scholarly journals Study on the Corrosion Mechanism of Zn-5Al-0.5Mg-0.08Si Coating

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Shiwei Li ◽  
Bo Gao ◽  
Ganfeng Tu ◽  
Yi Hao ◽  
Liang Hu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Salt Spray ◽  
Microstructural Characterization ◽  
Alloy Coating ◽  
Salt Spray Test ◽  
Corrosion Mechanism ◽  
Neutral Salt ◽  
Test Results ◽  
Coating Surface ◽  
New Type

A new type of hot-dip Zn-5Al-0.5Mg-0.08Si and Zn-5Al alloy coatings was performed on the cold rolled common steel. The hot-dip process was executed by self-made hot-dip galvanising simulator. SEM and EDS test results demonstrated that Mg was mainly distributed in crystal boundaries. XRD test results showed that the corrosion product of Zn-5Al-0.5Mg-0.08Si alloy coating was almost Zn5(OH)8C12⋅H2O. The features of Zn5(OH)8C12⋅H2O are low electric conductivity, insolubility and good adhesion.The corrosion resistance of alloy-coated steels was detected by neutral salt spray test. The microstructural characterization of the coating surface after neutral salt spray test and removing the corrosion products revealed that the corrosion process of Zn-5Al-0.5Mg-0.08Si coating was uniform and the coating surface was almost flat. As a result, the corrosion resistance of Zn-5Al-0.5Mg-0.08Si coating has a remarkable improvement with a factor of 9.2 compared with that of Zn-5Al coating.

The Corrosion Mechanism of Zn-5%Al-0.3%Mg Coating

2011 ◽  
Vol 189-193 ◽  
pp. 1284-1287
Author(s):  
Bo Gao ◽  
Shi Wei Li ◽  
Yi Hao ◽  
Gan Feng Tu ◽  
Liang Hu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Salt Spray ◽  
Alloy Coating ◽  
Mg Alloy ◽  
Corrosion Mechanism ◽  
Neutral Salt ◽  
Test Results ◽  
Crystal Boundary ◽  
Cold Rolled ◽  
Al Coating

A new hot dip Zn-5%Al-0.3%Mg alloy coating was performed on cold rolled common steel. The hot-dip process was executed by self-made hot dip galvanising simulator (China patent, No.201010160353). The corrosion resistance of alloy-coated steels was detected by neutral salt spray test . SEM and EDS test results demonstrate that Mg is mainly distributed in the crystal boundary. XRD test results shows corrosion product of Zn-5%Al-0.3%Mg alloy coating is mainly Zn5(OH)8Cl2•H2O. The characteristic of Zn5 (OH)8Cl2•H2O is dense and insoluble, so it is protective. In order to study the anticorrosion mechanism, all the tests of the Zn-5%Al-0.3%Mg alloy were carried out with Zn-5%Al coating together.

scholarly journals Ultrasonic Sensors-Assisted Corrosion Studies on Surface Coated AlSi9Cu3 Alloy Die Castings

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 85
Author(s):  
Yuh-Chung Hu ◽  
Senthil Kumaran Selvaraj ◽  
Manivannan Subramanian ◽  
Kathiravan Srinivasan ◽  
Srinivasan Narayanan
Keyword(s):  
Corrosion Resistance ◽  
Die Casting ◽  
Pure Aluminum ◽  
Salt Spray ◽  
Salt Spray Test ◽  
Al Alloy ◽  
Neutral Salt ◽  
Powder Coatings ◽  
Acrylic Paint ◽  
Epoxy Primer

A novel phenomenon known as Industry X.0 is becoming extremely popular for digitizing and reinventing business organizations through the adaption of rapid and dynamic technological, innovational, and organizational changes for attaining the profitable revenue. This work investigates the die-casted commercially pure aluminum alloyed with 9% silicon and 3% copper (AlSi9Cu3) that is produced through the gravity die casting process. Further, the degradation of surface coating on die-casted AlSi9Cu3 alloy was explored. The acrylic paint electrodeposition (ED) coat, 2-coat polyester without primer and 3-coat polyester with epoxy primer powder coatings were used in this study. Moreover, the 3.5 wt.% of sodium chloride (3.5 wt.% of NaCl) test solution was used for electrochemical and salt spray test and the tools used to assess electrochemical properties were electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and neutral salt spray test (NSS). The microstructure of AlSi9Cu3 after corrosion exposure was investigated; also, the microstructure of coated and uncoated AlSi9Cu3 samples was analyzed by SEM microscopy after corrosion exposure. Besides, the electrochemical studies were also carried out on the Al alloy die casting. It was found that acrylic paint ED coatings exhibited higher corrosion resistance than 2-coat polyester without primer & 3-coat polyester with epoxy primer powder coatings. Acrylic paint ED coating showed higher corrosion resistance in AC and a lower value in DC and 3-coat polyester with epoxy primer powder coating displayed higher corrosion resistance in DC and a lower value in AC.

