Synthesis And Properties Of Ti₃AlC₂ & ZrC/Ti₃AlC₂ Composites

Titanium aluminum carbide(Ti₃AlC₂)has attracted most attention because it combines the merits of both metal and ceramic.It is easily machinable, resistant to thermal shock and oxidation,and it has excellent electrical conductivity and high strength at high temperature.It needs a large amount of Ti₃AlC₂ powders with high purity and low cost as the applications of Ti₃AlC₂ materials in engineering. However,the present methods and starting compositions can't guarantee the synthesis of the high purity and low cost of Ti₃AlC₂ powders.The main purpose of the present study is to discuss the parameters and starting compositions to make the high purity and low cost of Ti₃AlC₂ powdersThe contents of this work are:using cheapness compounds of Ti replacing expensive Ti powder in the starting mixture to get a single phase of Ti₃AlC₂ by the pressureless sintering technology.The new mixtures and sintering technology decrease the cost of powders and favor the synthesis of the Ti₃AlC₂ powders in a large scale.Based on the above optimized parameters,dense Ti₃AlC₂ Bulk materials and ZrC/Ti₃AlC₂ composites were fabricated by in situ hot-pressing,and their mechanical properties were measured.The results show that the high purity of powder Ti₃AlC₂ powder has been synthesized by pressureless sintering a mixture of Ti/Al/TiC/Sn(Sn as a sintering additive)powders with a mole ratio of 1:1:1:0.1 in the temperature range of 1350-1500℃for 10 min in an Ar atmosphere.The Ti₃AlC₂ single-phase powder was also fabricated by pressureless sintering a mixture of TiH₂/Al/TiC/Sn with mole ratio of 1:1:1:0.1 at 1500℃for 10 min under a vacuum atmosphere.Using the technologies of XRD,SEM,EDS and DSC,etc,the characterization of the Ti₃AlC₂ powder and the reaction mechanism for the formation of Ti₃AlC₂ are systematically studied.Sn is an effective additive and its effect on the formation of Ti₃AlC₂ has been discussed.Dense Ti₃AlC₂ Bulk materials and ZrC particle reinforced Ti₃AlC₂ composites (ZrC/Ti₃AlC₂)were synthesized by in-situ hot pressing under 30 MPa at 1500℃for 1 h in an Ar atmosphere.The microstructure of the Ti₃AlC₂ and ZrC/Ti₃AlC₂ composites were studied by SEM and TEM.ZrC particles were uniformly distributed in the Ti₃AlC₂ matrix.Compared with the monolithic Ti₃AlC₂,the composites exhibit higher mechanical properties.