The deterministic microasperities play a vital role in reducing the coefficient of friction and wear of thrust surfaces and improve the tribological properties of the surfaces. Deterministic microasperities have a specific pattern in terms of size, shape and spacing. These specified geometries are controllable and repeatable. The microasperities are micron scaled asperities and cavities on a surface that form the surface roughness. The present thesis shows the detailed process to fabricate the deterministic microasperities on thrust surfaces, i.e. stainless substrate, using micro-fabrication processes such as lapping and ultra-violet photolithography in combination with an electroplating (nickel) process. A Novel alignment technique is used to align the photomask with the substrate to get repeatable and aligned patterns on the thrust surface. Deterministic microasperities are characterized by using precision instruments such as an Optical profilometer, Scanning Electron Microscope (SEM) and Optical microscope to study the various surface parameters such as Average roughness (Ra), Root mean square value (rms) and Peak value (PV) of the thrust surface.

Previous experimental and theoretical results indicate that the keys to successful radial lip seals are the surface characteristics of the shaft and the microasperity pattern that develops due to wear on the elastomer. In this study, the lip seal was tested against five different patterns of shaft surface: plain stainless steel, triangular cavities oriented towards air, triangular cavities oriented towards oil, triangular cavities leading and triangular cavities lagging. Using Zygo optical profilometer and scanning electron microscope, a thorough surface characterization of the micro-asperities and microcavities is done on the lip seal elastomer. Correlation coefficients were calculated between the surface parameters of the final shaft surface and elastomer. Although both the surface characteristics of the shaft and the micro-asperities that develop on the elastomer sealing zone are responsible for a successful operation of the lip seal, the deterministic triangular micro-cavity patterns created on the shaft surface dominated the pumping direction with a large variability in the pumping rate. This variability is due to the elastomer wear in. This study also finds a significant correlation between the axial position of minimum roughness on the sealing zone of the elastomer and the pumping rate of the lip seals.