Directional hemispherical reflectance (DHSR) of alumina ceramics was measured in the reststrahlen band (500-1000cm-1). Three different samples with different grain sizes of 3-5μm, 11-13μm, and 28-34μm were used. Comparing the measured DHSR to the calculated reflectance using published optical constants of α-Al2O3 single crystal, we observed some difference between these reflectance data. The origin of this difference was identified as the surface substructure on the grains after some calculations based on the effective medium approximation. The distribution of the probability of the effective polarization factor of the surface substructure was determined by the fitting of the calculated reflectance by taking account its effect. The obtained in homogeneity well corresponds to the surface morphology observed by SEM and AFM.
Effective thermal conductivity of liquid-gas foams was studied experimentally and analytically. The transient hot-wire method was employed in the measurement of the thermal conductivity of foams. Foam liquid was the dilute aqueous solution of a surface active agent (Kao MX-968). The expansion ratio of the foams fell in the range from 14 to 67. Mean bubble diameter of the foams was about 0.8mm. The experiments were conducted at the room temperature and atmospheric pressure. Measured thermal conductivity of foams was about four times larger than that of the dry air. This value is also in good agreement with the analytical prediction. From this result, it is concluded that latent heat transfer by the vapor diffusion plays a predominant role in the heat transfer through the liquid-gas foams.
Thermal diffusivity, α, of liquid germanium was determined by the laser flash method. One-dimensional analysis of curve fitting method was utilized to gain α free from the error of the thermal radiation loss. The thermal diffusivity abruptly increases on the melting. The thermal diffusivity increases with the temperature rise at a rate of 0.1%/K. Temperature dependence of the thermall conductivity deduced from α has some discrepancy with that deduced from the electrical conductivity by the Wiedemann-Franz-Lorenz law.
Isothermal vapor-liquid equilibrium measurement system with the computer was developed in the region of less than atmospheric pressure. Vapor-liquid equilibria were measured using a still with the aid of computer for control of temperature and measurement of total pressure. A modified Rogalski-Malanowski still with a provision for both vapor and liquid re-circulation was used for the determination of vapor-liquid equilibrium values. The performance of the apparatus was shown by the results of thermodynamic consistency tests for the experimental isothermal vapor-liquid equilibria.
The surface tension of molten silicon was successfully measured by an oscillating drop method using electromagnetic levitation over a wide temperature range from 1100 to 1500°C including the undercooling condition of 300K. Correction proposed by Cummings and Blackburn (J. Fluid Mech. 224 (1991) 395) was utilized for a deformed droplet under normal gravity condition. Silicon crystals heavily doped with B and Sb (resistivity as low as 1×10-4Ω⋅m) were successfully melted and levitated. The surface tension of molten silicon was 783.5×10-3N⋅m-1 at the melting point of 1410°C within the measurement accuracy of 3-4%. Its temperature coefficient was -0.65×10-3N⋅m-1⋅K-1. Secondary ion mass spectroscopy analysis showed that O and Sb evaporated during melting, while the B concentration after melting was unchanged. This means that surface tension and its measured temperature dependence correspond to those for a contamination-free silicon melt. Levitation and oscillation were confirmed using a parabolic flight of the NASA KC-135 aircraft. Surface tension measurement will be sure to be measured without correction using 10-second microgravity at a drop shaft.
Measurement of the sound velocity in materials is very useful tool for studying their physical properties under high pressure. In this paper, the velocities in helium and neon were measured up to around 3GPa at room temperature. The velocity changes induced by the phase changes were also described. The phase diagram of helium-krypton mixed gas was obtained from the velocity measurement.