天然石墨的组成和结构研究

A Study on the Composition and Structure of Chinese Natural Graphites

本工作是中国国产天然石墨应用系列研究之一,研究对象是不同牌号的商品石墨样品,利用X-射线衍射(XRD)和差热分析(DTA)等手段对其组成和结构进行了详细的研究。XRD分析表明,天然石墨中含有石墨碳(一种类石墨),其它除六方石墨外,还有适量的菱方石墨。XRD分析还很好地解释了某些高碳石墨样品之DTA曲线的双峰现象——石墨样品中碳素组成和结构不同致使氧化峰值温度不同。分析测试发现,石墨碳的氧化峰值温度比石墨的高约100℃,而且氧化峰值温度是随粒度的增大而提高。本文还通过多个样品的结构测定,归纳出一般石墨样品针对不同分析目的和层次所需采用的XRD分析方法。

The composition and structure of the commercial natural graphites was studied by means of X-ray diffraction (XRD) and differential thermal analysis (DTA) in this paper. The results showed that the commercial natural graphite is consisted of the rhombohedral graphite, and graphitic carbons except for the hexegonal graphite, and is contaminated with non-carbon materials, such as day, silicates and oxides. In XRD patterns of the graphite specimens, the (002) line profile was separated to distinguish the graphite and the graphitic carbons, and the (101) line profile was separated to find the relative content of the rhombohedral graphite in the graphite, by the multipeak-separation procedure; while the precise measurement of the inter-layer spacing in the hexegonal graphite was performed with the (008) line. On the other hand, the double peak of the DTA curves for high-carbon graphite specimens was interpreted by XRD analysis. It was indicated that the highest-peak oxidation temperature of the graphitic carbons was about 100℃ higher than that of the graphite, and the peak oxidation temperature increased with increasing of the grain size of the graphite specimens.