HVOF Diamalloy 2002 coating of steel surface: electrochemical corrosion resistance

2015 ◽  
Vol 67 (2) ◽  
pp. 119-123
Author(s):  
B. S. Yilbas ◽  
I.-H. Toor ◽  
F. Patel ◽  
Y. Al-Shehri ◽  
M. A. Baig
Keyword(s):  
Corrosion Resistance ◽  
Gas Turbines ◽  
Steel Surface ◽  
Electrochemical Corrosion ◽  
Experimental Investigations ◽  
Hvof Spraying ◽  
Content Type ◽  
Hvof Coating ◽  
Model Studies ◽  
Deep Pit

Purpose – The purpose of this paper is to investigate the corrosion resistance of high velocity oxy-fuel (HVOF)-sprayed Diamalloy 2002 coating on carbon steel. The coating microstructure is examined in line with the corrosion resistance. Design/methodology/approach – HVOF spraying of coating is achieved, and the coating response to electrolytic solution is measured experimentally in terms of corrosion resistance. Findings – HVOF coating improves the corrosion resistance of the substrate such that the corrosion rate of the substrate is 7.1 mpy and the coating results in 4.5 mpy. However, presence of deep pit sites at the surface suggests the occurrence of preferential corrosion around the splat boundaries. In addition, closely spaced surface texture peaks act as crevice corrosion centers at the surface while initiating the formation of deep pit sites. Research limitations/implications – This study is limited by experimental investigations. In future, it may be extended to include model studies. Practical implications – The findings of this study are very useful for those working in the coating industry. However, HVOF coating is limited to high temperature protection in harsh environments. Social implications – It is useful for the power industry, particularly for gas turbines. Originality/value – It is an original work and describes the corrosion resistance of the coating surface. It is found that the coating improved the corrosion resistance of the steel surface.

Effects of mass ratios on salt spray corrosion and electrochemical corrosion behaviors of laser cladded Cr–Ni coatings

2019 ◽  
Vol 66 (3) ◽  
pp. 352-359
Author(s):  
Li Jiahong ◽  
Kong Dejun
Keyword(s):  
Corrosion Resistance ◽  
Laser Cladding ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Mechanism ◽  
H13 Steel ◽  
Content Type ◽  
Salt Spray Corrosion ◽  
Electrochemical Tests ◽  
Mass Ratios

Purpose The purpose of this paper is to improve the salt spray corrosion and electrochemical corrosion performances of H13 hot work mould steel, Cr–Ni coatings with the different Cr and Ni mass ratios are fabricated using a laser cladding (LC), which provides an experimental basis for the surface modification treatment of H13 steel. Design/methodology/approach Cr–Ni coatings with the different Cr and Ni mass ratios were firstly fabricated on H13 hot work mould steel using a laser cladding (LC). The salt spray corrosion (SSC) and electrochemical corrosion performances of Cr–Ni coatings in 3.5 Wt.% NaCl solution were investigated to analyze the corrosion mechanism, and the effect of mass ratios of Cr and Ni on their corrosion mechanism was discussed. Findings The laser cladded Cr–Ni coatings with the different Cr and Ni mass ratios are composed of Cr–Ni compounds, which are metallurgically combined with the substrate. The SSC resistance of Cr–Ni coating with the Cr and Ni mass ratios of 24:76 is the highest. The electrochemical corrosion resistance of Cr–Ni coating with the Cr and Ni mass ratio of 24:76 is the best among the three kinds of coatings. Originality/value In this study, the corrosion resistance of laser cladded Cr–Ni coatings with the Cr and Ni mass ratios of 17: 83, 20: 80 and 24: 76 was first evaluated using salt spray corrosion (SSC) and electrochemical tests, and the effect of mass ratios of Cr and Ni on their corrosion mechanism was discussed.

