Papers by Author: Manabu Iguchi

Abstract: We introduce the concept of functional microchannel lining. As an example, we describe the composition and structure of a Ni-Al intermetallic layer lining the inner wall of the microchannel produced by a powder-metallurgical process utilizing microscopic reactive infiltration and/or diffusion. The Ni-Al lining layer is a thick film consists of multiple sub-layers and has a peculiar porous structure, in which long and thin micropores had grown along the thickness direction of the film. In our experiment, a nickel-powder compact containing shaped aluminum wire was sintered at temperatures between the melting points of nickel and aluminum. Molten aluminum migrated into the surrounding nickel powder and reacted with nickel, and thus a microchannel and a Ni-Al intermetallic lining layer were produced. In this process, nickel powder composed the device body, and the aluminum wire gave the shape of the microchannel and act as the aluminum source for the lining layer. Metallographical examinations revealed that both aluminum concentration and voidage in the Ni-Al lining layer show a graded distribution along the thickness direction of the layer. Such a porous structure is appropriate for a catalyst support used for high-temperature reactions.

Abstract: The solidification structure and hardness distribution in aluminum alloy duplex pipes produced by a two-step centrifugal casting have been investigated. In this process, two kinds of molten metals, i.e., the first melt and the second melt with a higher liquidus temperature were cast in sequence at a given interval into a rotating mold of a centrifugal caster. An Al-12mass%Si alloy was used for the first melt, and an Al-30mass%Ni or Al-32mass%Si-0.1mass%P alloy was used for the second melt. The second melt was cast after the solidified shell of the first melt had formed. The resultant cast pipes consisted of an outer side layer and a composite layer containing fine primary crystals. The outer side layer was a portion of the solidified shell of the first melt that survived after the contact with the higher-temperature second melt. The composite layer consisted of one or two layer(s). When the volume of the remelted part of the solidified shell was large, all the second melt mixed into the first melt and the resulted mixed melt formed the composite layer. On the other hand, the composite layer formed only from the second melt when the temperature of the solidified shell was low. In the intermediate case, the composite layer consisted of these two types of the layers.

Abstract: A microchanneling process utilizing microscopic reactive infiltration produces microchannels and alloy lining layers in metal bodies. We examined the composition and structure of a Ni-Al intermetallic lining layer with a peculiar porous structure produced by Ni-Al reactive infiltration. The Ni-Al lining layer is a thick film consists of multiple sub-layers and has many micropores. Such a porous structure and the heat resistance of Ni-Al intermetallic compound are appropriate for a catalyst support in high-temperature use. Image analysis and EPMA revealed that both aluminum concentration and voidage in the Ni-Al lining layer show a graded distribution along the thickness direction of the lining layer.

Abstract: Based on the relationship between quantified blurring degree of Kikuchi bands obtained by an electron backscattering diffraction (EBSD) technique and macroscopic strains measured by a strain gauge, the local compression strain SEBSD in sinter ore has been evaluated under various conditions. There is a good linear relationship between the SEBSD and the strains measured by a strain gauge. The local strain SEBSD evaluated by EBSD patterns can be used as an index of local strains.