The influence of boriding on the properties of cemented carbides

Sintered carbide boriding is used either to form interlayers to increase the adhesion of deposited diamond layers to them by chemical vapor deposition (CVD) or to form layers on machine tools, which are then used without further processing in machining. To this end, it is necessary to ensure that the layer formed has the desired properties, i.e. adhesion to the substrate of the sintered carbide (SC), phase composition and integrity. The article deals with the properties of different types of SC after the boriding process. The aim of the experiment was to verify the adhesion of the formed layers to the SC substrate, their resistance to dynamic stress and the changes in corrosion resistance in a chemically active environment of a 3.5% aqueous solution of sodium chloride. The adhesion-cohesive behaviour of the SC substrate and the formed layer was evaluated by the Mercedes test. The dynamic load rating was evaluated using impact testing. The change in corrosion resistance of SC was measured as the change in corrosion resistance and corrosion rate using a potentiostat. These experiments were supplemented by metallographic analysis after the boriding process, both on the surface of the samples and on a metallographic section, where the hardness depth profile was also measured. The metallographic analysis revealed changes in the SC surface layer after boriding. The boride layers formed were in most cases with low adhesion to the SC substrate. In addition, due to the boriding process, SC resistance to dynamic stress and corrosion resistance to the selected corrosion environment was reduced.