Effect of TiH₂ Content on the Interfacial Reaction Layer Characteristics and Wear Resistance of Diamond/Cu-Sn-Ti Composites Prepared by Spark Plasma Sintering

Diamond/Cu-Sn-Ti composites as potential superhard abrasives products have been successfully prepared by spark plasma sintering (SPS) at 1223 K. The different TiH₂ content on changes of wettability, phase composition, interface layer characteristics, such as reaction layer thickness and elemental distribution, and wear performance of bulk composites have been systematically studied. The results revealed that at 5wt.% TiH₂ content, all diamond grains were completely coated, showing sufficient wettability. In addition, an even thicker, more continuous, and uniform TiC layer have been generated at the interface, and the average thickness reaching a stable value of 1.72 μm, forming the strongest interfacial bonding strength. Whereafter, when content of TiH₂ increases to more than 5wt.%, coating morphologies and the homogeneity of reaction layer has no appreciable changes, indicating that the maximum extent wetting and interface reaction balance were achieved. However, excessive Ti may promote the formation of large amounts of brittle Cu₄₁Sn₁₁ phase, which will significantly weaken metal matrix strength and then leading inferior wear resistance. The minimum weight loss obtained at 5wt.% TiH₂ content, and the main way of weight loss was the wear and crushing of diamond grains. Meanwhile, through FIB-TEM, confirmed that the interfacial reaction layer was mainly composed of continuous TiC layer adjacent to diamond and discontinuous TiC layer in the filler metal, and constitute the formation of a high strength metallurgical interfacial bonding layer.