The Mechanical Properties And Corrosion Resistence Of AlN-SiC Ceramic Composites

With the development of smelting industry, electrolysis cells wall materials continuously proposed new requirements, a variety of special ceramic material with special structure and properties have been gradually introduced to this industry. In this work we gain AlN-SiC composites by Hot-Press. We add different content of SiC to find out its effect on microstructure and mechanical property and the resistance property to the corrosion of croylite. Besides, we use Al₂O₃ and Y₂O₃ as sintering additives to find out its effects on microstructure and mechanical property and the resistance property to the corrosion of croylite.Compared to the composites without sintering additives the composites with Al₂O₃ and Y₂O₃ have higher density. As for the two kinds of composites, when the weight of SiC and AlN is 3:7,the composites have highest density. The density of SA3 is 99.7%, it is almost completely dense. The texture disperse evenly, there is no union and abnormal growth. The sintered composites can be divided into white, dark gray and gray three areas. oxide grain boundary phase distribution in the white area, aluminum nitride the dark gray area and the solid solution the gray area.In the larger grains around the AlN, aluminum nitride and silicon carbide form a good solid solution. As for the composites with sintering additives the glass phases located in the triangle grain boundary. Internal sub-boundaries are found in single AlN crystal. It is helpful to improve strength. The solution increase with the increase of SiC content in the composites. The composites with sintering additives have higher solution. The solid solution results to a larger aluminum nitride lattice.Bending strength and fracture toughness of the composites without sintering additives, with SiC content increasing, tend to increase, the elastic modulus and hardness increases and then decreases. As for the composites with sintering additives, their bending strength increase with more SiC, but elastic modulus, fracture toughness and hardness increase and then decrease. The sintering additives can help to improve the mechanical properties. The fracture surface becomes complex and there is more terrace.With the holding time longer, the quality of composite materials per unit area show changes of parabola. When the holding time is 5 hours a small amount of insulation reduce. when 10 hours it increases. 15 hours after the resultant and the matrix stripping, the quality decreases. With the increase of SiC content, the reaction layer was thickened. The composites with sintering additives have a thicker reaction layer. Croylite and the matrix material produced nepheline. It has a high viscosity, so it can effectively prevent the spread of the diffusion.