Tungsten Cobalt -Cemented Carbide Production Process

       

To understand the production process of tungsten-cobalt cemented carbide, you must first know what it is composed of. Tungsten-cobalt cemented carbide is a cemented carbide composed of tungsten carbide and metallic cobalt. This alloy has a large output and a wide range of applications. The cobalt content varies from 3% to 13%, and the average grain size of WC is 1 to 5 μm; for the grades of wear-resistant parts, the cobalt content can reach 30%, and the average grain size of WC can be Up to 10μm. As the cobalt content and WC grain size increase, the hardness of the alloy decreases, and the bending strength and impact resistance increase. Adding a small amount of TaC (<5%) is an important way to improve the quality of tungsten-cobalt cemented carbide.

There are many types of tungsten-cobalt cemented carbide. According to its composition, it can be divided into three types: low-cobalt, medium-cobalt and high-cobalt alloy; according to the WC grain size, it can be divided into micro-grain and fine-grain. , 4 types of medium-grain and coarse-grain alloys; according to its use classification, it can be divided into 3 types of tungsten cutting tools, mining tools and wear-resistant tools.

Tungsten-cobalt cemented carbide production process: WC powder and cobalt powder are usually prepared by themselves during production, because the quality of the final product strongly depends on the performance of WC powder and cobalt powder, especially the particle size and particle size distribution of WC powder and cobalt powder And purity. Cemented carbide is usually pressed in a rigid press mold, and cold isostatic pressing is also used. After the compact is dried, dewaxed and pre-fired, it is sintered in a hydrogen-protected resistance furnace. Vacuum sintering can also be used. When the cemented carbide can be subjected to hot isostatic pressing, overpressure sintering and coating treatment, the performance of the product can be further improved.

The performance, alloy composition and structure of tungsten-cobalt cemented carbide are all related to the tungsten-cobalt cemented carbide production process. The most important factors are: the composition and content of the binder metal; the particle size and distribution of WC; and the carbon content ; The composition and content of additives, as well as various process factors that affect the alloy phase composition, WC grain size and densification. In the production process of tungsten-cobalt cemented carbide, the control of carbon content is one of the important factors. The normal tungsten-cobalt cemented carbide is composed of two phases of WC and γ. The carbon content determines whether the third phase graphite or η appears in the structure. The key factors of the phase, and it is strongly affected by the oxygen, carbon content, wet blind conditions, dewaxing, pre-sintering and sintering conditions in WC and cobalt powder. The control of the WC grain size in the alloy is another important factor, which seriously affects the properties of the alloy, and it is strongly affected by the particle size, size, distribution, wet density and sintering conditions of the original powder; alloy densification is the most important alloy performance An important sign, any structural defect will cause the alloy performance to be significantly reduced, and it is strongly affected by the original powder oxygen, carbon content, wet grinding conditions and pre-sintering and sint