High temperature corrosion of coatings and boiler steels in oxidizing chlorine-containing atmosphere

High temperature corrosion tests were performed on ferritic and austenitic boiler steels, five high velocity oxy-fuel (HVOF) coatings, laser-melted HVOF coating, and diffusion chromized steel. Synthetic atmosphere simulating biofuel combustion was created for the tests. The tests were performed in oxidizing atmosphere containing 500 vppm HCl, 20% H2O, 3% O2, and Ar as a balance. The test temperature was 550 °C and the test duration was 1000 h. The corrosion resistance of steels was determined by alloy content. Homogeneous and dense coatings with high chromium content performed well and protected the substrate material. Corrosive species were able to penetrate through some of the HVOF coatings and attack the substrate via interconnected network of voids and oxides at splat boundaries.