Study on tribological behavior, lubrication and anti-corrosion properties of W/O microemulsion for cold rolling of copper strip

Purpose The purpose of this paper is to improve lubrication and anti-corrosion properties of the water-in-oil (W/O) microemulsion for rolling of copper strip and sheet to replace the traditional rolling oil. Design/methodology/approach The W/O microemulsion is prepared by using hydrogenated base oil, a deionized aqueous solution of 0.03 mol/L of Na2SO4 and composite emulsifier such as Sp20, Tx-7 or sodium petroleum sulfonate. Tribological behavior of the microemulsions and traditional cold rolling oil was conducted by MR-10A four-ball tester. The lubrication performance of microemulsion for cold rolling of copper strip was performed by cold-rolling experiment. The morphology of worn surface and the rolled copper was characterized. Anti-corrosion properties of microemulsion for rolled copper was investigated, and the corroded surface was analyzed by X-ray photoelectron spectrometer (XPS). Findings The results show that the extreme pressure and antiwear properties of the microemulsions have been improved; the average friction coefficient of the improved microemulsion is 0.065, which is 30% lower than the commercial cold rolling oil. For cold rolling of copper strip, the microemulsion has a higher thinning effect than the commercial cold rolling oil, and a smooth surface is obtained and the surface roughness (Sa) is decreased by 6.8%. The XPS analysis indicated microemulsion adsorbed on the copper surface mitigate the corrosion of oils. Originality/value This paper used the prepared W/O microemulsion as a new lubricant in the process of rolling for copper strip and sheet in industry, demonstrating the microemulsion has broad application prospects in the future. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0227/