Coatability and characterization of fly ash deposited on mild steel by detonation spraying
TL;DR: In this article, the suitability of detonation spray system for coating fly ash onto a mild steel substrate has been demonstrated, and the result is that fly ash coatings are 2-3 times harder than the substrate material and also exhibit a 3-fold reduction in coefficient of friction under sliding wear conditions.
Abstract: Recently, considerable emphasis has been placed on the processing of low-grade ore minerals through thermal spray techniques. In the present investigation, the suitability of detonation spray system for coating fly ash onto a mild steel substrate has been demonstrated. Resultant coatings are 2–3 times harder than the substrate material and also exhibit a 3-fold reduction in coefficient of friction under sliding wear conditions. However, these coatings exhibit poor sliding wear resistance.
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TL;DR: In this paper, the micro arc oxidation (MAO) technique is being increasingly recognized as a novel and ecofriendly means of depositing dense ceramic oxide coatings on Al and its alloys.
Abstract: The micro arc oxidation (MAO) technique is being increasingly recognized as a novel and ecofriendly means of depositing dense ceramic oxide coatings on Al and its alloys. In the present study, the deposition kinetics, surface roughness, morphology, phase distribution and the microhardness of the MAO coatings deposited on ten different commercially available Al substrates having widely differing chemical composition has been investigated. Further, the tribological properties of the coatings obtained on different Al alloys in comparison with the bare substrates have also been evaluated using dry sand abrasion, solid-particle erosion and pin-on-disc dry sliding wear tests. The results clearly demonstrate that the alloying elements added to the Al substrate substantially influence the MAO coating deposition kinetics and coating properties. In the case of Al-Si alloys, the coating deposition kinetics is non-linear and the Al 6 Si 2 O 13 (mullite) is observed to form. With increasing Si content, the corresponding mullite phase also increases. Increasing mullite content in the coating adversely affects the tribological performance. Excepting Al-Si alloys, all other alloys investigated including commercial purity Al exhibit linear coating deposition kinetics. Of all the alloys investigated, Al-Li alloy exhibits the highest coating deposition rate and the 6061 T6 Al alloy exhibits the best coating properties.
49 citations
TL;DR: In this paper, a new class of metal-ceramic composite coatings were developed on aluminum substrates using fly ash pre-mixed with aluminum powder in different weight proportions at various plasma torch power levels ranging from 9 to 18kW DC.
Abstract: This paper describes the processing, characterization and the erosion wear response of a new class of metal–ceramic composite coatings deposited on metal substrates by plasma spraying Coatings are developed on aluminum substrates using fly ash pre-mixed with aluminum powder in different weight proportions at various plasma torch power levels ranging from 9 to 18 kW DC The coatings are characterized in terms of thickness, interface adhesion strength and deposition efficiency Maximum adhesion strength of about 35 MPa is recorded with coatings deposited at 12 kW power level It is noticed that the adhesion strength of fly ash coating is improved with pre-mixing of aluminum up to 15 wt% in the feed material To study the erosion wear behavior of the coatings, a plan of experiments based on the Taguchi technique is used to acquire the erosion test data in a controlled way An orthogonal array and signal-to-noise ratio are employed to investigate the influence of the impingement angle, impact velocity, erodent size, stand-off-distance and the aluminum content in the feed stock on the erosion rate The study reveals that the impact velocity is the most significant factor influencing the erosion wear rate of these coatings
48 citations
TL;DR: In this paper, the erosive behavior of NiCrAlY-25WC-Co/cenosphere coating on MDN 321 steel is investigated using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD).
Abstract: High temperature erosive behavior of plasma sprayed NiCrAlY-25WC-Co/cenosphere coating deposited on MDN 321 steel is investigated in the present work. Coating is characterized using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Microhardness, porosity, adhesion strength, fracture toughness and ductility of the coating are quantified. Solid particle erosion test is conducted at 200, 400 and 600 °C with 30 and 90° impact angles using alumina erodent. Optical profilometer is used to evaluate erosion volume loss. Erosion resistance of the coating is observed to be higher than the substrate for the test temperatures chosen and noted to be more prominent at lower impact angle and higher temperature. High temperature stability of mullite, alumina and oxide layer assists in increasing erosion resistance of coating. The eroded coating surface morphology reveals the brittle mode of material removal.
