High-Temperature Gas and Salt Corrosion of Nickel Alloy

The article presents the results of high-temperature gas and salt corrosion of a heat-resistant nickel alloy on an automated installation at temperatures of 750 and 850°C, a gas flow velocity of 270 m/s, and the supply of synthetic sea salt or a mixture salts of Na₂SO₄–NaCl (at a ratio of 3 : 1) as corrosive-active agents. It has been established that, with an increase in the number of heating/cooling cycles and the temperature of corrosion tests, the nickel alloy damage increases. As a result of corrosion tests when supplying an aqueous solution of synthetic sea salt and at temperature of 750°C, it was established that formation takes place of micrograined layers of magnesium oxides, which are products of thermohydrolysis of MgCl₂, on the surface sample of the nickel alloy. When the test temperature increases to 850°C, the process of thermohydrolysis of sea salt components is accompanied by the formation of oxide deposits with an abnormally high cobalt content. The increase in cobalt content in oxide deposits is caused by the action of the sea salt component NaCl. It has been established that a mixture salts of Na₂SO₄ and NaCl has the greatest negative effect on the alloy than salt corrosion caused by the action of synthetic sea salt. At the same time, the areas of intense corrosion were observed on the alloy surface and thinning-out of the sample working part due to spalling of brittle oxide deposits.