Study On The Performances And Formation Mechanism Of Graded Cemented Carbide With Cubic Carbide Free Layer Prepared On The Basis Of Nitrogen Free Raw Materials

The graded cemented carbide with cubic carbide free layer (CCFL) in the surface as a matrix coating of the matrix material, both require a higher hardness and need some toughness. In this paper, the graded cemented carbide with cubic carbide free layer (CCFL)in the surface was used as the object of study. The physical and mechanical properties of the alloy were analyzed by adding different original powder and process parameters. The sintering method was interrupted at different sintering stages. The microstructure and phase composition of the gradient layer were studied. The dynamic transformation of the microstructure and phase composition of the gradient layer and the dynamic migration of the elements were studied. Get the following main conclusions: With the increase of cobalt content, the overall density of the alloy decreases, the coercivity increases, the coercive force decreases and the magnetic saturation increases. Get a higher bending strength. The density of the alloy depends primarily on its initial composition. The increase of cobalt content is beneficial to the liquid phase migration. Under the same sintering process, the thickness of the graded cemented carbide increases rapidly with the increase of the cobalt content. However, compared with the gradient cemented carbide which is usually prepared by using the nitrogen-containing cemented carbide raw materials, especially in the gradient sintering stage, the holding time is short, The thickness of the formed graded cemented carbide is relatively small.The Co-enriched layer should be resulted from the combination action of vacancy diffusion of element Co and liquid phase migration, the difference of Co content inside the Co-enriched layer is generated by the process of liquid phase migration during the cooling stage.