Study on corrosion resistance behavior and formation mechanism of Ce conversion coating on manganese

2021 ◽  
Vol 118 (3) ◽  
pp. 319
Author(s):  
Sihua Lei ◽  
Fei Lu ◽  
Shuai Wang ◽  
Hong Zhong ◽  
Zhanfang Cao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Formation Mechanism ◽  
Electrochemical Impedance ◽  
Conversion Coating ◽  
Alkali Resistance ◽  
Conversion Coatings ◽  
Environmental Friendliness ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
Acid And Alkali Resistance

Ce conversion coatings have received extensive attention from researchers due to their excellent corrosion resistance and environmental friendliness. Here, Ce conversion coatings on manganese were prepared by treating in the cerium nitrate conversion solution. The influence of treating parameters was studied and optimized. The surface morphology, element composition and chemical state of Ce conversion coatings were studied by means of SEM, EDS, XRD and XPS. Electrochemical methods of polarization curve and electrochemical impedance were used to study the corrosion resistance of conversion coatings. The results showed that the Ce conversion coating contained mainly Mn, O and Ce, and its forms were manganese oxide and cerium oxide. Electrochemical tests showed that Ce conversion coating can not only effectively improve the corrosion resistance of manganese substrate, but also has good acid and alkali resistance. Discussion on the formation mechanism of cerium conversion coating shows that the conversion treatment is beneficial to inhibit the further oxidation of manganese to the higher valence state.

Synthesis and Characterization of Chrom-Free Dark Coating on AA6063 Aluminium Alloy with K2ZrF6

2014 ◽  
Vol 1053 ◽  
pp. 421-428
Author(s):  
Ting Yi Chen ◽  
Ye Qi Fu ◽  
Wen Lu ◽  
Wen Fang Li
Keyword(s):  
Corrosion Resistance ◽  
Aluminium Alloy ◽  
Corrosion Current ◽  
Visual Assessment ◽  
Electrochemical Analysis ◽  
Conversion Coating ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
New Treatment

A new passivation process has been developed for producing a chrome-free and coloured conversion coating on aluminium alloy AA6063 with K2ZrF6. The conversion coating obtained has a dark film, which enables visual assessment of the coating development and coating quality during processing. The colouring effect is a significant advantage over the zirconium based conversion coatings currently used in the industry, which are largely colourless. The new treatment process is simple and allows a uniform coating to be formed within a few minutes. The composition and the surface morphology of the coatings were characterized. The corrosion resistance of the coated samples was evaluated by electrochemical tests. Through electrochemical analysis, corrosion current of the coatings is low, it has excellent corrosion resistance; SEM, EDS and XRD are used to analyze the process coating.

scholarly journals Corrosion resistance of the biodegradable ZE41 magnesium alloy treated by unconventional fluoride conversion coating

2019 ◽  
Vol 63 (4) ◽  
pp. 138-147
Author(s):  
J. Drábiková ◽  
S. Fintová ◽  
P. Doležal ◽  
J. Wasserbauer ◽  
Z. Florková
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Positive Influence ◽  
Conversion Coating ◽  
Medical Applications ◽  
Biodegradable Implants ◽  
Conversion Coatings ◽  
Simulated Body Fluids

Abstract Magnesium based alloys are very promising material to be used mainly for biodegradable implants in medical applications. However, due to their very low corrosion resistance in the environment of in vivo is their use limited. Increase of the corrosion resistance of magnesium alloys in vivo can be achieved, for example, by a suitable choice of surface treatment while the biocompatibility must be ensured. Fluoride conversion coatings meet these requirements. Unconventional fluoride conversion coating was prepared on ZE41 magnesium alloy by dipping the magnesium alloy into the Na[BF4] salt melt at 450 °C for 0.5; 2 and 8 h. The morphology and thickness of the prepared fluoride conversion coatings were investigated as well as the corrosion resistance of the treated and untreated ZE41 magnesium alloy specimens. The corrosion resistance of the untreated and treated ZE41 magnesium alloy was investigated using electrochemical impedance spectroscopy in the environment of the simulated body fluids at 37 ± 2 °C. The obtained results showed a positive influence of the fluoride conversion coating on the corrosion resistance of the ZE41 magnesium alloy.

scholarly journals Design and Multidimensional Screening of Flash-PEO Coatings for Mg in Comparison to Commercial Chromium(VI) Conversion Coating

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 337
Author(s):  
Ewa Wierzbicka ◽  
Marta Mohedano ◽  
Endzhe Matykina ◽  
Raul Arrabal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Chromium Vi ◽  
Alkaline Electrolytes ◽  
Az31b Alloy ◽  
Plasma Electrolytic

REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations demand for an expedient discovery of a Cr(VI)-free alternative corrosion protection for light alloys even though the green alternatives might never be as cheap as current harmful technologies. In the present work, flash- plasma electrolytic oxidation coatings (FPEO) with the process duration < 90 s are developed on AZ31B alloy in varied mixtures of silicate-, phosphate-, aluminate-, and fluoride-based alkaline electrolytes implementing current density and voltage limits. The overall evaluation of the coatings’ anticorrosion performance (electrochemical impedance spectroscopy (EIS), neutral salt spray test (NSST), paintability) shows that from nine optimized FPEO recipes, two (based on phosphate, fluoride, and aluminate or silicate mixtures) are found to be an adequate substitute for commercially used Cr(VI)-based conversion coating (CCC). The FPEO coatings with the best corrosion resistance consume a very low amount of energy (~1 kW h m−2 µm−1). It is also found that the lower the energy consumption of the FPEO process, the better the corrosion resistance of the resultant coating. The superb corrosion protection and a solid environmentally friendly outlook of PEO-based corrosion protection technology may facilitate the economic justification for industrial end-users of the current-consuming process as a replacement of the electroless CCC process.

scholarly journals Effect of Mn Content and Solution Annealing Temperature on the Corrosion Resistance of Stainless Steel Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ihsan-ul-Haq Toor
Keyword(s):  
Corrosion Resistance ◽  
Annealing Temperature ◽  
Electrochemical Impedance ◽  
Austenitic Stainless Steels ◽  
Electrochemical Tests ◽  
Linear Polarization Resistance ◽  
Ni Content ◽  
Different Temperatures ◽  
Acidic Chloride ◽  
Mn Content

The corrosion behavior of two specially designed austenitic stainless steels (SSs) having different Nickel (Ni) and Manganese (Mn) contents was investigated. Prior to electrochemical tests, SS alloys were solution-annealed at two different temperatures, that is, at 1030°C for 2 h and 1050°C for 0.5 h. Potentiodynamic polarization (PD) tests were carried out in chloride and acidic chloride, whereas linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) was performed in 0.5 M NaCl solution at room temperature. SEM/EDS investigations were carried out to study the microstructure and types of inclusions present in these alloys. Experimental results suggested that the alloy with highest Ni content and annealed at 1050°C/0.5 hr has the highest corrosion resistance.

scholarly journals Effect of Temperature on Corrosion Resistance of Layered Double Hydroxides Conversion Coatings on Magnesium Alloys Based on a Closed-Cycle System

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1658
Author(s):  
Xiaochen Zhang ◽  
Zhijuan Yin ◽  
Bateer Buhe ◽  
Jiajie Wang ◽  
Lin Mao ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Chemical Composition ◽  
Photoelectron Spectroscopy ◽  
Conversion Coating ◽  
Effect Of Temperature ◽  
Conversion Coatings ◽  
Closed Cycle ◽  
Cycle System ◽  
Double Hydroxide ◽  
Double Hydroxides

The effect of temperature on the corrosion resistance of layered double hydroxide (LDH) conversion coatings on AZ91D magnesium alloy, based on a closed-cycle system, was investigated. Scanning electron microscopy (SEM), photoelectron spectroscopy (XPS), and X-ray diffractometry (GAXRD) were used to study the surface morphology, chemical composition, and phase composition of the conversion coating. The corrosion resistance of the LDH conversion coating was determined through electropotentiometric polarisation curve and hydrogen evolution and immersion tests. The results showed that the conversion coating has the highest density and a more uniform, complete, and effective corrosion resistance at 50 °C. The chemical composition of the LDH conversion coating mainly comprises C, O, Mg, and Al, and the main phase is Mg6Al2(OH)16CO3·4H2O.

MICROSTRUCTURE AND ELECTROCHEMICAL PROPERTIES OF Ni–B/GO ULTRASONIC-ASSISTED COMPOSITE COATINGS

2019 ◽  
Vol 26 (10) ◽  
pp. 1950080
Author(s):  
JIBO JIANG ◽  
HAOTIAN CHEN ◽  
LIYING ZHU ◽  
YAOXIN SUN ◽  
WEI QIAN ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Ultrasonic Field ◽  
Protective Material ◽  
X Ray ◽  
Electrochemical Tests ◽  
Ultrasonic Assisted ◽  
Corrosive Environments

Graphene oxide (GO) sheet and ultrasonic field (UF) were successfully employed to produce Ni–B/GO and UF–Ni–B/GO composite coatings on Q235 mild steel by electroless plating. The composite coatings’ structure and surface morphology were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Results showed that GO was successfully co-deposited in the Ni–B alloy. Moreover, UF–Ni–B/GO composite coatings have smoother surface and thicker cross-section than others. The microhardness and corrosion resistance of the sample coatings were determined using Vickers hardness tests, Tafel electrochemical tests and electrochemical impedance measurements (EIS) in 3.5[Formula: see text]wt.% NaCl solution to receive the effect of GO and ultrasonic. The findings indicated that UF–Ni–B/GO exhibited optimum hardness (856[Formula: see text]HV) and enhanced corrosion resistance (6.38 [Formula: see text][Formula: see text] over the Ni–B and Ni–B/GO coatings. Due to these interesting properties of the coating, it could be used as a protective material in the automotive and aerospace industries for parts of machines that were manipulated in high temperature and corrosive environments.

