Robert H. Heidersbach

Raman Spectra of Possible Corrosion Products of Iron

Raman spectra of FeO, Fe3O4, α-Fe2O3, α-FeOOH, and γ-FeOOH, the common products of iron oxidation, have been measured. The spectra of FeO and Fe3O4 appear to be identical. Armco iron oxidized in air at 250°C was examined by Raman spectroscopy after varying periods of exposure and the surface film was found to contain Fe3O4 and α-Fe2O3.

Raman and Infrared Spectroscopy of Aqueous Corrosion Films on Lead in O. 1 M Sulfate Solutions

Abstract : This report contains the manuscript of a paper submitted for publication in the Journal of the Electrochemical Society. The Pb-H20-SO4 pourbaix diagram was investigated by examining potentiostatically oxidized lead samples using Raman and infrared spectroscopy. In 0.1 M sulfate solutions surface film compositions were not in complete agreement with predictions of the calculated potential -pH diagram. The Pourbaix diagram did not predict the formation of PbO under any conditions; however, spectra indicated the presence of the oxide at certain potentials in acid and neutral solutions and at all potentials above the immunity region in basic solutions. Spectroscopic identification of insoluble surface species was in agreement with potentiodynamic polarization curves.

The Oxidation of Fe3O4 on Iron and Steel Surfaces

Abstract Infrared and Raman spectroscopy were used to study the oxidation of Fe3O4 on surfaces of weathering steel, carbon steel, and pure iron. Two sets of samples were polished and coated with an Fe3O4 paste. One set was moistened daily with distilled water and allowed to freely dry in air. The second set was treated in a similar manner except that every other day, a 0.1M Na2SO4 solution was used in place of the distilled water solution. In the set of samples treated only with distilled water, Fe3O4 was oxidized to γ-FeOOH on both the weathering and carbon steel surface, but oxidation of Fe3O4 was not observed on the pure iron surface. On all of the samples treated with 0.1M Na2SO4, Fe3O4 was oxidized initially to γ-FeOOH which converted to α-FeOOH after several weeks. The initial oxidation of Fe3O4 is proposed to occur by a reaction with H2O2 produced from the reduction of O2.

The Use of Infrared and Raman Spectroscopy to Study Corrosion Inhibitors on Metal Surfaces

Abstract Infrared and Raman spectroscopy have been used to study the effects of three organic inhibitor solutions on iron. Unique infrared and Raman spectra were obtained for each solution. Infrared spectra of surface films in the fingerprint region are different from one inhibitor to the next, and they are also dependent upon the pH of the applied solution. Spectra of films on iron formed from all three inhibitors suggest the presence of polymeric-like materials which are possibly chemically bonded to the iron surface.

Cathodic Protection Of Stainless Steels Against Crevice Corrosion

Crevice corrosion on stainless steel instrument components has been a problem affecting designers and operators of marine instrumentation packages for many years. A cathodic protection study of preventing crevice corrosion on stainless steel Types 316 and 17-4 PH was performed in flowing filtered seawater. Aluminum and low carbon steel anodes were used on the stainless steel panels installed with Delrin crevice-nut assemblies with both bare and partially painted panels. Results are presented in terms of percentage of crevice sites attacked, crevice pit depth, and separate metal rest potentials. Stainless steel Types 316 and 17-4 PH are frequently used in many sections of the marine environment. They are susceptible to both crevice corrosion and hydrogen embrittlement. This paper presents information to the designer about effective methods of preventing crevice corrosion in seawater without the risk of hydrogen embrittlement. Both the aluminum and steel anodes prevented crevices corrosion at all sites. Rest potentials indicate that the aluminum anode samples present the risk of overprotection and hydrogen embrittlement. Comparison with previous data demonstrates the effects of dissolved oxygen on the crevice corrosion severity of attack.

Morphology of Calcareous Deposits Produced on Cathodically Protected Steel in the Deep Ocean

Corrosion control of stationary offshore structures is accomplished by means of cathodic protection. The electric currents of the cathodic protection system cause the deposition of minerals on the submerged metal, and this mineral coating becomes the primary source of corrosion control. The results of a laboratory study of the effect of hydrostatic pressure on the minerology of deposits formed under cathodic protection conditions on carbon steel are presented. In deep ocean waters, the primary deposits are of magnesium minerals and calcareous deposits, if any, are secondary.

The Effects Of Sea Water On The Structural Properties Of Metal-Fiber Reinforced Concrete

Metal-fiber reinforced concrete is a structural material with several unique advantages for offshore applications. This paper describes a series of exposure tests undertaken to evaluate the suitability of metal-fiber reinforced concrete for marine applications. Corrosion exposure tests and freeze-thaw tests are discussed. (Copyright (c) 1978, Offshore Technology Conference.)