Shinji Fukumoto

Bio: Shinji Fukumoto is an academic researcher from Osaka University. The author has contributed to research in topics: Welding & Heat-affected zone. The author has an hindex of 21, co-authored 87 publications receiving 1333 citations. Previous affiliations of Shinji Fukumoto include University of Hyogo.

Hydrolysis behavior of aluminum nitride in various solutions

Abstract: The AlN powder was immersed in deionized water, HCl aq, NaOH aq and H3PO4 aq to investigate their hydrolysis behavior at 283 to 373 K. The pH of the solutions were not varied at the initial stage in the case of deionized water, and they increased abruptly after the incubation time with evolution of NH3. Time until the evolution of NH3 decreased with increasing temperature. The hydrolysis at the higher temperature was different from at the lower. Below 351 K a crystalline bayerite was produced on the surface of AlN particle, while a crystalline boehmite was produced at higher than 351 K. The AlN powder was hydrolyzed more efficiently in HCl aq and NaOH aq compared with in the deionized water. While, H3PO4 aq restrained hydrolysis of AlN powder.

Friction welding process of 5052 aluminium alloy to 304 stainless steel

Abstract: Type 5052 aluminium alloy was joined to type 304 austenitic stainless steel via a continuous drive friction welding process. The joint strength increased, and then decreased after reaching a maximum value, with increasing friction time. Joint strength depended on the size and shape of the tensile testpiece. Friction weldability could be estimated by electrical resistmetry. The process of friction welding between the aluminium alloy and the stainless steel is proposed to evolve as follows: welding progresses from the outer to the inner region; an unbonded region is retained at the centre of the weld interface with shorter friction time; longer friction time causes the formation of an intermetallic reaction layer at the weld interface; and the reaction layer grows as the friction time increases. When the thickness of the reaction layer increased above a critical value, the joint was brittle and fractured at the weld interface. The joint was sound when there was no unbonded region and a thin reaction...

Surface modification of titanium by nitrogen ion implantation

Abstract: Nitrogen ions were implanted in high purity titanium at various doses. The nitride phase, TiN, was identified using either grazing incidence X-ray analysis or transmission electron microscopy. AES depth profile of nitrogen was altered from Gaussian-like to a rectangle with increasing nitrogen doses. Both dissolved nitrogen and tendency to form TiN increased precipitates with increasing nitrogen doses. These TiN precipitates that size were several tens of nm were observed at a lower dose. They grew larger as nitrogen dose increased. The dynamic ultra-microhardness rose to a thickness of within 200 nm of the surface owing to TiN formation, resulting in improved wear resistance of titanium. The wear volume was minimum at a dose of 5×10 21 N 2 + m −2 .

Laser Material Processing

Abstract: In the laser treatment of a workpiece (9), e.g. for surface hardening, melting, alloying, cladding, welding or cutting, the adverse effect of reflectivity of the surface, when a pure, monochromatic laser (6) is used, is remedied by the simultaneous application of a relatively shorter wavelength beam (1). The two beams (1)(5) may be combined by a beam coupler (4) or may reach the workpiece (9) by separate optical paths (not shown). The shorter wavelength beam (1) improves the coupling efficiency of the higher- powered laser beam (5).