摘要
采用TIG热源在钛合金表面堆焊Ti-SiC和Ti-SiC-C两种体系的粉末,形成表面陶瓷涂层.利用SEM和XRD等分析手段对两种配方陶瓷涂层的微观组织和物相进行了分析,用热力学方法计算了两种系统中各种可能发生的化学反应的Gibbs自由能变化.结果表明,Ti-SiC系统熔敷层的微观组织主要由树枝状的TiC、针棒状和菊花状的Ti5Si3相组成,其反应机理为:8Ti+3SiC→3TiC+Ti5Si3.Ti-SiC-C系统熔敷层的微观组织除了树枝状的TiC相之外,还有TiSi2和Ti3SiC2,其反应机理为:6Ti+3SiC+C→Ti3SiC2+TiSi2+2TiC.通过对两种系统的微观组织及化学反应分析可得出,在Ti-SiC系统中适当的添加石墨,可生成具有自润滑性能的Ti3SiC2相,避免Ti5Si3脆性相的生成.
The surface ceramic coatings were prepared on Ti-5Al-2. 5Sn substrate by tungsten inert-gas arc depositon process. The microstructures and phases were analyzed using the method of SEM and XRD for the cladding coatings of Ti-SiC and Ti-SiC-C systems. Moreover,the changes of Gibbs energy for possible reactions in systems were calculated using thermodynamic analysis. The results shows that the main microstructure are composed with dendritic TiC and needle-shaped or chrysanthemum Ti5Si3 in the cladding coating of Ti-SiC system,the reaction mechanism is 8Ti + 3SiC→3TiC + Ti5Si3. However,in Ti-SiC-C system,there are TiSi2 and Ti3SiC2hybrid microstructure observed besides TiC. 6Ti + 3SiC + C→ Ti3SiC2+ TiSi2+ 2TiC is the main reaction mechanism. In addition,the addition of graphite in Ti-SiC system favors to the generation of self-lubricating Ti3SiC2 phases,while the brittle Ti5Si3 phases are avoided.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2014年第10期77-80,117,共5页
Transactions of The China Welding Institution
基金
湖北省教育厅资助项目(010403)
关键词
钨极氩弧焊熔敷
陶瓷涂层
反应机理
热力学分析
tungsten inert-gas arc cladding
ceramic coating
reaction mechanism
thermodynamic analysis
