Preparation and ablation behavior of Ti3SiC2 ceramics

Ti3SiC2 ceramic bulk with a relative density greater than 99% was prepared by hot pressing sintering ( HP) using Ti3SiC2 powder as raw material, and the hardness, flexural strength and fracture toughness of HP Ti3SiC2 bulk were 775HV, 520. 46 MPa and 7.62 MPa.m(1/2), respectively. To evaluate its oxidation-resistance and thermal shock resistance, ultra-high temperature ablation tests were conducted under oxyacetylene flame without cooling. The results show that the Ti3SiC2 ceramics remain flat within 10 s of the ablation, no macrocracks within 25 s. SEM and XRD analysis reveal that Ti3SiC2 samples are decomposed and oxidized during the ultra-high temperature ablation, elements Si and C are oxidized into gaseous Si-O and C-O compounds, TiO2 ( rutile) with a loose structure remains on the surface of the sample. To analyze the internal oxide layer, a dense layer composed of rutile TiO2 and Al2TiO2 is observed, under which an Al2O3 particle-enriched layer is found covering the substrate. The dense internal oxide layer can effectively prevent O-2 from diffusing inward, thereby reducing the oxidation rate of Ti3SiC2. The high melting point and high viscosity Al2O3 particle layer can absorb a large amount of heat and then reduce the transfer of heat flow to the Ti3SiC2 substrate, thus improving the anti -ablation of the Ti3SiC2 material.