Some results of microscopic and X‐ray investigations of calcium carbide

AbstractThe structure of calcium carbide is investigated using thin sections and ground sections. Depending on chemical and other factors, calcium carbide occurs in three types of structure, which are interpreted as conversion products resulting from a high‐temperature structure.The pavement‐like structure containing CaC2‐I is present in industrial carbide with a low content of nitrogen. With increasing fraction of lignite high‐temperature coke used for carbon supply as a substitute for coal coke in the production of carbide, the particle size decreases, and the micro hardness increases.The interlocked structure with CaC2‐II and higher contents of nitrogen, which has been detected in carbide produced in the laboratory, is extremely dense. No grain sizes can be given. This kind of carbide produced in the laboratory has a lower micro hardness than industrial carbide.The mixed crystal structure is typical of carbide with a high content of sulphur. CaC2—CaS‐I is present as a phase.In all three types, the respective carbide phases have a marked lamellar structure. No typical shapes of crystals can be detected. In consequence of poor crystal formation, the information obtained with a microscope about the phases contained in the material investigated is complemented by X‐ray diffraction methods.