(1. 湖南科技大学 高温耐磨材料及制备技术湖南省国防科技重点实验室,湘潭 411201;
2. 湖南科技大学 机电工程学院,湘潭 411201;
3. 盐城工学院 江苏省新型环保重点实验室,盐城 224051)
摘 要: 以MoSi2、Mo和Al粉末为原料,采用真空热压烧结制备不同Al含量的Mo(Si1-x,Alx)2材料,考察Al含量对MoSi2材料微观结构和高温氧化行为的影响。结果表明,当x=0和0.05时,Mo(Si1-x,Alx)2材料主要由呈C11b结构的MoSi2组成;当x=0.1时,该材料主要由呈C40结构的Mo(Si0.9,Al0.1)2和MoSi2组成;当x=0.2~0.4时,该材料由呈C40结构的Mo(Si1-x,Alx)2相组成。随着Al含量的增加,Mo(Si,Al)2晶格膨胀增大。1200 ℃氧化时,不同Al含量Mo(Si1-x,Alx)2材料的氧化动力学均呈抛物线规律;Mo(Si,Al)2中Al含量越高,氧化增量越大,抗氧化能力越低。当x=0和0.05时,材料表面氧化生成了连续致密的SiO2氧化膜;当x=0.1时,氧化层由SiO2?Al2O3混合氧化膜组成;当x=0.2~0.4时,材料表面氧化生成连续的Al2O3氧化膜。由于Si和Al的扩散,氧化膜与Mo(Si1-x,Alx)2界面处形成了Mo5(Si,Al)3过渡区。
关键字: MoSi2;Al合金化;氧化膜;氧化行为
(1. Hunan Provincial Key Defense Laboratory of High Temperature Wear-resisting Materials and Preparation Technology, Hunan University of Science and Technology, Xiangtan 411201, China;
2. College of Mechanic and Electrical Engineering, Hunan University of Science and Technology,
Xiangtan 411201, China;
3. Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province,
Yancheng Institute of Technology, Yancheng 224051, China)
Abstract:Mo(Si1-x,Alx)2 material was fabricated by hot press sintering using MoSi2, Mo and Al powders as raw materials. The effects of alloying element Al on the microstructure and high temperature oxidation behaviors of MoSi2 were investigated. The results show that the Mo(Si1-x,Alx)2 material mainly contains MoSi2 with C11b tetragonal structure at x of 0 and 0.05. At x of 0.1, the mixture phases of hexagonal C40 Mo(Si,Al)2 and MoSi2 are detected. Only hexagonal C40 Mo(Si,Al)2 phase is found when the Al content x changes from 0.2 to 0.4. The lattice of each structure generally expands with increasing the substitution ratio of Al. The oxidation kinetics of all materials at 1200 ℃ follows a parabolic rate law. The higher the Al content in Mo(Si,Al)2 is, the more the mass gain of Mo(Si,Al)2 is, and the lower the oxidation resistance is. A dense and continuous SiO2 scale forms on the surface of both MoSi2 and Mo(Si0.95,Al0.05)2. The oxide scale comprises of SiO2 and Al2O3 in Mo(Si0.9,Al0.1)2 material, and the Al2O3 oxide scale forms on the surface of Mo(Si0.8,Al0.2)2, Mo(Si0.7,Al0.3)2 and Mo(Si0.6,Al0.4)2 materials. The Mo5(Si,Al)3 transition layer is found between the boundary of oxide scale and the Mo(Si,Al)2 substrate because of the diffusion of Si and Al elements.
Key words: MoSi2; Al alloying; oxide scale; oxidation behavior