Key words: Ceramic tile; water absorption; bulk density; firing shrinkage; modulus of ruptureDOI: http://dx.doi.org/10.3329/bjsr.v24i2.10775 Bangladesh J. Sci. Res. 24(2):169-180, 2011 (December)

Bone ash has been prepared from waste cattle bone choosing two different calcination temperatures (1050 o C and 1100 o C). The heat treatment was performed by conducting quenching and without quenching techniques. The prepared bone ash was characterized using XRF, XRD and FTIR techniques which revealed that the observed data were in excellent agreement with the standard values for hydroxyapatite (the prime raw material of bone china) and could be used as the raw material for bone china ceramic ware.

Rubber-grade carbon black filler HAF(N330) was modified with a plant product (PP; long aliphatic chain substituted phenols), a proprietary item under patent application, in the presence or absence of hexamine (Hexa) or dicumyl peroxide (DCP) to put a flexible moiety in between the carbon black and the elastomer chain in order to improve some of its processing and reinforcement characteristics in natural rubber (NR). The modification process is simple and involves cheap materials. The modified carbon black was characterized and evaluated for its processability as well as reinforcing characteristics in NR vulcanizate. It was observed to show better processing behavior, without any processing aid, such as easy incorporation and uniform dispersion in the rubber phase without abnormal heat generation, and also improved vulcanizate properties, such as tensile strength, flex cracking resistance, and lower abrasion loss, without affecting other properties to a significant extent.

The bending strength of porcelain body has been experimentally studied because of its economic importance in ceramic industry. The maximum bending strength is obtained in the <44µ particle sized quartz containing porcelain at 1300 O C. The distribution of closed pores, their geometric shapes and possible link with each other control the bending strength of the ceramic body. The presence of unmelted fine quartz grains in the ceramic body also increases the bending strength. It has been found that the bending strength increases with increasing bulk density of the ceramic bodies and the firing temperature up to 1300 O C, but at temperature above 1300 O C, the bending strength decreases due to bloating of isolated pores and the disappearance of quartz, which are also associated with a decrease in bulk density. The purpose of this study is to investigate on the differential changes of bending strength of porcelain bodies upon using quartz of various grain sizes at different firing temperatures.

The physical and microstructural characteristics of Patia clay of different areas (Hydgaon-1, Hydgaon-2 and Kanchannagar) were investigated. Patia clays were beneficiated by repeated sedimentation method. The chemical compositions of raw (unwashed) and washed clay was determined. The physical properties of fired Patia clay were measured. Results show that the water absorption values decrease and the firing shrinkage values increase with increasing firing temperatures in all types of Patia clays (raw and washed) of three different areas. The microstructures of Patia clay pronounce that they contain kaolinite, illite and quartz as major phases and mica, gibbsite and hematite are present as minor phases.