Transformation Potential of Kalemaden Clay - 220 to Technological Ceramics

摘要

In this study, the Clay - 220 mineral of Turkish origin from Kalemaden A.S., having a composition of the quarts, kaolinite, feldspar and the others with the weight percent of 36.20, 12.66, 48.03 and 3.11, respectively, was used as a raw material to investigate its transferability potential to a technological ceramic. The mineral was in the form of conglomerate rocks, which were prepared in the consecutive mineral processing procedures before taken it to the stage where carbothermal reduction - nitridation (CRN) was performed in an atmosphere controlled environment. Various process parameters, i.e., temperature, time and N_2 - flow rate were tested in order to optimise the CRN process. SiAlON was formed at temperatures as low as 1300℃ and its content increased with reaction temperature up to 1475℃. Above 1425℃, SiC becomes more predominant phase in the powdered product after CRN. Fine powders formed at temperature of 1350℃, which is the lowest value reported among the current literature, contain single crystalline phase of β-SiAlON. The results indicated that the best transformations and yield to the SiAlON ceramic were occurred on the previously prepared Clay - 220 samples in powder form that were processed at 1350℃ for 6 hours with nitrogen flow rate of 1 lt/min.