Low pressure sintering nanocomposite WC-Co powder

As we all know, after vacuum sintering of cemented carbide products, the holes in the pressed parison can be eliminated, and the densification process is basically completed. However, in order to further improve the density and bending strength of cemented carbide, follow-up hot isostatic pressing is still required. , to eliminate micropores and dissolve the residual graphite in the liquid phase to eliminate the graphite phase by diffusion. However, in the process of hot isostatic pressing, if the parameters such as temperature, pressure and time are not selected properly, some WC grains will grow up, and the coarse WC, like micropores, often becomes the crack source of workpiece damage. Low-pressure sintering is a new type of sintering process developed internationally in the 1980s. It is a process of removing molding agent, pre-sintering, sintering and low-pressure hot isostatic pressing in the same equipment. Using this sintering process can effectively improve the performance of cemented carbide, obtain a uniform and void-free microstructure, and at the same time, the product grains will not grow excessively.

The nanocomposite WC-10Co powder prepared by spray pyrolysis-continuous reduction carbonization method was used as raw material, and the powder particle size was 20~50nm. By adding VC and Cr3C2 as inhibitors, adding paraffin and hexane, ball milling for 48h, and drying to granulate. It is formed by die pressing, and then vacuum sintered and low pressure sintered. Vacuum sintering system: temperature 1380 ℃, heat preservation 60min. Low pressure treatment system: Argon medium, pressure 5MPa, temperature 1320℃, heat preservation and pressure keeping for 60min. The process flow of the low-pressure sintering process system is: charging – vacuuming – heating – sintering temperature and heat preservation – Zheng – argon gas pressurization – heat preservation and pressure preservation – pressure reduction and cooling – discharge.

Among the two processes of vacuum sintering and low pressure sintering, the microstructure of ultrafine WC-Co cemented carbide prepared by low pressure sintering process is more uniform, without coarse grains, and has higher density and flexural strength. Using low-pressure sintering technology, we have successfully developed dual high-performance ultra-fine cemented carbide with hardness HRA>93, flexural strength exceeding 3800MPa, and grain size of 300-400nm.

Equipment selection: The RVS vacuum sintering furnace provided by SIMUWU is an excellent product for processing this kind of process. It has the characteristics of good temperature uniformity and high temperature control accuracy. SIMUWU provides a professional team of engineers who can solve various problems encountered in the production process and are committed to giving customers the most convenient and efficient experience.