Corrosion and abrasion of rings and liners from marine diesel engines using residual fuel
The aim of this research was to investigate the interaction of abrasion and corrosion on rings and liners from marine diesel engines using high sulphur residual fuels. Pure corrosion effects were simulated in a sealed vessel containing emulsified lubricant and acid. Graphite was found to stimulate corrosion of ferrite but phosphide eutectic and iron carbide remained unattacked. A reciprocating test was used to combine the mechanisms of abrasion and corrosion which have been identified as producing normal wear in marine engines. The severity of the mechanisms were balanced to produce surfaces similar to those often encountered over the centre of an engine stroke. Two engine tests, specified to compare the type and extent of wear using high and low sulphur fuels, showed that an increase in corrosion resulting from increased fuel sulphur was not directly responsible for a measured increase in top ring wear rate. Corrosion was thought to dissolve the ferritic phases to release hard phases into the system which intensified abrasion of the surfaces. It was also possible that phosphide eutectic was left at a sufficiently high level above the surface by corrosion of the matrix to cause direct abrasion of the ring. Throughout the experimental work particular emphasis was placed on examination and interpretation of the interaction of corrosion and abrasion in lubricated acidified environments.