start-ver=1.4 cd-journal=joma no-vol=20 cd-vols= no-issue=3 article-no= start-page=124 end-page=129 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250715 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Water Lubrication of Polysiloxane-Containing Polyimide Coatings on Stainless Steel Substrates en-subtitle= kn-subtitle= en-abstract= kn-abstract=This study investigated the water-lubricated tribological properties of coatings made of a novel polysiloxane-containing polyimide (si-PI) material that was recently developed for the aerospace industry and can be diluted with the harmless and environmentally friendly ethanol or water. The si-PI coatings were deposited on stainless steel (JIS SUS304) substrates at curing temperatures ranging from 160C to 275C. Their water lubrication properties were measured by rubbing the coatings against each other in water at room temperature. The coatings exhibited lower friction than conventional polyimide materials, with a minimum friction coefficient of 0.04, which was lower than that of polytetrafluoroethylene (PTFE) measured under the same sliding conditions. Unlike the conventional polyimide, the coatings did not exhibit any obvious wear or damage. The results demonstrate that the si-PI coating is a promising low-friction and highly durable coating for water lubrication. en-copyright= kn-copyright= en-aut-name=FanYuelin en-aut-sei=Fan en-aut-mei=Yuelin kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ShiotaTadashi en-aut-sei=Shiota en-aut-mei=Tadashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OmiyaYuya en-aut-sei=Omiya en-aut-mei=Yuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=FujiiMasahiro en-aut-sei=Fujii en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=polyimide kn-keyword=polyimide en-keyword=polysiloxane kn-keyword=polysiloxane en-keyword=resin coating kn-keyword=resin coating en-keyword=water lubrication kn-keyword=water lubrication en-keyword=wear resistance kn-keyword=wear resistance END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue=7 article-no= start-page=783 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190712 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Effect of Lubrication and Forging Load on Surface Roughness, Residual Stress, and Deformation of Cold Forging Tools en-subtitle= kn-subtitle= en-abstract= kn-abstract=Cold forging is a metal forming that which uses localized compressive force at room temperature. During the cold forging process, the tool is subjected to extremely high loads and abrasive wear. Lubrication plays an important role in cold forging to improve product quality and tool life by preventing direct metallic contact. Surface roughness and residual stress also greatly affects the service life of a tool. In this study, variations in surface roughness, residual stress, and specimen deformation with the number of cold forging cycles were investigated under different forging conditions. Specimens that were made of heat-treated SKH51 (59-61 HRC), a high-speed tool steel with a polished working surface, were used. The specimens were subjected to an upsetting process. Compressive residual stress, surface roughness, and specimen deformation showed a positive relationship with the number of forging cycles up to a certain limit and became almost constant in most of the forging conditions. A larger change in residual stress and surface roughness was observed at the center of the specimens in all the forging conditions. The effect of the magnitude of the forging load on the above discussed parameters is large when compared to the effect of the lubrication conditions. en-copyright= kn-copyright= en-aut-name=KarunathilakaNuwan en-aut-sei=Karunathilaka en-aut-mei=Nuwan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TadaNaoya en-aut-sei=Tada en-aut-mei=Naoya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=UemoriTakeshi en-aut-sei=Uemori en-aut-mei=Takeshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=HanamitsuRyota en-aut-sei=Hanamitsu en-aut-mei=Ryota kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=FujiiMasahiro en-aut-sei=Fujii en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=OmiyaYuya en-aut-sei=Omiya en-aut-mei=Yuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=KawanoMasahiro en-aut-sei=Kawano en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Zeno Tech Co., Ltd kn-affil= en-keyword=cold forging kn-keyword=cold forging en-keyword=high-speed tool steel kn-keyword=high-speed tool steel en-keyword=lubrication kn-keyword=lubrication en-keyword=residual stress kn-keyword=residual stress en-keyword=surface roughness kn-keyword=surface roughness en-keyword=tool deformation kn-keyword=tool deformation END