Several types of surface treatments have been evaluated for their ability to inhibit the corrosion of archaeological iron. These are, octadecyltrimethoxysilane (ODTMS), CH3(CH2)17Si(OCH3)3, IH, 1H,2H,2H-henicosafluorododecyltrimethoxysilane (HFTMS), CioF2iH4Si(OCH3)3, decylamine (DCA), C10H21NH2, octadecylamine (ODA), C18H37NH2, and isopropyl-triisostearoyltitanate (TTS), CH3.CH.CH3OTi(0C0.C17H35)3. These molecules bind to corrosion product surfaces, forming hydrophobic layers. Evaluation of treatments has been carried out using accelerated corrosion tests at elevated temperature and humidity. Assessments have also been made using electrochemical monitoring, water adsorption isotherms, Fourier transform infra-red spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and floatation tests. A method of producing corroded iron coupons containing the chlorine containing corrosion products akaganeite, found on archaeological iron, has been devised. TTS was found to be the most effective treatment of those investigated. Amine treatments gave some inhibition, but were not as effective as TTS. Floatation tests showed that amines are easily hydrolysed and detached from iron oxyhydroxide surfaces and they therefore are not as effective as corrosion inhibitors. An anomaly was found in the behaviour of HFTMS which contrary to expectation actually accelerated the rate of corrosion. This has been attributed to 'pin' holes in the inhibitor coating which allows the formation of differential aeration cells, and thus accelerates corrosion. The success of the TTS treatment is attributed to the fact that each molecule contains three Cig hydrocarbon chains, providing a more densely packed hydrophobic surface. Further long term testing of the TTS treatment on archaeological iron is recommended. Several forms of polyaniline were synthesised and tested as corrosion inhibitors for archaeological iron. These were found not to be effective inhibitors for corroded iron, although they have been found to be effective on clean iron surfaces. This may be because they work as anodic inhibitors and therefore need to be in contact with the metal surface.

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This work represents an investigation of the corrosion behaviour of primarily high-grade alloys in marine environments. A range of marine conditions of varying severity has been considered and their effect on the electrochemical corrosion characteristics assessed. The study has utilised a range of electrochemical monitoring techniques, light and scanning electro microscopy and other surface techniques to assess the extent and morphology of corrosion attack under certain conditions. Principal components of the study include the effect of elevated temperature (up to 60oC) on corrosion initiation and propagation in static and high velocity impinging seawater. In addition, the effect of micro and macro fouling has been assessed using immersion tests and a hydrodynamic model. Continuation of the biological effects on corrosion looked at the effect of the presence and activity of Sulphate Reducing Bacteria (SRB) on corrosion mechanism. Correlations between accelerated laboratory tests and the real time behaviour of materials have been successfully made. Methods to counteract fouling often include the use of biocides and, in this study, the effect of high levels of hypochlorite dosing has been investigated. Mechanical and corrosion effects by liquid impact and by liquid-solid impact constitute a major part of this work and the use of electrochemical tests has enabled the proportions of weight loss on a given material attributed to corrosion, erosion and a synergistic factor to be elucidated. Several options exist to combat excessive deterioration due to mechanical wear. Two processes, shot-peening and laser irradiation, have been assessed primarily for corrosion resistance in a marine environment.

In this work an investigation into the effect of alloying additions (Mn, Cu, Sb and Zr) on microstructure and corrosion of Zn alloys and hot dip galvanised coatings was undertaken. The first part of this thesis focuses on the effect of alloying additions on the corrosion of Zn alloys. The result shows that Mn is the most beneficial addition, which can significantly improve the resistance of Zn. The effect of Cu depends on its concentration. A high level of Cu addition has a deleterious effect on the corrosion resistance as the Cu-rich particles are catalytic cathodic sites for oxygen reduction. Additions of Zr and Sb were found to have minor effect on the corrosion behaviour of Zn alloys. The effect of these additions on the microstructure of hot dip galvanised coatings was investigated in the second part. Both Zr and Mn can inhibit the layer growth of active steels with high Si content. Thus, Mn and Zr might be an alternative addition to Ni which can control the excessive reaction of the active steels. Addition of 0.8 wt % Cu significantly increases the coating thickness of the galvanised steel containing 0.02 wt % Si. The growth kinetics of the alloy layers follows a linear law. The final part of this thesis focuses on the effect of these additions on the atmospheric corrosion resistance and electrochemistry of hot dip galvanised coatings. Among the alloying additions investigated in this study, Mn is the most beneficial addition to the Zn bath and can significantly improve the resistance of the hot dip galvanised coating to atmospheric corrosion. The effect of other additions on corrosion resistance is minor. The beneficial effect of Mn addition is mainly due to the formation of a Mn-rich oxide layer on the top surface during the galvanising process, which can greatly inhibit the cathodic reactivity of the hot dip galvanised coating. Coupled with the relatively low cost and ease of alloying of this element, these various factors suggest that Mn might have broader applications in general galvanising.