Fabrication, Microstructure And Properties Of Ti₃SiC₂/SiC₂Composites

As a novel ternary layered material, Ti₃SiC₂possesses many best attributes ofmetals and ceramics. Ti₃SiC₂shows good high oxidation resistance, good thermal shock,high temperature strength, high temperature chemical stability, acid and alkali resistance,high temperature ductility, good thermal conductivity and electrical conductivity, highYoung’s modulus, low hardness, easily processing and other excellence performances. Itis expected to be applied in the fields of high temperature structure ceramics, electrodematerial, machining ceramics, self-lubricating materials. Therefore, it has become acurrent research focus of many scholars to extend the application of Ti₃SiC₂.Ti₃SiC₂/SiC composites containing different contents of SiC were successfullyfabricated with Ti、SiC、Si and carbon black powders as raw materials by reactive hotpressing method. Ti₃SiC₂and Ti₃SiC₂/SiC composites were investigated by means ofoptical microscope, XRD, SEM, EDS, TG and other testing means and methods.Conclusions as follows:（1）The dense high-purity Ti₃SiC₂/SiC composites could be successfully preparedby reactive hot pressing method. The main phases of composites were Ti₃SiC₂and SiC,containing a small amount of impurity phase TiC. By scanning electron microscopyobservation, Ti₃SiC₂grian was lamellar, SiC was granular, and SiC uniformlydistributed in Ti₃SiC₂when it is fewer. But with the increasing content of SiC, it waseasy to the agglomeration of SiC in composites and the holes could be formed in theseSiC agglomeration.（2）The mechanical test showed:①With the increasing of SiC content, the flexuralstrength of composites decreased, but the fracture toughness was improved to some extent;②The flexural strength of Ti₃SiC₂/SiC composites prepared by using SiC as rawmaterial is lower than that of Ti₃SiC₂, but the fracture toughness was significantlyhigher than Ti₃SiC₂; however, the flexural strength and fracture toughness ofTi₃SiC₂/SiC composites prepared by using Si powder as raw material are higher thanthat of Ti₃SiC₂.（3） The isothermal oxidation behaviors of Ti₃SiC₂/SiC composites had beeninvestigated at1100～1500℃in air. The results showed that:①Ti₃SiC₂/SiCcomposites obeyed a parabolic law from1100℃to1500℃;②The oxidationresistance of composites can be improved when the content of SiC was added tocomposites;③T he oxidized layers ofTi₃SiC₂/SiC composites were composed of twolayers: the outer layer of TiO₂and the inner layer of mixtures of TiO₂and SiO₂.