Thermal Spray Method Research Articles

Investigate the corrosion properties of stellite coated on AZ91D alloy by plasma spray technique

Stellite alloys are primarily preferred in various component manufacturing industries due to its magnificent mechanical and electrochemical properties. The stellite powder is deposited over the materials by various thermal spray methods in industries. This research proposed investigating the microstructure and corrosion properties of stellite powder that is deposited on an AZ91D magnesium alloy substrate by atmospheric plasma spraying process. The SEM, optical microscopy, and atomic force microscopy are typical of the coatings. Immersion experiments in sodium chloride conditions are conducted at varying pH levels, chloride ion concentration, and exposure time. In addition, XRD examined the phase change properties of the powder and sprayed condition of coatings along with corrosion testing. The corrosion experiments were conducted to establish several regression models based on the central composite design and the response sur-face process. The accuracy of the regression models was sufficient to allow correlations between input parameters and responses through variance analysis. It was found that the pH value significantly influences the corrosion behaviour of stellite coatings followed by other parameters such as chloride ion concentration and exposure time, even in corrosion tests, plasma-sprayed coatings performed better.

A review on surface protective coating using cold spray cladding technique

Cold spray cladding, which is a part of the thermal spray cladding family, is a surface modification method that develops highly resistant layers on the substrate to generate coatings with improved surface properties. At temperatures below the melting point, powder-based spray particles are impinged on the substrate at supersonic speeds, resulting in efficient metallurgical and mechanical bonding. The cold spray has several benefits over traditional thermal spray methods, including lower oxidation, less coating porosity, no phase transitions, and no residual thermal stresses. Cold spray cladding can be applied over varieties of materials such as metals, composites, ceramics, and polymers. Significant studies have been done in the previous decade, and there is still a lot of opportunity for future work on this technique. This article highlights the existing research work on different substrates using different powder materials concerning deposited characteristics with their findings and applications. In this context, future research prospects in cold spray claddings are also explored.

Determination of Adhesive and Cohesive Strength in Metal Coatings Deposited by Hypersonic Metallization

. It is known that at present, methods of thermal spraying are widely used to restore and strengthen various worn-out machine parts. As a rule, metal coatings applied by thermal spraying have lower strength characteristics than solid materials. It is believed that the strength of coatings is proportional to their adhesive and cohesive strength. The value of adhesive and cohesive strength depends on various factors, including the nature of the materials and the technology of coating. An important factor characterizing the possibility of using metal coatings in various industries is the strength of adhesion of coatings to the base metal. The paper presents the determination of the adhesive and cohesive strength of coatings from different materials, applied by the method of hypersonic metallization. The results of testing the strength of metal coatings made of ER316LSi-grade wire, nichrome (Cr20Ni80) and molybdenum wire are given in the paper. Based on the results of metallographic studies, the proportion of the participation of cohesive and adhesive components in the strength of coatings has been determined, and some features of coating destruction have been described. It has been found that the participation of the cohesive and adhesive components of the coating strength differs depending on the material used. The cohesive component prevails in the strength of coatings made of high-alloy wire of the ER316LSi-grade, at which destruction mainly occurs along the coating-base boundary. For nichrome coatings and especially for coatings made of molybdenum, the cohesive component is predominant, in which the destruction of the coating occurs not along the coating-base boundary, but between the coating layers.

Polymer metallization via cold spray additive manufacturing: A review of process control, coating qualities, and prospective applications

Polymer metallization via cold spray additive manufacturing is an emerging thermal spray approach for deposition of thick metallic coatings on polymers and fiber-reinforced composites that promises high productivity, ecofriendliness, and scalability of the coating process. In polymer metallization via cold spray, solid metallic powder is accelerated by a supersonic stream of preheated gas and propelled toward a polymer substrate, where it is built layer-by-layer via impact-induced heating and particle deformation. Since the pioneering study at Cambridge in 2006, nearly 50 experimental reports on polymer metallization via cold spray have been published, half of which have appeared within the past three years. This review distinguishes cold spray from other thermal spray methods, analyzes the peculiarities of cold spraying on polymers and fiber-reinforced composites, outlines the historical establishment of the field, and summarizes the available literature on polymer metallization via cold spray. The major focus here is on the influence of the cold spray process parameters on the deposition efficiency, adhesion strength, electrical conductivity and other properties of metallic coatings formed on polymers and fiber-reinforced composites. The promising applications of cold spray additive manufacturing in lightning strike protection, electroplating, osseointegration, antifouling, antivirus, e.g. anti-Covid-19 surfaces, and other surface functionalizations have been reviewed. Finally, recommendations were given on how to enhance the data reuse in future studies on polymer metallization via cold spray.