41 citations
Dissertation•
01 Nov 2005
TL;DR: In this article, a series of plasma-sprayed coatings made with red mud and red mud pre-mixed with different proportions of fly ash and powders of aluminium and carbon are characterized to evaluate their potential as wear resistant coatings.
Abstract: Red mud emerges as the major waste material during production of alumina from bauxite by the Bayer’s process. It comprises of oxides of iron, titanium, aluminium and silica along with some other minor constituents. The present investigation explores the coating potential of this industrial waste. It envisages the processing and characterization of a series of plasma sprayed coatings made with red mud and red mud pre-mixed with different proportions of fly ash and powders of aluminium and carbon. These materials do not belong to the so called “plasma sprayable” category. They have been deposited on aluminium, copper, mild steel and stainless steel substrates by atmospheric plasma spraying. The coatings are characterized to evaluate their potential as wear resistant coatings. Micro-structural characterization of the coatings has been carried out using scanning electron microscopy, x -ray diffraction and image analysis technique. It is found that red mud is eminently coatable. The coating...
30 citations
TL;DR: In this paper, the fly ash coating has been obtained by shrouded plasma spray process on carbon steel and the coating was characterized with relative to important behavioural parameters such as wear, oxidation and salt corrosion behaviour.
Abstract: In a wide variety of applications, mechanical components are subjected to severe conditions, such as high load, speed or temperature and hostile chemical environment. Thus, their surface modification is necessary in order to protect them against various types of degradation. Thermal spraying has emerged as an important tool of increasingly sophisticated surface engineering technology. Plasma spraying is a rather simple process from a practical point of view. In the present investigation, the fly ash coating has been obtained by shrouded plasma spray process on carbon steel. The coating was characterized with relative to important behavioural parameters. Wear, oxidation and salt corrosion behaviour have also been evaluated. The coating has found to posses much higher hardness values than base steel and its porosity is slightly higher than the range of porosity for plasma spray coatings. The coating was effective to increase the oxidation and salt corrosion resistance of the given carbon steel. However, the wear resistance of fly ash coated steel was observed to be lesser than the bare steel probably due to coarse grain size.
29 citations
References
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Book•
14 Feb 1995
TL;DR: In this article, the authors present a detailed overview of the main steps in the process of spraying particles and their properties, including properties such as temperature, surface properties, and surface properties.
