RU2095193C1 - Method of preparing titanium carbide-based composite material - Google Patents

Abstract

FIELD: powder metallurgy. SUBSTANCE: powder mixture of initial components is prepared including titanium, chromium, and carbon taken in amount required to form desired material containing chromium and titanium carbides in 1: (1-10) molar ratio. Mixture is then placed into reactor and synthesis is carried out in burning mode involving local ignition of mixture under pressure 0.005-0.05 MPa. Product is discharged, disintegrated, and fractioned. Mixture can be supplemented by 15-35 wt % nickel powder, and, after mixing, can be briquetted in the form of granules or pellets. Material is fit to be applied onto metal surfaces as protective coating. EFFECT: improved abrasive characteristics. 3 cl

Description

 The invention relates to powder metallurgy, in particular, to methods for producing powder composite materials based on titanium carbide in the mode of self-propagating high temperature synthesis (SHS), which can be used as an abrasive grinding material in the machine tool industry, as well as as a material for applying wear-resistant and corrosion-resistant coatings on various metal parts of machines in engineering, shipbuilding, aviation and other industries .

A known method of producing a composite material based on titanium carbide, comprising preparing a mixture by mixing the powders of the starting components of titanium carbide and chromium carbide and subsequent hot pressing of the mixture at high temperature [1]
The method is time-consuming (more than 5 hours), and the target material has insufficiently high abrasive and polishing properties.

Closest to the invention is a method for producing a composite material based on titanium carbide, comprising preparing the mixture by 2-stage mixing of the powders of the starting components containing titanium, boron, carbon and chromium-nickel bronze (Cr-2.8%), chromium, pressing the mixture and placing it into the reactor, local ignition of the mixture, followed by high-temperature reaction of the components in the combustion mode, compaction of the synthesis product and extraction of the target product [2]
The method allows to obtain a monolithic target composite carbide material containing, by weight. titanium diboride 54; titanium carbide 36 and chromium-nickel bronze 10 with a content of 2.8% chromium, which is used for the manufacture of cutting tools.

The objective of the invention is to provide a method for producing a powder composite material based on titanium carbide having high abrasive characteristics and a coating material having high wear resistance and heat resistance in oxidizing environments at temperatures above 1000 ^o C.

The objective is achieved in that a method for producing a composite material based on titanium carbide includes:
preparing the mixture by mixing the powders of the starting components containing titanium, chromium and carbon, taken in the amount necessary to obtain the target material containing chromium carbide and titanium carbide in their molar ratio of 1: 1-10;
placing the mixture in the reactor;
local ignition of the mixture with subsequent high-temperature reaction of the components in the combustion mode under a pressure of 0.005-0.05 MPa;
extraction of the target product, its grinding and fractionation.

 At the same time, 15-30 wt. nickel powder, and after mixing, the mixture can be briquetted in the form of granules or tablets.

 To implement the method, powders of the starting components supplied by domestic and foreign industry can be used. For example, titanium powders PTM, TU 14-1-958-74, TU 14-3086-80, dispersion less than 100 microns; carbon (soot) grade PM-15TS, TU 38-1158-71, P804 and other chromium grades PH-IC, TU 14-1-1474-75, PHP.

 Briquetting is carried out by pressing the initial mixture to a relative density of 0.4-0.6. Another briquetting option is to prepare pellets from the feed mixture in a screw press through die or by extrusion. The shape of the granules can be different: spherical with a diameter of up to 10 mm, elongated along the length of 8-12 mm and a diameter of 4-6 mm.

 Example 1. To obtain a composite material containing titanium carbide and chromium carbide in their composition at a molar ratio of 1: 1, a mixture of powders of 20 wt. titanium, 15 wt. soot and 65 wt. chromium, after thoroughly mixing the mixture in a ball mill for 20 hours, pour it into the reactor, slightly pressurize the mixture, bring the tungsten spiral into contact with the surface of the mixture, seal the reactor and create a pressure of 0.005 MPa, locally ignite the mixture by applying a voltage of 40-60 V at the spiral a current of 60-80 A. After local ignition in the mixture, a high-temperature reaction of the components occurs in the combustion mode for 10-30 s. After passing the combustion front through the reaction mixture, the contents of the reactor are cooled, the target product is recovered, which is a porous, easily destructible mass, which is then subjected to grinding in a ball mill and fractionation.