Research on Heavy-Duty Coating Protection System of Magnesium Alloy

2015 ◽  
Vol 1119 ◽  
pp. 525-528
Author(s):  
Ru Tang Yan ◽  
Yuan Yuan Li ◽  
Chun Wei She ◽  
Hua Geng Li ◽  
Hua Pan Li
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Salt Spray ◽  
Salt Spray Test ◽  
Protection System ◽  
Test Time ◽  
Test Results ◽  
Ageing Test ◽  
Micro Arc Oxidation ◽  
Resistance Performance

The poor corrosion resistance of magnesium alloys become the bottleneck restricting its development. Based on micro-arc oxidation (MAO) technology and the characteristics of fluorocarbon coating the surface of magnesium alloy build a high corrosion protection system, namely: Based on micro-arc oxidation coating fluorocarbon coatings. The formation of the composite coating through the resistance to ageing test through the resistance to ageing test, acid and alkali experiment and salt spray test results show the excellent corrosion resistance performance. Among them, the resistance to salt spray test time can reach 1500 h, which breaks the bottleneck of magnesium alloy corrosion resistance of 1000 h.

A New Chromate-Free Insulating Coating on Silicon Steel

2014 ◽  
Vol 1004-1005 ◽  
pp. 757-762 ◽  
Author(s):  
Shuang Hong Wang ◽  
Yong Feng Long ◽  
Shi Lu Zhao ◽  
Cheng Qiang An ◽  
Ke Ding
Keyword(s):  
High Temperature ◽  
Salt Spray ◽  
Silicon Steel ◽  
Salt Spray Test ◽  
Neutral Salt ◽  
Test Results ◽  
High Temperature Annealing ◽  
Electrochemical Test ◽  
Comprehensive Performance ◽  
Resistance Value

The water-based paint had been examined to prepare a new chromate-free insulating coating on silicon steels. The structure of the insulating coating was characterized by scanning electron microscopy, energy dispersive spectroscopy and infrared spectroscopy. Adhesion, high temperature annealing, and surface insulating resistance were measured. Corrosion resistance was investigated by neutral salt spray test and electrochemical test. Results exhibited that the insulating coating had excellent comprehensive performance. The adhesive level was 5B degree; the high temperature annealing test showed no coating degradation after heat treatment of 2 h at 450 °C in air or at 750 °C in nitrogen; the salt spray test showed the corrosion area was less than 2 % after the 12 h salt spray; when the coating thickness was 1.0-1.2 μm, the surface insulating resistance value was 380-420 Ω/mm2.

scholarly journals Comparative Study on the Corrosion Resistance of Inorganic Zinc-Rich Coating and Thermal-Spray Zinc Coating

2021 ◽  
Author(s):  
Weiliang Ni ◽  
Peng Li ◽  
Yajun Zhu ◽  
Zhigang Di ◽  
Liangliang Guo ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Thermal Spray ◽  
Salt Spray ◽  
Zinc Coating ◽  
Steel Structures ◽  
Salt Spray Test ◽  
Shielding Effect ◽  
Corrosion Mechanism ◽  
Time Varying ◽  
Zinc Coatings

Abstract The corrosion resistance of two steel coatings (inorganic zinc-rich coating and thermal-spray zinc coating) was studied in detail by using the electrochemical and salt spray test, and the salt spray corrosion thickness was calculated by the time-varying equation established from the mathematical fitting method. The result show that the corrosion mechanism of the two types of coatings was the same that based on the sacrificed of zinc through anodizing phenomenon. The main reason for the difference of corrosion resistance between the two anticorrosive coatings was that the coating density and shielding effect of corrosion products were different. The 7500-hours salt spray test showed that the corrosion rates and microstructure characteristics of both types of zinc coatings were homogeneous on the premise of ensuring coating reliability. The time-varying equation can be used to evaluate the service life of the zinc coatings and judge their corrosion resistance quickly, that providing theoretical support for the maintenance of steel structures as well as the accelerated selection and design of coating formulations.

