Wetting of Cu-SiC Composite Material Modified by Nanosecond Laser Radiation and Liquid Spreading over It

Abstract

In the framework of this work, the surface properties of Cu-SiC composite material were studied when spreading micro- and nanoliter liquids. The Cu-SiC samples with a SiC content of 5 to 20 wt.% were fabricated by spark plasma sintering at temperatures from 700 to 850 °C. The Cu-SiC surfaces were processed by two different methods: using abrasive materials and nanosecond laser radiation. Surface analysis was performed by scanning electron microscopy, profilometry, energy dispersive spectroscopy and Vickers methods. The surface properties (wetting and dynamic characteristics of spreading) were studied using a shadow optical technique when interacting the Cu-SiC surfaces with water (up to 10 μL). It was proved that the recorded deterioration of the wettability properties of Cu-SiC surfaces processed by abrasive materials with an increase in their sintering temperature and the reason for the spontaneous hydrophobization of the Cu-SiC composite materials modified by nanosecond laser radiation, are due to the adsorption of airborne hydrocarbon contaminants, similar to the known wetting inversion of metal surfaces. It was established that the wetting properties of materials prior to modification by laser radiation do not affect the intensity, duration of stages, and steady-state values of contact angles upon wetting inversion of Cu-SiC composite materials. It was also found that the processing of Cu-SiC surfaces by laser radiation makes it possible to change the dynamic characteristics of the liquid spreading (at a flow rate of 5 μL/min, the liquid front speed is more than three times, and the dynamic contact angles are in the range of 30°).