Since high social demands have been focused on detoxification as well as recycling of industrial wastes, the role of melting furnaces for wastes has been highlighted these days. However, due to scattering of compositions of components in industrial wastes, we are required to operate melting furnaces stably and to elucidate adequate operating conditions even for some compounds which are difficult to be melted under usual operations. In the present paper, we investigated 1) phase equilibria by thermodynamic databases, and 2) fluidity of molten slag for several compounds provided in melting furnaces. Then, we found that beneficial information was available on composition and temperature ranges of molten slag by thermodynamic investigation, which could provide useful guide to melt even asbestos and high-melting point compounds.

View full abstract

Surface tensions of molten alloys are of importance for effective designs of the materials manufacturing processes such as welding and die casting, and are strongly decreased by surface active species. Although the oxygen effect is especially paid attention for the actual process, the mechanism for its adsoption on alloy surfaces has not been clarified sufficiently. In the present work, the adsoption of oxygen on metal and alloy surfaces as oxides are described successfully by Belton’s equation on the basis of the assumption that the “associated compounds” form at metal atoms on the surface.

View full abstract

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated at the interface of the diamond film and Mo substrate. This was caused by the thermal stresses due to a mismatch of thermal expansion between the diamond film and the Mo substrate. In previous study, a three-step synthesis method was proposed. And, scratching treatments on the surface of the substrate (#180, 400, 800, 1500) and distances of the flame inner cone from the substrate (d=1.0, 1.5, 2.0, 2.5, 3.0mm) were investigated as influence factors of the delamination. To prevent the delamination, optimal conditions #400 and d=1.5mm of diamond films synthesized using combustion flame were obtained. The results showed that the delamination was able to prevent by high probability, but it was not able to protect completely. This research investigated the nucleus generation of the diamond film for 60 seconds of first step of the method. The nucleus generation of the diamond film was most important to prevent the delamination. The results showed that the effects of the nucleus generation on the delamination and the bonding strength became clear. Under optimal conditions #400 and d=1.5mm, the nucleus density was large and the nucleus size was small. It confirmed that the delamination was able to protect for these reasons at #400 and d=1.5mm. The delamination test by the indentation to delamination-free diamond films synthesized by the method was performed, and the bonding strength was discussed. It was concluded that diamond films synthesized by the method at d=1.5mm had high bonding strength.

View full abstract