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Fabrication of diamond-transition metal carbide composites

金刚石-过渡金属碳化物复合材料的制备

基本信息

批准号：
03555162
负责人：
SHIMADA Shiro
金额：
$ 5.63万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03555162/
关键词：
Diamond Transition metal carbide Composites oxidation mechanism Formation of carbon Single crystals 酸化

项目摘要

The oxidation of powder ZrC samples was carried out at temperatures of 380 to 550ﾟC and oxygen partial pressures of 4 to 16 KPa. It was found that the partial oxidation of the ZrC samples at 400 to 500ﾟC produces cubic ZrO_2 as well as carbon containing a very small amount of hexagonal diamond. Since it is possible to fabricate a diamond-ZrC composite by utilizing this partial oxidation of ZrC, the oxidation mechanism of ZrC using the powder and single crystal samples was investigated to reveal the deposition process of carbon containing diamond. Furthermore, the oxidation of HfC, TiC and NbC was performed to clarify its mechanism and to examine whether the carbon is formed during their oxidation.It was found on the basis of the EPMA, SEM and XPS results that the crack-free. compact layer of the ZrO_2 oxide 1 - 3 um thick containing 30 - 100 mol % carbon, which adhered to ZrC, was formed inside the porous, cracked layer of the oxide. The thickness of the former layer is kept constant during oxidation, being time-independent, whereas that of the latter layer grew linearly with time. The results similar to those of ZrC were obtained on oxidation of HfC single crystals. The oxidation mechanism of TiC and NbC was discussed from a kinetic viewpoint in connection with crystallization of the oxide (anatase and Nb_2O_5) and cracking as well as the formation of titanium and niobium suboxide.

氧化反应的温度为380~550ﾟC，氧分压为4~16kPa.结果表明，在40 0~5 0 0ﾟC的部分氧化过程中，生成了立方氧化锆和含有极少量六方金刚石的碳。由于利用ZRC的这种部分氧化可以制备金刚石-ZRC复合材料，因此利用粉末和单晶样品研究了ZRC的氧化机理，以揭示含碳金刚石的沉积过程。此外，还对HFC、TiC和NbC的氧化进行了研究，以阐明其氧化机理，并考察它们在氧化过程中是否生成了碳。1-3微米厚的含30-100摩尔%碳的氧化锆氧化物致密层与氧化锆结合在一起，在氧化层内部形成多孔的裂纹层。前一层的厚度在氧化过程中保持不变，与时间无关，而后一层的厚度随时间呈线性增长。在HFC单晶的氧化实验中，得到了与ZRC相似的结果。从动力学角度讨论了TiC和NbC的氧化机理，包括氧化物(锐钛矿和Nb_2O_5)的晶化、裂解和钛、Nb次氧化物的形成。