Effects of sintering temperature on microstructures and properties of Cu-C-SnO₂ porous materials

The Cu-C-SnO₂ composite porous materials were prepared by pressureless sintering with the addition of SiO₂-B₂O₃-Al₂O₃ scaling powders. The effects of sintering temperature on the microstructures and properties of the Cu-C-SnO₂ porous composites were investigated. The results show that, the porous composites are composed of metal Cu, graphite, and oxide ceramic phases. As the sintering temperature increases, the content of SnO₂ decreases and the content of oxide ceramic phases (such as mullite) increases. The content of Cu₂O increases when the sintering temperature rises from 750 ℃ to 800 ℃, which decreases as the sintering temperature above 800 ℃. At the sintering temperature of 950 ℃, the Cu grains coarsen observably because of the recrystallization. The electric resistivity, oil penetration rate, and air permeability coefficient of the composites vary similarly with the change of the sintering temperature, and there are the minimum values in the sintering temperature range of 850 ℃ to 900 ℃. The sintering shrinkage and density of the sintered compact vary similarly with the change of the sintering temperature, and there are the critical values at the sintering temperature near 800 ℃. The change rates of the sintering shrinkage and density of the sintered compact are significantly different on the both sides of the critical values. The hardness of the sintered compact increases with the rising of sintering temperature and shows a jump in the range of 800 ℃ to 850 ℃.