The Preliminary Study of Sintering Behavior and Coloring Mechanism of CaCO3

• Main Authors: Chen, HungWen, 陳鴻文
• Other Authors: Teng, MaoHua
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/83606368137045539500

碩士 === 國立臺灣大學 === 地質科學研究所 === 89 === Marble has high economic value and has found many applications in industrial and stone materials, and its beautiful color pattern is an important factor to evaluate the economic value. The purpose of this work is to study the sintering of the CaCO3 powders into high strength and colored bulks by ceramic processing methods. There are few researches about the sintering of CaCO3, this is probably because that CaCO3 will decompose into CaO and CO2 at high temperature. Therefore, the major part of this work is to find out how to increase the apparent density and strength of a sintered CaCO3, i.e., the basic research of CaCO3 sintering；the second part is an attempt to change the colors of sintered CaCO3 by adding different coloring additives. The addition of small amount of Li2CO3 into CaCO3 can indeed help the sintering of CaCO3. The factors that affect sintering include sintering atmosphere, the amount of Li2CO3, sintering temperature, sintering time, and forming pressure. The sintering results showed that CaCO3 with 1% Li2CO3 had the best relative final density (95%), and which increased with the sintering temperature. An important factor that affects the sintering of CaCO3 with addition of 5% and 10% Li2CO3 is the occurrence of eutectic reaction between CaCO3 and Li2CO3, when CO2 starts to dissolve in the liquid and trapped even after sintering. The Mastering Sintering Curve (MSC) analysis showed that although the fitting error of the derived MSC from the data was less than 0.5%, but the result of some special designed experiments could not fit very well with the MSC predictions. This proves that there are still limitations in using Master Sintering Curve model on a complicated system. In addition, we had added third phases (1% Ni or Fe2O3) to the Li2CO3-CaCO3 system to study the coloring behaviors of the sintered bulks. The results showed that the presence of a colored phase could effectively reveal its color in the bulk. The relative density, however, can only reach 91%, because of the more complicated compositions in the system.