Stainless Steel In Neutral Solutions Research Articles

Parametric optimization of pulsed laser ablation on stainless steel for improving corrosion resistance by Taguchi method

In the present study, pulsed laser ablation in liquid (PLAL) treatment has been optimised for ASTM 304/2B stainless steel using Taguchi method. PLAL experimental trials were carried out using fiber laser source by varying laser parameters include overlap rate, scanning speed, laser irradiation power and the number of laser pulses. The optimum laser parameters have been derived by considering the response which is corrosion potential of metal targets. Analysis of Variance (ANOVA) and signal to noise ratio are used to analyse the effect of different laser parameters on the responses. The laser irradiation power is the most dominant factors affecting the corrosion resistance of stainless steel in neutral solution; the overlap rate is the most significant impact corrosion resistance of metal in acidic solution. The responses of the optimized laser parameters obtained implementing the Taguchi method has been verified experimentally and hence supporting the accuracy of optimization of laser parameters under the given set of experimental conditions.

Investigations of Thiosulfate Accumulation on 304 Stainless Steel in Neutral Solutions by Radioactive Labeling, Electrochemistry, Auger Electron and X‐Ray Photoelectron Spectroscopy Methods

Thiosulfate accumulation on 304 stainless steel in near neutral solutions (pH ∼ 5.6) was studied using in situ techniques: electrochemistry and radiochemistry, as well as by Auger electron spectroscopy depth profiling and angle‐resolved x‐ray photoelectron spectroscopy in ultrahigh vacuum. It was found that thiosulfate accumulation is an irreversible process and occurs over a broad electrode potential range. Thiosulfate surface concentration is very small, below −1.0 V vs. Ag/AgCl reference. In the potential range from −1.0 to −0.50 V the surface concentration increases linearly with potential, reaches a maximum at −0.30 V, and at even more positive potentials, decreases to a slightly lower level. Ultrahigh vacuum spectroscopic measurements indicate that the irreversible surface behavior can be attributed to thiosulfate incorporation into the substrate passive film. The present data obtained with 304 stainless steel are compared to previous results published from this laboratory on thiosulfate adsorption on 316 stainless steel, and the role of molybdenum surface enrichment in the thiosulfate accumulation reversibility is discussed. The effect of chloride on thiosulfate accumulation was also investigated. At high concentrations of chloride, thiosulfate is desorbed from the surface due to chloride‐induced dissolution of the stainless steel. At very negative potentials, the thiosulfate surface concentration increases upon chloride addition, most probably due to the surface microroughening caused by chloride adsorption.

Investigation of Thiosulfate Adsorption on 316 Stainless Steel in Neutral Solutions by Radioactive Labeling, Electrochemistry, and Auger Electron Spectroscopy

We report on thiosulfate adsorption on a 316 stainless steel electrode in neutral solutions by radiochemical, electrochemical, and Auger electron spectroscopy (AES) measurements. In contrast to previous work on thin metal films or metal electrodeposits to model real‐life metal (alloy) samples, our radiochemical approach permits coverage measurements of labeled adsorbates on smooth solid electrodes of convenient size and thickness. A dedicated electrode preparation yields a reproducible surface for fast and reversible thiosulfate adsorption from a perchlorate solution. However, on the same time scale, reversible adsorption is impeded in sulfate media. Further, no thiosulfate adsorption occurs in borate buffer solution, and complex thiosulfate adsorption behavior predominates in solutions containing varying amounts of chloride anions, initially increasing with bulk chloride concentration, maximal at , and decreasing at higher chloride concentration. We conclude that small amounts of surface chloride assist the thiosulfate adsorption, but increasing surface Cl− coverage becomes competitive to that of thiosulfate. The chloride adsorption enhancing mechanism probably results from a destabilization of the locally ordered thiosulfate surface structure. Radiochemistry and AES show that long exposure to thiosulfate solutions results in permanent thiosulfate immobilization on the stainless steel surface.

ChemInform Abstract: Photoelectrochemical Study of Passive Films on Stainless Steel in Neutral Solutions.

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Photoelectrochemical study of passive films on stainless steel in neutral solutions

Passive films formed on AISI 304 stainless steel in neutral solutions are studied using photoelectrochemical technique. Photocurrents were investigated as a function of the wavelength of the incident light, the electrode potential and the time. The results of the measurements together with capacity measurements indicate that the passive film on AISI 304 shows characteristics of a highly doped amorphous or highly disordered n-type semiconductor. The potential dependence of the optical gap values and of the photocurrent transients can be interpreted assuming that the passive film is an iron-chromium oxide solid solution.

Laser etching of metals in neutral salt solutions

We report new findings that relate to rapid maskless laser etching of steel and stainless steel in neutral solutions of sodium chloride, sodium nitrate, and potassium sulfate. Etch rates have been determined as a function of laser power, laser on-time, and solution concentration. The morphology of laser-etched holes obtained in these solutions was compared with holes obtained in pure water. Results indicate that some controlled melting occurs under certain laser conditions in addition to the metal dissolution process induced by the locally intense heat of the laser beam.

高温中性水溶液中における SUS 304 ステンレス鋼の不働態化挙動

高温中性水溶液中における SUS 304 ステンレス鋼の不働態化挙動