QTM 500 device, is used for thermal conductivity, is a production of Kyoto Electronics Manufacturing Co. Ltd., Japan. Measurement range is 0.0116–6 W/mK. Measurement precision is ±5% of reading value per reference plate. Reproducibility is ±3% of reading value per reference plate. Measurement temperature is−100 to 1000 °C (external bath or electric furnace for temperature other than room). Sample size required is two pieces of 100W×80L×40 mm thick or more. Measuring time is standard 100–120 s.