High-temperature oxidation of intermetallics formed by group IV transition metals with chromium

We have studied the oxidation resistance of chromium intermetallics: TiCr₂, HfCr₂, and ZrCr₂, in the temperature interval 873–1473 K with isothermal holding of the specimens for up to 20 h. We have shown that the intermetallics TiCr₂ and HfCr₂ are oxidized 2–3 times more slowly than pure titanium and hafnium, but more than 1–2 orders of magnitude faster than chromium at T≤1273 K and 4–6 times faster at 1473 K. In this temperature interval, the intermetallic ZrCr₂ is rapidly oxidized at an increasing rate as the heating temperature rises. The scaling resistance of intermetallics of Group IV d metals with chromium is determined by formation of scales in which the major role is played by the oxides TiO₂, HfO₂, and ZrO₂, with weak protective properties.     

High-temperature salt and gas corrosion of refractory alloys based on nickel

We present the results of investigations of chloride corrosion and oxidation of refractory éP539 and éP99 nickel-base alloys. We established that the heat-resistance of these alloys is rather high up to a temperature of 1273 K, whereas, at a temperature of 973 K, the chloride corrosion proceeds intensively and has an intercrystalline character. Under the same kinetic conditions, the rate of chloride corrosion is greater than the rate of oxidation by two to three orders of magnitude. éP539 alloy is more resistant against chloride corrosion than éP99 alloy by a factor of 1.1–1.3, but the heat-resistance of the former is less than that of the latter by the same factor. Frantsevich Institute for Problems of Materials Technology, Ukrainian National Academy of Sciences, Kiev. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 36, No. 1, pp. 87–92. January–February, 2000.     

Distinctive features of corrosion damage to low-alloy chromium subjected to high-temperature salt corrosion

We study the influence of alloying elements (La, V, Al, Si) on the mechanism of interaction of chromium with NaCl and Na₂SO₄ salt melts at a temperature of 900°C. Alloying elements form chemically stable scales with enhanced adhesive properties and reduce the rate of salt corrosion largely due to a decrease in the share of grain-boundary damage.Institute of Problems in Materials Science, Ukrainian Academy of Sciences, Kiev. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 31, No. 2, pp. 103–108, March – April, 1995.     

High-temperature chloride corrosion of industrial ЭИ827 and BЖ-85 nickel alloys

High-temperature chloride corrosion (ChC) of ЭИ827 and BЖ-85 nickel alloys was investigated in a temperature range of 773 to 1173 K and exposure time of 1 to 50 h in the MgCl₂-KCl-NaCl ternary eutectic and oxidation in air (at 873 to 1273 K for 500 h). The ChC is intergranular, intensely develops starting from a temperature of 973 K, and results in softening due to the strong extraction of chromium and aluminum from the base alloy. Other things being equal, the ChC rate exceeds the oxidation rate in air by two to three orders of magnitude. Original Russian Text ? I.V. Oryshich, 2006, published in Zashchita Metallov, 2006, Vol. 42, No. 6, pp. 640–644.     

Evaluation of the Heat Resistance of Low-Alloy Chromium Alloys by the Parametric Method

We construct the parametric heat-resistance diagrams for low-alloy VKh-2K and VKh1-17A chromium alloys recommended for the production of units operating at high temperatures. These diagrams allow one to determine the increment in the weight of alloys at temperatures of oxidation of 1000–1400°C and holding of up to 1000 h and can be used as a bank of experimental data.