Thermal ablation resistance of melt-infiltrated titanium diboride-(copper, nickel) composites

TiB2/(Cu, Ni) melt-infiltrated composites with high ceramic volume fraction were prepared via powder pre-sintering and melt-infiltration processing in vacuum. Infiltrated TiB2/(Cu, Ni) composite shows enhanced damage tolerance and good mechanical properties, i.e., fracture toughness up to 12.5 MPa m(0.5) and bending strength up to 844.7 MPa. The thermal shock and plasma ablation behavior of TiB2/(Cu, Ni) composites were conducted by plasma arc heater. The initial microstructure, interfacial bonding and ablated morphology were investigated. The experimental results show that the ablation mechanism of TiB2/(Cu, Ni) composites are mainly attributed to the transpiration cooling of metallic phase to bring away inner heat at elevated temperature. The microstructure analysis and properties measurement before and after ablation test reveals a clue of redistribution of infiltrated (Cu, Ni) so as to deduce and explain the functioning of transpiration cooling at ultra-high temperature. (C) 2007 Elsevier B.V. All rights reserved.