STUDY OF THEMAL DIFFUSIVITY AND POROSITY OF COMPOSITE MATERIALS BY THE ELECTROMAGNETIC ULTRASONIC TECHNIQUE

电磁超声技术研究复合材料的热扩散率和孔隙率

基本信息

批准号：
02452128
负责人：
NAGASHIMA Akira
金额：
$ 4.42万
依托单位：
KEIO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

项目摘要

1. Development of the electromagnetic ultrasonic technique : The electromagnetic ultrasonic wave was successfully generated and detected in the sample, and the method to measure the velocity of sound by monitoring the phase difference between these waves was studied. The ultrasonic velocities in aluminum, stainless steel and carbon brick were measured successfully by the through-transmission method. But in this measurement, the temperature rise due to the induction heating by one pulse current was not large enough to apply a electromagnetic ultrasonic transducer to the surface heating in the measurement of thermal diffusivity. Therefore the pulse current of a few amperes and of 1 kHz as the peak value in repetition frequency was supplied into the transducer. The temperature profile was observed at the sample surface, and the thermal diffusivities of stainless steel and carbon brick were measured by the stepwise heating method. The influence of the distribution of internal heat production on the thermal diffusivity was also investigated and further, the conditions to measure the thermal diffusivity and the ultrasonic velocity simultaneously at high temperature was discussed.2. Development of the method and measurement at high temperature : The system to detect the electromagnetic ultrasonic wave had to be sealed against the unnecessary electromagnetic wave. It was confirmed that the temperature of the carbon-carbon (C/C) composite rose by the induction heating at the temperature of up to 1200ﾟC. The temperature profile of C/C composite with Fourier's number of less than 1 was observed and the thermal diffusivity was measured successfully in the temperature range up to 700ﾟC. The thermal diffusivity of these samples showed negative temperature dependence.

1. 电磁超声技术的发展：成功地在样品中产生并检测到电磁超声波，并研究了通过监测这些波之间的相位差来测量声速的方法。通过透射法成功地测量了碳砖和碳砖，但在该测量中，由一个脉冲电流感应加热引起的温升不足以将电磁超声换能器施加到表面。在热扩散率的测量中，将几安培的脉冲电流作为重复频率的峰值提供给传感器，观察样品表面的温度分布，并观察不锈钢的热扩散率。采用分级加热法对碳砖进行了测量，研究了内产热分布对热扩散率的影响，并探讨了高温下同时测量热扩散率和超声速度的条件。 2．高温下的方法和测量的开发：检测电磁超声波的系统必须密封以防止不必要的电磁波。已确认碳-碳（C/C）复合材料的温度因感应加热而上升。在高达1200°C的温度下观察到傅里叶数小于1的C/C复合材料的温度分布，并成功测量了高达1200°C的温度范围内的热扩散率。 700°C。这些样品的热扩散率表现出负温度依赖性。