Research on the wettability of localized pulse electrolytic machining mold steel (GCr12)

As one of the most widely used metal materials, steel takes on an important role in deep sea and space exploration fields. However, the annual economic loss caused by steel corrosion is immeasurable. To resolve the problem, the localized pulse electrochemical machining (PECM), an efficient, fast and environment-friendly method, was introduced to fabricate microstructures on the surface of mold steel (GCr12). Results show that a super-hydrophobic surface has been obtained and its corrosion resistance has been significantly enhanced without the need to modify the surface by low surface energy solution. Thanks to the optimal working parameters (7.9 V and 2 ms) identified from the processing, the water contact angle of 161.8° was obtained. After fabrication by PECM, the surface microstructure, chemical element, and wettability were characterized and analyzed by scanning electron microscope (SEM), laser scanning confocal microscope (LSCM), EDS energy spectrometer, and optical contact angle measuring instrument, respectively. According to the experimental results, the surface honeycomb structure (micro/nano binary structure) is proven to be the main factor affecting wettability. Next, durability tests and corrosion resistance tests were carried out and the contact angle decreased by 4.4% and 6.7% respectively compared with the original contact angle, indicating that the surface after PECM has strong durability and good corrosion resistance, which can effectively solve the corrosion problem of steel. Therefore, using localized PECM technology to prepare microstructure on the surface of mold steel has a good application prospect in industry.