High Temperature Corrosive Environment in a Sintering Plant for Pig Iron Production and Its Effect on Different Steel Grades
The harsh environment in a sintering plant for pig iron production leads to high temperature corrosion of the sinter grates. In the present study, a detailed analysis of the corrosives in such applications is given to understand materials failure. Various steels are tested, revealing effects of various alloying concepts, the resulting phases and their corrosive behavior in this complex corrosive environment at ≈900 °C. In order to understand the underlying corrosion mechanisms, detailed analyses are performed. Results indicate mainly chlorine, sulfur, and oxidation based corrosive decay at elevated temperature and a high relevance of protecting alloying elements within the steels.
High temperature corrosion studies of cermet particle reinforced NiCrBSi hardfacings
Abstract Metal matrix composite hardfacings provide various types of heat and wear resistant products. They are widely used in high temperature aggressive environments due to their excellent high temperature corrosion and wear resistance. In this study, Cr3C2–Ni and TiC–NiMo particles were used to reinforce a NiCrBSi matrix in plasma transferred arc welding process. These cermet particle reinforced hardfacings were examined on their oxidation behaviour and high temperature corrosion in different solid salts to optimise the field of application under high temperature conditions. Corrosion behaviour in solid salts is strongly dependent on the corroding anion. Cr3C2–Ni reinforced hardfacings behave better in oxidative and sulphate/phosphate environment, while TiC–NiMo hardfacings show better resistance against chlorine and carbonate ions up to 700 °C. Additionally, oxidation is no critical exposure for these types of hardfacings.
Recalculation of Mass Defects
THE well-known mass defect curve of the old nuclear scheme calculated with regard to α-particles and protons presented a difficulty with its minimum of binding energy for tin and an increasing portion between tin and lead. On the other hand, the mass defect values against protons give a rather smoothly decreasing curve.1 As has already been pointed out,2 the number of α-particles must be considerably reduced from the point of view of the new scheme, which does not admit any electrons in nuclei, but only neutrons and protons (presumably joined as α-particles). The curve of mass defect against protons and neutrons (perhaps with a single ‘central’ α-particle) is very similar to the old curve against protons, but decreases less rapidly. Clearly the new mass defect values relatively to α-particles, neutrons and protons must lie somewhere between the old values computed relative to protons and α-particles respectively (because the number of α-particles is decreased). We may emphasise that this new mass defect curve shows no increasing portion between tin and lead. For illustration we give two typical values: Old: 50Sn124 = 31α + 12&#38;epsiv;; mass defect = 0.158 (in mass units); 82Pb208 = 52α + 22&#38;epsiv;; mass defect = 0.035. New: 50Sn124= 25α + 24ω (ω = neutron); mass defect = 0.304; 82Pb208 = 41α + 44ω; mass defect = 0.366.