scholarly journals Advanced Coatings by Thermal Spray Processes

Technologies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 79
Author(s):  
Joshi ◽  
Nylen
Keyword(s):  
Thermal Spray ◽  
High Velocity ◽  
High Performance ◽  
Fine Particles ◽  
Thermal Spraying ◽  
Atmospheric Plasma ◽  
Processing Temperature ◽  
Diverse Application ◽  
Liquid Feedstock ◽  
Thermal Spray Processes

Coatings are pivotal in combating problems of premature component degradation in aggressive industrial environments and constitute a strategic area for continued development. Thermal spray (TS) coatings offer distinct advantages by combining versatility, cost-effectiveness, and the ability to coat complex geometries without constraints of other in-chamber processes. Consequently, TS techniques like high-velocity oxy-fuel (HVOF) and atmospheric plasma spray (APS) are industrially well-accepted. However, they have reached limits of their capabilities while expectations from coatings progressively increase in pursuit of enhanced efficiency and productivity. Two emerging TS variants, namely high-velocity air-fuel (HVAF) and liquid feedstock thermal spraying, offer attractive pathways to realize high-performance surfaces superior to those hitherto achievable. Supersonic HVAF spraying provides highly adherent coatings with negligible porosity and its low processing temperature also ensures insignificant thermal ‘damage’ (oxidation, decarburization, etc.) to the starting material. On the other hand, liquid feedstock derived TS coatings, deposited using suspensions of fine particles (100 nm–5 µm) or solution precursors, permits the production of coatings with novel microstructures and diverse application-specific architectures. The possibility of hybrid processing, combining liquid and powder feedstock, provides further opportunities to fine tune the properties of functional surfaces. These new approaches are discussed along with some illustrative examples.

Microstructure and Selected Properties of WC-Co-Cr Coatings Deposited by High Velocity Thermal Spray Processes

2016 ◽  
Vol 246 ◽  
pp. 117-122
Author(s):  
Hanna Myalska ◽  
Krzysztof Szymański ◽  
Grzegorz Moskal
Keyword(s):  
Thermal Spray ◽  
High Velocity ◽  
Liquid Fuel ◽  
Steel Substrate ◽  
Thermal Spraying ◽  
Three Generations ◽  
Thermal Spray Processes ◽  
Spraying Method

Selected information about high velocity thermal spraying method were presented in this article. Three generations of thermal spraying processes based on oxygen with propane mixture, liquid fuel with oxygen and propane with air were characterized. A powder of WC-Co-Cr 86-10-4 was used for coatings deposition on a steel substrate. Four coatings were deposited by different thermal spraying systems such as Diamond Jet, JP 5000, Micro HVOF and HVAF.

scholarly journals A Study on the Microstructural Characterization and Phase Compositions of Thermally Sprayed Al2O3-TiO2 Coatings Obtained from Powders and Water-Based Suspensions

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2638 ◽  
Author(s):  
Monika Michalak ◽  
Filofteia-Laura Toma ◽  
Leszek Latka ◽  
Pawel Sokolowski ◽  
Maria Barbosa ◽  
...  
Keyword(s):  
Phase Composition ◽  
Plasma Spraying ◽  
Microstructural Characterization ◽  
Atmospheric Plasma ◽  
Coating Morphology ◽  
Liquid Feedstock ◽  
Α Al2o3 ◽  
Titania Coatings ◽  
Thermal Spray Processes ◽  
Oxygen Fuel

In this work, the alumina (Al2O3) and alumina-titania coatings with different contents of TiO2, i.e., Al2O3 + 13 wt.% TiO2 and Al2O3 + 40 wt.% TiO2, were studied. The coatings were produced by means of powder and liquid feedstock thermal spray processes, namely atmospheric plasma spraying (APS), suspension plasma spraying (SPS) and suspension high-velocity oxygen fuel spraying (S-HVOF). The aim of the study was to investigate the influence of spray feedstocks characteristics and spray processes on the coating morphology, microstructure and phase composition. The results revealed that the microstructural features were clearly related both to the spray processes and chemical composition of feedstocks. In terms of phase composition, in Al2O3 (AT0) and Al2O3 + 13 wt.% TiO2 (AT13) coatings, the decrease in α-Al2O3, which partially transformed into γ-Al2O3, was the dominant change. The increased content of TiO2 to 40 wt.% (AT40) involved also an increase in phases related to the binary system Al2O3-TiO2 (Al2TiO5 and Al2−xTi1+xO5). The obtained results confirmed that desired α-Al2O3 or α-Al2O3, together with rutile-TiO2 phases, may be preserved more easily in alumina-titania coatings sprayed by liquid feedstocks.

