Description
A method for determining high-temperature thermal properties of thick solid materials involves short-term radiation pulses (20–200 s) on the front surface of a sample via a light guide, such as a quartz or sapphire rod. The magnitude of the flux absorbed must be accurately known for thermal conductivity, but not for thermal diffusivity. Power sources may include a lamp or laser but each has difficulties. For example, a lamp often has too little power and needs complex optics, and a laser beam may have excessive power that also lacks control. A heated sample transmits considerable radiation that varies with temperature and distance from the end of the light guide. This article explores the use of reflected radiation from a sample above about 700 K. Variables include geometry, type of light guide, and sample emissivity. Work with molybdenum and alumina samples has demonstrated the technique.
Keywords
thermal conductivity, diffusivity, front surface heating, light guide, reflection, radiation
DOI
10.5703/1288284315553
Included in
High-Temperature Thermal Properties Using Reflected Sample Generated Radiation
A method for determining high-temperature thermal properties of thick solid materials involves short-term radiation pulses (20–200 s) on the front surface of a sample via a light guide, such as a quartz or sapphire rod. The magnitude of the flux absorbed must be accurately known for thermal conductivity, but not for thermal diffusivity. Power sources may include a lamp or laser but each has difficulties. For example, a lamp often has too little power and needs complex optics, and a laser beam may have excessive power that also lacks control. A heated sample transmits considerable radiation that varies with temperature and distance from the end of the light guide. This article explores the use of reflected radiation from a sample above about 700 K. Variables include geometry, type of light guide, and sample emissivity. Work with molybdenum and alumina samples has demonstrated the technique.