Characterization of D-gun sprayed Al2O3-13%TiO2 and Al2O3-40%TiO2 coatings on ASTM 316 boiler steel and their microstructure

Coating by thermal spray method has proved to be the widely used and most economic way for developing coatings on various different materials in order for achieving all the needed material characteristics. Protective Coatings are most broadly and preferably produced and experimentally tested for various industrial areas namely automobile industry, thermal power plants etc. D-gun sprayed coating method can really be considered as unique coating method well known for producing coatings with very dense microstructure, low porosity, stronger and Erosion-corrosion resistant coatings. In this present study work Al2O3-13%TiO2 and Al2O3-40%TiO2 Coatings were deposited over ASTM 316 Boiler tube Steel with D-Gun spraying method. Various different methods namely X-Ray diffraction (XRD), SEM and X-Ray Mapping were used to characterize both the above mentioned coatings. After the investigation it was found that both of these coatings which we wanted to establish have been successfully established.

Development of high entropy alloys in Australia: a review

ABSTRACT First reported in the early 2000s, a new generation of metals called ‘high-entropy alloys’ (HEAs) have the potential to outperform conventional alloys that rely on a primary base metal. The plethora of five or more metallic elements when alloyed in equiatomic or near equiatomic creates a vast HEA material hyperspace that can lead to exceptional technical properties. This paper provides insights into HEAdevelopment in Australia; in particular, the additive manufacturing of HEA deposits through thermal spray and laser-based methods.

A Review on the Wear, Corrosion and High-Temperature Resistant Properties of Wire Arc-Sprayed Fe-Based Coatings.

Among different thermal spraying methods, arc-spraying has been widely used due to its low operating costs and high deposition efficiency. The rapid progress of cored wire technology in arc-spraying has increased possibilities for the preparation of new Fe-based coating materials with enhanced properties by adding reinforcement particles and alloying elements to suit the different applications. Fe-based coatings have been extensively used because of their high strength, toughness, lower production costs, and availability of raw materials. This makes them suitable replacements for Ni-based coatings in ambient and high-temperature applications. This review discusses the research status and developments of the arc-sprayed Fe-based coatings. The study specifically reviews the wear behavior, corrosion analysis, and high-temperature resistant properties of arc-sprayed Fe-based coatings, aiming to develop an understanding of the protection mechanisms for Fe-based coatings. The performance of the Fe-based coatings depends on the integrity of the coating structure. Optimizing arc-spraying parameters minimizes defects (pores, grain boundaries, unmelted particles, oxides, and microcracks) that deteriorate the coating properties. High amorphous phase content, ceramic reinforcement particles and alloying elements enhance the corrosion, tribological, and high-temperature resistant properties of Fe-based coatings. In high-temperature applications, Fe-based coatings form oxide scales that protect the coating from further oxidation; thus, it is important to select the optimum composition for the alloying elements.

