Increasing the reliability of cylinder liners of marine diesel engines: problems and solutions

One of the main problems in reducing the reliability of the cylinder bushings of most diesel engines is the high wear rate of the working surfaces which leads to their premature failures. The article deals with the working conditions and peculiarities of the wear of cylinder liners of ship diesels. There are many methods to improve the wear resistance of cylinder liners of ship diesels which increases their service life from a few percent to several times. To increase the wear resistance and, consequently, the reliability of cylinder bushings, the following technological methods have been widely used: the creation of new materials for the production of bushings, the formation of optimum macro and microstructure parameters by honing, the laser hardening of the working surface, the application of antifriction coatings with flame spraying and galvanic chrome plating, and the formation of wear-resistant thin-film coatings by using tribotechnical materials of various types. All the existing methods of hardening (except for the use of tribotechnical materials) require the availability of technological equipment and significant material costs. For cylinder liners of ship diesels with high wear values, most methods of coating restoration and surface hardening are not very commonly used due to the considerable cost of the process (galvanic coatings) or the insufficient adhesion of the coating and the base metal (spraying methods). At present, a great deal of tribotechnical materials are used to harden friction surfaces by modifying and forming thin-film antifriction coatings on conjugated surfaces which, as a rule, exceed the wear-resistant coatings obtained with the use of the traditional technological methods of hardening. The most promising tribotechnical materials for additives to machine oils and tribomodification when repairing engine parts are the organo-inorganic compositions and composites based on the modified vermiculite.