石墨粉中添加含硼化合物合成金刚石的颜色与热稳定性

Color and thermal stability of diamond synthesized by adding boron-containing compounds into graphite powder

为了研究不同含硼添加剂对合成金刚石的颜色和耐热性能的影响,以石墨和触媒粉末作原料,分别用碳化硼、硼酸和硼酸氨作添加剂,在高温高压下合成出含硼金刚石。在相同的合成工艺条件下,当反应体系中的含硼量接近时,不同的添加剂合成的金刚石颜色差异较大。添加硼酸和硼酸氨的溶液时,易于合成出黄色透明的金刚石。采用动态空气流条件下的热重和差示扫描量热方法对金刚石进行了热稳定分析,结果表明:用三种添加含硼化合物合成金刚石的初始氧化温度超过830℃,最高达到990℃;在1200℃时,金刚石的失重在38%-85%之间;氧化反应放热峰在1000℃左右。

In order to investigate the effect of different boron - containing additives on the color and thermal stability of synthetic diamond, boron - doped diamond was synthesized under high pressure and high temperature, using graphite and alloy catalyst powder as starting materials, and respectively boron carbide, boric acid and ammonium borate as additives. The remarkably different colors of diamond crystals obtained from the three additives were observed, even if the near content of boron in the present reaction system and the same synthetic conditions were applied. Yellow transparent diamond crystals were readily obtained when the solution of boric acid or a mmonlum borate is added into graphite powders. Thermogravimetnc analysis （TGA） and differential scanning calorimetry （DSC） in flowing air were used to analyze thermal stability of synthetic diamond. The results indicated that diamond synthesized from the three addictives had the initial oxygenation temperature of over 830 ℃, even up to 990 ℃, the weight loss from 38% to 85% at 1200 ℃ and the exothermic summit of approximate 1000℃.