Corrosion Behavior of Ni-Based Metallic Coatings Deposited by Thermal Spray Method on Low Nickel Austenitic Stainless Steel

Corrosion Behavior of Ni-Based Metallic Coatings Deposited by Thermal Spray Method on Low Nickel Austenitic Stainless Steel

MWCNTS-YSZ coating deposited by plasma thermal spray on INCONEL 738 low carbon substrate

The surface of Inconel 738 LC samples has been coated with carbon nanotube and yttria stabilized zirconia utilizing the plasma thermal spray method. Various percentages of carbon nanotubes and yttria stabilized zirconia were utilized in the coating (100 percent nano YSZ, 96 percent nano YSZ +4 percent CNTs, 94 percent nano YSZ +6 percent CNTs, and 92 percent nano YSZ +8 percent CNTs). After coating, a cyclic hot corrosion testing has been conducted, followed by SEM and XRD on all samples. SEM cross-section micrographs were utilized to quantify coating thickness. After 50 hrs of corrosion in 67 percent wt. V2O5 +33 percent wt. Na2SO4 at 950 degree centigrade, the changing weight of absence and coated specimens was measured. The cumulative weight change per surface area of coated specimens at temperatures of 950 °C was found to be 0.0095, 0.0075, 0.006, and 0.0057 mg.cm–2, (E,F,G,H) respectively. The best coating to resist hot corrosion was showed by specimens coated with 92% wt. yttria +8%wt. carbon nanotube. There are no oxides in the base specimens, according to X-rays of coated samples. Images of scanning electron microscopy for the surface layer revealed that it has a significant porosity and that some of the layer of coating s had microcracks.

Large-scale manufacturing route to metamaterial coatings using thermal spray techniques and their response to solar radiation

Metamaterials, an artificial periodic two- or three-dimensional configuration, can change propagation characteristics of electromagnetic waves (i.e., reflection, transmission, absorption). The current challenges in the field of metamaterial coatings are their manufacturing in a large-scale and large-length scale. There is a clear need to enhance process technologies and scalability of these. Thermal spraying is a method used to deposit small- to large-scale coatings where the sprayed layer is typically formed by the successive impact of fully or partially molten particles of a material exposed to various process conditions. This work aims to investigate the feasibility to manufacture large scale metamaterial coatings using the thermal spray technique and examine their response to solar radiation. Two types of coatings namely, Cr2O3 and TiO2, were deposited onto various substrates (e.g., steel, aluminium, glass, indium tin oxide (ITO)–coated glass) with a fine wire mesh (143 µm and 1 mm aperture sizes) as the masking sheet to manipulate the surface pattern using suspension high-velocity oxy-fuel thermal spraying (S-HVOF) and atmospheric plasma-sprayed (APS) methods, respectively. Post deposition, their responses subjected to electromagnetic wave (between 250 and 2500 nm or ultraviolet (UV)-visible (Vis)-infrared (IR) region) were characterised. The additional microstructural characterisation was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), three-dimensional profilometry, and optical spectroscopy. It is demonstrated that through novel application of thermal spray techniques, large-scale manufacturing of metamaterial coating is possible, and such material can affect electromagnetic wave propagation. Comparison between Cr2O3 and TiO2 coatings on aluminium substrates showed reduced three orders of reduced reflectance for Cr2O3 coatings (for 1-mm aperture size) throughout the spectrum. It was concluded that for a similar bandgap, Cr2O3 coatings on aluminium substrate will yield improved optical performance than TiO2 coating, and hence more useful to fabricate opto-electronic devices.Graphical abstract

Hard Anodization Film on Carbon Steel Surface by Thermal Spray and Anodization Methods.

In this paper, we used two mass-produced industrial technologies, namely, thermal spraying and anodization methods, to enhance the surface characteristics of AISI 1045 medium carbon steel for use in special environments or products. The anodic film can effectively improve the surface properties of carbon steel. A sequence of treatments of the carbon steel substrate surface that consist of sandblasting, spraying the aluminum film, annealing, hot rolling, cleaning, grinding, and polishing can increase the quality of the anodized film. This paper proposes an anodization process for the surface of carbon steel to increase the corrosion resistance, hardness, color diversification, and electrical resistance. The resulting surface improves the hardness (from 170 HV to 524 HV), surface roughness (from 1.26 to 0.15 μm), coloring (from metal color to various colors), and corrosion resistance (from rusty to corrosion resistant). The electrochemical corrosion studies showed that the AISI 1045 steel surface with a hard anodized film had a lower corrosion current density of 10−5.9 A/cm2 and a higher impedance of 9000 ohm than those of naked AISI 1045 steel (10−4.2 A/cm2 and 150 ohm) in HCl gas.

