Effects of TiO(2) Nanoparticle Addition on Microstructure and Selected Properties of Ag–xTiO(2) Composites

The paper presents the results of a study of the microstructure and selected properties of silver-based composites reinforced with TiO(2) nanoparticles, produced by the powder metallurgy method. Pure silver powders were mixed with TiO(2) reinforcement (5 and 10 wt%) and 5 mm steel balls (100Cr6) for 270 min in a Turbula T2F mixer to produce a homogeneous mixture. The composites were made in a rigid die with a single-action compaction press under a pressure of 400 MPa and 500 MPa and then sintered under nitrogen atmosphere at 900 °C. Additionally, to improve the density and mechanical properties of the obtained sinters, double pressing and double sintering operations were conducted. As a result, compacts with a density of 90–94% were obtained. The microstructure of the sintered compacts consists of uniform grains, and the TiO(2) reinforcement phase particles are located on the grain boundaries. There were no discontinuities at the Ag–TiO(2) contact boundary, which was confirmed by SEM and TEM analysis. The use of a higher pressure had a positive effect on the hardness and flexural strength of the tested materials. It was found that the composites with 5 wt% TiO(2) pressed under 500 MPa are characterized by the highest level of mechanical properties. The hardness of these composites is 57 HB, while the flexural strength is 163 MPa.