Abstract
The paper discusses the possibility of improving resistance of heat exchangers made of gray cast iron with flake graphite to hightemperature
corrosion by providing them with metallic coatings. A metallic coating containing 76.9% Ni, 19.8% Cr, 1.7% Si, 0.9% Fe, and
0.9% Mn was applied by means of the plasma spraying method and subjected to cyclically variable thermal loads in the atmosphere of
solid fuels combustion products (oxygen, sulfur, chlorine, and sodium). In a 30-day thermal load test held at temperature 500°C it has been
found that thickness of the metallic coating decreased from the initial (240 ± 6) μm to (231 ± 6) μm. The depth to which sulfur, chlorine,
and sodium penetrated the coating was about 30 μm. Increased oxygen content occurred along the whole coating depth. In the coating area
adjacent to the substrate surface, the content was twice as high compared to this observed in the initial coating material. Although presence
of oxygen was found within the whole depth of the coating, i.e. (231 ± 6) μm, no signs of susceptibility of the sprayed metallic layer to
separation from substrate of gray cast iron with flake graphite were found.
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