can be synthesized₄C、Al₄C₃、MoSi₂And WC, and the like.

Claims

1. A method for preparing titanium carbide micropowder by a self-propagating high-temperature synthesis-chemical reaction furnace is characterized by comprising the following steps:

(1) firstly, the intermediate compound TiC is synthesized in a self-propagating high-temperature synthesis furnace under the protection of argon and the conditions of normal temperature and normal pressure for ignition and combustion within minutes_0.5；

(2) Then adding an intermediate compound TiC_0.5Mixing with 0.5C, molding into blocks; (3) moulding into blocks (TiC)_0.5+0.5C) is arranged in the inner layer of the self-propagating high-temperature synthesis-chemical reaction furnace, the outer layer is (Ti + C) mixture, the outer layer is ignited and burnt by an electric heating wire or an electric arc under the protection of argon at normal temperature and normal pressure, the (Ti + C) of the outer layer reacts rapidly to generate TiC particles with the particle size of 20-80 mu m, and The (TiC) of the inner layer_0.5+0.5C) under the action of high temperature of reaction heat released by chemical reaction of the outer layer, simultaneously and rapidly reacting to generate TiC micro powder with the particle size of 2-8 mu m.