Building of Protective Coating Against Corrosion by Flame Spraying of Mechanofused Composite Particles

2015 ◽  
Vol 1765 ◽  
pp. 37-44
Author(s):  
A. Molina-Díaz ◽  
J. Delgado-Venegas ◽  
F. Juárez-López ◽  
G. Velázquez-García ◽  
R. Cuenca-Álvarez
Keyword(s):  
Protective Coating ◽  
Steel Substrate ◽  
Salt Spray ◽  
Thermal Spraying ◽  
Corrosion Damage ◽  
Flame Spraying ◽  
Composite Particles ◽  
Substrate Roughness ◽  
Alumina Layer ◽  
Splat Formation

ABSTRACTA protective coating was built and assessed in order to reduce the degradation of metallic substrates caused by corrosion damage. Hence, a set of coatings with different configurations, in terms of layer arrangement, was produced by flame-spraying of composite powder (AISI 316L stainless steel coated with an α-alumina layer) onto an AISI 1018 steel substrate. In order to ensure a homogeneous dispersion of phases, a correlation was established between the operating parameters of thermal spraying (roughness and surface temperature of substrate, spraying distance, passing speed) and the splat formation. Then, corrosion damage caused in the coated samples by exposure to a salt spray was monitored through weight measurements and observations with optical and scanning electron microscopy. The results show that corrosion still remains in all cases; however, it proceeds at lower rates for coatings made with composite particles plus an α-alumina layer. The weight loss due to corrosion damage was reduced in approximately 94% as compared with the substrate without protection. Coating adhesion was also improved by an increased substrate roughness, with no need for an intermediate layer.

Varying of Oil Consumption of Fluid-Film Bearing’s Surface Layer by Means of Application of Anti-Friction Coatings

2018 ◽  
Vol 284 ◽  
pp. 1263-1267
Author(s):  
Alexey Yu. Rodichev ◽  
A.V. Sytin ◽  
V.O. Tyurin
Keyword(s):  
Surface Layer ◽  
Steel Substrate ◽  
Thermal Spraying ◽  
Fluid Film ◽  
Flame Spraying ◽  
Oil Consumption ◽  
Fluid Film Bearings ◽  
Inner Surface ◽  
Accessible Method ◽  
Gas Flame

Gas flame spraying is the most accessible method of gas-thermal spraying. Pores are formed on the inner surface of the bimetallic fluid-film bearings as a result of the application of anti-friction coating on the steel substrate. The presence of such pores, the "microfibre effect", affects positively on life expectancy of fluid-film bearings. The study of the oil consumption of anti-friction coatings allows recommendation of these coatings for using in the manufacturing process of bimetallic fluid-film bearings.

The Effect of Substrate Preheating and Surface Organic Covering on Splat Formation

1998 ◽  
Author(s):  
C.J. Li ◽  
J.-L. Li ◽  
W.-B. Wang
Keyword(s):  
Stainless Steel ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Thermal Spraying ◽  
Splat Morphology ◽  
Organic Substances ◽  
Splat Formation ◽  
Molten Droplet ◽  
Preheating Temperature

Abstract The splashing usually occurs when a droplet impact on a substrate surface during thermal spraying, which results in the formation of splat with irregularly complicated morphology. In present study splats are formed on polished stainless steel substrate surface covered with different organic substances with different boiling points by plasma spraying under different preheating temperature of substrate in order to clarify the factors which control the splashing during droplet flattening in thermal spray process. The droplet materials used are aluminum, nickel, copper, Ah03 and molybdenum. Three kinds of organic substances used are xylene, glycol and glycerol which are brushed on the surface of substrate before spraying. It is found that when the preheating temperature exceeds 50°C over the boiling point of organic substance brushed on substrate surface the regular disk type splats are formed in the case that no substrate melting occurs by molten droplet. When the flattening of droplet causes the melting of substrate such as the combination of Mo droplet with stainless steel substrate, the preheating of substrate has no influence on splat morphology. The evaporated gas induced splashing and substrate surface melting induced splashing models are proposed to interpret the formation of the annulus-ringed splat

Effect of Substrate Temperature on Microstructural Characteristics of Thermal Sprayed Superalloys

2011 ◽  
Vol 495 ◽  
pp. 13-17
Author(s):  
Fardad Azarmi ◽  
Ghodrat Karami
Keyword(s):  
Substrate Temperature ◽  
Plasma Spraying ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Thermal Spraying ◽  
Air Plasma ◽  
Microstructural Characteristics ◽  
Splat Formation ◽  
Vacuum Plasma Spraying ◽  
Porosity Level

