Fabrication of permanent self-lubricating 2D material-reinforced nickel mould tools using electroforming. (November 2021)

• Record Type: Journal Article
• Authors: Zhang, Honggang; Guan, Tianyu; Zhang, Nan; Fang, Fengzhou
• Is Part Of: International journal of machine tools & manufacture. Volume 170(2021)
• Publication Date: 2021-11
• Subjects: 2D material -- Mould tools -- Electroforming -- Self-lubrication -- Microfluidic chips; Machine-tools -- Periodicals; Manufacturing processes -- Periodicals; Machines-outils -- Périodiques; Fabrication -- Périodiques; Electronic journals; 621.902
• DOI: 10.1016/j.ijmachtools.2021.103802
• Languages: English
• ISSNs: 0890-6955

Abstract

Abstract: In the replication of polymeric micro/nano structures, adhesion and friction between mould tool and polymer cause significant feature failure. For the first time, this work developed a novel strategy for the fabrication of high-hardness and self-lubricating 2D material-reinforced nickel mould tools using electroforming to achieve high precision replication of polymeric micro structures. In this study, layered 2D material, including graphene oxide (GO), molybdenum disulfate (MoS2 ), and tungsten disulfide (WS2 ), for the fabrication of self-lubricating mould tools, were systematically studied. Our results demonstrated that nickel/WS2 mould tools, followed by nickel/GO and nickel/MoS2 mould tools, presented the most significant microhardness improvement. A maximum microhardness of ∼660 HV together with a minimum crystallite size of 12 nm was achieved from 0.5 g/L WS2, indicating a 3.67 times microhardness increase and 3 times crystallite size reduction relative to the pure nickel mould tool. The enhanced microhardness can be attributed to the 2D material-induced crystal refinement, and inherent hardness and incorporation content of 2D material. Additionally, friction and wear tests revealed that a low concentration of WS2 at 0.14 g/L achieved the lowest coefficient of friction (COF) and superior wear resistance. The COFs in the initial stage and steady state stage were 0.08 and 0.18, respectively, implying decreases of 42.8% and 72.3%, respectively, and a 27-fold increase in lifetime compared with those of the pure nickel mould tool. Such a significant improvement in tribological properties was due to the formation of self-lubricating transfer film by the interlayer shear effect of few-layered 2D material nanosheets. Finally, defect-free polymeric microfluidic chips were micro hot embossed using an optimal self-lubricating nickel/WS2 mould tool for validation. This work provides significant insight into the fabrication of potential self-lubricating micro/nano mould tools for microfluidics applications. Graphical abstract: Image 1 Highlights: Novel 2D material-reinforced nickel composite mould tools were fabricated by the electroforming process. Nickel/WS2 mould tools presented optimal hardness and friction coefficient of 660 HV and 0.18, respectively. The reduction of friction coefficient was related to the self-lubricating properties of 2D material. Nickel/WS2 mould tool achieved high-quality replication of microfluidic chips.