Investigations of corrosion resistance of Fe-, Ni- and Co-based hardfacings

In the present paper, the potential of surface coatings to increase corrosion of internal combustion engine valves is discussed. The corrosion tests were carried out to study in simulated engine chamber environment the performance of Ni-, Co- and Fe-based materials used for plasma deposition. Hot corrosion tests were performed in air, sulphur dioxide containing atmosphere and in molten synthetic ash. The crucible-sorting test was used to simulate deposits on valve seats from residual fuel combustion which are responsible for rapid corrosion due to the presence of molten phase. The new alloys containing Ni and Co can be potentially applied as valve hardfacings.