Study On Process And Mechanism Of Joining SiC Ceramics By Using Self-propagation High-Temperature Synthesis Of Ti-Si-C Ternary System

SiC ceramic has the advantages of high temperature resistance,corrosion resistance and oxidation resistance,etc.In addition,it also exhibits low neutron activity,irradiation stability and other advantages.SiC ceramic is the key element in constructing a nuclear fusion reactor in the future.However,SiC ceramic has the high brittleness and low ductility,making it difficult to be deformed and cut.Therefore,only by joining the small pieces of SiC ceramic can we get a component of complex structure.Ti3SiC2 has the advantages of high melting point and thermal conductivity.Meanwhile,it possesses the characteristics of ceramic materials and metal materials.Therefore when the Ti3SiC2 as intermediate layer materials are used to joining the SiC ceramic,it can not only meet the requirements of high temperature applications,but also can fully fulfill their comparative advantages.This kind of application has a great implication for making high temperature resistant and anti-oxidation structure parts.This paper uses high-frequency induction heating ignition Ti-Si-C ternary system of Self-propagating High-temperature Synthesis reaction to prepare Ti3SiC2 and joining SiC ceramic.The method has the advantages including low energy consumption,environmental protection,and high productivity,low cost.Also it can realize the preparation of materials under or without pressure/ordinary pressure.Moreover,this paper designed and developed a set of induction heating furnace in the experiment which can provide inert gas protection and are equipped with pressure system.First,This paper investigates the induction heating ignition Ti-Si-C ternary system of Self-propagating High-temperature Synthesis reaction of induced current,cold compression molding pressure,different starting powder,starting powder ratio,particle size and combustion improver Al for sintered products,Ti3SiC2 phase content and microscopic structure of the effect.Research results show that under the 3Ti-Si-2C reaction system,induction current and combustion improver Al exert a significant impact on the Ti3SiC2 phase formation and its relative content in the reaction product.However,after ball milling,the particle size decreases on the reaction synthesis of Ti3SiC2 phase has inhibitory effect,Si content and cold pressing pressure of Ti-Si-C synthesis reaction formation of Ti3SiC2 content of small.The contents of Si and cold pressing molding pressure shows little impact on the Ti3SiC2 content of Ti-Si-C synthesis reaction.Secondly,the induction current of 50A was used to ignite 3Ti-Si-2C system Self-propagating High-temperature Synthesis reaction for the purpose of joining SiC ceramic.The influence of heat insulation,different joining pressure and combustion improver A1 on joint reliability has been studied.Also the shear strength has been experimented on joints at room temperature.The results are as follows.When the joining pressure is 1MPa,the shear strength is 5.87MPa and 32.93Mpa separately at the condition of no heat insulation and 30min's heating at 30A insulation.It is shown that heat insulation can significantly improve the mechanical properties of SiC ceramic joint.The shear strength is 32.93MPa,42.39MPa and 42.81MPa at the joining pressure of 1MPa,3Mpa and 6Mpa.It is shown that the increase of the joining pressure has the effect of improving the shear strength of the joint.However,the effect of increasing the shear strength of the joint is not obvious when the joining pressure increases to a certain degree.As for 3Ti-Si-2C-0.1Al system,the shear strength of joint is the highest which is 66.79Mpa under the condition of 1MPa joining pressure and 30min's heating at 30A insulation.Through the analysis,the combustion improver Al will greatly improve the product of Ti3SiC2 phase content.Therefore it can apparently improve the properties of SiC ceramic joint.