Yoshinobu Takeda

Reduction mechanism of surface oxide in aluminum alloy powders containing magnesium studied by x-ray photoelectron spectroscopy using synchrotron radiation

We investigated the reduction mechanism of surface oxide on aluminum alloy powders containing magnesium, by x-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). The reduction is the initial reaction in a new aluminum nitridation method developed by one of the authors. In heating the powders to 823 K, magnesium soluted in the powders moves from the inner region to the surface at temperatures below 573 K, and finally, above 773 K, the magnesium reduces the aluminum oxide of powder surfaces by chemical reaction, which breaks the surface oxide films, and metallic aluminum appears on the topmost surface of the powders. These results suggest that the SR-XPS system is very useful for dynamic chemical reaction analysis of the surface via in situ measurement.

Thin film magnetic heads and substrates therefore

A novel thin film magnetic head is provided characterized by the use of a new substrate material excellent in mechanical property as well as machinability. This substrate is composed of a ceramic compact comprising 4 to 45% by volume of Component A, 55 to 96% by volume of Component B and at most 3% by volume of unavoidable impurities: Component A: at least one member selected from the group consisting of carbides, nitrides, carbonitrides, carboxides, oxynitrides and carboxynitrides of Group IVa, Va and VIa elements of Periodic Table and mixtures or solid solutions thereof. Component B: ZrO2 consisting of at least 70% by weight of tetragonal and/or cubic system and the balance of monoclinic system, in which at least one member selected from the group consisting of oxides of Group IIIa elements of Periodic Table, CaO and MgO, and mixtures thereof is dissolved to form a solid solution.

Process and properties of PM AL-Si-X alloys

The automotive, home appliance, and other civil industries need alloys which could replace cast iron and steel products. The alloys’ qualities should include high strength, wear resistance, high modulus of elasticity, low thermal expansion, good machinability, and good deformability. Rapidly solidified powder metallurgy (PM) Al-Si-X alloys provide such properties. The effects of rapid solidification make it possible to refine crystals, eliminate large intermetallic compound formation, and extend the solid solubility. However, these features are not thermally stable, and, therefore, the consolidation process condition is carefully optimized. This paper describes the process and properties of rapidly solidified PM Al-Si-X alloys.

Rotary car air conditioner made with PM AlSi wrought alloys

Abstract Sumitomo Electric Industries has developed PM AlSi wrought alloys with high strength and high wear resistance for use in the rotors and vanes of rotary car air conditioners. In addition, combined with the development of near-net-shape extrusion technologies, through a joint project with Diesel Kiki Co Ltd, it has succeeded in the worlds first mass production of rotors made of PM aluminium wrought alloy. In this paper, the properties and production technology of vanes and rotors made with PM AlSi wrought alloys are presented.

Mechanical Properties of rapidly solidified aluminium alloys

Abstract Aluminium is often selected for use in applicationssuch as aerospace where lightweight is important. However properties, like strength at room and elevated temperatures are inferior to those of steel. The possibility of improving the mechanical properties of aluminium by rapid solidification processing has been investigated. In this paper, the properties of two kinds of powder made by rotating disk atomization and conventional air atomization and alloys made from these powders were evaluated and compared. The causes of the differences in the two kinds of materials were then investigated.

High Density Sintered Stainless Steel

At present, most stainless steel materials are sintered at high temperatures to achieve the desired mechanical, corrosion and high-temperature properties through densification. Although this method of processing achieves the desired properties, the resulting dimensional change can be difficult to control. A potential alternative to reduce the amount of densification required would be stainless steel powders with higher compressibility, which can reach higher green densities at reasonable compaction pressures. The purpose of this paper will be to compare different techniques to attain the desired sintered properties. The mechanical properties and green and sintered densities reached with these techniques will also be discussed. Introduction The automotive industry’s increasing interest in using stainless steel P/M parts emphasizes the property requirements for the powder materials used. For many of the produced components, the density required to achieve satisfactory corrosion and high-temperature properties is a minimum of 7.2 g/cm, [1] [2]. To achieve these kinds of densities, elevated sintering temperatures (above 2280°F / 1250°C) are necessary. One way of reaching higher sintered densities, and thus better mechanical properties, is to increase the compressibility of the powder. An effective way of doing so is by warm compaction, a technique already shown to increase compressibility of stainless steels with about 0,2 g/cm, [3]. Another advantage with the warm compaction technique is that, in general, it creates an even density within the component, [4]. This indicates a possibility for manufacturing high-density P/M stainless steel components, e.g. exhaust flanges or HEGO bosses, with close tolerances. The paper is divided in to two studies. In study 1 warm compaction is compared to conventional when using the same process parameters in order to reach high densities. The material used for this study was ferritic stainless steel 409L. Study 2 compares warm compaction to two other methods of reaching a sintered density of 7.2 g/cm with austenitic stainless steel 316L powder. Study 1: Warm compaction of 409L The powder used for this study was as-atomised 409L with a particle size <150μm. This material is commonly used in the production of exhaust flanges that require a sintered density of >7,2 g/cm. The theoretical density of the material is around 7,7 g/cm. To obtain the required density, conventional compaction followed by densification with high temperature sintering is common practice. The composition of the material is shown in table A.