Phase composition, microstructure and properties of sintered La2O3-doped lime and dolomite grains

• Published in: Ceramics international 1990, Vol.16 (4), p.215-223
• Main Authors: GHONEIM, N. M, MANDOUR, M. A, SERRY, M. A
• Format: Article
• Language: English
• Subjects: Applied sciences; Basic refractories; Building materials. Ceramics. Glasses; Chemical industry and chemicals; Exact sciences and technology; Refractory products
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/0272-8842(90)90069-R

The effect of La2O3-doping on the sinterability of Egyptian dolomite and limestone-derived lime on firing up to 1600 C was investigated. The La2O3/CaO ratios ranged between 0.4 and 1.5 mole% of the investigated materials. The composition of the phases formed on firing and the microstructures of the obtained grains were studied using chemical analysis, XRD and reflected light microscopy techniques. Densification parameters and technological properties of the obtained grains were also determined. It was found that doping of limestone-derived lime with 1.0 mole% La2O3 and firing at 1600 C offers dense grains wiht uniform texture having directly bonded particles of comparable size. The impurities present in the raw material helped in the formation of a limited amount of a liquid phase, which also contributed to the densification process. Hydration-resistant refractory lime grains having high cold crushing strength were produced. The doping of natural dolomite with 0.5 mole% La2O3 and sintering at 1600 C offers dense dolomite grains with a developed periclase-bonded network including most of the disseminated lime clusters. This La2O3 content is sufficient to inhibit the grain growth of lime clusters while allowing the development of a periclase cluster network. The obtained grains exhibit the best densification, refractory and hydration-resistance properties. 24 refs.