Fabrication And Properties Of TiB₂-Cu Transpiration Cooled Ceramic Matrix Composites

According to the served requirements of gas vane materials for solid rocket motor, the TiB₂-(Cu,Ni) matrix interpenetrating phase composites(IPCs) were prepared by high temperature sintering and subsequently melt infiltration on the base of material and experimental design.The microstructure and properties of the composites were investigated by the means of SEM, TEM, HRTEM micstructure analysis and properties measurement techniques. Using mercury intrusion porosimeter to investigate pore structure of TiB₂ porous ceramic.The initial pressure have an important influence on the microstruture of porous TiB₂ ceramic. The relative density of TiB₂-(Cu,Ni) composites(IPCs) decreased with the increasing initial pressure. The melt infiltration is affected by pore diameter, total pore area and porosity of porous ceramic.The TiB₂ ceramic phase formed scaffold structure, in which metal binder phase exist, after melt infiltration. The TEM and HRTEM of TiB₂-(Cu,Ni) composites(IPCs) show that the interface between reinforcement and metal binder is clear and no interfacial phases are found. However, new diffusion layer was found on the interface of TiB₂ and (Cu,Ni) phase by HRTEM. Moreover there are dislocation and displacement that resulted from residual thermal stress in the metal phase.The relative density of TiB₂-(Cu,Ni) composites(IPCs) decreased with the increasing to volume content, and the bending strength increased initially and then decreased with the increase of ceramic volume content, as well as the fracture thoughness. The maximal bending strength reached to 844.7MPa for 81.6%TiB₂-(Cu,Ni) composite,while the maximal value of fracture toughness attained 12.5MPa·m1/2 for 79.5% TiB₂-(Cu,Ni) composite.