Properties of ceramic coatings in engine cylinder liners restoration using combined technology

In the course of vehicle operation with internal combustion engines, due to various reasons, defects occur on the cylinder mirror, resulting in the need for repair work to eliminate them. For non-cylinder blocks most often requires replacement with a new block, which is economically very costly. The technologies of liner restoration are very diverse and their application depends on the available equipment and material of the liner. The aim of the work is to develop a new combined technology for the restoration of liners and cylinder blocks regardless of the material for their manufacture. As a technology of restoration of the geometry of the mirror of the liner the method of cold gas dynamic spraying with the use of aluminum powder is considered. Subsequent application of the plasma electrolytic oxidation (PEO) technology makes it possible to obtain on the mirror a ceramic coating with thickness of 80-100 microns, which is sufficient for long-term operation of the internal combustion engine. On the basis of GZ-195N liner the technology of cylinder mirror restoration was worked out and the process of plasma electrolytic oxidation (PEO) was carried out. Research has shown that the hardening of the coating occurs to the depth of 100 microns required by the technology. The wear resistance of the coating exceeds the wear resistance of the reference sample, its wear factor is 1.27 times less than that of the reference pair. The possibility of using the technology of aluminum coating by cold spray on any metal makes the combined technology of cylinder liner repair applicable to achieve the desired result - to restore the performance of the cylinder block or liner and increase their wear resistance. The obtained positive results require the development of industrial technology of combined coating and experimental testing on a running engine.