Corrosion and passivation behaviors of molybdenum in aqueous solutions of different pH

Recently, stainless steel has been widely used as the solar cell substrate. In this paper, chemical mechanical polishing technique was employed to prepare the ultra-smooth 316L stainless steel surface for such application. The effects of solid content, pH, H 2 O 2 and benzotriazole (BTA) on the polishing performance of 316L stainless steel were investigated. The results indicated that, at pH 4.00, with the increase in the H 2 O 2 concentration, the MRR first dramatically increases due to the fact that, with the addition of small amount of H 2 O 2 , a porous outer layer mainly consisting of iron-enriched oxides with relatively low mechanical strength of the bilayer-structure oxide film is rapidly formed on the surface. After reaching the maximum value, the MRR gradually decreases since the outer layer gradually grows compact by the transformation of γ-FeOOH into α-FeOOH and even into α-Fe 2 O 3 . With the addition of BTA, the MRR can be suppressed, which is probably attributed to the formation of BTA passivating film on the top surface. Finally, a two-step polishing method was proposed, by which the ultra-smooth 316L stainless steel surface with the surface roughness R a about 2.0 nm can be achieved within 30 min and it can be subsequently used for thin-film solar cells. Stainless steel plays an important role in the mechanical industry due to the excellent mechanical properties, the high thermostability and the strong corrosion resistance. Recently, various types of stainless steels have been intensively used in precise devices, 1-4 especially been used as the substrate for thin-film solar cells. [5][6][7][8][9][10] In order to achieve satisfactory performance of solar cells, low roughness, low defects as well as excellent flatness of the stainless steel substrate are intensively demanded and even indispensable. It is reported that, by improving the surface roughness of stainless steel substrate from 38 nm to 23 nm, the conversion efficiency of hydrogenated amorphous silicon thin-film solar cells can greatly increase to 5.4%. 10 As is revealed, chemical mechanical polishing (CMP) combines the synergetic effects of chemical corrosion and mechanical abrasion, and can achieve both local and global planarization of the substrate surface. 11-14Hu et al.2 used colloidal silica as the abrasive and investigated the effects of pH and oxidizer on the polishing performance of stainless steel, and it was reported that the combination of oxidizer and strong acidity was the prerequisite for high material removal rate (MRR). However, the microscopic defects of 1-2 μm in size cannot be effectively avoided on the polished surface. Lee et al.10 used electrochemical mechanical polishing technique, which applied an additional anodic potential on the stainless steel substrate besides CMP, to polish the stainless steel surface, and it was reported that the polished surface roughness was reduced from about 38 nm to about 23 nm. However, more detailed polishing performance and the mechanism of chemical reactions during the polishing pr...

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“…44,45 It should be noted that, as shown in Fig. 12, the weak signal of the peak at 397.4 eV should correspond to Mo3p 3/2 of the Mo(VI) oxides.…”

Section: Resultsmentioning

confidence: 91%

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Jiang

Yang

2015

ECS J. Solid State Sci. Technol.

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“…In the neutral and alkaline solutions, MoO 2 dissolves to MoO 4 2− at the rate depending on pH [32].…”

Section: Photoelectrochemical Performance Of Electrode Smentioning

confidence: 99%

Photoelectrochemical properties of MoO2 thin films

Dukštienė

Sinkevičiūtė

2013

J Solid State Electrochem

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Thin MoO 2 films were electrodeposited on a selenium pre-deposited SnO 2 |glass plate. The photoelectrochemical properties of MoO 2 films were investigated in 0.1 M Na 2 SO 4 solution by the ultraviolet-visible spectrophotometry, linear sweep voltammetry, and altering current impedance measurement techniques. It was found that under illumination with the incident light of λ=366 nm, the photo response of the MoO 2 |SnO 2 |glass electrode resulted from the MoO 2 layer, while the SnO 2 layer served as a sink for photogenerated charge carriers. The MoO 2 film exhibited ntype conductivity. A schematic band structure diagram of MoO 2 in 0.1 M Na 2 SO 4 solution was constructed. The flat band potential (E fb ), the donor concentration (N D ), the photogeneration current efficiency depended on MoO 2 film thickness. The [Fe(CN) 6 ] 4−/3− redox PEC cell with MoO 2 | SnO 2 |glass plate as a photoanode was constructed. Power output characteristics such as the open circuit voltage (V OC ), short circuit current (I SC ), the fill factor (FF), and the lightto-electrical conversion efficiency (η) were determined. The maximum light-to-electrical conversion efficiency exhibited by the PEC cell was 0.94 %.

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“…Although there are several studies about the electrochemical behavior of Mo and its role to increase the corrosion resistance properties of the SS, the presence of this element in the passive film and its influence on the pitting corrosion mechanism is not clearly understood (Halada et al, 1995). However, several works with pure Mo were done in order to understand its influence on the corrosion resistance mechanism of SS (Halada et al, 1995;Badawy et al, 1998;Yang et al, 1984;Ürgen et al, 1990;Lu et al, 1989).…”

Section: Introductionmentioning

confidence: 99%

Influence of Mo alloying on pitting corrosion of stainless steels used as concrete reinforcement

Mesquita¹,

Chauveau²,

Mantel³

et al. 2013

Rem: Rev. Esc. Minas

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Corrosion of reinforcement steels, induced by chloride ions penetrating into the concrete, is the main cause of early damage, loss of serviceability and safety of reinforced concrete structures, which can be even more severe in the presence of concomitant concrete carbonation. In order to prevent reinforcement steel corrosion in highly aggressive alkaline environments, the use of stainless steels is becoming increasingly popular in coastal and marine constructions. Although widely used as an increasing corrosion resistance element in acidic environments, the influence of Mo addition on pitting corrosion resistance of stainless steels is not very clear in these conditions. Understanding Mo mechanism on corrosion resistance in alkaline media is hence of major importance, particularly for new lean grades with low Nickel and Molybdenum contents which presents a good balance between the properties required in these applications and the final cost of the material. In this work we will show the effect of Mo addition on pitting corrosion properties of austenitic, ferritic and duplex SS. A comparison between Mo content steels (alloys: 1.4404, 1.4113 and 1.4462) and very low molybdenum contents steels (alloys: 1.4301, 1.4016 and 1.4362) is done considering their pitting corrosion resistance (pitting potential E pit ) in different corrosion conditions. The results are discussed with respect to the influence of Mo addition on pitting behaviors for the different stainless steel rebar families in several aggressive media mainly in synthetic, chlorinated and carbonated solution reproducing the real concrete pore environments (pH10 solution with carbonates and chlorides ions). Keywords

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Corrosion and passivation behaviors of molybdenum in aqueous solutions of different pH

Cited by 125 publications

References 24 publications

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Chemical Mechanical Polishing of Stainless Steel as Solar Cell Substrate

Photoelectrochemical properties of MoO2 thin films

Influence of Mo alloying on pitting corrosion of stainless steels used as concrete reinforcement

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