Application of high-speed gas-flame technology for hardening the surfaces of machines and robots of automatic gas-flame spraying

The article discusses the main types of installations (HVOF / HVAF (High Velocity Oxy / Air-Fuel),the Russian analogue of which is HPS/SGV (gas-flame supersonic/supersonic gas-air, activated arcmetallization ADM devices) and the use of high-speed gas-flame technology for surface hardening formachine parts. Here we considered all types of flame treatment (welding, oxyfuel cutting, brazing, surfacehardening, flame straightening, metallization, welding and spraying of non-metals), the performance ofvarious methods of thermal spraying (GTN), and also considered the properties, methods of productionand use of gases used in flame processing, modern equipment and equipment for all considered processes.The main task of the coating obtained by the method of flame spraying is also considered. It is shown thatthe deposition of coatings by the method of high-speed gas-flame spraying and effective materials forprotection is promising. In addition, safety precautions for gas-flame processing are considered. The stateis analyzed that the abrasive wear resistance of steel is a structurally sensitive characteristic, therefore, aneffective wear-resistant material must have the ability to harden under the influence of working loads, duringoperation, and from this, materials are effective materials for protection under abrasive wear; correspondingto the principle of metastable austenite. The characteristics of a heterophase jet obtained under optimalspraying modes are estimated on the basis of a calculation using a mathematical model of a two-phase flow. Key words: thermal spraying, electroplating, flame technology, corrosion, robots of automatic gas – flamespraying.

Experimental study of bubble behaviors during boiling of a hydrocarbon refrigerant

The present work emphasizes the experimental observation of bubble behaviors in pool boiling of a pure (hydrocarbon, HC) refrigerant on coated surfaces. A refrigerant R-600a was used as one of HC refrigerants in this study. The coated surface was prepared by using a thermal spraying method where copper powder was coated over the copper substrate surface having an inside diameter of 16.6 mm and 201 mm length. The bubble behaviors during the saturated boiling of refrigerant were captured by a high-speed camera and characterized as number of nucleation sites, diameter of departing bubbles, and departure frequency. The boiling augment depends on the surface characterization, which affects the bubble dynamics during boiling processes. The number of nucleation sites and diameter of departing bubbles vary as an increase of applied heat flux. The departure frequency of bubble reduces as heat flux increases. The present outcomes compared with the experimental data of refrigerant R-134a to demonstrate the reason behind the current results. Data of this study were correlated in the form of non-dimensional terms and differentiated with the available predicted correlations.

Effect of ultrasonic nanocrystal surface modification on wear mechanisms of thermally-sprayed WC-Co coating

High-pressure common rail injection systems lubricated with low-lubricity fuel may be made more resistant to wear and scuffing with robust coatings. In this study, a WC-Co coating was deposited onto heat-treated SAE 52100 steel substrates using a thermal spray method. The coated substrates were then treated using an ultrasonic nanocrystal surface modification (UNSM). Wear performance of the coating was evaluated by ball-on-disk tribometer lubricated with three different fuels against three different materials. Besides, the changes in surface roughness, hardness, microstructural evolution and critical load resulting from UNSM were systematically investigated. The UNSM controlled the surface roughness and hardness due to the grain size refinement, surface integrity and pore reduction. The application of UNSM exhibited higher wear resistance than the as-sprayed coating. Wear mechanisms were investigated based on the results of surface characterizations, where the abrasion and oxidative wear modes took place.

Формування газотермічних покриттів

Розглянуто перспективи використання методу неруйнівних випробувань безперервним вдавленням індентора для визначення механічних властивостей газотермічних покриттів. Проведено випробування з оцінки мікротвердості й модуля пружності композиційних покриттів на основі карбідів вольфраму і хрому, отриманих методом детонаційно-газового напилення. Розглянуто діаграми проникнення для покриттів з порошків ВК8, ВК15, ВК18С, КХН15С. Показано, що при оптимальних режимах напилювання мікротвердість одержуваних покриттів близька до мікротвердості спечених твердих сплавів того ж складу. Визначено значення коефіцієнтів варіації значень мікротвердості зі збільшенням глибини відбитка для зразків зі спеченого твердого сплаву і напилених покриттів. При оптимальних режимах напилювання досягаються не тільки максимальні значення мікротвердості та модуля пружності покриттів, але і більш однорідні структура і механічні властивості покриттів. Більш чутливими до змін технологічних параметрів є значення модуля пружності напилених покриттів, що більш зручно при відпрацюванні технологічних процесів.

