排序方式: 共有20条查询结果,搜索用时 15 毫秒
1.
2.
3.
研究了表面氧含量对高纯硅原料在氮氢气氛下直接氮化行为的影响,并合成高α相氮化硅。研究结果表明,硅粉在氮氢气氛下1 350℃保温3h,氮化产物中α-Si_3N_4含量随原料氧含量的增加呈先增加后减少的趋势,当硅原料表面氧含量为3.91%时,氮化产物中α-Si_3N_4含量可达97%以上,残留硅含量低于1%,产物中部氧含量为1.71%,在此环境下硅粉氮化主要以化学气相沉积的方式进行,产物形貌以杆状α-Si_3N_4晶须为主。硅原料表面氧含量低于4.38%时,氮化产物α-Si_3N_4含量均在95%以上,另有少量的β-Si_3N_4和残留硅,XRD测试精度范围内无氮氧化硅相存在。当硅原料氧含量高于5.61%时,产物中则出现氮氧化硅,随着原料氧含量增加,氮氧化硅含量明显上升。当硅原料氧含量低于5.61%时,残留硅含量随氧含量增加明显减少,说明原料中氧的增加可以显著加快氮化速率,降低氮化产物中残留硅的含量。 相似文献
4.
实验研究了经酸洗除杂的冶金级硅粉在空气中进行高温处理以再次造成表面杂质偏聚,然后继以二次酸洗去吸附除杂的方法。结果表明这种方法因其硅粉表面形成的硅氧化物进一步提高了金属杂质表面扩散偏聚的能力,比保护气氛条件下的高温处理有更好的偏聚效果,二次酸洗后金属杂质含量进一步降低。 相似文献
5.
6.
7.
利用镁热、碳热还原钛铁矿,原位燃烧合成制备了超细 TiC 粉体。通过理论分析、实验研究分析了燃烧合成的规律及镁含量对产物特性的影响。结果表明,钛铁矿-镁-碳是一个强放热体系,体系开始反应的温度为 577.7 ℃,当钛铁矿与镁的摩尔比为 1:4 时,燃烧合成酸洗出的 TiC 微粉纯度最高,并显示了较窄的粒度分布,其平均粒度为 229.6 nm。 相似文献
8.
Physical-chemical characteristics of the band sawing dusts regarding to recovery of pure silicon from them were investigated.The experimental results show 50vol%-60vol% amorphous phases exist in the dusts,which is mostly amorphous silica.The as-received saw dusts are found to form hard agglomerates of larger than 50 microns in diameter.The iron-based inclusions collected by magnets are found to match well with the band saw material in XRD patterns.Weight loss in heating was observed by thermal gravity tests,up to 900 ℃,presumably due to reaction of the amorphous silica with carbon contaminant in the dusts.The saw dusts were variously treated to examine their physical-chemical responses,and the results were also presented. 相似文献
9.
10.