Adsorption and lubricating properties of HFBII hydrophobins and diblock copolymer poly(methyl methacrylate-b-sodium acrylate) additives in water-lubricated copper vs. a-C:H contacts. (October 2015)

• Record Type: Journal Article
• Authors: Hakala, Timo J.; Metsäjoki, Jarkko; Granqvist, Niko; Milani, Roberto; Szilvay, Géza R.; Elomaa, Oskari; Deng, Mengmeng; Zhang, Jianjun; Li, Feng
• Is Part Of: Tribology international. Volume 90(2015)
• Page Start: 60
• Page End: 66
• Publication Date: 2015-10
• Subjects: DLC -- Water lubrication -- Hydrophobins -- Tribology; Tribology -- Periodicals; 621.89
• DOI: 10.1016/j.triboint.2015.04.006
• Languages: English
• ISSNs: 0301-679X

Abstract

Abstract: In a metal forming process the adhesion between the workpiece and the tool needs to be minimised, which can be achieved by use of lubricants and coatings. Here adsorption and lubrication properties of HFBII hydrophobins and diblock copolymer poly(methyl methacrylate-b-sodium acrylate) in water-lubricated copper vs. a-C:H coating contacts were studied by Surface Plasmon Resonance (SPR) and by a pin-on-disc (POD) tribometer. Hydrophobins formed a dense monolayer film on a-C:H surface and reduced friction by 13–30% but increased the wear of copper compared to pure water lubrication. Poly(methyl methacrylate-b-sodium acrylate) formed a sparse lubricating layer compared to HFBII lubricated contacts, but the friction coefficient was lower. HFBII molecules prevented copper oxide tribofilm formation on the copper pin. Highlights: HFBII hydrophobins formed a dense monolayer film on a-C:H surface. HFBII molecules reduced friction by 13–30% compared to pure water lubrication. HFBII molecules increased the wear of copper pin compared to pure water lubrication. HFBII molecules prevented copper oxide tribofilm formation on the copper pin.