High Velocity Oxy-fuel Thermal Spraying Research Articles

Nanocrystalline NiAl Coating Prepared by HVOF Thermal Spraying

Nanocrystalline NiAl intermetallic powder was prepared by mechanical alloying (MA) of Ni50Al50 powder mixture and then deposited on low carbon steel substrates by high velocity oxy fuel (HVOF) thermal spray technique using two sets of spraying parameters. X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness test were used to characterize the prepared powders and coatings. The MA of Ni50Al50 powder mixture led to the formation of NiAl intermetallic compound. The resulting powder particles were three dimensional in nature with irregular morphology and a crystallite size of ~10 nm. This powder was thermally sprayed by HVOF technique to produce coating. The deposited coating had a nanocrystalline structure with low oxide and porosity contents. The hardness of coatings was in the range of 5.40-6.08 GPa, which is higher than that obtained for NiAl coating deposited using conventional powders.

MODIFIKASI PENGUJIAN KEKUATAN LEKAT LAPISAN HVOF THERMAL SPRAY DENGAN SERBUK WC PADA NOSEL ROKET

Modification of Bonding Strength Test of WC HVOF Thermal Spray Coating on Rocket Nozzle. One way to reduce structural weight of RX-100 rocket is by modifying the nozzle material and processing. Nozzle is the main target in weight reduction due to the fact that it contributes 30 % to the total weight of the structur. An alternative for this is by substitution of massive graphite, which is currently used as thermal protector in the nozzle, with thin layer of HVOF (High Velocity Oxy-Fuel) thermal spray layer. This paper presents the characterization of nozzle base material as well as the modification of bonding strength test, by designing additional jig to facilitate testing processes while maintaining level of test accuracy. The results showed that the material used for RX-100 rocket nozzle is confirmed to be S45C steel. Modification of the bonding strength test was conducted by utilizing chains, which improve test flexibility and maintains level of accuracy of the test.

The Influence of Powder Porosity on the Bonding Mechanism at the Impact of Thermally Sprayed Solid Particles

High-velocity oxy-fuel (HVOF) thermal spraying can generate dense depositions without melting the powders during spraying. Our previous study showed that most HVOF-sprayed particles are in solid state prior to impact on the substrate. The deposition of solid particles requires sufficient deformation of the particles as a result of a high impact. This report is a continuation of our previous work to study the bonding mechanism for thermally sprayed solid particles. The same hard material, WC-Co powder, is studied by considering the porosity inside the particles. The detailed deposition mechanism is examined by dynamically tracking the particle impingement using finite element analysis (FEA) models. The results confirm that the deposition of high-speed solid particles is caused mainly by the particle deformation and further implies that deformation is enhanced with increase in porosity alone. Therefore, a possible way to increase the deposition efficiency of hard cermet coating could be to use a properly designed porous powder.

IMPROVING THE SURFACE PROPERTIES OF INCONEL 718 BY APPLYING A CO2 LASER HEAT TREATMENT TO A HIGH-VELOCITY OXY-FUEL COATING OF WC-CrCo POWDER

A micron-sized WC-CrCo powder was coated onto an IN718 substrate using high-velocity oxy-fuel (HVOF) thermal spraying. To further improve the surface properties, the HVOF coating was heat-treated by a CO2 laser. The surface properties of both the coating and the laser-heated coating were then compared. The HVOF optimal coating process (OCP) for a coating with the highest surface hardness was determined with the Taguchi program. The friction and wear behaviors of the coating, an electrolytic hard chrome (EHC)-plated coating and IN718, were comparatively investigated via a reciprocating sliding wear test at both 25 and 450°C. The friction coefficient (FC) for all three samples decreased when the sliding surface temperature increased from 25 to 450°C. The FC of the coating decreased with increasing surface temperature: 0.33 ± 0.02 at 25°C to 0.26 ± 0.02 at 450°C; the coating had the lowest FC among the three samples. At both temperatures, the coating wear depth (WD) was smaller than those of the EHC sample and IN718. At room temperature, WC-CrCo and the EHC coatings had good wear resistance and had only a shallow WD. IN718, however, had poor wear resistance with 50 μm deep grooves created from fretting corrosion that arose during the 1500 reciprocating slides (2.5 Hz, 10 min sliding wear test). At 450°C, the coating WDs were much shallower than those for the EHC coating and IN718: 0.5-μm deep grooves compared to 60–70-μm deep grooves. These results proved that the coating provided a protective coating for IN718 and other metal components. With the OCP coating fabricated from the powders on the IN718 surface, the surface hardness increased 316% from 399 Hv to 1260 Hv. Furthermore, by laser heating the coating surface for 0.6 s, the hardness increased 44% from 1260 ±30 Hv to 1820 ±100 Hv, porosity decreased more than five times from 2.2 ± 0.3% to 0.4 ± 0.1%, and the coating thickness decreased 17% from 300 to 250 μm. These results showed that both the WC-CrCo powder coating and the laser-heating improved the surface properties of IN718.

