Kazuhiro Hasezaki

High-temperature erosion rates of Fe–Cr–C alloys produced by mechanical alloying and sintering process

Abstract In order to develop a material having high erosive wear resistance at elevated temperature, the alloys of the ternary Fe–Cr–C system were produced by mechanical alloying (MA) and sintering process. Three kinds of alloys which have different contents of M 23 C 6 carbide were made, and observation of the microstructure, measurement of the hardness and erosive wear test were carried out on each alloy. As a result the Fe–Cr–C alloys made by MA and sintering process have fine microstructure. The Vickers hardness of the MA-Fe–50% Cr–4.8% C alloy is more than 6 GPa at 973 K, and the erosive wear resistance of this alloy at 973 K is almost the same as that of sintered Cr 3 C 2 /Ni cermet, which is the commercially available material with high wear resistance.

Structural Differences between Hydrogenated and Deuterated Amorphous Silicon Films Prepared by Plasma-Enhanced Chemical Vapor Deposition

Hydrogenated and deuterated amorphous silicon films were investigated to determine the origin of the lower photodegradation rates reported for deuterated films. Deuterated layers were deposited onto hydrogenated films and were ineffective in changing the photodegradation rate, implying that hydrogenated and deuterated films exhibit structural differences related to the bulk. Deuterium effused as low as 250°C, compared with 325°C for hydrogen, and the deuterium effusion was greater at temperatures below 400°C. Raman scattering intensities of the TO band were also slightly broader and shifted to higher energy for the deuterated films.

Control of Photo-Induced Degradation in a-Si:H Prepared from Xe-Diluted Silane

Films were prepared by the Xe-dilution method in an attempt to mimic the microstructure found in low-photodegradation deuterated films which show a greater number of clustered deuterium and microvoids when compared to conventional hydrogenated films. Common features were found for the light soaking behaviors in the film properties characterized by the electron spin resonance, gas thermal evolution, Raman spectroscopy, and infrared spectroscopy among deuterated, conventional hydrogenated, and Xe-diluted films.

Effect of Tellurium Doping on the Thermoelectric Properties of ZnSb

n-type tellurium doped ZnSb was prepared by direct melting at 923 K after which it was quenched in water within an evacuated quartz ampoule. All the ingots were heat treated at 723 K for 100 h. The resultant samples were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and by measurement of their Seebeck and Hall coefficients. XRD and DTA indicated that the solubility limit of tellurium in ZnSb was less than 3 at%. The samples with 0, 1 and 3 at% tellurium were p-type while those with 1.90 and 2.06 at% tellurium were n-type. These results indicated that n-type ZnSb samples can be obtained by the proper doping of tellurium. Excess doping with tellurium resulted in precipitation of the ZnTe phase and a change in conduction from n- to p-type. The maximum power factor for the 2.06 at% tellurium doped n-type sample was found to be 0.84×10-3 Wm-1 K-2 at 573 K.

Effect of ion bombardment on the properties of hydrogenated amorphous silicon prepared from undiluted and xenon-diluted silane

The contribution of ion bombardment to the growth of hydrogenated amorphous silicon prepared by plasma-enhanced chemical vapour deposition from silane and xenon-diluted silane source gases was studied by applying an external d.c. voltage to the substrate electrode. The role played by the xenon ions in the growth of the materials prepared from xenon-diluted silane source gas has been considered. It is demonstrated that the xenon ions are responsible for the growth of the materials showing stable photoconductivity behaviour under light illumination.