Appraisal on corrosion performances of CrNi, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings on H13 hot work mold

2020 ◽  
Vol 67 (2) ◽  
pp. 150-157
Author(s):  
Kong Dejun ◽  
Li Jiahong
Keyword(s):  
Corrosion Resistance ◽  
Salt Spray ◽  
Test Chamber ◽  
Electrochemical Corrosion ◽  
Optical Microscope ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
H13 Steel ◽  
Content Type ◽  
Electrochemical Corrosion Resistance

Purpose The purpose of this paper is to evaluate the salt spray corrosion (SSC) and electrochemical corrosion performances of CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings on H13 steel, which improved the corrosion resistance of H13 hot work mold. Design/methodology/approach CrNi, TiAlN/NiCr and CrNi–Al2O3–TiO2 coatings were fabricated on H13 hot work mold steel using a laser cladding and cathodic arc ion plating. The SSC and electrochemical performances of obtained coatings were investigated using a corrosion test chamber and electrochemical workstation, respectively. The corrosion morphologies, microstructure and phases were analyzed using an electron scanning microscope, optical microscope and X-ray diffraction, respectively, and the mechanisms of corrosion resistance were also discussed. Findings The CrNi coating is penetrated by corrosion media, producing the oxide of Fe3O4 on the coating surface; and the TiAlN coating is corroded to enter into the CrNi coating, forming the oxides of TiO and NiO, the mechanism is pitting corrosion, whereas the CrNi–Al2O3–TiO2 coating is not penetrated, with no oxides, showing the highest SSC resistance among the three kinds of coatings. The corrosion potential of CrNi coating, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings was –0.444, –0.481 and –0.334 V, respectively, and the corresponding polarization resistances were 3,074, 2,425 and 86,648 cm2, respectively. The electrochemical corrosion resistance of CrNi–Al2O3–TiO2 coating is the highest, which is enhanced by the additions of Al2O3 and TiO2. Originality/value The CrNi, TiAlN/CrNi and CrNi–Al2O3–TiO2 coatings on H13 hot work mold were firstly evaluated by the SSC and electrochemical performances.

Electrochemical corrosion behavior and surface passivation of bulk nanocrystalline copper in alkaline solution

2020 ◽  
Vol 67 (5) ◽  
pp. 465-472
Author(s):  
Wei Luo ◽  
Lei Hu ◽  
Yimin Xv ◽  
Jian Zhou ◽  
Wentao Xv ◽  
...  
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Passive Film ◽  
Corrosion Behavior ◽  
Potentiodynamic Polarization ◽  
Electrochemical Corrosion ◽  
Content Type ◽  
Naoh Solution ◽  
Electrochemical Corrosion Behavior ◽  
Bulk Nanocrystalline

Purpose This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments. Design/methodology/approach The electrochemical corrosion behavior of bulk nanocrystalline (NC) copper prepared by inert gas condensation and in situ warm compress technique was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy tests in de-aerated 0.1 M NaOH solution. Findings NC copper exhibited a typical active-passive-transpassive behavior with the formation of duplex passive films, which was qualitatively similar to coarse-grain (CG) copper. Although a compact passive film formed on NC copper surface, the corrosion resistance of NC copper was lower in comparison with CG copper. The increase in corrosion rate for NC copper was mainly attributed to the high activity of surface atoms and intergranular atoms. These atoms led to an enhancement of passive ability and an increase of dissolution rate of passive film in oxygen-deficiency solution. For NC copper, the corrosion resistance decreased as grain size increased in NC range. Originality/value The difference in corrosion resistance between bulk NC copper and its CG counterpart is dependent upon the corrosion solution. In a previous work, the potentiodynamic polarization tests revealed that NC copper bulks (grain size 48, 68, 92 nm) had identical corrosion resistance to CG copper bulk in naturally aerated 0.1 M NaOH solution. The results might be related to the dissolved oxygen in the medium.

