A high speed infrared radiation thermometer was developed for laser flash thermal diffusivity measurements. The radiation thermometer consists of an InSb detector, a reflection type finder, a reference blackbody and a simple infrared optical system. The elimination of a mechanical chopper from the optical system realized the response time at temperature detection as short as 1μs. The radiation thermometer is calibrated in the temperature range from 0 to 300°C, where nonlinear dependence of the output on temperature must be corrected for accurate thermal diffusivity measurements. The measurable temperature range can be extended up to 1500°C by attenuation of incident radiation with an iris diaphragm. The noise equivalent temperature difference is 0.039°C at room temperature for an integration time of 1.6μs. A thermal diffusivity measurement with the half rise time as short as 1.85ms and the maximum temperature rise of 6.6°C is feasible with a laser flash system using this infrared radiation thermometer.
A system to measure the thermal conductivity of thin films deposited on a pure quartz glass substrate has been developed by using the transient hot-wire comparison method. Each film of silica from 1 to 20um in thickness was deposited on the glass at total gas pressure of 2.4Pa by the sputtering method as the sample. The hot-wire having rectangular cross-section of 0.5um in thickness and 10um in width was made on the substrate by the sputtering and the photolithography technique before making the sample film. Another pane of the quartz glass was put on the sample so as to cover the wire area. The wire was heated by a highly accurate constant power supplier made by the authors which was able to keep constant power in spite of change of electric resistance of the hot-wire. An average value of the measured thermal conductivity of each quartz glass substrate was 1.47W/(m·K) at 60°C. It is almost same as a literature value of 1.42W/(m·K) at 60°C. That of each silica film was 1.37W/(m·K) at 35°C. It is about 5 percent lower than that of the quartz glass substrate. Effect of thickness and width of the hot-wire on the measured value of thermal conductivity of the film is also discussed.
Thermal diffusivities of intermetallic compound TiAl base alloys have been examined in the temperature range 300 to 900K under a vacuum of 1 mPa. Testing samples are listed in Table 1. Measureing method of thermal diffusivity is based on both the direct electrical heating method and the so- called Laplace transform method. Simultaneous measurements of electrical resistivity, thermal expansion and total hemispherical emittance were performed prior to measuring thermal diffusivity. The precision of the thermal diffusivity is estimated to be less than 10%. As a result, Ti-36wt%Al has a fairly ordered crystal structure with the existence of covalent bond, and thereby its thermal diffusivity is 67% higher than those of the other samples. Such singularity of the thermophysical properties of TiAl base alloys is found to originate only in Ti-36wt%Al.
The vapor pressures of pentamethylbenzene and m-diisopropylbenzene were measured by means of a flow apparatus in the temperature ranges of 237.52-422.06K and 332.55-421.96K, respectively. The accuracy of each measurement i n this work is estimated to be within ±0.5 percent from error analysis. The present data could be correlated within less than 1 percent absolute average deviation by the Abrams-Massaldi-Prausnitz (AMP) equation.
The ways in which fundamental measuring standards are defined have changed in close connection with increased understanding of thermophysical properties. The expression of uncertainty in calibration of the measurement equipment and of accuracy in measurement performed during research in thermophysical properties are closely linked to each other and require similar treatment of data. This report is a summary of measuring standards and the expression of uncertainty in calibration a well as their links with measurement of thermophysical properties.