Enhanced thermal and mechanical properties of Sr0.2Ba0.8TiO3/Cu composites by introducing Cu2O interface coating

Abstract

Ferroelectric ceramic with negative thermal expansion during the phase transformation from T-phase to C-phase can be used as reinforcement to obtain low thermal expansion metal matrix composites. Interface bonding plays an important role in determining thermal and mechanical properties of the composites. Here, we designed and applied Cu2O coating on the surface of Sr0.2Ba0.8TiO3 (SBT) particles by heterogeneous precipitation method, and subsequently obtained low thermal expansion Cu2O/SBT/Cu composites with excellent mechanical properties. It was found that the semi-coherent relationship can be formed in both Cu/Cu2O and Cu2O/SBT interfaces, which benefits the reduction of composites thermal expansion. The relationship among Cu2O content, SBT phase transformation and thermal expansion has been discussed. Compared with SBT/Cu composite, the average coefficient of thermal expansion of 6%Cu2O/SBT/Cu composite can be reduced from 12.97 × 10−6 °C−1 to 11.44 × 10−6 °C−1. Moreover, with the introduction of Cu2O coating, the compressive strength of the composite can reach up to 722.7 MPa. This work provides a promising method to improve the thermal expansion and mechanical property of ferroelectric reinforcement metal matrix composites. Keywords: Sr0.2Ba0.8TiO3/Cu composite, Cu2O coating, Phase transformation, Thermal expansion