To investigate the corrosion behavior of the stainless steel joints brazed with nickel-based brazing filler metals in the heat exchanger, electrochemical measurement of SUS316L and filler metals were carried out. BNi-5 (Ni-Cr-Si alloy) and FP-613 (Ni-Cr- P-Si alloy) filler metals were prepared as nickel-based brazing filler metals. Corrosion potential, galvanic current and polarization curves of SUS316L, BNi-5 and FP-613 were measured in a 0.06 mol/L NaCl solution at 25℃ and 80℃. After the measurement, the microstructures of specimens were observed with an electron probe X-ray micro analyzer (EPMA). As a result, it was found that BNi-5 preferentially dissolves in the SUS316L joint with BNi-5 filler, and SUS316L preferentially dissolves in the joint with FP-613 filler in the NaCl solution. The EPMA analysis clarified that Si-rich Ni-Si-Cr-Fe phases and the Cr and P-rich phases preferentially dissolve in BNi-5 and FP-613, respectively.

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The purpose of this study is to investigate the effect of addition of trace Ni and Ge into Sn-6.4Sb-3.9Ag（mass%）lead-free solder on its mechanical properties using miniature size specimens. As the solder alloy in which trace Ni and Ge are added, Sn-6.4Sb- 3.9Ag-0.25Ni-0.003Ge（mass%）lead-free solder was prepared. Tensile test and fatigue test were conducted at 25℃ and 200℃. 0.1% proof stress and tensile strength of both solder increase with increasing strain rate and decrease with increasing temperature. Although tensile strength of both alloys are almost equal at 25℃ and 200℃, that of Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge is superior to that of Sn-6.4Sb-3.9Ag when the strain rate is 2.0×10-1 s-1. In contrast, elongation of Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge is inferior to that of Sn-6.4Sb-3.9Ag at 25℃. Furthermore, it was confirmed that the relationship between inelastic strain range and the number of cycles to fatigue failure obeys the Manson-Coffin equation and both alloys have excellent fatigue properties even at 200℃. From the results of electron backscatter diffraction pattern analysis, it was found that the crack grows at high angle grain boundaries with continuous recrystallization in Sn-6.4Sb-3.9Ag at 200℃. In Sn-6.4Sb-3.9Ag-0.25Ni-0.003Ge, the crack grows at grain boundaries formed by solidification.

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Nickel based alloy with corrosion and heat resistance characteristics is used for products which are required high temperature corrosion resistance such as industrial turbine machinery. With the large scale structures, nickel based alloy is used as overlay welding material in order to obtain its excellent characteristics. Moreover, for butt welding of Liquefied Natural Gas（LNG）tank wall, nickel based alloy is used as welding material for the sake of its low-temperature strength and toughness. Then nickel based alloy welding with 100% argon shielding gas gathers attention as not only securing toughness for cryogenic service products but also its high quality of welding metal. In the overlay welding to obtain the excellent characteristics of overlaid metal, it is required that the dilution of a base metal is low. In other word, it is necessary to weld suppressing the heat input. On the other hand, weld defect like lack of fusion caused by insufficient heat input must be avoided. And the wettability of beads is also the problem with low heat input. Therefore, the key technique of overlay welding is controlling the heat input properly. Duplex Current Feeding MIG（DCF-MIG）welding has the feature that controlling the wire feeding speed and the current（i.e. heat input）independently. In this study, the experimental study was conducted applying DCF-MIG to overlay welding using nickel based alloy welding material. As the experimental result, the characteristics of DCF-MIG using nickel based alloy welding material was clarified. And it was found out that the size of droplet was related to the shape of penetration. Furthermore, it is shown that DCF-MIG has an advantage on overlay welding.

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We have investigated factors affecting the energy balance of the anode and the bulb using a unified 2D numerical simulation model by changing the thermodynamic and transport properties（thermal conductivity and viscosity）for Xenon. The influence of the thermodynamic and transport properties on the arc voltage, temperature field, radiative efficiency and gas convective pattern and also the blackening location was examined. The thermal conductivity affected the thermal pinch effect on the arc. As a result, the energy balance of the anode is affected. The thermal conductivity and the viscosity affects the gas convective pattern, and then affects the transport of W vapor produced from the electrode. When the W thin film is formed at a position affected by the radiant energy emitted from the arc, heating of the bulb occurs locally. This indicates that by controlling the blackening position, it is possible not only to reduce the breakage risk, but also to suppress a decrease in the brightness of the lamp.

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