Abstract: Preface to the Second Edition. Preface to the First Edition. Acronyms, Abbreviations and Symbols. 1 Materials Used for Spraying. 1.1 Methods of Powders Production. 1.1.1 Atomization. 1.1.2 Sintering or Fusion. 1.1.3 Spray Drying (Agglomeration). 1.1.4 Cladding. 1.1.5 Mechanical Alloying (Mechanofusion). 1.1.6 Self-propagating High-temperature Synthesis (SHS). 1.1.7 Other Methods. 1.2 Methods of Powders Characterization. 1.2.1 Grain Size. 1.2.2 Chemical and Phase Composition. 1.2.3 Internal and External Morphology. 1.2.4 High-temperature Behaviour. 1.2.5 Apparent Density and Flowability. 1.3 Feeding, Transport and Injection of Powders. 1.3.1 Powder Feeders. 1.3.2 Transport of Powders. 1.3.3 Injection of Powders. References. 2 Pre-Spray Treatment. 2.1 Introduction. 2.2 Surface Cleaning. 2.3 Substrate Shaping. 2.4 Surface Activation. 2.5 Masking. References. 3 Thermal Spraying Techniques. 3.1 Introduction. 3.2 Flame Spraying (FS). 3.2.1 History. 3.2.2 Principles. 3.2.3 Process Parameters. 3.2.4 Coating Properties. 3.3 Atmospheric Plasma Spraying (APS). 3.3.1 History. 3.3.2 Principles. 3.3.3 Process Parameters. 3.3.4 Coating Properties. 3.4 Arc Spraying (AS). 3.4.1 Principles. 3.4.2 Process Parameters. 3.4.3 Coating Properties. 3.5 Detonation-Gun Spraying (D-GUN). 3.5.1 History. 3.5.2 Principles. 3.5.3 Process Parameters. 3.5.4 Coating Properties. 3.6 High-Velocity Oxy-Fuel (HVOF) Spraying. 3.6.1 History. 3.6.2 Principles. 3.6.3 Process Parameters. 3.6.4 Coating Properties. 3.7 Vacuum Plasma Spraying (VPS). 3.7.1 History. 3.7.2 Principles. 3.7.3 Process Parameters. 3.7.4 Coating Properties. 3.8 Controlled-Atmosphere Plasma Spraying (CAPS). 3.8.1 History. 3.8.2 Principles. 3.8.3 Process Parameters. 3.8.4 Coating Properties. 3.9 Cold-Gas Spraying Method (CGSM). 3.9.1 History. 3.9.2 Principles. 3.9.3 Process Parameters. 3.9.4 Coating Properties. 3.10 New Developments in Thermal Spray Techniques. References. 4 Post-Spray Treatment. 4.1 Heat Treatment. 4.1.1 Electromagnetic Treatment. 4.1.2 Furnace Treatment. 4.1.3 Hot Isostatic Pressing (HIP). 4.1.4 Combustion Flame Re-melting. 4.2 Impregnation. 4.2.1 Inorganic Sealants. 4.2.2 Organic Sealants. 4.3 Finishing. 4.3.1 Grinding. 4.3.2 Polishing and Lapping. References. 5 Physics and Chemistry of Thermal Spraying. 5.1 Jets and Flames. 5.1.1 Properties of Jets and Flames. 5.2 Momentum Transfer between Jets or Flames and Sprayed Particles. 5.2.1 Theoretical Description. 5.2.2 Experimental Determination of Sprayed Particles' Velocities. 5.2.3 Examples of Experimental Determination of Particles Velocities. 5.3 Heat Transfer between Jets or Flames and Sprayed Particles. 5.3.1 Theoretical Description. 5.3.2 Methods of Particles' Temperature Measurements. 5.4 Chemical Modification at Flight of Sprayed Particles. References. 6 Coating Build-Up. 6.1 Impact of Particles. 6.1.1 Particle Deformation. 6.1.2 Particle Temperature at Impact. 6.1.3 Nucleation, Solidification and Crystal Growth. 6.1.4 Mechanisms of Adhesion. 6.2 Coating Growth. 6.2.1 Mechanism of Coating Growth. 6.2.2 Temperature of Coatings at Spraying. 6.2.3 Generation of Thermal Stresses at Spraying. 6.2.4 Coatings Surfaces. 6.3 Microstructure of the Coatings. 6.3.1 Crystal Phase Composition. 6.3.2 Coatings' Inhomogeneity. 6.3.3 Final Microstructure of Sprayed Coatings. 6.4 Thermally Sprayed Composites. 6.4.1 Classification of Sprayed Composites. 6.4.2 Composite Coating Manufacturing. References. 7 Methods of Coatings' Characterization. 7.1 Methods of Microstructure Characterization. 7.1.1 Methods of Chemical Analysis. 7.1.2 Crystallographic Analyses. 7.1.3 Microstructure Analyses. 7.1.4 Other Applied Methods. 7.2 Mechanical Properties of Coatings. 7.2.1 Adhesion Determination. 7.2.2 Hardness and Microhardness. 