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Abstract: Scratch testing has been well applied towards the adhesion and failure testing of thin, hard ceramic coatings upon numerous different types of substrate materials. It is common that the test sample is scratched with a contact tip that will not easily deform, such as a Rockwell C diamond tip. Such tips are often not relevant to real, industrial cases, in which the materials of the two counter surfaces are both subjected to some degree of wear. The present paper describes the use of a scratch tester with a newly developed steel wire sample geometry replacing the conventional diamond tip, and the results of the effect of increasing load, loading rate and lubrication may have upon an industrially relevant nodular cast iron versus steel wire contact scenario. [Copyright &y& Elsevier]

Abstract: It has been demonstrated that tetrahedral amorphous carbon (ta-C) films provide excellent wear and friction properties in dry sliding. Recently the applications of ta-C coatings in lubricated conditions have become more important. The use of carbon coatings aims at reducing the wear and coefficient of friction under minimum lubrication and without hazardous lubricant additives. For optimum tribological performance, a modification of the ta-C coated surfaces is required. The present paper describes an innovative method of coated surface texturing, by which nanometer and micrometer size pores are processed by various methods. Particle masking was used for processing micrometer size pores and for controlling the coating growth conditions in order to produce nanometer size pores in the ta-C surface. The masking by particles yielded a pore geometry which varied from complex shaped channels to small individual pores. The texturing was performed by distributing metallic powder particles on the surface or by direct chemical deposition of metal particles on the substrate in prior to pulsed vacuum arc deposition. The tribological characterization was carried out by applying reciprocating friction tests with controlled lubricant replenishment, in order to simulate metal forming processes. The friction reducing effect, which was observed in the tribological tests, indicated a microlubrication effect of the textured coating surfaces. [Copyright &y& Elsevier]