An investigation of corrosion resistance of HVOF coated ASME SA213 T91 boiler steel in an actual boiler environment

2017 ◽  
Vol 64 (5) ◽  
pp. 499-507 ◽  
Author(s):  
Varinder Pal Singh Sidhu ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Original Research ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Spraying Process ◽  
Minimum Resistance

Purpose This paper aims to use the high-velocity oxy fuel (HVOF) spraying process for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91 to study the corrosion resistance of these coatings in an actual boiler environment. Design/methodology/approach The HVOF spraying process was used for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91. All the coatings obtained are found to be uniform, dense and having thickness between 200 and 250 μm. All the coatings were exposed in an actual boiler environment at 900°C temperature for 10 cycles. Each cycle consisted of 100 h heating followed by 1 h cooling at ambient conditions. X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy techniques were used to analyse corrosion products. Findings All the coated samples were found to be having higher corrosion resistance than the uncoated samples. Among coated specimens, 93(WC–Cr3C2)–7Ni coating has shown maximum and 75Cr3C2–25NiCr coating has shown minimum resistance to corrosion. Originality/value This paper is original research.

Salt spray corrosion and electrochemical corrosion performances of Dacromet fabricated Zn–Al coating

2019 ◽  
Vol 66 (5) ◽  
pp. 565-572
Author(s):  
Xiaoxiao Liu ◽  
Dejun Kong
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Product ◽  
Cathodic Protection ◽  
Corrosion Potential ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Mechanism ◽  
Content Type ◽  
Salt Spray Corrosion ◽  
Al Coating

Purpose This study aims to investigate the salt spray corrosion (SSC) and electrochemical corrosion of obtained Zn–Al coating, which provided a basis for comprehensive analysis of corrosion behavior of Zn–Al coating. Design/methodology/approach A Zn–Al coating was fabricated on Q235A steel using a Dacromet method. The SSC and electrochemical corrosion performances in 3.5 Wt.% NaCl solution were investigated using an SSC chamber and electrochemical workstation, respectively, and the corrosion mechanism of Zn–Al coating was discussed. Findings The Dacromet fabricated Zn–Al coating is primarily composed of Zn and Al phases, its residual stress of −11.1 ± 4 MPa is compressive stress, which is beneficial to improve its corrosion resistance. In the SSC process, the corrosion product of Zn5(OH)8Cl2H2O enhances the corrosion resistance of Zn–Al coating, which provides sufficient cathodic protection for the substrate. The corrosion potential of Zn–Al coating is lower than that of substrate, which provides sufficient cathodic protection to the substrate, the Zn–Al coating in the immersion periods is protected by the corrosion product and Zn–Al sheets. Originality/value In this study, a Zn–Al coating was first fabricated on Q235A steel using a Dacromet method.

Study on the corrosion of copper alloy by friction stir surface processing

2016 ◽  
Vol 63 (3) ◽  
pp. 190-195 ◽  
Author(s):  
Song Weiwei ◽  
Xiaojing Xu ◽  
Dunwen Zuo ◽  
Jianli Wang
Keyword(s):  
Corrosion Resistance ◽  
Surface Modification ◽  
Copper Alloy ◽  
Rotation Speed ◽  
Electrochemical Corrosion ◽  
Test Results ◽  
Surface Processing ◽  
Content Type ◽  
Friction Stir ◽  
Modified Surface

Purpose This paper aims to investigate the modification of surface of a copper alloy by friction stir surface processing (FSSP). Design/methodology/approach The metallographic condition of the surface modification was observed using microscopy. Electrochemical corrosion tests were carried out on the modified surface and the corroded surface was observed by scanning electron microscopy (SEM). Findings The test results showed that FSSP resulted in refinement of the surface grains of the copper alloy. The degree of refinement was increased with rotation speed and increased in the descending distance of the stirring tool. The corrosion resistance of the modified surface was superior to the base metal except for the surface generated by a rotation speed of 800 rpm and a descending distance 0.1 mm. For the surface modification of the rotation speed of 800 rpm, its corrosion resistance was lower than for the other two rotation speeds. When the rotation speed is specified, the corrosion resistance is improved with increased descending distance. When the descending distance is specified, the corrosion resistance is improved with the rotation speed. Originality/value In this study, it was confirmed that the corrosion resistance of the surface modification was best at the rotation speed 1200 rpm and descending distance 0.2 mm.

