Study On Synthese And Properties Of Ti₃SiC₂/Al₂O₃ Composites By Hot Pressing

The application in plasticity and pliability of trational ceramic malterials is usually confined for their brittleness. A new type structure ceramic material is studied dedicatedly by some specialists in recent years, that is the ternary carbide Ti₃SiC₂ material, which combines many of the best attributes of both metals and ceramics.For the comprehensive mechanical property of this material, it is deemed as one of the most developping perspective new ceramic materials. However, However, some weaknesses, such as low hardness and low creep strength, limit the potential application of Ti₃SiC₂ as a high-temperature structural material.Owing to the high hardness, high modulus, excellent chemical stability, and approximate thermal expansion coefficient, Al₂O₃ here in is chosen to produce Ti₃SiC₂ /Al₂O₃ composites in order to increase the hardness and strength of Ti₃SiC₂ Because the solid state displacement in-situ reaction route is simple in fabrication and low in Price, so it becomes the main approach of preparing Ti₃SiC₂ /Al₂O₃ composite materials.The paper adopts the solid state displacement reactions to synthesize in-suit composite of Ti₃SiC₂ /Al₂O₃.The means is using good mechanical property of Ti₃SiC₂-matrix composite.Principle, reaction route and mechanism of the solid state displacement reaction are researched.In this dissertation, the solid replacement in-situ synthesizing reaction path between TiO₂/Al, the vacuum hot Pressing of TiO₂, Al, TiC, Ti and Si powder have been reseached in preparing Ti₃SiC₂/Al₂O₃ composite materials. The mechanism of solid state replacement in-situ has been studied, and the solid state reaction path has been analyzed, and the mechanical property of composite materials has been tested.The main research topics and results are as follows:(1) The thermodynamic anlyses in preparing Ti₃SiC₂/Al₂O₃ composite materiais have been suggested:(2) The phase composing and the appearance analysi from the prepared composite materiais suggested:We can prepare Ti₃SiC₂/Al₂O₃ composite materials using solid replacement in-situ reaction that we deaigned.But the dissimilitude of preparing technology made the prepared composite materials contain TiC phase.We analyzed thereason of this phase(3) We have measured the performance of prepared composite materials samples.The density of composite materials is above 99%.We found that the rigidity of samples was increasing with the increasing of AI2O3.Temperature and Soaking time effected the structure of composite materials strongly.The flexural strength of O3 composite remarkably improved to 475Mpa;thefracture toughness increased to 5.8 MPam1/2. Meanwhile, Ti3SiC2/Al2O3 isa good thermal and electrical conductor. The corrosion resistance ofTi3SiC2/Al2O3 in dilute HNO3 was more excellent than Ti3SiC2.There are some definite innovative in our study results. The results havesuggested that Ti3SiC2 /AI2O3 composite materials can be prepared with usingTiC>2> Al> TiC, Ti and Si powder and adopting solid state replacement in-situreaction method. The corrosion resistance of Ti3SiC2/ AI2O3 in dilute HNO3 wasmore excellent than...