The present state of technologies for thin film preparation of high Tc oxide superconductors, (La, Sr)2CuO4 and Ba2YCu3O7-y, is reviewed with a special attention to the vacuum evaporation and sputtering method. The epitaxial thin film growth is also stated from the point of view of substrate materials. Finally, some anisotropic properties of epitaxially grown Ba2YCu3O7-y thin films are remarked.
This investigation has been carried out to determine the influence of specimen size and side groove depth on elastic-plastic fracture toughness parameters. Elastic-plastic fracture toughness JIC and tearing modulus Tmat were evaluated by the unloading compliance method which was described in ASTM E813-81 standards. Compact tension specimens were prepared from SUS316LN and the test were conducted at cryogenic temperature 4.2K. It is understood that JIC and Tmat are independent of specimen size when the specimen satisfies ASTM standard size requirements. JIC and Tmat decrease with the increase of side groove depth for 0-12.5% of original thickness, and they are independent of side groove depth when the depth is 12.5-37.5%. These results suggest that a 0.5CT small specimen with 25% side grooves can provide proper JIC and Tmat values independent of specimen size and side groove depth.
We have investigated preliminarily the heat transfer characteristics in hybrid cooling in which one of the heated surfaces of a conductor is cooled by saturated He II (He IIs) and the other side of the surfaces simultaneously cooled by pressurized HeII (He IIp). Not that the transition to the film boiling state in the hybrid cooling is dominated by lower peak heat flux in He IIs, but that the observed peak heat flux was close to the average value of those obtained in He IIs and He IIp each. The mechanism of the transition to the film boiling state is explained by the super-heating and the temperature fluctuation between the double transition peculiar to the hybrid cooling.