According to x-ray diffraction, metallographic and chemical analyzes, the target material is a solid solution of chromium carbide in titanium carbide and titanium carbide with a molar ratio of titanium carbide to chromium carbide equal to 1: 1. From fractionated powders, a powder with a grain size of 28/20 μm is isolated, in which 80% of the particles are isometric in shape. The microhardness of such particles is 3800 kg / mm ² . Tests of this fraction for the abrasive ability and surface roughness of finishing samples from ШX-15 steel, carried out according to the TU 2-037-273-80 method, showed that the removal of the surface layer during processing is 35 mg, and the roughness is 0.114 μm.

 Example 2. To obtain a composite material containing chromium carbide and titanium carbide in their molar ratio of 1:10, a mixture of powders of titanium (61.5 wt.), Graphite (18.5 wt.), Chromium (20 wt. .), additionally introduced into the mixture of 35% nickel powder by weight of these components, mixed in a ball mill until a homogeneous mass. From the obtained mixture by extrusion, granules with a diameter of 4.0 and a length of 10 mm are obtained, they are placed in a solution, a pressure of 0.05 MPa is created, and then as in Example 1.

The isolated composite material is a homogeneous solid solution of Cr ₃ C ₂ -10TiC with a molar ratio of chromium carbide to titanium carbide equal to 1:10, while the particles of the solid solution are uniformly coated with a nickel shell.

 The resulting composite material is ground in a ball mill and subjected to fractionation in order to extract powders with a grain size of 40/28 and 60/40 microns. These classified powders were used to apply plasma heat-resistant coatings to X12M steel surfaces. Plasma spraying of the powders was carried out at the UPU-3 unit using an argon-hydrogen mixture to a coating thickness of 0.3-0.4 mm. The wear test of the coating was carried out with a counterbody of X12M steel and the adhesion strength was determined. Wear tests were carried out on a MI-IM machine. The amount of wear is taken as the amount of wear. The adhesion strength of the coatings to the X12M steel substrate was determined by the normal tear-off method of the cone pin and washer.

For the obtained composite material, coating wear at a load of 400 MPa was 0.005 mm ³ , at 800 MPa it was 0.011 mm ³ , at 2000 MPa it was 0.025 mm ³ , and the adhesion strength was 20.5 MPa.

 Example 3. To obtain a composite material containing chromium carbide and titanium carbide in their molar ratio of 1: 3, a mixture of powders of titanium (40 wt.), Chromium (43.3 wt.) And soot (16.7 wt.), additionally introduced into the mixture of 15% nickel powder by weight of these components, mixed in a ball mill, then briquetted in the form of tablets with a diameter of 30 mm and a height of 20 mm with a relative density of 0.5, place the tablets in the reactor, create a pressure of 0, 01 MPa. Further, as in example 2.

40/28 μm fractionated powders were used to apply plasma coatings to the surface of a titanium alloy. The resulting coatings reliably protected the surface from intense oxygen exposure at an atmosphere above 1000 ^o C.

Claims (3)

 1. A method of obtaining a composite material based on titanium carbide, including preparing a mixture by mixing powders of the starting components containing titanium, chromium and carbon, placing the mixture in the reactor, local ignition of the mixture, followed by high-temperature reaction of the components in the combustion and extraction of the target product, characterized in that the starting components are taken in the amount necessary to obtain the target material containing chromium carbide and titanium carbide with a molar ratio of 1 1 10, the process s is carried out at a pressure of 0.005 0.05 MPa, and after extraction, the target material is subjected to grinding and fractionation. 2. The method according to claim 1, characterized in that the mixture is additionally introduced 15
35 wt. nickel powder.  3. The method according to PP. 1 2, characterized in that after mixing the mixture is briquetted in the form of granules or tablets.