Контактна взаємодія частинок з поверхнею основи при газотермічному напиленні

Показана роль контактної взаємодії частинок, що напилюються, з основою у формуванні міцних газотермічних покриттів. В якості основних структуроутворюючих елементів в покриттях прийняті сплети – поодинокі напилені частинки. Проаналізовано основні фактори, що визначають структуру і властивості газотермічних покриттів в процесі напилення, причому найважливішу роль відіграє утворення контакту частинка – основа і процеси, що протікають на ньому. Проаналізовано основні фактори, що визначають взаємодію матеріалів частинки та основи. Розглянуто основні роботи, присвячені проблемі схоплювання частинок з основою при напиленні. Запропоновано при аналізі утворення фізичного контакту розглядати площу контакту, що утворюється, з урахуванням розмірів напилюваних частинок і наявності на поверхні основи мікро- і наношорсткості чотирьох рівнів: номінальної, контурної, фактичної і фізичної. Фізична площа контакту на кілька порядків менше контурної площі та на її площадках формуються найбільш міцні адгезійні зв'язки. Запропоновано рівняння для оцінки фізичної площі контакту в зоні дії напірного тиску.

The Influence of the Powder Characteristics on 316L Stainless Steel Coatings Sprayed by Cold Gas Spray

Thermally sprayed 316L stainless steel coatings are commonly used on metallic structures due to their corrosion and wear resistance when compared to carbon steel. Cold Gas Spray (CGS) is a convenient thermal spray process to deposit 316L coatings, producing thick and very dense coatings, with almost no deleterious changes on the feedstock properties to the coating condition. The powder characteristics have influence on the microstructure of the coating, such as porosity and oxide contents, which alter its corrosion and wear behavior. CGS is an efficient technique to reduce the problems associated with material melting commonly found in other conventional thermal spray methods. In this work, different 316L powders, produced by different manufacturers, were deposited by CGS, applying the same equipment and parameters, with the objective to evaluate the relation between the powders’ characteristics and coating properties. Their microstructure, adherence, hardness, as well as the performance on corrosion and wear testing were evaluated. The water atomized powders presented in general better results than gas atomized powders.

Study Effect Treatment Thermal for Cermet Composite Prepared by Flame Thermal Spray Method.

Flame thermal spraying technology was used in the production of 25% zirconia composite material with 25% alumina particle with binder material of 50% Al-Ni alloy base on 316L alloy steel base, after preparation the base surface with a method of roughing the granular. Spraying was carried out using a spray distance (12,14,16,18,20) cm. Hardness tests were carried out on the composite material to study the effect of changing spray distance on the properties of the resulting layer. The thermal treatment was performed on the samples at (850,950,1050,1150) for an hour. The results of the tests confirmed that the best spraying distance (16 cm) and the thermal treatment (1050 ) have a significant effect on improving the hardness of the layers of the composite material.

ТЕОРЕТИЧЕСКОЕ ОБОСНОВАНИЕ АДГЕЗИИ ПОКРЫТИЙ ПРИ ГАЗОТЕРМИЧЕСКОМ НАПЫЛЕНИИ

The article provides a brief overview of modern methods of thermal spraying. Particular attention is paid to high–speed flame spraying. The theoretical substantiation of the adhesion of coatings formed on machine parts using the methods of thermal spraying is presented.

Demonstration of a New Thermal Spraying Method by Fusion of HVOF and Punching for the Production of Laminated Structure Film

Demonstration of a New Thermal Spraying Method by Fusion of HVOF and Punching for the Production of Laminated Structure Film