A Study on the Sintering of a Mixed Powder Containing Alumina and Aluminum for Control of Volume Shrinkage during Sinter
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JMEPEG https://doi.org/10.1007/s11665-020-05078-0
A Study on the Sintering of a Mixed Powder Containing Alumina and Aluminum for Control of Volume Shrinkage during Sintering KenÕichiro Kita, Naoki Kondo, and Mikinori Hotta (Submitted December 2, 2019; in revised form July 21, 2020) We studied the sintering of mixed powders in which either alumina or aluminum was coated with polysiloxane derived from aqueous slurry in order to avoid using organic solvent and to confirm the change of sintering process by coating only one of the powders. We found that similar characteristics of porous alumina can be obtained by sintering the mixed powder derived from an aqueous slurry and the mixed powder derived from an ethanol slurry. Coating the alumina powder with polysiloxane prevented the volume expansion of samples during sintering, thus increasing the density of the porous alumina and wettability between alumina and aluminum. Keywords
alumina, aluminum, porous ceramics, precursor polymer, sintering
1. Introduction Ceramic porous materials have several desirable characteristics such as low density, high surface area, low thermal conductivity, and biological compatibility (Ref 1-5). Alumina is a well-known ceramic which includes many excellent characteristics such as high thermal resistance, environmental resistance, good strength, and low cost. Therefore, porous alumina materials are promising inexpensive materials with potential applications such as filters, catalyst carriers, light structural materials, and artificial bones (Ref 6-9). Porous alumina is usually made from alumina powder compact and a partial sintering process. During sintering, particles in the compact are bonded by surface diffusion or evaporation–condensation processes derived from heat treatment and the bonding process needs to be halted before full densification of the alumina powder compact (Ref 10). The bonding area and the process are called ‘‘neck’’ and ‘‘necking’’ respectively, and Green et al. reported that growth of the neck can enhance the mechanical reliability of the resulting materials (Ref 11, 12). Therefore, many remarkable processes of partial sintering and necking have been reported (Ref 11, 13-19). During partial sintering, organic binders such as polyvinyl alcohol and paraffin are used to maintain the shape of the
This article is an invited paper selected from presentations at the ‘‘11th International Symposium on Green and Sustainable Technologies for Materials Manufacturing and Processing,’’ held during Materials Science & Technology (MS&TÕ19), September 29–October 3, 2019, in Portland, OR, and has been expanded from the original presentation. KenÕichiro Kita, Naoki Kondo, and Mikinori Hotta, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Shimo-shidami, Moriyama-ku, Nagoya 463-8560, Japan. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
porous alumina during sintering (Ref 20, 21). However, the use of organic binders for sintering reduces the mechanical reliabi
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