Abstract
The objective of this study is to investigate the tribological behavior of graphene nanoplatelets (xGnPs) as nano-solid lubricants, and to evaluate their applicability to the micro-drilling of multi-directional carbon fiber-reinforced plastic (MD-CFRP). To verify the tribological effect of nano-solid lubricants, three kinds of xGnPs (xGnP C-750, xGnP M-5, and xGnP H-5), multiwall carbon nanotubes (MWCNTs), and hBN are compared by the ball-on-plate test. Of these, three xGnPs are selected as nano-solid lubricants to investigate the micro-drilling performance of MD-CFRP using nano-solid dry lubrication, and the experimental results demonstrate that all xGnPs can enhance lubrication action in terms of surface quality (delamination, uncut fiber, and inner surface) and tool wear. In particular, larger graphene nanoplatelets (xGnP M-5 and xGnP H-5) are superior to the smaller one (xGnP C-750) by guaranteeing enhanced sliding action between the tool grain and the CFRP composite.