Study On Fabrication And Mechanical Properties Of Ti₃ SiC₂, SiC And Their Composite

In Ti-Si-C systerm, Ti₃SiC₂ and SiC are two kind of advanced ceramics that attract much attention. Whereas there are much limitation in preparation and capability. To optimize there sintering process and capability, the interaction between Ti₃SiC₂ and SiC through the process of Spark Plasma Sintering(SPS) was investigated.In this work, SiC/Ti₃SiC₂ nanocomposite was prepared through SPS technology. The effect of sintering temperature and content of SiC were investigated. Furthermore, dense SiC ceramic was prepared at lower temperature through using Ti₃SiC₂ as additive and mechanical activated sintering.Experimental research shows that SiC/Ti₃SiC₂ nanocomposite could be prepared from TiC/Si/C powders by SPS at 1350℃with a holding time of 10 min. The grain size of Ti₃SiC₂ and SiC were respectively about 6 um and 100 nm. It showed obvious promoting effect on the mechanical properties that elevating sintering temperature. Increase of SiC content could evidently improve Vickers hardness and fracture toughness, but it is harmfull to flexural strength. Ti₃SiC₂, as additive, could obviously accelerate the sintering of SiC. SiC ceramic with high relative density could be obtained at 1800℃with Ti₃SiC₂ addition amount of 30vol.%. TiC was the primary minor phase. It could evidently improve the mechanical properties that eleveting sintering temperature and increasing Ti₃SiC₂ addition amount.β-SiC powder can be prepared from Si/C powders by mechanical alloying for 30 h. The grain size was about 10 nm. Pure SiC ceramic with a relative density of 97.3% was prepared by SPS technology at 1800℃using the MAed SiC powder. The grain size was about 100 nm. The Vickers hardness, flexural strength and fracture toughness respectively reached 21.1 GPa, 476 MPa and 3.53 MPa·m1/2。SiC ceramic with higher relative density and improved mechanical properties could be obtained using Ti₃SiC₂ as additive. It could evidently improve the relative density and mechanical properties that eleveting sintering temperature and increasing Ti₃SiC₂ addition amount. Over high sintering temperature and Ti₃SiC₂ addition amount could lead to excessive grain growth. As a reasult, the mechanical properties reduced.