Recently, there has been a huge interest in application of thermal spraying processes to apply a protective layer on the surface of engineering components. Thermal spraying as a near net shape forming technique has also found applications in manufacturing of advanced engineering components. Spraying methods such as High Velocity Oxygen Fuel (HVOF), Vacuum Plasma Spraying (VPS), and Air Plasma Spraying (APS) are among the most commonly used deposition techniques. Coatings are built up from impact of molten particles on the substrate surface and their flattening and solidification (splat formation). Deposition of millions of individual splats connected to each other at different layers will result in a lamellae type structure. This is a typical example of an anisotropic microstructure. The microstructural features such as porosity, oxide layers define the physical and mechanical properties of coating material. This study investigates the influence of substrate temperature on microstructural characteristics of APS deposited superalloy 625 on steel substrate. The coatings were deposited on substrates at different temperatures. The porosity level was measured using prosimetry. Both image analysis technique and Electron Probe Microanalysis (EPMA) was used to measure the amount of oxide phase. The results indicated that lower substrate temperature results in lower oxide in microstructure. There has been no significant change in porosity level due to substrate temperature.

Influence of substrate temperature on adhesion of thermally sprayed Ni-5%Al coatings

2017 ◽  
Vol 1 (83) ◽  
pp. 33-40
Author(s):  
D. Ostrowski ◽  
R. Starosta
Keyword(s):  
Adhesion Strength ◽  
Steel Substrate ◽  
Thermal Spraying ◽  
Coating Material ◽  
Flame Spraying ◽  
Al Alloy ◽  
Thermally Sprayed Coatings ◽  
Machine Parts ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Purpose: In the paper effect of pre-heating the steel substrate on the adhesion of thermally sprayed Ni-5%Al alloy coatings was presented. The reason for the topic was the discrepancy between the literature data on the effect of the preheating of the substrate on the adhesion of the coatings and the guidelines of the coating material manufacturer. Design/methodology/approach: As a coating material the ProXon 21021 was used. It is an alloy of nickel aluminium and molybdenum. This material is often used during the regeneration of machine parts in the shipbuilding industry. The coatings by flame spraying using the Casto-Dyn DS 8000 torch were obtained. The samples were made of steel C45. The specimens to which the coating was applied were characterized by a similar surface roughness. Before applying the coatings, the samples were preheated to a temperature of 50 to 400°C. The coatings tested were similar in thickness. Adhesion strength of the coatings was determined by the pull-off method. Findings: The quantitative comparative assessment of the adhesion strength of thermally sprayed coatings can be implemented by a pull-off. The highest value of adhesion strength for coatings applied on substrates of 50, 300 and 400°C was found. Considering that the technical thermally sprayed coatings of Ni-5% Al, often require an additional machining, they must be applied to the steel substrate surface at 50°C. Research limitations/implications: The adhesion test of the coatings has not been executed in accordance with the requirements of PN-EN 582 Thermal spraying - Determination of tensile adhesive strength. Therefore, the quantitative results obtained are only comparative. Practical implications: The results obtained show that the regeneration coatings of ProXon 201021 material should only be applied to pre-heated by flame (among other things, to degrease the surface of the substrate) to a temperature of approximately 50°C. At the time the coatings are characterized by the greatest adhesion to the steel substrate. Originality/value: The study demonstrated the usefulness of cheaper method of pull-offs to evaluate the adhesion of flame sprayed coatings. The results show that there is no need for a pre-heating of the substrate between 150 and 250°C before thermal spraying. This article may be useful for technologists designing the process of regeneration of machine parts using flame spraying.

scholarly journals Sacrificial Dissolution of Zinc Electroplated and Cold Galvanized Coated Steel in Saline and Soil Environments: A Comparison

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 744
Author(s):  
Ameeq Farooq ◽  
Umer Masood Chaudry ◽  
Ahsan Saleem ◽  
Kashif Mairaj Deen ◽  
Kotiba Hamad ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Saline Soil ◽  
Steel Substrate ◽  
Salt Spray ◽  
Steel Structures ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Transfer Resistance ◽  
Soil Solutions

To protect steel structures, zinc coatings are mostly used as a sacrificial barrier. This research aims to estimate the dissolution tendency of the electroplated and zinc-rich cold galvanized (ZRCG) coatings of a controlled thickness (35 ± 1 μm) applied via brush and dip coating methods on the mild steel. To assess the corrosion behavior of these coated samples in 3.5% NaCl and 10% NaCl containing soil solutions, open circuit potential (OCP), cyclic polarization (CP), and electrochemical impedance spectroscopy (EIS) tests were performed. The more negative OCP and appreciably large corrosion rate of the electroplated and ZRCG coated samples in 3.5% NaCl solution highlighted the preferential dissolution of Zn coatings. However, in saline soil solution, the relatively positive OCP (>−850 mV vs. Cu/CuSO4) and lower corrosion rate of the electroplated and ZRCG coatings compared to the uncoated steel sample indicated their incapacity to protect the steel substrate. The CP scans of the zinc electroplated samples showed a positive hysteresis loop after 24 h of exposure in 3.5% NaCl and saline soil solutions attributing to the localized dissolution of the coating. Similarly, the appreciable decrease in the charge transfer resistance of the electroplated samples after 24 h of exposure corresponded to their accelerated dissolution. Compared to the localized dissolution of the electroplated and brush-coated samples, the dip-coated ZRCG samples exhibited uniform dissolution during the extended exposure (500 h) salt spray test.

