摘要
Ti元素是钎焊SiO2f/SiO2复合材料重要的活性元素,因此,使用第一性原理计算研究了Ti和SiO2的界面结合机制.分别建立了两种不同的终止面和化学计量比的界面,使用界面分离功、电子行为和界面能研究了界面原子间的结合.结果表明,在O终止界面中,界面处Ti和O形成很强的离子-共价键,界面分离功最大可达到8.99 J/m2.在Si终止面界面中,Ti和Si形成共价-离子键,界面分离功为2.65 J/m2.在温度为1173 K时,当Si的活度大于e−35时,富Si界面的界面能更低,界面倾向于形成Ti-Si化合物.当Si的活度小于e−35时,富O界面在热力学上更加稳定,界面倾向于形成Ti-O化合物.SiO2中的Si被Ti置换出后,Si扩散进入钎料,活度升高,与钎料中的Ti反应生成Ti-Si化合物,所以界面结构为SiO2/Ti-O化合物/Ti-Si化合物/钎料.
Ti is an important active element to join SiO2f/SiO2 composite materials.Therefore,the bonding mechanism of Ti and SiO2 was studied by using first principle calculation.Two kinds of interfaces with different termination and stoichiometric ratio were studied by the results of work of separation(Wsep),electron behavior and interface energy.It is found that in the O-terminated interface,Ti and O atoms form a strong ionic-covalent bonding,resulting in the largest Wsep of 8.99 J/m2.In the Si-terminated interface,Ti and Si atoms form covalent-ionic bonding,and the Wsep is 2.65 J/m2.At the temperature of 1173 K,when the activity of Si is larger than e−35,the interface of Si-terminated interface is more lower.The Ti-Si compounds are more favored at the interface.When the activity of Si is smaller than e−35,the O-terminated interface is more stable in thermodynamics and the Ti-O compounds are more favored at the interface.After Si in SiO2 in replaced by Ti,Si will diffuse into the solder and react with Ti in the solder to form Ti-Si compounds,so the interface struture is SiO2/Ti-O compound/Ti-Si compound/solder.
作者
薛海涛
魏鑫
郭卫兵
张小明
XUE Haitao;WEI Xin;GUO Weibing;ZHANG Xiaoming(Hebei University of technology,Tianjin,300130,China)
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2020年第1期67-71,I0004,I0005,共7页
Transactions of The China Welding Institution
基金
河北省高等学校科学技术研究项目(QN2019028)
河北省自然科学基金(E2019202407)。
关键词
钛/二氧化硅
第一性原理
界面结合机制
分离功
电子行为
Ti/SiO2
first principle calculation
interface bonding mechanism
work of separation
electron behavior
