Surface modification of h-BN and its influence on the mechanical properties of CuSn10/h-BN composites

CuSn10 matrix composites with hexagonal boron nitride (h-BN) in concentrations of 4, 7, 10, and 14 vol.% were prepared using a powder metallurgy process. The effect of modifying the h-BN with anionic polyacrylamide (APAM) by high-energy ball milling was investigated. The bonding mechanism between h-BN and APAM was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The microstructure, hardness, tensile strength, and bending strength of sintered composites were investigated. The composite CuSn10-4 vol%h-BN showed the lowest porosity of 20.1%. The long APAM chains could be introduced on the h-BN surface without altering its crystal structure. The surface modified h-BN exhibited less agglomeration in the matrix than pristine h-BN, due to the physical entanglement and chemical bonding between h-BN and APAM. Comparing the composites with 4 vol.% h-BN, without and with APAM modification, a reduction in the porosity from 20.1% to 5.5%, and increase in the tensile strength from 134 to 147 MPa, and a significantly increased in the bending strength from 238 to 351 MPa, respectively, were observed.