金刚石微粉表面的纳米硅烷化改性及其抗氧化性能

Nano silylation modification of diamond powder surface and its oxidation resistance

采用溶胶−凝胶技术和正硅酸乙酯(TEOS)的水解−缩合反应,在金刚石微粉表面包覆一层厚度为2~10 nm的富含活性氧基团的纳米氧化硅非晶凝胶膜,凝胶膜在加热至一定温度后,其二氧化硅可由非晶相向晶体相转变。金刚石微粉在空气中的初始氧化温度从原料金刚石的500℃提升到其TEOS覆膜改性后的550℃。在TEOS覆膜中添加纳米硅粉改性后,金刚石微粉样品在空气中的初始氧化温度可进一步提升至610℃;且经过800℃的热处理后,样品剩余量比之原料金刚石量大幅度提升,表明TEOS覆膜中添加纳米硅粉后可进一步提升金刚石微粉的高温抗氧化性能。TEOS覆膜中富含的活性氧基团能与树脂/陶瓷结合剂间产生化学反应,有利于提高结合剂对金刚石的把持力,可为制备高性能的树脂/陶瓷结合剂金刚石工具提供良好的功能化改性原材料。

Using sol-gel technology and hydrolysis condensation reaction of tetraethyl orthosilicate(TEOS),a nano silica amorphous gel film with a thickness of 2~10 nm and rich in active oxygen groups is coated on the surface of dia-mond powder.When the gel film is heated to a certain temperature,the silicon dioxide in it can change from amorphous phase to crystalline phase.The initial oxidation temperature of diamond powder in air increases from 500℃of raw dia-mond to 550℃after TEOS coating modification.After adding nano silicon powder to TEOS coating,the initial oxida-tion temperature of diamond powder sample in air can be further increased to 610℃.After 800℃heat treatment,the residual amount of the sample is significantly higher than that of the raw diamond,which indicates that the high temper-ature oxidation resistance of diamond powder can be further improved by adding nano silicon powder to TEOS coating.The rich reactive oxygen groups in TEOS coating can produce chemical reaction with resin/ceramic bond,which is con-ducive to improving the holding force of bond on diamond,and can provide good functional modified raw materials for preparing high-performance resin/ceramic bond diamond tools.