| Ti3SiC2possesses many excellent properties of metals and ceramics.When thetemperature is higher than1100℃, Ti3SiC2is prone to be oxidated. In order to improveits oxidation resistance, TaC/Ti3SiC2composites was fabricated by reactive hot pressingmethod using Ti, SiC, graphite and TaC powders as raw materials.The microstructureand properties of TaC/Ti3SiC2composites were investigated by means of XRD, EDS,SEM, TG, conductivity meter. Conclusions as follows:（1）The dense TaC/Ti3SiC2composites could be fabricated by reactive hot pressingmethod. The results of XRD showed:①The main phases of composites are Ti3SiC2andTaTiC2, containing TiC as minor phase.②It is beneficial for the formation of Ti3SiC2to increase hot pressing temperature.（2） XRD and scanning electron microscopy observation discovered:①Ti3SiC2grain is lamellar or granular, TaTiC2solid solution is granular, and TiC embeded inTi3SiC2.②When the content of TaC is above40wt%, lamellar Ti3SiC2grain willdecrease.（3）①The flexural strength and fracture toughness ofTaC/Ti3SiC2increase withthe increasing of hot pressing temperature.②There are several energy absorbingmechanisms during the composites fracture such as intragranular fracture, graindelamination, crack deflection, grain pullout, et al.These energy absorbingmechanisms could increase the flexural strength and fracture toughness.③With theincreasing of TaC content, the flexural strength and the fracture toughness of compositeswill increase.But when the TaC content is too high, the mechanical properties of the composites will be reduced.（4） The oxidation experiment of TaC/Ti3SiC2composites had been carried out at1100～1500℃in air. Conclusions as follows:①TaC/Ti3SiC2composites obeyed aparabolic law from1100℃to1500℃.②The oxidation resistance of TaC/Ti3SiC2ismuch higher than that of monolithic Ti3SiC2and SiC/Ti3SiC2composites. The oxidizedlayers of TaC/Ti3SiC2are composed of the outer layer of TiO2and the inner layer ofmixtures of TiO2, SiO2and the eutectic of TiO2and Ta2O5.（5） The electrical conductance of TaC/Ti3SiC2composites has been tested. Theresults showed that: With the increasing of TaC content, the electrical conductivitieswill decrease. |
PDF Full Text Request