Si_3N_4/TiN复相陶瓷的抗氧化性能

Oxidation Resistance Performance of Si_3N_4/TiN Multiphase Ceramic

以铁尾矿和含钛高炉渣为主要原料合成了Si3N4/TiN复相陶瓷,在热力学分析的基础上,研究了Si3N4/TiN复相陶瓷的抗空气氧化性能,并对其氧化过程进行了动力学分析。采用X射线衍射、扫描电镜和能谱等对Si3N4/TiN复相陶瓷的氧化过程、氧化后样品显微形貌进行了表征,并通过分析样品的恒温氧化质量增加曲线研究了其抗氧化过程的动力学规律。结果表明:样品在空气中的氧化主要由TiN、Si3N4和O′-sialon的氧化3部分组成。材料在1 100～1 240℃下氧化后断面明显分为3层,外层是由熔融氧化物形成的致密"保护膜"层,主要由Fe2TiO5、SiO2和TiO2组成;中间层是固相氧化物层;内层是未被氧化的本体Si3N4/TiN。其氧化过程遵循两段模型,即氧化前期为直线模型,中后期为抛物线模型。两阶段氧化过程的表观活化能分别为1.354×105 J/mol和1.896×105 J/mol。

The oxidation resistance of Si3N4/TiN multiphase ceramic prepared using iron tailing and high titanium slag as raw materi-als was investigated based on the thermodynamic analysis,and the dynamics of oxidation process was also analyzed.The oxidation process and the micro-morphology of the samples after oxidized were characterized by X-ray diffraction,scanning electron micro-scope and energy spectrum analysis.The dynamics of oxidation resistance of the Si3N4/TiN was investigated via the analysis of the constant temperature oxidation mass gaining curves.The results show that the oxidation process of Si3N4/TiN multiphase ceramic in air mainly consists of TiN,Si3N4 and O′-sialon oxidation.The section after oxidized at 1 100-1 240 ℃ involves three layers,namely,the out layer（the dense ＂protective coating＂ formed by melted oxides that mainly have Fe2TiO5,SiO2 and TiO2）;the middle layer（solid oxides）;the inner layer（the unoxidized body of Si3N4/TiN）.The oxidation process follows a two-stage model that appears a linear model in the initial stage and a parabola model in the final stage.The apparent activation energies of the two-stage oxidation process are 1.350 × 105 J/mol in the initial stage and 1.896 × 105 J/mol in the final stage,respectively.