Abstract
The paper presents the results of a study of the microstructure and selected properties of silver-based composites reinforced with TiO2 nanoparticles, produced by the powder metallurgy method. Pure silver powders were mixed with TiO2 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 TiO2 reinforcement phase particles are located on the grain boundaries. There were no discontinuities at the Ag–TiO2 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% TiO2 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.
Highlights
Metal–ceramic composites have attracted much attention due to their extraordinary properties such as high strength, low weight, high fatigue strength or electrical properties when compared to traditional materials [1,2]
Pure silver is an excellent conductor of heat and electricity [4]; introducing reinforcing particles affects its thermal conductivity
Wieczorek et al [5] showed that the presence of a reinforcing phase in the form of Al2 O3 and SiC particles leads to a decrease in the thermal conductivity in relation to pure silver
Summary
Metal–ceramic composites have attracted much attention due to their extraordinary properties such as high strength, low weight, high fatigue strength or electrical properties when compared to traditional materials [1,2]. Pure silver is an excellent conductor of heat and electricity [4]; introducing reinforcing particles affects its thermal conductivity. Wieczorek et al [5] showed that the presence of a reinforcing phase in the form of Al2 O3 and SiC particles leads to a decrease in the thermal conductivity in relation to pure silver. To improve its strength properties and wear resistance, reinforcing phase particles are introduced into the silver matrix [7]. Rigou et al [8], in their study, added diamond particles as suspension to the plating silver bath to improve the sliding wear behavior of silver-plated surfaces, which are normally characterized by low hardness and poor wear resistance. The results show that the surface of the silver coating containing diamond particles exhibited low values of the coefficient of friction and wear rate
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