以Cr_3C_2为碳源合成Cr_2AlC陶瓷粉体及其动力学

Synthesis and kinetics of Cr_2AlC ceramics using Cr_3C_2 as carbon source

以Cr、Al、Cr3C2为原料,在700～1350℃温度范围内氩气环境下,采用无压烧结法合成Cr2AlC陶瓷粉体。研究了原料组成、烧结温度对合成Cr2AlC的影响。结果表明,原料摩尔比为1 Cr3C2/2.2Al/1Cr,温度1250℃时,样品中含有少量Cr7C3杂质,温度升高到1350℃时,获得高纯的Cr2AlC陶瓷。温度低于800℃时,Cr3C2和Al反应生成Cr2AlC和Al4C3。950℃时Cr2Al和C反应得到Cr2AlC。1350℃Cr2Al、Cr3C2和Al反应生成目标相Cr2AlC。用Kissinger方法和Owaza方法计算得到反应的表观活化能分别为362.24 k J/mol和389.01 k J/mol。

Powders of Cr2AlC were synthesized by pressure-less sintering using Cr,Al and Cr3C2 as raw materials in the temperature range of 700-1350 ℃ under argon atmosphere.The effects of the raw materials composition and sintering temperature on phases of the samples were studied.The results indicate that when molar ratio of the raw material is Cr∶ Al ∶ Cr3C2= 1 ∶ 2.2 ∶ 1,Cr2AlC with small amount of Cr7C3 is obtained at 1250 ℃ and high purity Cr2AlC ceramics is synthesized at 1350 ℃.Cr3C2 reacts with Al to form Cr2AlC and Al4C3 below 800 ℃.The reaction between Cr2Al and C leads to the formation of Cr_2AlC at 950 ℃.Cr2AlC formed by reacting of Cr3C2,Cr2Al and Al at 1350 ℃.The apparent activation energy of the reaction is 362.24 k J / mol and 389.01 k J / mol by using the Kissinger and DoyleOzawa methods,respectively.