Effect of oil quality on in vitro embryonic development in the bovine

Abstract

Sub-melting point hot corrosion is referred to as the hot corrosion occurring at temperatures well below the melting point of the original salt deposit. From the point of view of the melts formed, two types of sub-melting point hot corrosion are often encountered. One is related to the formation of a binary or ternary sulphate resulting from sulphation of the base metal oxide. The other is associated with the formation of a melt by the reaction between some refractory metal oxide and the sulphate deposit.The phenomena and mechanism of sub-melting point hot corrosion of nickel and cobalt base alloys including MCrAlY coatings (namely low-temperature hot corrosion or Type II hot corrosion) caused by an Na2SO4 deposit are reviewed. The sub-melting point hot corrosion of iron, AISI 304 stainless steel, and FeCr alloys caused by a K2SO4Na2SO4 deposit is reported and its mechanism is proposed in the light of which the hot corrosion is attributed to the dissolution of iron as cations at the oxide-melt interface and precipitation of Fe2O3 as porous particles at the melt-gas interface. The hot corrosion behaviour of B-1900 alloy in the presence of an Na2SO4 coating was studied at 827 °C as well as at 750 °C, and the alloy was found to experience catastrophic oxidation in this case. The experimental results lead to a proposition that MoO3 (probably as Mo2O72−) takes part in the reduction reaction. The sub-melting point hot corrosion of a number of superalloys containing molybdenum coated with CaSO4 has been studied. The resistance to sub-melting point hot corrosion of CoCrX (X ≡ Si, Hf or Y) coatings and aluminium and chromium diffusion coatings is briefly discussed.