Experimental Investigation Into Micro-Textured Surface Generation by Through-Mask Electrochemical Micromachining

Abstract

Micro texturing with dimples is one of the most established methods for the enhancement of lubrication and tribological performance. In this work, a novel approach of through-mask electrochemical micromachining is instigated to fabricate high-aspect-ratio circular micro-dimples utilizing a low-cost photoresist (AZ-4903) as mask. Experiments were performed to understand the influence of the applied voltage along with the electrolyte type and concentration on the machining precision and surface characteristics of the generated micro array. The influence of three electrolytes has been studied and it has been experimentally established that 10% NaCl + 10% NaNO3 is favorable during maximization of the depth of the generated micro-dimples to 39.03 µm whereas undercut is minimized to 15.15 µm by utilizing 20% NaNO3. The surface quality of the generated micro-dimples has been found to be the finest, i.e. 0.062 µm, for the samples machined with 10% NaNO3. Patterned arrays containing micro-dimples having maximum depths of 30 μm, 35 μm, and 40 μm were successfully fabricated over a stainless steel (SS304) substrate by using these electrolytes with considerable accuracy and repeatability. The experiments confirm possibility to obtain high-aspect-ratio micro-dimples with the least degree of undercut using this technique. Further, friction test results were analyzed to figure out the alterations in the frictional coefficient of the micro-dimples with different depths as well as with non-dimpled samples.