Study on the Syntheis of Ti3SiC2 by Melt Infiltrating Sintering Method and Its Frictional Wear Properties
|School||Xi'an University of Technology|
|Course||Materials Science and Engineering|
|Keywords||melt infiltrating sinter Ti3SiC2 reaction mechanism influencing factor frictional wear properties|
In recent years, the ternary layered compounds Ti3SiC2 which has special physical and chemical properties of metal and ceramic has attracted materials science researchers to study.In this paper, the purer bulk Ti3SiC2 ceramic had been prepared from Ti/Si/C and Ti/Si/TiC mixed powders by use melt infiltrating method, respectively. The content of Ti3SiC2 in the two test samples can be up to 93.6% and 96.2%, respectively. The results showed that the reaction mechanism of Ti3SiC2 by melt infiltrating sintering method is that:above 1300℃and before the melting infiltrating takes place, the content of Ti is higher than that of Si in the sample and the Ti5Si3 is easier to form in the rich Ti areas. With the increase of temperature, few Ti5Si3 react withβ-Ti to become liquid mix phase of Ti-Si. With the liquid Si melting infiltrating, flowing and diffusing at 1500℃, great liquid Si will react with the rest Ti5Si3 to become liquid mix phase of Ti-Si. And then the liquid mix phase of Ti-Si will cover the TiC particle to take place liquid phase reaction. A great deal of Ti3SiC2 can be formed from this process. The reaction process is:5Ti+3Si=Ti5Si3, Ti5Si3+2Si+10TiC=Ti3SiC2The main influencing factors of infiltrating sinter such as protect gas, the ratio of raw materials and the infiltration holding time also were studied in this paper. Research shows that: 1) Under the condition that the wetting property of raw materials meet the infiltrate reaction, the protect gas determines whether a great deal of melted Si can be infiltrated into preformed sample, and affect the infiltration reaction can be fully carried out. In this experiment, Ar gas is not involved in reaction, and has large molecular weight, so when Ar gas flows from preformed sample to bring out the molten state Si less, and the generation of Ti3SiC2 reaction can be fully carried out.2) High purity Ti3SiC2 ceramic materials can be prepared by infiltration sintering with the three types of raw materials ratio of TiC/Ti/Si/C, TiC/Ti/Si and Ti/Si/C in this study, but the main difference is the improvement of the material compactness. Ti3SiC2 content in sample can be as higher as 96.2% in the preparation and the porosity is only 7.86% by use TiC/Ti/Si. It is the best raw materials selection.3) The holding time determines the degree of infiltrating reaction taking place. When the holding time is too little, the infiltrating reaction can not be fully carried out; but the holding time is too long, the production of melting infiltration will be decompose. The best holding time corresponded to the selected sample size in this study is 30 min.The mechanical properties and friction and wear properties of infiltration sintering Ti3SiC2 block were studied in this article. The results showed that with the increase of the content Ti3SiC2, a large number of pores in the bulk Ti3SiC2 ceramic materials will be filled and its soundness will be increased when the bulk Ti3SiC2 is prepared by infiltration sintering with the three types of raw materials ratio of TiC/Ti/Si/C (petroleum coke), TiC/Ti/Si and Ti/Si/C, and its bending strength and hardness are increased with the increase of content of Ti3SiC2. When the content of Ti3SiC2 is up to 96.2%, its flexural strength can be up to 132.60 MPa, and Brinell hardness will also reach the maximum 156 HB. The mechanical properties of Ti3SiC2 can be improved greatly.With the increase of content of Ti3SiC2, the friction coefficient and wear rate of bulk Ti3SiC2 ceramic materials prepared by infiltration sintering with the raw materials ratio of TiC/Ti/Si/C and Ti/Si/TiC will be decreased, and the higher purity of Ti3SiC2 is, the lower friction coefficient and wear rate of Ti3SiC2 is. When the content of Ti3SiC2 is 96.2%, its friction coefficient is just 0.211, its wear rate is 1.8×10-6mm3N-1m-1. This proves that the friction and wear properties of Ti3SiC2 have better.