Development of the Remote Temperature Response Acquisition System and Its Data Processing for the Thermal Diffusivity Measurement at High Temperature

激光闪光法最近已用于测量各种无机物在1000 K以上高温下的热扩散率和热导率。虽然在其数据处理中包括辐射热传递的所谓的双层技术已经很好地建立，但是通过常规热电偶获得的温度响应包含来自样品的挥发物质的电或电化学噪声，所述挥发物质是通过闪光激光束和在加热元件中诱导的振荡电场产生的。为此，本文研制了一种改进的锗红外探测器遥感数据采集系统，以获得无噪声的温度响应。这个新系统的数据处理也已开发，其有用性已被证实的碳酸钠和硅酸钠的测量。用激光闪光法系统地测量了铁酸钙在1000 ~ 1673 K温度范围内的热扩散系数。采用对数法分析了背表面温升的初始短时区，以减小辐射热流和径向热流对热扩散率的影响。熔融铁酸钙的热扩散率被发现增加作为CaO含量的增加。这种行为是一致的，形成一定的本地订购建议的结构数据，通过X-射线衍射和粘度测量。

The laser flash method have been recently employed for the measure-ment of thermal diffusivity and conductivity of various inorganic substances at high temperature above 1000 K. Although the so-called two-layered technique including radiative heat transfer in its data processing is well established, the temperature responses obtained by conventional thermocouples contain the electrical or electrochemical noises from volatized species of the sample by a flashed laser beam and oscillatory electric field induced in the heating element. Thus, the improved data acuisition system by remote sensing using a germanium infrared detector has been developed in this work to obtain the noise free temperature responses. The data processing of this new system has also been developed and its usefulness was confirmed by the measurements for sodium carbonates and sodium silicates. Particluarly, this system is found to be effective for the sample containing volatile components.Thermal diffusivities of calcium ferrites has been systematically measured by the laser flash method presently developed over the temperature range between 1000 and 1673 K. The logarithmic method analyzed the initial short time region of temerature rise of the back surface was used for reducing the deviation of thermal diffusivity by both radiation and radial heat flows. The thermal diffusivity of molten calcium ferrites was found to increase as the CaO content increases. This behaviour is consistent with the formation of a certain local ordering suggested from the structural data by x-ray diffracation and the viscosity measurements.