Electrochemical corrosion performances of laser thermal sprayed amorphous Al–Ti–Ni coatings in marine environment

2020 ◽  
Vol 67 (2) ◽  
pp. 140-149
Author(s):  
Kong Dejun ◽  
Chen Haixiang
Keyword(s):  
Corrosion Resistance ◽  
Marine Environment ◽  
Laser Power ◽  
Electrochemical Corrosion ◽  
Amorphous Coating ◽  
Corrosion Performance ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Electrochemical Corrosion Resistance

Purpose The purpose of this paper is to investigate the effects of laser power on the electrochemical corrosion performance in 3.5% NaCl, 0.1 M H2SO4 and 0.1 M NaOH solutions, which provided an experimental basis for the application of Al–Ti–Ni amorphous coating in marine environment. Design/methodology/approach Amorphous Al–Ti–Ni coatings were fabricated on S355 structural steel by laser thermal spraying (LTS) at different laser powers. The surface and cross-section morphologies, chemical element distribution, phases and crystallization behaviors of obtained coatings were analyzed using a scanning electron microscope, energy-dispersive X-ray spectroscope, X-ray diffraction and differential scanning calorimetry, respectively. The effects of laser power on the electrochemical corrosion performances of Al–Ti–Ni coatings in 3.5% NaCl, 0.1 M H2SO4 and 0.1 M NaOH solutions were investigated using an electrochemical workstation. Findings The crystallization temperature of Al–Ti–Ni coatings fabricated at the laser power of 1,300 and 1,700 W is ∼520°C, whereas that fabricated at the laser power of 1,500 W is ∼310°C. The coatings display excellent corrosion resistance in 3.5% NaCl and 0.1 M NaOH solutions, while a faster dissolution rate in 0.1 M H2SO4 solution. The coatings fabricated at the laser power of 1,300 and 1,700 W present the better electrochemical corrosion resistance in 3.5% NaCl and 0.1 M NaOH solutions, whereas that fabricated at the laser power of 1,500 W exhibits the better electrochemical corrosion resistance in 0.1 M H2SO4 solution. Originality/value In this work, Al-wire-cored Ti–Ni powder was first on S355 steel with the laser power of 1,300, 1,500 and 1,700 W, and the effects of laser power on the electrochemical corrosion performance in 3.5% NaCl, 0.1 M H2SO4 and 0.1 M NaOH solutions were investigated using an electrochemical workstation.

Electrochemical corrosion behavior of HVOF sprayed WC–12Co coating on H13 hot work mould steel

2019 ◽  
Vol 66 (6) ◽  
pp. 827-834
Author(s):  
Kong Weicheng ◽  
Shen Hui ◽  
Gao Jiaxu ◽  
Wu Jie ◽  
Lu Yuling
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Curvature Radius ◽  
Nacl Solution ◽  
Content Type ◽  
Capacitance Curve ◽  
Electrochemical Corrosion Behavior ◽  
Corrosion Behaviors

Purpose This study aims to investigate the electrochemical corrosion performance of high velocity oxygen fuel (HVOF) sprayed WC–12Co coating in 3.5 Wt.% NaCl solution, which provided a guiding significance on the corrosion resistance of H13 hot work mould steel. Design/methodology/approach A WC–12Co coating was fabricated on H13 hot work mould steel using a HVOF, and the electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution was measured using open circuit potential (OCP), potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) tests. Findings The OCP and PPC of WC–12Co coating positively shift than those of substrate, its corrosion tendency and corrosion rate decrease to enhance its corrosion resistance. The curvature radius of capacitance curve on the WC–12Co coating is larger than that on the substrate, and the impedance and polarization resistance of WC–12Co coating increase faster than those of substrate, which reduces the corrosion process. Originality/value The electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution is first measured using OCP, PPC and EIS tests, which improve the electrochemical corrosion resistance of H13 hot work mould steel.

