Design and Construction of Insulation Configuration for Ultra‐High‐Temperature Microwave Processing of Ceramics

Abstract

A multilayer insulation configuration suitable for microwave sintering of ceramics up to 2100°C was designed and tested successfully. The configuration is based on porous, granular BN/ZrO2 fiber composite powder for packed beds and spacer cylinders. This insulation allows stable, controlled microwave sintering and can be modified to microwave process materials with different thermal, dielectric properties with improved properties.

Microwave sintering of AlN powder synthesized by a SHS method

“…It could also avoid arcing and assure a stable and uniform heating. Many researchers [15][16][17][18][19][20][21][22] found that multilayer designs of insulation package were capable of achieving high sintering temperatures. Such multilayer insulation packages are usually composed of several layers of alumina board, porous ceramics and packing powder.…”

“…[15][16][17][18][19][20][21][22] A proper insulation package could reduce heat loss and thus a high sintering temperature could be achieved. It could also avoid arcing and assure a stable and uniform heating.…”

“…17 However, due to the nature of microwave heating mechanism, a suitable insulation package is required to obtain a high enough temperature for AlN sintering and the package has been usually constructed in a complex design. [15][16][17][18][19][20][21][22] The present study is aimed at studying the microwave sintering of the AlN powder synthesized by the combustion synthesis method developed recently by the authors as mentioned previously. 6 A simple insulation package was developed and a high sintering temperature (1900 • C or higher) was readily achieved.…”

Effect of Thickness and Orientation of Alumina Fibrous Thermal Insulation on Microwave Heating in a Modified Domestic 2.45 GHz Multi‐mode Cavity

“…In this way, thermal insulation has been widely used in MW sintering to prevent heat loss from the susceptor and to improve temperature uniformity. Additionally, thermal insulation design is one of the most important parts for the success of MW processing because it must not only minimize the heat loss from the susceptor but also help to optimize MW power distribution within the load 9 …”

“…These insulation materials are commercially available. In addition, they are highly porous with very low thermal conductivity and nearly transparent to MW at room temperature 9,10 …”