Boron-containing gradient hard alloy with shell structure and preparation method of boron-containing gradient hard alloy

Abstract

The invention discloses a boron-containing gradient hard alloy with a shell structure and a preparation method of the boron-containing gradient hard alloy. According to the preparation method, a sintered compact hard alloy base body is subjected to boronisation thermal treatment in a boron-containing filler; the temperature of thermal treatment is slightly lower than a liquid phase point of the hard alloy base body. The boron-containing gradient hard alloy is provided with three structures including a surface layer, a secondary surface layer and a core part, wherein the surface layer is a shell tissue with uniformly distributed boron-containing phases; the secondary surface layer is of a gradient transitioning structure with uniformly changed boron-containing phases; the core part is a hard alloy tissue which does not contain the boron-containing phases; the concentrations of the boron-containing phases are gradually reduced from an interface of the surface layer and the secondary surface layer and are completely eliminated at an interface of the secondary surface layer and the core part. The usability of the boron-containing gradient hard alloy is obviously higher than that of a common hard alloy; by the existence of a gradient layer, sudden failure caused by performance difference between a boronisation shell layer and the alloy base body is avoided.

Description

technical field [0001] The invention relates to the technical field of hard alloy material manufacture, in particular to a boron-containing gradient hard alloy with a shell structure and a preparation method thereof. Background technique [0002] Cemented carbide is widely used in metal processing, engineering machinery, mold manufacturing and other fields. With the continuous upgrading of the manufacturing industry, the service conditions of cemented carbide have become increasingly stringent, and various cemented carbide strengthening technologies have continued to develop. Among them, the method of introducing B, C, N and other elements and their compounds (especially compounds with IV B, V B, VI B group metals) into the cemented carbide can make the mechanical properties of the cemented carbide have a gradient distribution, which is effective. Improving the hardness and wear resistance of cemented carbide has been widely used. [0003] Boride has extremely high melting...

AI Technical Summary

Problems solved by technology

At present, the representative methods of cemented carbide boronizing include: 1. "Cemented Carbide Surface Boronizing Treatment Method", Patent No. Publication No. CN 101948997 B; this method puts cemented carbide in the composition of boron donor, activator and filler. In the solid boronizing agent, a dense boronizing layer of tens to hundreds of microns can be formed on the surface of the cemented carbide after the temperature is raised to 800-1300°C under negative pressure and kept for 0.5-8 hours; the disadvantage of this method is: The boron layer is too thin, less than 1 mm. Under actual service conditions, such as cemented carbide buttons for geological and mining drill bits, the actual wear thickness of the alloy usually exceeds 1 mm; in addition, due to the thin boronizing layer, the boronizing layer and the The transition area between the substrates is also narrow, resulting in a sudden change in performance from the boronizing layer to the substrate, which is prone to stress concentration and damage during use, which is not conducive to the extension of the service life of the cemented carbide

2. "Cemented Carbide Treated with Boron", Patent Publication No. CN 1039837C; This method provides a boronizing method, placing cemented carbide in alumina fillers containing BN and C, in hydrogen or nitrogen Or after raising the temperature to above 1400°C for 70 minutes in a mixed atmosphere of the two, a boronizing layer with a depth of more than 3 mm of a dispersed boron-containing phase can be obtained; although this method obtains a thicker boronizing layer, it is hard The number of boron-containing phases on the surface of the alloy decreases continuously, resulting in a rapid decline in the performance of the alloy in the later period of service; at the same time, the amount of boron-containing phases on the surface layer of this method is less than that of the first method, and the strengthening effect is also weak

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