Research on the Performance of Shielded Wire Passivated by 823 Preservatives in Neutral Salt Spray Test

2014 ◽  
Vol 556-562 ◽  
pp. 3-5
Author(s):  
Ke Shun Dai ◽  
Wen Kai Xiao ◽  
Tan Yu
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Polarization Curve ◽  
Salt Spray ◽  
Corrosion Cracking ◽  
Salt Spray Test ◽  
Normal Operation ◽  
Neutral Salt

The corrosion cracking of Shielded wire could result in protection equipments and automatic devices failing to work, which seriously affects the normal operation of the grid [1]. Therefore, researching the corrosion of Shielded wire has an important meaning. This article, through measurements of the polarization curve of the shield, researched the corrosion rate of different spray time and treatments, and came to a conclusion that the corrosion resistance after passivated by 823 preservatives is higher than before it.

Optical and Corrosion Studies of Spray Pyrolysis Coated Titanium Dioxide Thin Films

2018 ◽  
Vol 24 (8) ◽  
pp. 5836-5842 ◽  
Author(s):  
V. P. Muhamed Shajudheen ◽  
K. Anitha Rani ◽  
V. Senthil Kumar ◽  
A. Uma Maheswari ◽  
M Sivakumar ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Titanium Dioxide ◽  
Spray Pyrolysis ◽  
Salt Spray ◽  
Salt Spray Test ◽  
Neutral Salt ◽  
X Rays

In the present work, nanostructured thin films of titanium dioxide (TiO2) have been coated on the stainless steel (SS 304L) substrate by spray pyrolysis coating technique. The surface morphology and chemical constituents of the thin film have recorded using Field Effect Scanning Electron Microscopy (FESEM) and Energy Dispersive Analysis of X-rays (EDAX) respectively. The structural and optical properties of the films of as deposited were examined by Micro Raman, Photoluminescence Spectroscopy (PL) and UV-Vis absorption method. The FESEM micrograph showed the microporous nature of the film. EDAX spectrum illustrated the presence of Ti and O on the coated surface of the steel substrate. The peaks in the micro Raman spectrum indicated that the TiO2 samples of present study are in rutile phase of titanium dioxide. A strong emission peak around 350 nm was observed in the Photoluminescence spectrum of the samples. The anti-corrosion properties of the TiO2 coated samples were investigated by neutral salt spray test for 390 h. Electrochemical Impedance Spectroscopy (EIS) analysis and Tafel analysis were performed before and after salt spray test and the results suggested an increase of corrosion resistance of the titanium dioxide thin film in a corrosive environment. The positive shift of equilibrium corrosion potential (Ecorr) of bare stainless steel to thin film coated stainless steel (from −0.96 V to −0.38 V) in the electrochemical Tafel analysis implied the significant increase of corrosion resistance.

Corrosion Resistance of the Nanometer Organic Coating in Grotto Environment

2014 ◽  
Vol 1004-1005 ◽  
pp. 768-773
Author(s):  
Miao Lou ◽  
Yu Feng Lu ◽  
Meng Zhou ◽  
Fei Lu ◽  
Yin Jun Huang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Salt Spray ◽  
Organic Coating ◽  
Salt Spray Test ◽  
Coating Surface ◽  
Good Protection

Accelerate the corrosion of the nanometer organic coating by design salt spray test. Research the corrosion resistance of the nanometer organic coating in grotto environment by EIS. The results show that prolong time of the salt spray test, the coating surface become to coarseness, the colour occur slight change, but no blistering and flake away. The Rc and Rt descend, every ten days the corrosion rate of coating augment decuple, at forty days is 3.14μm/a and the steel is not corrosion. The nanometer organic coating behave good protection ability and corrosion resistance in the grotto environment.

The Corrosion Resistance of Zn-Plated Samples with Blackish Green Passivation Film

2011 ◽  
Vol 383-390 ◽  
pp. 3081-3085
Author(s):  
Yu Bao Cao
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Sample Surface ◽  
Corrosion Current ◽  
Electrochemical Process ◽  
Salt Spray Test ◽  
Neutral Salt ◽  
Passivation Film ◽  
Passivated Sample

The corrosion resistance of blackishgreen passivation films on zinc-plated steel sheet was studied by polarization curve measurement, electrochemical impedance spectroscopy and neutral salt spray test. The passivated sample featured a more positive corrosion potential and much lower corrosion current density as compared to non-passivated sample in 5% (mass fraction) NaCl solution. The Nyquist plots of the samples with and without passivation were characterized as two complete capacitive arcs, indicating that the corrosion is controlled by electrochemical process. The radii of capacitive arcs of the passivated sample are larger than those of non-passivated sample, because the passivation film formed on the sample surface increases the reaction resistance in corrosion process, thus the corrosion resistance of the sample is improved. The anti-white rust time of the passivation film in neutral salt spray test is 400 h.

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.

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