Surface chemical analysis steel

Rust samples scraped off from exposed AISI 1019 steel surfaces were ground to fine size in a morter with a pestle. A fraction of the samples was subjected to a salts extraction process using distilled water to determine the concentration of most common ions by chemical analysis and to study changes in adsorption isotherm after elimination of hygroscopic salts. Samples were obtained from AISI 1019 steel coupons, exposed for up to six months at coastal and rural locations. 

The pipe joint had been leaking steam and water prior to the failure, and chemical analysis of the scale deposits on the clamp surface after the failure confirmed the presence of a number of sodium-based mineral compounds from the leaking steam, including approximately 10% sodium chloride. The presence of high concentrations of moist, hot chloride salts on the highly stressed austenitic stainless steel surface, particularly with concurrent exposure to atmospheric oxygen, created an ideal chloride stress-corrosion cracking (SCC) environment. 

Reflection-Absorption Infrared Spectroscopy (RAIS) operating at the grazing-angle which is one of the most powerful resonance absorption phenomenon and is the most sensitive optical absorption technique available for measuring low concentrations of chemical componnds adhered to surfaces and even allows for the non-destractive mono layer chemical analysis on the surface. Figure 6 shows the FOC-GAP-FTIR spectra 5 and 10 ug/cm 2-CEES deposited as a trace residue on stainless steel surface. It is clear from the spectra shown that low limits of detection (LOD) achievable could be as low as nanograms/cm (milligrams/m ). 

Another theory claims that a protective complex between the metal and the CP is formed in the metal-polymer interface. Kinlen et al. [73] found by electron spectroscopy chemical analysis (ESCA) that an iron-PANl complex in the intermediate layer between the steel surface and the polymer coating is formed. By isolating the complex, it was found that the complex has an oxidation potential 250 mV more positive than PANI. According to Kinlen et al. [73], this complex more readily reduces oxygen and produces a more efficient electrocatalyst. 

Improvement in oxidation resistance of iron by alloying with aluminum or chromium probably results from a marked enrichment of the innermost oxide scale with respect to aluminum or chromium. The middle oxide scales are known, from chemical analysis, to be so enriched, and electron-microprobe analyses confirm marked enrichment of chromium in the oxide adjacent to the metal phase in the case of chromium-iron alloys [52]. These inner oxides resist ion and electron migration better than does FeO. For chromium-iron alloys, the enriched oxide scale is accompanied by depletion of chromium in the alloy surface immediately below the scale. This situation accounts for occasional rusting and otherwise poor corrosion resistance of hot-rolled stainless steels that have not been adequately pickled following high-temperature oxidation. 

Horton et al. [55] observed that when steels containing Cu and Ni are exposed in industrial and marine atmospheres, the Cu and Ni appear in the mst layers both in the loose outer and adherent inner mst on skyward and ground ward surfaces. Also it was shown by chemical analysis that Ni, Cu, Cr and Mn from weathering steel appear in the mst layer and provides protection. Presence of chlorides in the atmosphere accelerates corrosion of steels leading to the formation of basic Fe ", Fe chlorides and jS FeOOH. Townsend et al. [56] conducted 8-year atmospheric corrosion tests on weathering steel in mral, industrial and marine environments with different heated conditions and indicated that heat treatments have no effect on the corrosion resistance/performance of weathering steels. 

Thickness of shell should not be less than 12 mm. Boiler quality steel should be used since these units run at high internal temperature for long time continuously. Internal lining details (e.g. type of insulating and refractory bricks used, their alumina percentage, thickness of layer, castable refractory, expansion joints provided. (Vendor to submit copies of their test certificates giving chemical analysis, refractory properties, thermal conductivities if asked for by the purchaser. The expected maximum temperature at outer surface of the shell should not normally exceed 60—65 °C.)... 

Thus, on the basis of the spectral data alone we cannot draw a conclusion concerning the preferable dissolution order of the above mentioned elements. However, the absence of absorption peaks of MoClg , NiCl4 , TiCls " complex ions indicates that these elements do not transfer to the electrolyte during the anodic dissolution of steel. This was also confirmed by the results of the chemical analysis of melt samples. From the electrochemistry point of view, the fact that electropositive nickel [30] and molybdenum [31] remain in the anode material points to the electrochemical nature of the corrosion process. The results of the spectroscopy measurements and chemical analysis were confirmed by X-ray microanalysis - the electrode surface after 2 h of anodic dissolution was slightly depleted in iron and chromium and was enriched in nickel. 

If the rf source is applied to the analysis of conducting bulk samples its figures of merit are very similar to those of the dc source [4.208]. This is also shown by comparative depth-profile analyses of commercial coatings an steel [4.209, 4.210]. The capability of the rf source is, however, unsurpassed in the analysis of poorly or nonconducting materials, e.g. anodic alumina films [4.211], chemical vapor deposition (CVD)-coated tool steels [4.212], composite materials such as ceramic coated steel [4.213], coated glass surfaces [4.214], and polymer coatings [4.209, 4.215, 4.216]. These coatings are used for automotive body parts and consist of a number of distinct polymer layers on a metallic substrate. The total thickness of the paint layers is typically more than 100 pm. An example of a quantitative depth profile on prepainted metal-coated steel is shown as in Fig. 4.39. 

Figure 8. XPS analysis of elemental composition as a function of sputter depth (a) zinc phosphated steel (b) interfacial substrate surface of zinc phosphated steel after adhesion failure of epoxyester coating in cathodic polarization testing. Reproduced from Ref. copyright 1983, American Chemical Society.

Radioactivity transport in reactor coolant circuits involves both surface corrosion and deposition. Several XPS studies(8,9) of reactor boiler alloys have been reported which show the very strong effect of coolant chemistry on the films deposited. The chemistry of corrosion products precipitated on ZrO and Al O surfaces has been studied using XPS.ly More recently, chemical decontamination of radioactive boiler circuits has been assisted by XPS analysis of the surface-active decontaminating agent.(1 ) Surface oxidation in gas-cooled reactor circuits has also been investigated. AES has been used to follow the CC>2 oxidation of a chromium steel(H) and some pure metals. (12)... 

For better judgement of corrosion and, respectively, the corrosion inhibition, REM photographs of the sample surface were taken. An energy-disperse analysis gives information about the chemical composition of the surface layer. The material samples were made out of building-steel St 1203 and V2A-high-grade steel 1.4541. 

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