Question

Suggest and describe a process that can be used to artificially build up the protective oxide layer on the surface of aluminium. Describe one benefit of this process (other than corrosion protection) Two uncoated 70/30 brass plates are joined together using a 70/30 brass bolt. A small overlap area results. Suggest one possible type of corrosion the design may suffer from and describe the corrosion mechanism. Propose an improvement to the design to eliminate the risk of corrosion A welded austenitic stainless steel is found to suffer corrosion close to the weld area. Propose and describe a corrosion mechanism that is likely to be responsible for this. Suggest one way that may prevent this type of corrosion An anodic coating can be used as a coating for mild steel in order to protect it from corrosion. Explain the function of such a coating. Suggest one metal that can be used as an anodic coating and describe what will happen if the coating was to be damaged to expose the steel A 70/30 brass is exposed to wet and moist conditions. After a few months, the surface of the brass becomes spongy Suggest and describe the mechanism that led to this problem The Pilling-Bedworth ratio is used to assess whether a metal oxide is protective or not. By using the data provided, calculate the Pilling-Bedworth ratio for the tungsten (W)-tungsten oxide (WO) system (i) Atomic mass of tungsten -184 g.gmol Density of tungsten 19.25 Mg.m Molecular weight of tungsten oxide 232g.gmol Density of tungsten oxide 7.3 Mg.m3 (i) On the basis of the value of the Pilling-Bedworth ratio obtained above, assess the ability of WOs to be protective

Answer 1