Showing papers by "Fujio Abe published in 1994"

Development of reduced-activation martensitic 9cr steels for fusion reactor

Abstract: In order to develop reduced-activation ferritic/martensitic steels potentially suitable for fusion reactor applications, the effect of principal alloying elements Cr, W and V on the micro- structural evolution, toughness and high-temperature creep strength was systematically investigated for relatively simple Cr-W-V steels. Based on the results on the simple steels, two kinds of martensitic 9Cr steels with low and high levels of W were alloy-designed: 9Cr-1WVTa and 9Cr-3WVTa. They exhibited excellent toughness and high-temperature strength. Irradiation hardening was the smaller for the reduced-activation 9Cr-1WVTa and 9Cr-3WVTa steels than for the conventional 9Cr-lMoVNb and it was smaller for the low W steel than for the high W steel. It is concluded that from the aspect of toughness the 9Cr-1WVTa steel is the most promising alloy for the first wall and blanket structures which will be operated at low temperatures below 773 K (500°C). Another 9Cr-3WVTa steel is the most promising in terms of high- temper...

Impurities and evaluation of induced activity of SiC composites prepared with chemical vapor infiltration

Abstract: Carbon fiber reinforced SiC (C/SiC) and SiC fiber reinforced SiC (SiC/SiC) composites were fabricated by a chemical vapor infiltration (CVI) method to obtain the composites with minimized impurity contamination. The neutron activation analysis showed that 30 elements were detected as impurities. However total impurity concentrations in the C/SiC and SiC/SiC were lower than 14.5 wt ppm and 9.80 wt ppm, respectively. The evaluation of induced activity under the simulation of fusion neutron irradiation of 10 MW.y/m 2 was made based on the impurity concentration. The dose rates of both composites were assumed to decrease by about 6 orders of magnitude in one day cooling and by 9 orders of magnitude in several ten years. The results indicate that the present composites behave excellent in terms of low activation and the CVI is a potential process to obtain high-purity composites

Production of crystalline sic film

Abstract: PURPOSE:To obtain a high-quality crystalline SiC film by photo-CVD by vapor- depositing or sticking carbon on a substrate in a specified thickness and irradiating the substrate with light in an atmosphere of a gaseous mixture of gaseous silane with a gaseous carbon source. CONSTITUTION:Carbon is vapor-deposited or stuck on a substrate of a metal, ceramics or an org. material in a thickness above that of a monoatomic layer. The substrate is then irradiated with light from ArF laser, etc., preferably at <=250 deg.C constant temp. in an atmosphere of a gaseous mixture of gaseous silane such as monosilane or disilane with a gaseous carbon source such as acetylene or methane to synthesize crystalline SiC. The pref. ratio between the gaseous silane and hydrocarbon is about (1:5)-(1:10). A crystalline SiC film can be produced by photo-CVD by operation in a low temp. range.