Quality improvement of deteriorated cutting fluid treated by atmospheric-pressure plasma jet and in-liquid plasma

抄録

In this study, we proposed a sterilization technique for cutting fluids using plasma treatment under atmospheric pressure and in-liquid and investigated the characteristics of sterilization and the fluids’ surface properties (e.g., wear resistance and wettability). The results show that the number of bacterial colonies in the fluid sterilized by atmospheric-pressure plasma and in-liquid plasma was reduced by more than 90% compared with the number in the untreated fluid. The lubricating properties of the plasma-treated cutting fluids were well improved compared with those of the untreated fluid, as determined from a comparison of the results of specific wear rate tests. The adhesive energy of the plasma-treated cutting fluids was greater than that of the untreated fluid, as revealed by the results of sliding angle measurements. However, the adhesive energy decreased over time; that is, the duration of the effect was limited. The results of this study demonstrate that the life of a cutting fluid can be prolonged by plasma treatment, with an associated improvement in the fluid’s tribological properties. This research can help reduce the frequency of maintenance required for coolants used in cutting applications.