Boronizing mechanism of cemented carbides and their wear resistance

•Investigation of the boronizing mechanism shows that KBF4 and B4C play a major role in the boronizing.•Single KBF4 as boronizing agent will brings about pores in WC-Co cemented carbides during boronization.•Hydrogen is very helpful to promote boronization reactions.•Induction-heating should be favorable to the diffusion of B element in Co phase of the cemented carbide.•The boronization made wear resistance of the cemented carbide improve significantly.

Embedded in the solid-state boronizing agent sealed in a container, WC–Co cemented carbides were boronized at an elevated temperature. With the help of microstructure investigation and X-ray diffraction examination of the agent and surface layers of the cemented carbides after boronization, it is determined that KBF4 comes into play to boronize the cemented carbides only on the existence of substance such as B4C, which is capable of providing boron. Induction-heating and hydrogen atmosphere are better for the boronization than resistance heating and argon atmosphere, and the presence of SiC and rare-earth elements is also favorable. The boronizing mechanism was studied based on experimental results. Abrasion test was applied with the result that the boronization made the wear resistance improve significantly.