Research On The Properties Of PbTiO₃ Particle Reinforced Copper Matrix Composites

Lead titanate ceramic particles which have negative thermal expansion properties are choosen as the reinforcement and copper which have high heat conductivity are choosen as matrix of composites. Different volume fraction of lead titanate particles reinforced copper matrix composites are prepared by Spark Plasma Sintering. Using the methods of microstructure analysis(XRD, SEM, TEM, etc.) to observe the morphology of reinforcement and matrix in composites, interfacial characteristics, dislocations and twins. Using thermal expansion instrument and thermal conductivity equipment to test and analyse the thermal expansion and thermal conductive ability of the composites. Using Electronic Universal Testing Machine to test the compress yield strength of composites; Using Intelligent resistance tester to test the conductivity of the composites.XRD and microstructure observation results show that the Pb Ti O3/Cu composites interface is smooth, clear. There is no interface reaction, and the interface bonds are weak.The TEM observation confirms that there exist a lot of dislocations and twins in the as-sintered composites, which indicates massive thermal mismatch stress in the composites.Thermal expansion coefficients increase with the volume fraction. Internal residual stress in the composites is complex, and the residual stress has a significant effect on composites’ thermal expansion coefficient. The thermal expansion coefficient is not stable, but it can be stabilized with proper heat treatment process.Zr doping can reduce the Curie temperature of lead titanate, PZT/Cu composites at low temperature could produce a narrow and strong negative thermal expansion.The thermal conductivity of the composites is mainly associated with the volume fraction and distribution state of PT particles. When the volume fraction rises, as the PT particles have negative thermal expansion, so that the composites show a lower thermal expansion. However, the thermal conductivity of composites decreases because of the bad thermal conductivity of PT particles.The interface bonding and the distribution of PT particles influence the compress yield strength of composites. The conductivity of the composites increases as the volume fraction rises, and thermal treatment will improve the conductivity of the composites.