Effect Of Cr Dopant On Structure Ang Properties Of Zr₂Al₄c₅carbides Ceramic

Zr2Al4C5ceramic shows superior strength, fracture toughness, excellent roomand high-temperrature stiffness and chemical inert. However, its low brittle and pooroxidation resistance are critical shortcomings that limit its extensive application asstructure material. In this paper,[Zr（Cr）]₂Al₄C₅samples were fabricated by hotpressing zirconium, chromium, aluminum, and graphite powders. Meanwhile,explored the effect of the temperature, Cr content and Al content on the structureand properties of materials, as well as Cr dopant on fracture behavior. Mufflefurnace were used to explore into oxidation mechanism of [Zr（Cr）]₂Al₄C₅ceramicthrough the investigation of unit area weight gain, surface microscopic structure andphase composition of oxidation layer after oxidation. Phase content, microstructurecharacteristics and performance were analyzed and characterized in the usage ofmany analyzing and testing technologies.The comprehensive performance of [Zr（Cr）]₂Al₄C₅ceramics is the best in theconditions of sintering temperature of1950℃, sintering pressure for30MPa, heatpreservation for1h; Cr dopant do not change the grain shape, but to a certain extentrestrains its growup, make the fracture mode change; When Cr dopant content ismore than solid solution limitation, Cr element turns to the Cr3C2phase,andincreases with the increase of the content of Cr.The oxidation dynamic curve of [Zr（Cr）]₂Al₄C₅ceramic followed y=a·xbparabolic law at the oxidation temperature of700℃to1000℃.[Zr0.9Cr0.1]₂Al₄C₅ceramic performanced the best oxidation resistancen in the same oxidationconditions through the comparison of unit area weight gain. According to XRDanalysis for the surface of oxidation layer, We found that external oxidation layermainly composed of （Zr,Cr）O₂and Al₂O₃. The formation of protective oxide（Zr,Cr）O₂, and Al₂O₃, which can effectively prevent the oxygen to spread within.