Lubrication performance evaluation of Al₂O₃ /SiO₂ mixed nanofluid for minimum quantity lubrication in milling

Due to hybrid nanofluids having better thermophysical properties than fluid single nanoparticle, the cutting properties of 45 steel were studied with pure Al₂O₃, pure SiO₂ and different mass ratio of nanofluids for minimum quantity lubrication (MQL) milling. The results showed that hybrid nanofluids had lower milling force, contact angle and better micromorphology than pure SiO₂. However, hybrid nanofluids with different ratios of nanoparticles showed different lubrication effects. When the ratio of Al₂O₃ was less than that of SiO₂, SiO₂ were not completely covered by Al₂O₃ nanoparticles, so the lubrication effect was bad. With the increase of Al₂O₃’ proportion, the cutting force and contact angle were significantly reduced, and the surface quality of the workpiece was improved. When the mass ratio of Al₂O₃∶SiO₂ was 3∶1, the milling force, surface roughness and contact angle were the smallest, and the workpiece surface quality was the best. It could be seen that the content of Al₂O₃ affected the lubrication effect of hybrid nanofluids.