Synthesis and characterization of Cu-ZrO2 nanocomposite produced by thermochemical process

The objective of this work is to study the synthesis of Cu-ZrO2 nanocomposites using the thermochemical process followed by powder metallurgy method, and investigate their mechanical properties. Cu-ZrO2 nanocomposite has been formed in-situ by adding ammonia to ZrOCl2 solution, then adding Cu(NO3)2 solution to the deposition, precipitate heating them at 600 °C for 1 h and reduction by hydrogen atmosphere. The analysis of powders structure were examined by X-ray diffraction (XRD) which indicated the presence of CuO and ZrO2 after oxidizing whereas copper oxide is transformed into elementary copper and ZrO2 particles remain in its form after reduction. Cu-ZrO2 powder mixtures were compacted under a compressive force of 700 MPa and sintered at 950 °C for 2 h in hydrogen atmosphere. The results of FE-SEM and EDS studies showed Cu-ZrO2 composites have a uniform microstructure in which zirconia nanoparticles (45 nm) are distributed uniformly in the Cu matrix. The relative densities of the nanocomposites decreased gradually from 96.1% to 90.2% with increasing zirconia content up to 9 wt. %. The results indicated that microhardness, compressive strength and wear resistance increased with increasing ZrO2 content. The wear rate of the nanocomposites increased with increasing applied loads or sliding velocity.