【摘要】 超细金刚石(UFD)粉体高温易氧化、分散稳定性差使其在高温、溶液等环境中的应用受到极大限制。采用硅低温热解-活化-包覆复合工艺实现了超细金刚石表面包覆改性，成功制备了具有纳米尺度核-壳结构的UFD/Si复合粉体。用拉曼和透谢电镜分别表征了包覆粉末石墨化程度，探究包覆前后粉体的相成分，复合粉体形貌及包覆层厚度；用热重分析仪和傅里叶红外光谱结合粉体在10%硫酸悬浮液中的稳定静置时间分别测定UFD包覆前后的抗氧化性和分散稳定性。结果表明，850℃时的原位热解反应使Si活化量充足，无定型硅层均匀包裹着金刚石颗粒呈椭球形，包覆层厚度为10～30 nm,物相主要为金刚石和无定型硅。核-壳结构的UFD/Si复合粉体具有抗高温氧化性，硅层阻隔了金刚石与氧气直接接触，其初始氧化温度较纯UFD从500℃提高到780℃,945℃时才被彻底氧化。包覆减少了金刚石表面的官能团，减弱了颗粒之间的吸附，包覆Si后的UFD粉体在10%稀硫酸悬浮液中的沉降时间较纯UFD提升了12 h以上。更多还原

【Abstract】 The poor solution dispersion stability and high temperature oxidation resistance limits the usage performance of ultra-fine diamond(UFD). Hereby, a combined process of silicon in-situ pyrolysis, activation, and coating was designed to achieve the surface-coating modification of UFDs, and as a result, UFD/Si composite-powders materials with a core-shell structure with nanometer Si coatings are developed. The morphology, phase, composition, graphitization and the coating thickness of the coated UFD/Si powder was characterized by TEM, XRD and Raman respectively, and the high temperature oxidation resistance and the dispersion stability in the 10% dilute sulfuric acid of UFDs and UFD/Si composite-powders were investigated by thermogravimetric analysis and Fourier transform infrared spectroscopy. The results showed that the reaction of the combined process of silicon in-situ pyrolysis, activation, and coating was sufficiently active at 850 ℃, and the original UFDs were evenly coated by the amorphous silicon layer with a thickness about 10-30 nm in an ellipsoidal shape The core-shell structure coated UFD/Si presented a higher oxidation resistant temperature of 780 ℃ than that(500 ℃) of the original UFDs, and its settling time in 10 % dilute sulfuric acid was also 12h longer than that of the original UFDs, because the coated amorphous silicon layer prevented the contact between UFDs and the environment oxygen, and reduced the functional groups on the UFDs surface and the adsorption adhesion strength between UFDs.更多还原