Improvement of Corrosion Resistance of Type 420J2 Martensitic SLaser thermal Processing Y. Tsutsumi 1, T. Manaka 2 M. Goto3, M. Kadowaki1, T. Ishimoto2 and H. Katayama1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) 2 Aluminum Research Center, University of Toyama 3 Fuji High-Frequency Co., Ltd. The laser thermal processing was utilized to improve the corrosion resistance of martensitic stainless steel. Type 420J2 stainless steel plate was prepared and the steel surface was subjected by laser irradiation to form partially-remelted and recrystallized layer. The top surface showed roughened and dull-colored morphology due to thermal oxidation just after the processing. Newly-formed inner remelted and recrystallized layers was found under the outermost oxidized film. The depth of the two layers was about several hundred micrometers and they showed excellent corrosion resistance in chloride containing testing solution. In addition, the Vickers hardness of both layers were much higher than that of untreated steel. Therefore, laser thermal processing was found to realize both hardening and corrosion resistance improvement for martensitic stainless steels. Low-Temperature and Non-vacuum Surface MBonding A. Shigetou 1 and N. Hosoda 1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) For the social implementation of automatic traffic control using the mobile IoT (Internet of things), the use of terahertz-band electromagnetic waves, which are tolerant to the ambient environment, is expected to increase. For this purpose, device substrates and structural materials must be assembled (bonded) individually all at once. Such hybrid bonding should be obtained without high temperature and a vacuum atmosphere, and the method must be industrially simple. Particularly for the use of organic materials, anti-hydrolysable reliability is required. Given heat-resistant resin such as polyimide (PI) and metals such as Cu and Ti as typical materials for forming such hybrid bodies, the key issue is achieving a pseudo-hydrophobic interfacial bridge layer. For organic materials, the surface had to be hydrophilized to form an adhesion layer. However, hydrophilic surfaces degrade the interfacial reliability by hydrolysis reactions. One of the most promising candidate structures is the alkyl chain carrying hydroxyl- (or amine-) only at the ends. For this, we developed a vapor-assisted vacuum ultraviolet (V-VUV) surface modification method. This method uses VUV irradiation in a nitrogen atmosphere, including vapor of chemical solvent’s vapor. The radical species, obtained by dissociating vapor molecules, help generate ultrathin bridge layers. In this study, the growth conditions of the bridge layer were optimized using Xray photoelectron spectroscopy (XPS). Then bonding experiments were performed in various combinations of materials. For the bonded interfaces, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) analyses were carried out. Poster Presentation ｜NIMS Award Symposium 2023odification for Anti-Hydrolysis Hybrid P1 ｜ Processtainless Steel by PP11--0055 PP11--0066 37
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