Control morphology and properties in additive manufacturing of functional gradient cemented carbides for polycrystalline diamond substrates

Cemented carbide substrates contribute mainly to the strength and impact toughness of polycrystalline diamond composites (PDC). By using a PW-MW-HDPE-EVA-SA mixed polymeric binder and combining Powder Extrusion Printing (PEP) with densification sintering processes, the YG10/YG15 functionally gradient cemented carbides (FGCCs) with different powder loadings were prepared. This study focuses on exploring process feasibility and the integrated regulatory mechanisms for FGCCs morphology and performance. The results showed that the configured cemented carbide feedstocks with different powder loadings exhibited uniform composition and good shear-thinning characteristics, making them suitable for extrusion printing. The FGCC green parts formed by PEP have macro-structurally intact, dense surfaces and uniformly stacked extrusion filaments with a roughness of 12.25 mu m. After degreasing and sintering, FGCCs with densities exceeding 99.43% were obtained. The shrinkage and Co gradient distribution of the inner and outer layers were regulated by powder loading design, achieving integrated control of FGCCs morphology and properties. With powder loading increase in YG15, the density of FGCCs remained stable between 14.01 and 14.03 g/cm3, the gradient dimensions difference decreased from 14.34% to 7.9%, and the maximum hardness difference increased from 78 to 121 HV1/15.