Research on the method of enhancing the hydrophobicity of planar and cylindrical-curved ceramic by atmospheric pressure plasma jet

Atmospheric pressure plasma jet (APPJ) has unique advantage for treating materials with non-planar structure. Current studies mainly focus on the performance of plane surface, while the effect of surface geometry on the treatment method and performance requires to be further investigated. In this paper, comparative studies are carried out for the treatment of planar and cylindrical curved ceramic with APPJ to improve surface hydrophobicity. The Ar plasma jet was generated by nanosecond pulse power excitation, and the influence of treatment material shape on discharge characteristics was studied with discharge images and discharge voltage and current waveforms. The momentum PDMS was mixed with Ar to conduct hydrophobic treatment on the planar and columnar ceramic materials respectively. The treatment effects were compared and analyzed through the distribution of water contact angles on the surfaces under different treatment distance. The results show that the shape of the material has little effect on the discharge characteristics of the jet, and it is explained combining with the equivalent circuit model. The treatment effect shows that the material shape has a significant influence on the water contact angle distribution, where the plane is in a circular distribution, and the cylinder is in an elliptical distribution. When the processing distance is in the range of 10 20 mm, no matter the plane or cylindrical material, the super-hydrophobic treatment can be realized at the center position, and increasing or reducing the processing distance will make the treatment effect worse. In addition, when the treatment distance is 20 mm, the surface treatment effect is the best, as the super-hydrophobic treatment covers a larger region. This result can provide guidance for the application of atmospheric pressure plasma jet for non-planar material surface treatment.