Metal-ceramic composite coatings today predominate in most diesel engine applications as armoring for the running face of piston rings.  The MKP 81A coating is used particularly successfully in different applications subject to increased risk of scuffing.

• Compression rings
• Technological properties: High wear resistance, low cylinder wear and enhanced thermal loading capacity
• Coating material: Powder composed of molybdenum and hard material
• Coating application process: Plasma spraying
• Chemical composition of the coating (%): Mo: 67-77, Ni: 16-24, Cr: 3.0-7.0, C: 0.5-2.0
• Hardness of coating: Average 370 - 860 HV 0.1
• Strength: minimum 35N/mm²

In order to improve the wear resistance and tribological properties of the rings, different coatings have been used on running surfaces for many years. Galvanic coatings, thermal coatings and PVD coatings are used.   Spray coatings on piston rings in the top groove are preferred to hard chromium plated rings above all when engines - chiefly diesel engines - are subject to increased risk of scuffing. Materials deposited by a spray process can better withstand this adhesive wear caused by direct metal-to-metal frictional contact, as in some cases they have a very high ceramic content.  Metal-ceramic composite coatings today predominate in most applications as armoring for the running face of piston rings in diesel engines, while molybdenum coatings are now only used occasionally because of their comparatively low wear resistance. The plasma spraying process is still largely used when manufacturing metal-ceramic composite coatings. The MKP 81A coating is successfully used in a variety of applications.