7.2.3 Elastic Moduli, Strength and Ductility. 7.2.4 Properties Related to Mechanics of Coating Fracture. 7.2.5 Friction and Wear. 7.2.6 Residual Stresses. 7.3 Physical Properties of Coatings. 7.3.1 Thickness, Porosity and Density. 7.3.2 Thermophysical Properties. 7.3.3 Thermal Shock Resistance. 7.4 Electrical Properties of Coatings. 7.4.1 Electrical Conductivity. 7.4.2 Properties of Dielectrics. 7.4.3 Electron Emission from Surfaces. 7.5 Magnetic Properties of Coatings. 7.6 Chemical Properties of Coatings. 7.6.1 Aqueous Corrosion. 7.6.2 Hot-gas Corrosion. 7.7 Characterization of Coatings' Quality. 7.7.1 Acoustical Methods. 7.7.2 Thermal Methods. References. 8 Properties of Coatings. 8.1 Design of Experiments. 8.2 Mechanical Properties. 8.2.1 Hardness and Microhardness. 8.2.2 Tensile Adhesion Strength. 8.2.3 Elastic Moduli, Strengths and Fracture Toughness. 8.2.4 Friction and Wear. 8.3 Thermophysical Properties. 8.3.1 Thermal Conductivity and Diffusivity. 8.3.2 Specific Heat. 8.3.3 Thermal Expansion. 8.3.4 Emissivity. 8.3.5 Thermal Shock Resistance. 8.4 Electric Properties. 8.4.1 Properties of Conductors. 8.4.2 Properties of Resistors. 8.4.3 Properties of Dielectrics. 8.4.4 Electric Field Emitters. 8.4.5 Properties of Superconductors. 8.5 Magnetic Properties. 8.5.1 Soft Magnets. 8.5.2 Hard Magnets. 8.6 Optical Properties. 8.6.1 Decorative Coatings. 8.6.2 Optically Functional Coatings. 8.7 Corrosion Resistance. 8.7.1 Aqueous Corrosion. 8.7.2 Hot-medium Corrosion. References. 9 Applications of Coatings. 9.1 Aeronautical and Space Industries. 9.1.1 Aero-engines. 9.1.2 Landing-gear Components. 9.1.3 Rocket Thrust-chamber Liners. 9.2 Agroalimentary Industry. 9.3 Automobile Industry. 9.4 Ceramics Industry. 9.4.1 Free-standing Samples. 9.4.2 Brick-Clay Extruders. 9.4.3 Crucibles to Melt Oxide Ceramics. 9.4.4 Ceramic Membranes. 9.5 Chemical Industry. 9.5.1 Photocatalytic Surfaces. 9.5.2 Tools in Petrol Search Installations. 9.5.3 Vessels in Chemical Refineries. 9.5.4 Gas-well Tubing. 9.5.5 Polymeric Coatings on Pipeline Components. 9.5.6 Ozonizer Tubes. 9.6 Civil Engineering. 9.7 Decorative Coatings. 9.8 Electronics Industry. 9.8.1 Heaters. 9.8.2 Sources for Sputtering. 9.8.3 Substrates for Hybrid Microelectronics. 9.8.4 Capacitor Electrodes. 9.8.5 Conductor Paths for Hybrid Electronics. 9.8.6 Microwave Integrated Circuits. 9.9 Energy Generation and Transport. 9.9.1 Solid-oxide Fuel Cell (SOFCs). 9.9.2 Thermopile Devices for Thermoelectric Generators. 9.9.3 Boilers in Power-generation Plants. 9.9.4 Stationary Gas Turbines. 9.9.5 Hydropower Stations. 9.9.6 MHD Generators. 9.10 Iron and Steel Industries. 9.10.1 Continuous Annealing Line (CAL). 9.10.2 Continuous Galvanizing Section. 9.10.3 Stave Cooling Pipes. 9.11 Machine Building Industry. 9.12 Medicine. 9.13 Mining Industry. 9.14 Non-ferrous Metal Industry. 9.14.1 Hot-extrusion Dies. 9.14.2 Protective Coatings against Liquid Copper. 9.14.3 Protective Coatings against Liquid Zirconium. 9.15 Nuclear Industry. 9.15.1 Components of Tokamak Device. 9.15.2 Magnetic-fusion Energy Device. 9.16 Paper Industry. 9.16.1 Dryers. 9.16.2 Gloss Calender Rolls. 9.16.3 Tubing in Boilers. 9.17 Printing and Packaging Industries. 9.17.1 Corona Rolls. 9.17.2 Anilox Rolls. 9.18 Shipbuiding and Naval Industries. 9.18.1 Marine Gas-turbine Engines. 9.18.2 Steam Valve Stems. 9.18.3 Non-skid Helicopter Flight Deck. References. Index.