Thermal Spray Alternatives for Electroplated Chromium

1996 ◽  
Author(s):  
G. Irons ◽  
W. Kratochvil ◽  
M. Schroeder ◽  
C. Brock
Keyword(s):  
Thermal Spray ◽  
Thermal Spraying ◽  
Spray Coating ◽  
Ceramic Materials ◽  
Thermal Spray Coating ◽  
Waste Products ◽  
Spray Process ◽  
Arc Spray ◽  
Chromium Plating ◽  
Thermal Spray Processes

Abstract Many thermal spray coatings provide excellent wear and corrosion resistance, while providing die same surface finish offered by chromium plating. In the past, the choice between thermal spraying or plating was usually based on part size, area to be coated, cost and familiarity with one or the other method. Today, the thermal spray processes are showing greater popularity due to: ♦ New thermal spray processes and coatings with better properties ♦ Increased chromium plating costs due to stricter regulations on the process and the disposal of its waste products ♦ The closing of chromium plating facilities Thermal spraying offers an opportunity to select a coating from a wide variety of processes and materials that will meet the specific requirements of each application. While this may cause some difficulty in selecting the optimum coating, the selected thermal spray coating often has superior propolies and/or lower cost compared to chromium plating. The highest quality coatings are sprayed by the HVOF process, many with carbide containing materials. Dense plasma grayed ceramic materials offer good wear resistance plus elevated temperature capability. The most economical replacements for chromium plate are applied by the two-wire arc spray process. This paper examines the properties and costs of eight different dismal sprayed coatings and compares them with electroplated chromium.

Method for Identifying In-Flight Particles based on Digital Image Technologies in Thermal Spraying

2021 ◽  
Author(s):  
Yijun Yao ◽  
Shaowu Liu ◽  
Marie-Pierre Planche ◽  
Sihao Deng ◽  
Hanlin Liao
Keyword(s):  
Thermal Spray ◽  
Digital Image ◽  
Thermal Spraying ◽  
Imaging Systems ◽  
Tracking Problem ◽  
Coating Performance ◽  
Image Frame ◽  
Thermal Spray Processes

Abstract In thermal spray processes, the characteristics of in-flight particles (velocity and temperature) have a significant effect on coating performance. Although many imaging systems and algorithms have been developed for identifying and tracking in-flight particles, most are limited in terms of accuracy. One key to solving the tracking problem is to get an algorithm that can distinguish different particles in each image frame. As the study showed, when noise and interference are treated, particles are more readily identified in the background, leading to more accurate size and position measurements with respect to time. This approach is demonstrated and the results discussed.

Towards a Better Control of Thermal Spray Processes

1998 ◽  
Author(s):  
C. Moreau
Keyword(s):  
Thermal Spray ◽  
Intelligent Control ◽  
Control Strategy ◽  
Thermal Spraying ◽  
The State ◽  
Basic Knowledge ◽  
Current Sensing ◽  
The Future ◽  
Consistent Manner ◽  
Thermal Spray Processes

Abstract Developing and using efficient controls for thermal spray processes is essential to produce coatings in a more consistent manner day after day. This paper discussed the different approaches that can be used, today or in the future, to better control spray processes. The various steps or sub-processes involved in thermal spraying are first reviewed identifying the key parameters that can be monitored and controlled. An overview of current sensing techniques and those under development for probing the state of these key parameters will then be presented. Finally, different control approaches will be reviewed looking at the basic knowledge and models required to implement an efficient and intelligent control strategy for thermal spray processes.

scholarly journals High Velocity Suspension Flame Spraying (HVSFS) of Metal Suspensions

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 621 ◽  
Author(s):  
Blum ◽  
Krieg ◽  
Killinger ◽  
Gadow ◽  
Luth ◽  
...  
Keyword(s):  
Thermal Spray ◽  
High Velocity ◽  
Thermal Spraying ◽  
Flame Spraying ◽  
Metal Coatings ◽  
Fine Grained ◽  
Aqueous Solvent ◽  
Coating Morphology ◽  
Oxygen Fuel ◽  
Suspension Preparation

Thermal spraying of metal materials is one of the key applications of this technology in industry for over a hundred years. The variety of metal-based feedstocks (powders and wires) used for thermal spray is incredibly large and utilization covers abrasion and corrosion protection, as well as tribological and electrical applications. Spraying metals using suspension- or precursor-based thermal spray methods is a relatively new and unusual approach. This publication deals with three metal types, a NiCr 80/20, copper (Cu), and silver (Ag), sprayed as fine-grained powders dispersed in aqueous solvent. Suspensions were sprayed by means of high-velocity suspension spraying (HVSFS) employing a modified TopGun system. The aim was to prepare thin and dense metal coatings (10–70 µm) and to evaluate the process limits regarding the oxygen content of the coatings. In case of Cu and Ag, possible applications demand high purity with low oxidation of the coating to achieve for instance a high electrical conductivity or catalytic activity. For NiCr however, it was found that coatings with a fine dispersion of oxides can be usable for applications where a tunable resistivity is in demand. The paper describes the suspension preparation and presents results of spray experiments performed on metal substrates. Results are evaluated with respect to the phase composition and the achieved coating morphology. It turns out that the oxidation content and spray efficiency is strongly controlled by the oxygen fuel ratio and spray distance.