Study on Properties of Zn-Al-Mg-RE Coatings by Arc Spraying

2013 ◽  
Vol 804 ◽  
pp. 79-84
Author(s):  
Fei Lu ◽  
Zhao Qian Xie ◽  
Yu Feng Lu ◽  
Miao Lou ◽  
Meng Zhou ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Arc Spraying ◽  
Long Term Effects ◽  
Electrochemical Protection ◽  
X Ray ◽  
Electrochemical Tests ◽  
Excellent Corrosion Resistance ◽  
Corrosion Reaction ◽  
High Velocity Arc Spraying

In order to improve the organization, reduce the porosity, compact the structure and enhance the corrosion resistance of the coating, Zn-Al-Mg-RE coating system was prepared by high velocity arc spraying. The surface appears, phase composition and electrochemical properties of the coating were characterized by scanning electron microscope, X-ray radiation diffaction and electrochemical workstation. The results indicated that the coatings were compact. The coatings were mainly zinc and aluminum phase. In corrosion of immersion, the reaction resistance and coating resistance of coatings quickly become bigger, the surface of coatings become more compact, and the corrosion reaction is more difficult. Electrochemical tests showed that the coating had excellent corrosion resistance. The electrochemical protection and self-sealing effect of coatings can have long-term effects on anticorrosion.

Properties of Conversion Coating of Magnesium Alloys by a Phosphate-Permanganate Solution

2005 ◽  
Vol 488-489 ◽  
pp. 665-668 ◽  
Author(s):  
Shu Sen Wu ◽  
Ming Zhao ◽  
Ji Rong Luo ◽  
You Wu Mao
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Adhesion Force ◽  
Conversion Coating ◽  
Resistance Test ◽  
Az91d Alloy ◽  
Conversion Coatings ◽  
Good Adhesion ◽  
Better Than

A chromium-free conversion coating for AZ91D magnesium alloys has been obtained by using a phosphate-permanganate solution. Examinations have been carried out on the conversion coating for morphology, composition, adhesion force and corrosion resistance. Results show that the conversion coatings are relatively uniform and continuous, with thickness from 7µm to 10µm. They exhibit good adhesion to matrix and have some non-penetrate tiny holes on the surface. The main elements of the conversion coating of AZ91D alloy are Mg、O、P、K、Al、Mn. Results of corrosion resistance test indicate that the corrosion resistance of the conversion coating by phosphate-permanganate solution is in match to that of the conversion coating formed in a chromate solution, but for the corrosion resistance after painting, the former is better than the later.

scholarly journals Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sheng-xue Yu ◽  
Rui-jun Zhang ◽  
Yong-fu Tang ◽  
Yan-ling Ma ◽  
Wen-chao Du
Keyword(s):  
Corrosion Resistance ◽  
Salt Solution ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Impedance Spectrum ◽  
Conversion Coating ◽  
Mg Alloy ◽  
Electrochemical Impedance Spectrum ◽  
X Ray ◽  
Titanium Salt

Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF60.75 g·L−1, NaF 1.25 g·L−1, MgSO41.0 g/L, and tetra-n-butyl titanate (TBT) 0.08 g·L−1. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrum (FT-IR) were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS). Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment.

Corrosion Resistance of Nitric Acid Passivated Cr-Ni-Mo Stainless Steel

2016 ◽  
Vol 858 ◽  
pp. 196-201
Author(s):  
Viera Zatkalíková ◽  
Lenka Markovičová
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Nitric Acid ◽  
Biomedical Applications ◽  
Electrochemical Impedance ◽  
Austenitic Stainless Steels ◽  
Mass Losses ◽  
Excellent Corrosion Resistance ◽  
Acidic Chloride Solution ◽  
Acidic Chloride

Austenitic stainless steels are considered materials with excellent corrosion resistance, and with acceptable mechanical properties. Therefore they are recommended for various constructional, industrial and biomedical applications. However they are prone to the pitting corrosion in aggressive chloride environments. The aim of this study is to evaluate the corrosion resistance of AISI 316Ti stainless steel with nitric acid passivated surface at the temperature range 22 – 80 °C in 1M acidic chloride solution. Evaluation of the corrosion resistance is based on the results of exposition immersion tests (visual and microscopic observation of attacked surfaces, mass losses of specimens) and the results of the electrochemical impedance spectroscopy (EIS) tests.

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