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    Effect of water vapour on the high temperature oxidation of stainless steels
    (2020-01-01)
    Chandra-Ambhorn, Somrerk
    ;
    Wongpromrat, Patthranit
    ;
    Thublaor, Thammaporn
    ;
    Chandra-Ambhorn, Walairat
    This chapter primarily reviews the nature of water vapour when it presents in bulk gas. The change in a ratio between water vapour and corresponding dissociated hydrogen, which determine the thermodynamic stability of the oxide formation, is analysed when the oxidation kinetics are linear and parabolic. When water vapour reaches the solid/gas interface, chromium species volatilisation and oxidation controlled by surface reaction can occur. The adsorbed water vapour can be further incorporated into the oxide possibly in the form of hydrogen defects. The role of these defects on altering the defect structure of the oxide is discussed. Finally, characteristics of the oxide scale on stainless steels formed in the atmosphere containing water vapour are reviewed.
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    High temperature oxidation of stainless steels
    (2020-01-01)
    Chandra-Ambhorn, Somrerk
    ;
    Hayashi, Shigenari
    ;
    Latu-Romain, Laurence
    ;
    Wongpromrat, Patthranit
    This chapter is dedicated to the description of high temperature oxidation of both chromia and alumina forming alloys. The defect structures of iron and chromium are firstly reviewed. The effects of elements on stainless steel oxidation behaviour are further addressed. For the chromia-forming stainless steel, the oxidation rate is reduced with the increased silicon content but not in a monotonic manner. Titanium and niobium can reduce breakaway oxidation of Fe–18Cr–10Ni austenitic stainless steel. Titanium can enhance the adhesion of scale to the Fe–18Cr by mechanical keying effect of TiO2 formed at the steel/scale interface. For the alumina-forming stainless steel, the formation of alumina and its transformation during oxidation are reviewed. Chromium can be added to reduce the critical aluminium content in the steels in order to form alumina at high temperatures. The addition of reactive elements with appropriate level can improve scale adhesion and reduce the steel oxidation rate. Refractory element like molybdenum can increase strength of material but also accelerate the oxidation rate of the steels containing reactive elements. The development of new alumina-forming austenitic alloy grades is finally described.
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    Physical properties of Sn58Bi-xNi lead-free solder and its interfacial reaction with copper substrate
    (2015-12-05)
    Kanlayasiri, Kannachai
    ;
    Ariga, Tadashi
    The aims of this research are to investigate the effects of Ni on the physical properties of Sn58Bi-xNi lead-free solder, and to examine its interfacial reaction with the copper substrate. In the experiments, four concentrations of Ni (i.e. 0.05, 0.1, 0.5 and 1.0wt.%) were individually added into Sn58Bi and their respective microstructure, tensile strength, elongation, melting temperature, wettability and electrical resistivity of Sn58Bi-xNi were subsequently measured. The results indicated that Ni refined the microstructure of the solder matrix and induced the formation of Ni<inf>3</inf>Sn<inf>4</inf> intermetallic phase, and that the size and volume fraction of Ni<inf>3</inf>Sn<inf>4</inf> were positively correlated to the Ni content. The optimal concentration of Ni to enhance the tensile strength of the alloy was 0.1wt.%, but the elongation of the alloy was inversely correlated to the Ni content. The addition of Ni contributed positively to the melting temperature and wetting behavior of the alloy, whereas no significant change in the electrical resistivity of Sn58Bi-xNi was detected. In addition, Ni increased the thickness of the intermetallic layer at the interface, and only monoclinic η'-Cu<inf>6</inf>Sn<inf>5</inf> phase was present at the intermetallic layer. Nevertheless, the intermetallic phase of this research was dissimilar from the findings of existing literature.