Because of natural combination of wear and aging, all industrial equipment gets damaged and eventually fails. Abrasion is the primary cause of such damage. To combat abrasion in sliding machine parts, heat treated and various surface coating methods are essentially applied. On the other hand, the abrasive wear may occur by the wear and foreign particles between sliding machine parts. The most cost effective way is the hard coatings such as TiN, Al2O3, diamond-like carbon (DLC). Of those, DLC has various advantages such as high levels of hardness, low COF, and low wear rates.
In this paper, to investigate the failure coated steel surface by hard particle and to design optimum coating conditions, a sliding contact problem DLC coated steel surface related to spherical particle, seal contact problem with particle and a three elastic body sliding contact problem modeled and analyzed using a nonlinear finite element code MARC.
Analysis was conducted in three steps.
The first analysis is contact problem between spherical particle and coated steel surface. The indentation and sliding of a particle can results in very high stress fields on the coated steel surface to the point that it will exceeded its yield strength, and produce plastic deformations such as groove and torus. The residual stress level and surface deformation are highly dependent on thickness and material of coating. In case that hard supporting layer is inserted between the DLC layer and steel substrate, the plastic deformation and the maximum principal stress on the coating surface are reduced. On the other hand, probability of crack caused by the high tensile stress within coating layer is increased.
The second analysis is O-ring and U-cup seal included a hard particle. It causes fatal damage on seal such as crack and nibbling. Especially when working pressure is increased and the particle size is small, the maximum von-Mises stress is increased.
The third analysis is a three elastic body sliding contact problem between seal, particles and steel shaft. As sliding of seal, the plastic deformation such as groove and torus occurred on the steel surface by the action of particles embedded in the seal. When there is multiple particles between seal and sealing surface, deformed shape of sealing surface is mainly determined by large particle.
Therefore, present coating type and contact model can be applied in design of various optimum coating systems, and further studies are required.