MEASUREMENT OF THERMAL DIFFUSION RATE BY LASER FLASH METHOD

摘要

PURPOSE: To improve the analysis speed by establishing a theoretical formula for temperature rise by using the dimensionless time difined by a specific formula, obtaining the dimensionless time required until the temperature rises by a specific ratio of a maximum temperature rise value, and finding out the thermal diffusion rate of a specimen based on both the obtained dimensionless time and the time obtained from actually measured temperature rise curve. ;CONSTITUTION: The thickness of a specimen is represented by b, the inner and outer radiuses in a surface irradiation area by r₁ and r₂, the inner and outer radiuses in a rear surface heat radiation area by r₃ and r₄, the thermal diffusion rate by α, respectively. Then, a representative time t_c1 is defined by the effective distance 1 defined by the formula, and further the actual time t is divided by the time t_c1 to define the dimensionless time. Since a theoretical response formula for temperature rise may be calculated unless the heat loss is taken into account, various data of the specimen are substituted into it to obtain a temperature rise curve. The curve is used to calculate the time t_1/2* required until the temperature rises a half of a maximum temperature rise value. On the other hand, a laser is actually cast on the specimen and the time t_1/2 required until the temperature rises a half of the maximum temperature rise value is measured actually. The thermal diffusion rate α can be obtained from a formula, α=t_1/2*1²/t_1/2.;COPYRIGHT: (C)1995,JPO