USE OF IBA TECHNIQUES TO CHARACTERIZE HIGH VELOCITY THERMAL SPRAY COATINGS

2001 ◽  
Vol 15 (28n29) ◽  
pp. 1428-1436 ◽  
Author(s):  
W. TROMPETTER ◽  
A. MARKWITZ ◽  
M. HYLAND
Keyword(s):  
Thermal Spray ◽  
High Velocity ◽  
Sliding Wear ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Spray Coatings ◽  
The Past ◽  
Composition And Structure ◽  
Wide Range ◽  
Sprayed Coating

Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO 2/ CrO 3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.

scholarly journals Columnar Thermal Barrier Coatings Produced by Different Thermal Spray Processes

2021 ◽  
Author(s):  
Nitish Kumar ◽  
Mohit Gupta ◽  
Daniel E. Mack ◽  
Georg Mauer ◽  
Robert Vaßen
Keyword(s):  
Thermal Conductivity ◽  
Plasma Spraying ◽  
Thermal Spray ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Deposition Process ◽  
Cyclic Fatigue ◽  
Atmospheric Plasma ◽  
Plasma Sprayed ◽  
Thermal Spray Processes

AbstractSuspension plasma spraying (SPS) and plasma spray-physical vapor deposition (PS-PVD) are the only thermal spray technologies shown to be capable of producing TBCs with columnar microstructures similar to the electron beam-physical vapor deposition (EB-PVD) process but at higher deposition rates and relatively lower costs. The objective of this study was to achieve fundamental understanding of the effect of different columnar microstructures produced by these two thermal spray processes on their insulation and lifetime performance and propose an optimized columnar microstructure. Characterization of TBCs in terms of microstructure, thermal conductivity, thermal cyclic fatigue lifetime and burner rig lifetime was performed. The results were compared with TBCs produced by the standard thermal spray technique, atmospheric plasma spraying (APS). Bondcoats deposited by the emerging high-velocity air fuel (HVAF) spraying were compared to the standard vacuum plasma-sprayed (VPS) bondcoats to investigate the influence of the bondcoat deposition process as well as topcoat–bondcoat interface topography. The results showed that the dense PS-PVD-processed TBC had the highest lifetime, although at an expense of the highest thermal conductivity. The reason for this behavior was attributed to the dense intracolumnar structure, wide intercolumnar gaps and high column density, thus improving the strain tolerance and fracture toughness.

scholarly journals Development of Photocatalytic Active TiO2Surfaces by Thermal Spraying of Nanopowders

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Filofteia-Laura Toma ◽  
Ghislaine Bertrand ◽  
Didier Klein ◽  
Cathy Meunier ◽  
Sylvie Begin
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Photocatalytic Performance ◽  
Thermal Spraying ◽  
Environmental Water ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Spray Process ◽  
Coating Characteristics ◽  
Titania Coatings

Titanium dioxide is a very useful photocatalyst for the decomposition and diminution of environmental water and air pollutants. In such applications, it can be used as slurry or as immobilized coating obtained by different deposition methods. The studies performed in the last years showed that thermal spraying could be employed to elaborate TiO2coatings with high performance for the decomposition of organic compounds. This manuscript presents a comparative study on the microstructure and photocatalytic performance of titania coatings obtained by different thermal spray techniques: atmospheric plasma spraying (APS), suspension plasma spraying (SPS) and high-velocity oxygen fuel spray process (HVOF). Different titania powders and suspensions were used to study the influence of the feedstock materials on the coating characteristics. The deposits were mainly characterised by SEM and X-ray diffraction. The photocatalytic performance was evaluated from the removal of nitrogen oxides. The experimental results showed that a drastic reduction of the pollutant concentration was obtained in presence of coatings elaborated by suspension plasma spraying. TiO2coatings resulting from the spraying of agglomerated powder presentd less efficiency. That was mainly explained by the significant phase transformation from anatase to rutile that occurred in the enthalpic source during the spray processes.

Modelling Sequential Impact of Molten Droplets on a Solid Surface in Plasma Spray Process

2011 ◽  
Vol 227 ◽  
pp. 111-115
Author(s):  
Ilhem R. Kriba ◽  
A. Djebaili
Keyword(s):  
Plasma Spray ◽  
High Performance ◽  
Spray Deposition ◽  
Thermal Spraying ◽  
Spray Coating ◽  
Atmospheric Plasma ◽  
Formation Mechanisms ◽  
Temperature Plasma ◽  
Spray Process ◽  
Spraying Process

Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry. In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings, in which entrained particles are modeled by stochastic particle models, fully coupled to the plasma flow. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process in order to create a basis for numerically modeling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact.

Sign in / Sign up

Export Citation Format

Share Document