A study of surface texturing of carbon steel by photochemical machining

Photochemical machining (PCM) was utilized to fabricate microtextures on carbon steel surfaces in this study. A series of experiments were carried out in the two stages of this process, photolithography and wet chemical etching. In the first stage, the influences of photolithography parameters, including spin coating speed, exposure time and development time, on the patterning of photoresist films were investigated, and the optimum process parameters were found. In the second stage, through a trial and error approach, it has been found that the mixture solution of HNO3:H3PO4:H2O = 8.5%:59.5%:32% (mass percentage) is a suitable etchant for the wet chemical etching of carbon steel. Based on the optimum results, the microtextures of circles and right triangles with different sizes were fabricated on the end faces of carbon steel discs. The variation of the end face profiles and etching depths of the microtextures with the etching time was studied. A prediction model of the geometry of the fabricated microtextures was proposed. Its accuracy was verified by comparison with additional experiment results, and its application scope was also discussed. It makes the precise control of microtexture profiles possible, and facilitates the use of precise microtexture profiles in the hydrodynamic lubrication analysis of textured surfaces.