ANTICORROSION PERFORMANCE OF SELF-HEALING POLYMERIC COATINGS ON LOW CARBON STEEL SUBSTRATES

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
Muhammad Ashraff Ahmad Seri ◽  
Esah Hamzah ◽  
Abdelsalam Ahdash ◽  
Mohd Fauzi Mamat
Keyword(s):  
Steel Substrate ◽  
Salt Spray ◽  
Immersion Test ◽  
Salt Spray Test ◽  
Test Method ◽  
The Self ◽  
Self Healing ◽  
Pure Epoxy ◽  
Steel Substrates ◽  
Epoxy Paint

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.

Comparison between Tribological Characteristics of Al-Cu-Fe-B Quasicrystalline and Mo Coatings

2007 ◽  
Vol 26-28 ◽  
pp. 715-718
Author(s):  
Bong Hwan Kim ◽  
Sang Mok Lee
Keyword(s):  
Mechanical Properties ◽  
Surface Energy ◽  
Bonding Strength ◽  
Tribological Behavior ◽  
Thermal Spraying ◽  
Microstructural Characterization ◽  
Flame Spraying ◽  
Energy Calculation ◽  
Air Plasma ◽  
Oxygen Fuel

Al-Cu-Fe-B quasicrystalline and Mo coatings were obtained on the mild steel and brass substrates by thermal spraying routes for the purpose of replacement of Mo coatings with quasicrystalline ones. Quasicrystalline coatings were prepared by air plasma spraying and/or HVOF (High Velocity Oxygen Fuel) techniques followed by subsequent heat treatment, and Mo coatings, wire flame spraying. For comparative studies of important properties for industrial application, mechanical properties, bonding strength, surface energy, and tribological behavior were investigated based on microstructural characterization. Basic mechanical properties such as hardness, fracture toughness, and elastic modulus of quasicrystalline coating showed comparable values with those of Mo coatings. De-bonding tests of coatings deposited onto brass substrate indicated that the bonding strength of quasicrystalline coatings obtained by HVOF techniques exhibit higher value to Mo coatings. Non-sticking property analogized from surface energy calculation and friction coefficient of quasicrystalline coatings also showed better performance during the tests. It is suggested from this investigation that the quasicrystalline coating can be effectively used as a replacement of the Mo coating, which has shown a recent steep price rise and problems of accidental existence of minor environment harmful elements such as Cr6+, Pb, Cd, and Hg.

Development & Characterization of Alumina Coating by Atmospheric Plasma Spraying

2018 ◽  
Vol 877 ◽  
pp. 104-109 ◽  
Author(s):  
Jobin Sebastian ◽  
Abyson Scaria ◽  
Don George Kurian
Keyword(s):  
Plasma Spraying ◽  
Elevated Temperatures ◽  
Steel Substrate ◽  
Oxide Coating ◽  
Ceramic Coatings ◽  
Substrate Material ◽  
Atmospheric Plasma ◽  
Flame Spraying ◽  
Alumina Coating ◽  
Spray Process

Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results

Thermally Sprayed Ternary Materials for Enhanced Corrosion Protection

1997 ◽  
Author(s):  
T. Lester ◽  
S.J. Harris ◽  
D. Kingerley ◽  
S. Matthews
Keyword(s):  
Barrier Layer ◽  
Salt Spray ◽  
Thermal Spraying ◽  
Steel Structures ◽  
Deposition Efficiency ◽  
Aqueous Corrosion ◽  
Metal Coatings ◽  
Zinc Coatings ◽  
Thermally Sprayed ◽  
Better Than

Abstract Thermal spraying has been used to protect many steel structures from aqueous corrosion using Zinc and Aluminium, and to some extent their alloy coatings to provide galvanic protection. The lifetimes of the coatings can approach 50 years even when exposed in severe marine environments. Zinc coatings work by continuously sacrificing themselves and slowly dissipating over time. Aluminium coatings passivate more readily and form a barrier layer, the passivity makes them less able to protect damaged areas and to self heal. A new ternary coating system involving Aluminium, Zinc and Magnesium has been shown to be capable of providing both a passive barrier layer as well as being able to give galvanically active protection. Salt spray tests have shown that the resistance to red rust of these new coatings increases by 300% over similar thicknesses of the separate metal coatings. Processing by arcspray is straightforward and both adhesion and deposition efficiency are better than where Zinc is sprayed alone.

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