Ultra-high Temperature Environments Research Articles

イメージベース有限要素法によるＡｌ２Ｏ３／ＹＡＧ共晶複合材料の定常クリープ特性の推算

Al2O3/YAG eutectic composite has been developed for a structural material used in ultra high temperature environments more than 1500°C such as in a gas turbine. Creep behavior is one of the important material properties in ultra high temperature materials. In the present study, we propose image-based finite element analysis for estimating the steady state creep behavior of the Al2O3/YAG eutectic composite. In the image-based finite element analysis, micro-structure of the material taken by a SEM is modeled into a finite element mesh using a software for image processing. Then finite element creep analysis is carried out to obtain the steady state creep behavior of the Al2O3/YAG eutectic composite by using steady state creep constitutive equations for both Al2O3 single crystal and YAG single crystal. The results of steady state creep behavior obtained from the image-based finite element analysis are compared with the experimental results. It is found that the steady state creep behavior of the Al2O3/YAG eutectic composite is accurately estimated by the image-based finite element analysis. Furthermore, we examine the effect of volume fractions of the constituents on the steady state creep behavior of the Al2O3/YAG eutectic composite.

Development of a new ULT Scanning Tunneling Microscope at University of Tokyo

We describe design concepts and some technical details of a new ultra-low temperature scanning tunneling microscope (ULT-STM) which is now under construction at University of Tokyo. It is designed to work with an atomic resolution at temperatures down to 20 mK and in magnetic fields up to 6 T. It is possible to change samples and STM tips keeping ultra high vacuum and low temperature environments, which allows us to study almost all conducting materials and adsorbed samples.