Corrosion Behaviour of Zn-Al Pseudo-Alloy Coating on Carbon Steel in Chloride Environments

2012 ◽  
Vol 567 ◽  
pp. 45-48 ◽  
Author(s):  
An Qiang Liu ◽  
Kui Xiao ◽  
Chao Fang Dong ◽  
Xiao Gang Li

In this work, Zn-Al alloy and Zn-Al pseudo-alloy coatings are deposited on carbon steel by arc spray technology. The corrosion behaviour of the coatings has been studied by salt spray test and electrochemical experiment. The morphology of the coatings exposed to salt spray test for 400 h was analyzed using SEM and EDS. Results show that corrosion rate of Zn-Al alloy coating is faster than that of Zn-Al pseudo-alloy coating and the steel substrate is attacked. The corrosion products formed on the surface of Zn-Al alloy coating were loose, with a large number of cracks and holes, but the Zn-Al pseudo-alloy coating is converted into a stable Al-rich oxide layer, which protects the steel substrate against corrosive attacks and enhances the corrosion resistance of the Zn-Al pseudo-alloy coating. Electrochemical tests show the Zn-Al pseudo-alloy coating as a sacrificial protection coating has the capability of providing sacrificial protection for the steel substrate.

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
Muhammad Ashraff Ahmad Seri ◽  
Esah Hamzah ◽  
Abdelsalam Ahdash ◽  
Mohd Fauzi Mamat

Recently, self-healing coating is classified as one of the smart coatings which has the ability to heal or repair damage of the coating to prevent further corrosion. The aim of this study is to synthesize the self-healing coatings from polymeric material and evaluate the performance and their corrosion behavior when coated on steel substrates. The corrosion tests were performed using immersion test and salt spray test method at room temperature. The immersion test shows that self-healing coating gives lower corrosion rate compared to pure epoxy paint, with a value of 0.02 and 0.05 mm/year respectively. Also, salt spray test shows similar trend as the immersion test, which is 0.11 and 0.19 mm/year for self-healing coating and pure epoxy paint respectively. While uncoated samples without any protection corroded at 0.89 mm/year. It was also found that the damage on self-healing coating was covered with zeolite from the microcapsules indicating that the self-healing agent was successfully synthesized and could function well. In other words, self-healing coating shows better corrosion resistance compared to the pure epoxy coating on steel substrate.


2012 ◽  
Vol 57 (2) ◽  
pp. 517 ◽  
Author(s):  
M. Żelechower ◽  
J. Kliś ◽  
E. Augustyn ◽  
J. Grzonka ◽  
D. Stróż ◽  
...  

The Microstructure of AnnealedGalfanCoating on Steel SubstrateThe commercially availableGalfancoating containing 5-7wt.% of Al deposited on the low carbon steel substrate by hot dipping has been examined with respect to the microstructure of the coating/substrate interface area. The application of several experimental techniques (SEM/EDS, XRD, TEM/AEM/EDS/ED) allowed demonstrating the two-phase structure of the alloy coating in non-treated, commercially availableGalfansamples: Zn-rich pre-eutectoidηphase grains are surrounded by lamellar eutectics ofβ-Al andη-Zn. The transition layer between the alloy coating and steel substrate with the considerably higher Al content (SEM/EDS, TEM/EDS) has been found in both non-treated and annealed samples (600°C/5 minutes). Only the monoclinic FeAl3Znxphase however was revealed in the annealed sample (TEM/electron diffraction) remaining uncertain the presence of the orthorhombic Fe2Al5Znxphase, reported by several authors.


Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1960 ◽  
Author(s):  
Yue Li ◽  
Chunchun Wu ◽  
Ming Xue ◽  
Jiawen Cai ◽  
Yi Huang ◽  
...  

Anticorrosive coatings prepared by sol-gel derived approaches have become an emergent research area in the field of corrosion prevention materials. Furthermore, enhanced coating thickness can greatly improve the barrier effect of the sol-gel coatings, thus influencing their service life in industrial applications. Here, we propose the preparation of a two-layer coating system using a low-cost sol-gel derived method. The coating structure was composed of first an underlying layer incorporated with silica and titania powder as filler and pigment materials, and a second translucent topcoat containing a colloidal silica sol-gel matrix crosslinked by methyltrimethoxysilane (MTMS). This coating system was applied on Q235 carbon steel substrate by a two-step spray deposition method, resulting in an enhanced coating thickness of around 35 μm. The physical and morphological properties of the coatings were characterized using multiple techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The anticorrosion performance of the sol-gel coatings was studied by a salt spray test, outdoor exposure test and electrochemical impedance spectroscopy (EIS). Results revealed that this two-layer coating system exhibited excellent physical and anticorrosion properties, and that the topcoat played a crucial role in maintaining the barrier effect and preventing water leakage.


Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5642
Author(s):  
Mohamed Ramadan ◽  
Abdulaziz S. Alghamdi ◽  
K. M. Hafez ◽  
Tayyab Subhani ◽  
K. S. Abdel Halim

Interfacial bonding highly affects the quality of bimetallic bearing materials, which primarily depend upon the surface quality of a solid metal substrate in liquid–solid compound casting. In many cases, an intermediate thin metallic layer is deposited on the solid substrate before depositing the liquid metal, which improves the interfacial bonding of the opposing materials. The present work aims to develop and optimize the tinning process of a solid carbon steel substrate after incorporating flux constituents with the tin powder. Five ratios of tin-to-flux—i.e., 1:1, 1:5, 1:10, 1:15, and 1:20—were used for tinning process of carbon steel solid substrate. Furthermore, the effect of volume ratios of liquid Al-based bearing alloy to solid steel substrate were also varied—i.e., 5:1, 6.5:1 and 8.5:1—to optimize the microstructural and mechanical performance, which were evaluated by interfacial microstructural investigation, bonding area determination, hardness and interfacial strength measurements. It was found that a tin-to-flux ratio of 1:10 offered the optimum performance in AlSn12Si4Cu1/steel bimetallic materials, showing a homogenous and continuous interfacial layer structure, while tinned steels using other percentages showed discontinuous and thin layers, as in 1:5 and 1:15, respectively. Furthermore, bimetallic interfacial bonding area and hardness increased by increasing the volume ratio of liquid Al alloy to solid steel substrate. A complete interface bonding area was achieved by using the volume ratio of liquid Al alloy to solid steel substrate of ≥8.5.


Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 85
Author(s):  
Yuh-Chung Hu ◽  
Senthil Kumaran Selvaraj ◽  
Manivannan Subramanian ◽  
Kathiravan Srinivasan ◽  
Srinivasan Narayanan

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.


Author(s):  
Filip Pastorek ◽  
Milan Štrbák ◽  
Daniel Kajánek ◽  
Martina Jacková ◽  
Jana Pastorková ◽  
...  

A surface treatment process, composed of plasma electrolytic oxidation (PEO) and sealing by temporary oil preservation system containing corrosion inhibitors, was performed on AZ31 magnesium alloy in order to improve its corrosion resistance in environments containing chlorides. Both atmospheric and immersion conditions were evaluated by electrochemical tests in 0.1M NaCl solution together with salt spray test according to STN EN ISO 9227 standard. The obtained results confirmed significant improvement of corrosion resistance reached by the PEO sealing in aggressive environments compared to the pure PEO coating on AZ31 surface. Hence, such a duplex coating is a very perspective alternative for magnesium alloy applications in severe conditions or for temporary protection of magnesium products coated by the PEO during marine transport.


2015 ◽  
Vol 813-814 ◽  
pp. 135-139 ◽  
Author(s):  
K.G. Girisha ◽  
R. Rakesh ◽  
C. Durga Prasad ◽  
K.V. Sreenivas Rao

In this present research work, corrosion behaviour of grit blasted AISI 410 steel substrate coated with NiCr/Al2O3,NiCr/ZrO2 particles was investigated using salt spray test as per ASTM B117. Coatings were prepared using air Plasma spray process. Nickel chromium was used as bond coat for obtaining good fastening between the base metal and coated particles. The microstructures of the coated and un-coated specimens were characterized using scanning electron microscope and optical microscope. Distribution coated particle was found uniform throughout the steel substrate was revealed from SEM microphotographs. The obtained results shows significant improvement in corrosion resistance and micro hardness for NiCr/Al2O3 and NiCr/ZrO2 coating deposited on steel by plasma spray process than the as sprayed base steel substrates.


2015 ◽  
Vol 658 ◽  
pp. 42-52
Author(s):  
Polporn Chatisathien ◽  
Nuttapon Suttitam

Accelerated atmospheric corrosion behavior of carbon steel pipes subjected to cyclic salt spray test was performed according to ISO 14993 – Corrosion of metals and alloys – Accelerated testing involving cyclic exposure to salt mist, “dry” and “wet” conditions [1]. In order to investigate the effect of degree of exposure to environment of inner surface of the pipe on corrosion behavior of inner surface of the specimens, degree of completeness of weldment, 0%, 50%, 80%, and 100%, of steel cover plate is varied. Exposure times in this study are 168, 336, and 504 hours which can be correlated to 10, 20, and 30 years exposed to C3 corrosivity category according to the definition of ISO 9223 – Corrosion of metals and alloys – Corrosivity of atmospheres – Classification, determination and estimation [2,3]. After testing, visual inspection on outer and inner surfaces of the specimens were performed. In addition, average corrosion rate of the specimens were performed according to ISO 8407 – Corrosion of metals and alloys – Removal of corrosion products from corrosion test specimens [4]. The results show that as-received steel pipe specimens exhibited great degree of corrosion attack on the inner surface of the specimens while slight amount of corrosion was observed from the welded pipe specimens.


2013 ◽  
Vol 774-776 ◽  
pp. 1132-1136 ◽  
Author(s):  
Tai Xiong Guo ◽  
Xue Qiang Dong ◽  
Shu Hui Deng ◽  
Feng Li ◽  
Yi Lin Zhou

Simulation experiment was done to investigate the effects of rare earth on hot-dipped Zn-55%Al alloy coating. The results show that the rare earth has little effect on the zinc dross and its burning loss is about 10%. The microstructure of coating is similar to that of solidification bath, and which is made up of phases of rich aluminum, rich zinc, rich silicon and rare earth, and intermetallic layer of Al-Zn-Fe-Si. The rare earth phase is needle or rod, and mainly distributed inside rich zinc phase and on the interface between the coating and steel substrate. The rare earth has no obvious influence on coating grain and spangle size. The appropriate addition of rare earth would be helpful to improve the coating bending formability and corrosion resistance.


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