1,688 citations
"Coatability and characterization of..." refers background in this paper
...[ 1-3 ] Among the thermal spray coating techniques available commercially, the detonation spray coating (DSC) technique has long retained a preeminent position as a process to produce hard, dense, and wear-resistant coatings....
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TL;DR: In this paper, the influence of the thermal spraying process parameters on the microstructure of carbide-containing and oxide ceramic coatings was analyzed under simulated service conditions, and the coatings were also characterized with regard to micro-structure, composition and fracture toughness.
Abstract: In the area of antiwear coatings, carbide-containing coatings ( Cr 3 Cr 2 -NiCr, WC-Co, WC-Ni etc.) and oxide ceramic coatings ( Al 2 O 3 , Cr 2 O 3 etc.) are applied using different thermal spray processes in the form of individual layers. In many industries these coatings have become technically significant on components where wear and friction can cause critical damage in the form of abrasion, erosion and scuffing together with corrosion. Carbide-containing and ceramic coatings have been produced with different thermal spray processes (atmospheric plasma spraying, vacuum plasma spraying, high velocity flame spraying and detonation gun spraying) for the determination of abrasive, adhesive and erosive wear resistance. Two types of abrasion test, namely an adhesion wear test and an erosion test in water at a high velocity (up to 170 m s −1 ), were used for the characterization of wear resistance under different conditions. The coatings were also characterized with regard to microstructure, composition and fracture toughness. The influence of the thermal spraying process parameters on the microstructure is presented together with the influence of the microstructure on the behavior of the coatings under simulated service conditions.
129 citations
TL;DR: The relationship between these unique microstructures and the properties of the material is discussed in this article, where the areas of bond strength, transient and residual stresses, density, corrosion characteristics, and wear resistance are at least briefly surveyed.
Abstract: The microstructures of materials produced by plasma spraying or detonation gun techniques consists of thin lenticular particles with a very fine grained (perhaps even amorphous) structure. They are rapidly quenched from the molten, or near molten state, and may have a high degree of residual stress. This review is concerned with the relationship between these unique microstructures and the properties of the material. The areas of bond strength, transient and residual stresses, density, corrosion characteristics, and wear resistance, as well as mechanical, thermal, and electrical properties are at least briefly surveyed. The methods of deposition, i.e., plasma torch operating conditions, heat transfer to the particles, etc., are not covered. It is evident that, although a sufficient amount of information is available for most engineeering applications of these materials, a great deal remains to be learned about the fundamental relationships between their structure and properties.
84 citations
TL;DR: In this paper, a fly ash pre-mixed with Al powder was used to create a composite coating on metal substrates using fly ash (the thermal power plant waste) pre mixed with Al powders.
Abstract: Plasma spray technology has the advantage of being able to process low-grade-ore minerals to produce value-added products, and also to deposit ceramics, metals and a combination of these, generating homogenous coatings with the desired microstructure on a range of substrate. The present work deals with the development of a ceramic composite coating on metal substrates using fly ash (the thermal power plant waste) pre-mixed with Al powder. Mixtures of fly ash with 5 and 15 wt.% Al powder were plasma sprayed onto copper and stainless steel substrates at various plasma torch power levels ranging from 10 to 20 kW DC. The coatings produced were characterised by X-ray diffraction, optical and electron microscopic studies and measurement of interface adherence strength. A maximum strength of 52 MN m −2 was recorded with a copper substrate. It is found that the coating quality and properties are improved with higher aluminium content in the feed material and are affected by the operating power level of the plasma.
63 citations
"Coatability and characterization of..." refers methods in this paper
...In this context, Mishra et al. [ 10 ] have recently used the plasma spray coating technique to obtain coatings of fly ash mixed with 5-15 wt.% Al powder on stainless steel substrates....
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