Preparation and properties of Al2O3-reinforced Cu-Ni-Sn metallic matrix for applications in diamond-cutting tools

A Cu-Ni-Sn matrix reinforced by Al2O3 particles (referred as CuNiSn/Al2O3) has been developed as a potential substitute for cobalt to fabricate diamond-cutting tools. CuNiSn/Al2O3 powder was first prepared through high energy ball milling, which was consolidated by hot pressing at 880 °C to a virtually pore-free matrix and diamond tools containing 10 vol% diamond grits separately. For comparison, a cobalt matrix and cobalt diamond tools were also prepared. The friction and wear behaviors of the matrixes and the diamond tools were investigated against ZrO2 balls under dry sliding in air on a ball-on-disk tester. The hardness, bending strength and bending elastic modulus of the CuNiSn/Al2O3 matrix are 99 HRB, 1308 MPa and 75.6 GPa, respectively, which are close to those of the cobalt matrix. However, the CuNiSn/Al2O3 matrix exhibits a more stable friction coefficient and higher wear resistance than the cobalt matrix, and ZrO2 can be more effectively grinded off by CuNiSn/Al2O3 diamond tools than cobalt diamond tools. With detailed microstructural analyses, the possible friction and wear mechanism are discussed. The new CuNiSn/Al2O3 matrix is promising for fabricating diamond tools with low cost, high processing efficiency and long service life.