NEW COATINGS AND FINISHING METHODS FOR TOP PISTON RINGS OF DIESEL ENGINES TO REDUCE FRICTIONAL LOSS AND TO ENSURE ADEQUATE BEHAVIOUR UNDER MOST DIFFICULT REGIMES OF OPERATION

Abstract

As a part of a most comprehensive research wok, the present paper is enhancing the role of a rightly chosen and realised coating and finishing for the top piston ring sliding surface to diminish friction and wear, to ensure adequate resistance to its ever harder operating conditions, and to prolong its life in the couple cylinder-piston ring. Composition, hardness, crystalline structure and orientation, resistance to scuffing, wear, and, most of all, to peeling-off tendency, are important characteristics to be analysed and solved with the coating of the top piston ring. New finishing methods are also required for the piston ring active surface to generate extra oil micro-reservoirs to ensure a minimum oil film under the worst operating regimes(o avoid in any case, metal-to-metal contact that is characterized by importantly increased frictional loss and worsened functioning).