Thermophysical properties and processing of ceramics

Investigation on thermal properties, required for various design considerations, have recently emerged as a key issue in functional ceramics and ceramic composites. This issue of Advances in Applied Ceramics presents a selection of papers on thermal properties and processing, which were discussed at the 10th Asian Thermophysical Properties Conference (ATPC). ATPC took place from 29th September to 3rd October 2013, in Jeju, Korea. The main themes of the conference were; thermodynamic properties, transport properties, optical and thermal radiative properties, thermoelectric properties and materials. Particularly, thermal expansion coefficients, thermal conductivity, as well as high-temperature strength and phase stability are deemed as important factors for the high-temperature application of ceramics. The six papers selected for this special issue represent current research trends and applications in the field.

In the first part of the issue, various thermal properties such as coefficients of thermal expansion, thermal conductivity of monolithics and composites, and viscosity of glass composites are discussed. Ceramics researchers have been widely interested in mullite because of its excellent properties such as low thermal expansion coefficient, low thermal conductivity, high-temperature strength, and phase stability at high temperatures. Hemra et al.¹ report the effect of zirconia content on the mechanical and thermal properties of mullite–zirconia composites. The thermal expansion of sintered specimens showed linear and hysteresis loop changes: Hysteresis loop obtained with increased zirconia content resulted in the t–m phase transformation. Kwon et al.² show the thermal conductivities of reaction-sintered SiC ceramics prepared by the silicon-melt infiltration method. In this work, the effect of the carbon and silicon content of the starting materials on the thermal conductivities and microstructures of the ceramics, as well as the effect of sintering temperature and time were studied. Glass–filler composites used for sealing have low sealing temperatures and are particularly useful for sealing ceramic materials used in microelectronic packaging. The physical and thermal properties of these composites are important factors that affect the adhesion and interfacial interaction between glass and ceramic fillers. Seo et al.³ report variations in the viscous-flow behavior, and extent of glass fluidity in glass–filler composites with respect to various factors such as filler type, content, size, and density.

In the second part, thermal processing for developing porous ceramics, SiC, and nanomaterials is presented. Nanoporous SiC fibres can be a potential candidate in catalysts and catalytic supports for high-temperature applications. Shin et al.⁴ report that nanoporous SiC fibres, in which the nanopores were uniformly distributed on the fibre surface, were investigated by controlling the thermal oxidation and heat-treatment conditions; their microstructural evolution with formation behavior are also discussed. Kim et al.⁵ present that cellulose–calcium silicate (CCS) nanocomposites were fabricated through an environmentally friendly process from waste wood, glass, and clamshells. The effect of heat treatment on the synthesis of CCS nanocomposites was investigated in terms of the precursor ratio and firing temperature. Recently, SiC single-crystal growth has become a topic of interest as a new alternative semiconducting material. In this regard, Jung et al.⁶ show the purification and particle size control of β-SiC powder using a thermocycle process. They suggest that purified β-SiC powder with a large particle size can be a good source material for SiC single-crystal growth.

It is my hope that this dedicated issue of Advances in Applied Ceramics will be useful for researchers looking for in depth studies on thermal properties and processing in order to develop further applications at high temperature.

Guest editor

Professor Hyungsun Kim,

Inha University, Korea