问题 问答题 简答题

简述研磨、抛光时加工表面产生变质层的机理和减少变质层的办法。

答案

参考答案:

硬脆材料经研磨后的表面,由于有微细的裂纹,加工后会在该部位继续留有裂纹。例如,对经研磨的单晶硅表面,使用氟、硝酸系列的溶液进行化学浸蚀,依次去掉表层,用电子衍射法进行晶体现察时,从表层向内部的顺序为非晶体层或多晶体层、镶嵌结构层、畸变层和完全结晶结构。在研磨金属材料时,虽不发生破碎,但是磨粒转动和刮削时,由于材料承受了塑性变形,通常形成与上述硅片相类似的加工变质层。

抛光时,由表层向组织内部的结构顺序是抛光应力层,经腐蚀出现的2次裂纹应力层,2次裂纹影响层和完全结晶层。整个深度为3μm。

单项选择题

People are indulging in an illusion whenever they find themselves explaining at a cocktail(鸡尾酒) party, say, that they are "in computers," or "in telecommunications," or "in electronic funds transfer". The implication is that they are part of the high-tech world. Just between us, they usually aren’t. The researchers who made fundamental breakthroughs in those areas are in a high-tech business. The rest of us are () of their work. We use computers and other new technology components to develop our products or to organize our affairs. Because we go about this work in teams and projects and other tightly knit working groups(紧密联系在一起的工作小组), we are mostly in the human communication business. Our successes stem from good human interactions by all participants in the effort, and our failures stem from poor human interactions. The main reason we tend to focus on the () rather than the human side of the work is not because it’s more () , but because it’s easier to do. Getting the new disk drive installed is positively trivial compared to figuring out why Horace is in a blue funk(恐惧) or why Susan is dissatisfied with the company after only a few months. Human interactions are complicated and never very crisp(干脆的,干净利落的) and clean in their effects, but they matter more than any other aspect of the work. If you find yourself concentrating on the () rather than the (), you’re like the vaudeville character(杂耍人物) who loses his keys on a dark street and looks for them on the adjacent street because, as he explains, "The light is better there!".

The rest of us are () of their work

A.creators

B.innovators

C.appliers

D.inventors

单项选择题