Study on the effect of surface tannic acid/silane conversion film on properties of epoxy resin coatings

2019 ◽  
Vol 66 (4) ◽  
pp. 446-453
Author(s):  
Tianji Xing ◽  
Lixia Ying ◽  
Chunxi Wu ◽  
Zhen Fu ◽  
Guixiang Wang
Keyword(s):  
Corrosion Resistance ◽  
Epoxy Resin ◽  
Tannic Acid ◽  
Steel Surface ◽  
Steel Substrate ◽  
Sodium Molybdate ◽  
Content Type ◽  
Binding Force ◽  
Main Components ◽  
Effect Of Surface

Purpose The purpose of this paper is to improve binding force between the coating and the steel substrate by using chemical modification on the steel surface; at the same time, it can also increase the corrosion resistance of the coating. Design/methodology/approach The main components of the conversion film include tannic acid, sodium molybdate and silane coupling agent KH560. After the preparation was completed, the samples were tested and analyzed, including surface morphology, conversion film components, bonding force with organic resins and corrosion resistance. Finally, it drew a conclusion that the conversion film can greatly improve the bonding strength of the steel substrate and epoxy resin. Findings When the content of tannic acid is 4 g/L meanwhile the content of KH560 is 20 g/L, the conversion film has the strongest binding force with epoxy resin, from 2.15 Mpa of untreated steel to 4.60 Mpa, growth of 140 per cent. At the same time, the resulting conversion film also improves the corrosion resistance of the steel surface by a small margin. Originality/value A method of enhancing the bond between an epoxy coating and steel is provided. Verify the mechanism of this method.

Electrochemical corrosion resistance of thermal oxide formed on anodized stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Hongda Deng ◽  
Yongliang Liu ◽  
Zhen He ◽  
Xiantao Gou ◽  
Yefan Sheng ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Design Methodology ◽  
Electrochemical Corrosion ◽  
Constant Density ◽  
Content Type ◽  
Thermal Oxide ◽  
Pitting Corrosion Resistance ◽  
Dynamic Potential ◽  
Electrochemical Corrosion Resistance

Purpose The purpose of this paper is to investigate and explain thermal oxide effect on electrochemical corrosion resistance anodized stainless steel (SS). Design/methodology/approach Electrochemical corrosion resistance of thermal oxides produced on anodized 304 SS in air at 350°C, 550°C, 750°C and 950°C in 3.5 wt.% NaCl solution have been investigated by dynamic potential polarization, EIS and double-loop dynamic polarization. Anodized 304 SS were obtained by anodization at the constant density of 1.4 mA.cm-2 in the solution containing 28.0 g.L-1H3PO4, 20.0 g.L-1C6H8O7, 200.0 g.L-1H2O2 at 70°C for 50 min. SEM and EDS had been also used to characterize the thermal oxides and passive oxide. Findings Interestingly, anodized 304SS with thermal oxide produced at 350°C displayed more electrochemical corrosion and pitting resistance than anodized 304 SS only with passive oxide, as related to the formation of oxide film with higher chromium to iron ratio. Whereas, anodized 304SS with thermal oxide formed at 950°C shows the worse electrochemical corrosion and pitting resistance among those formed at the high temperatures due to thermal oxide with least compact. Originality/value When thermally oxidized in the range of 350°C–950°C, electrochemical corrosion and pitting corrosion resistance of anodized 304 SS decrease with the increase of temperature due to less compactness, more defects of thermal oxide.

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