THE EFFECT OF FUEL TO OXYGEN RATIOS ON THE PROPERTIES OF HIGH VELOCITY OXY-FUEL TiO2 NANO-PHOTOCATALYST COATINGS

A liquid fuel high velocity oxy-fuel (HVOF) thermal spray process has been used to deposit TiO 2 photocatalytic coatings utilizing a commercially available anatase/rutile nano-powder as the feedstock. The coatings were characterized in terms of the phases present, its crystallite size and coating morphology by means of X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy, respectively. The results indicate that the sprayed TiO 2 coatings were composed of both TiO 2 phases, namely anatase and rutile with different phase content and crystallite size. A high anatase content of 80% by volume was achieved at 0.00015 fuel to oxygen ratio with nanostructure coating by grain size smaller than feedstock powder. It is found that fuel to oxygen ratio strongly influenced on temperature and velocity of particles in stream jet consequently on phase transformation of anatase to rutile and their crystallite size and by optimizing the ratio which can promote structural transformation and grain coarsening in coating.

The effects of microstructural features on the performance gap in corrosion resistance between bulk and HVOF sprayed Inconel 625

It is commonly observed that there is a performance gap between the corrosion resistance of thermally sprayed coatings and the equivalent bulk material. This is attributed to the significantly modified microstructure of the sprayed coatings. However, currently there is no detailed understanding of which aspects of microstructural modification are primarily responsible for this performance gap. In this work several deliberately microstructurally modified versions of the Ni-based superalloy Inconel 625 were produced. These were subjected to potentiodynamic electrochemical testing in 0.5 M H 2SO 4 to investigate the links between specific microstructural features and electrochemical behaviour. Samples were prepared by high-velocity oxy-fuel (HVOF) thermal spraying, laser surface remelting using a high power diode laser and conventional powder sintering. Microstructural features were examined by optical and scanning electron microscopy and X-ray diffraction. Potentiodynamic testing was carried out on the following forms of Inconel 625: wrought sheet; HVOF sprayed coatings; sintered powder compacts; laser melted wrought sheet and HVOF sprayed coatings. Using the corrosion behaviour, i.e. passive current density, of the wrought sheet as a baseline, the performance of different forms of Inconel 625 was compared. It is found that a fine dendritic structure (with associated microsegregation) produced by laser remelting wrought sheet has no significant effect on corrosion performance. Up to 12% porosity in sintered powder samples increases the passive current density by a factor of only around 2. As observed previously, the passive current density of HVOF sprayed coatings is 20–40 times greater. However, HVOF coatings subjected to laser surface remelting are found to have a passive current density close to that of wrought material. It is concluded that, whilst porosity in coatings produces some decrease in corrosion resistance, the main contributing factor is the galvanic corrosion of localised Cr-depleted regions which are associated with oxide inclusions within HVOF sprayed samples.

One-dimensional analysis of supersonic two-stage HVOF process

The one-dimensional calculation of the gas/particle flows of a supersonic two-stage high-velocity oxy-fuel (HVOF) thermal spray process was performed. The internal gas flow was solved by numerically integrating the equations of the quasi-one-dimensional flow including the effects of pipe friction and heat transfer. As for the supersonic jet flow, semi-empirical equations were used to obtain the gas velocity and temperature along the center line. The velocity and temperature of the particle were obtained by an one-way coupling method. The material of the spray particle selected in this study is ultra high molecular weight polyethylene (UHMWPE). The temperature distributions in the spherical UHMWPE particles of 50 and 150μm accelerated and heated by the supersonic gas flow was clarified.

Microstructure and Hardness Characterization of a NiCr/Cr<sub>3</sub>C<sub>2</sub> Coating by High-Velocity Oxy-Fuel Thermal Spraying

A NiCr/Cr3C2 composite coating with a thickness of approximately 200 m was deposited onto 1Cr18Ni9Ti stainless steel substrate by high-velocity oxy-fuel (HVOF) thermal spraying. Microstructure of the coating was characterized using X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The coating comprised a NiCr matrix and two types of carbides. The NiCr matrix was composed of an amorphous phase and nanocrystalline grain with a size of 10–50 nm. The microhardness of the coating was found to be 1200Hv, which is significantly greater than that of the stainless steel (1Cr18Ni9Ti) substrate (285 Hv).

Bonding Mechanism from the Impact of Thermally Sprayed Solid Particles

Power particles are mainly in solid state prior to impact on substrates from high velocity oxy-fuel (HVOF) thermal spraying. The bonding between particles and substrates is critical to ensure the quality of coating. Finite element analysis (FEA) models are developed to simulate the impingement process of solid particle impact on substrates. This numerical study examines the bonding mechanism between particles and substrates and establishes the critical particle impact parameters for bonding. Considering the morphology of particles, the shear-instability–based method is applied to all the particles, and the energy-based method is employed only for spherical particles. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results confirm that in the HVOF process, the kinetic energy of the particle prior to impact plays the most dominant role in particle stress localization and melting of the interfacial contact region. The critical impact parameters, such as particle velocity and temperature, are shown to be affected by the shape of particles, while higher impact velocity is required for highly nonspherical powder.

Development of Wear Resistant Nanostructured Duplex Coatings by High Velocity Oxy-Fuel Process for Use in Oil Sands Industry

Oil sands deposits in Northern Alberta, Canada represent a wealth of resources attracting huge capital investment and significant research focus in recent years. As of 2005, crude oil production from the current oil sands operators accounted for 50% of Canada's domestic production. Alberta's oil sands deposits contain approximately 1.7 trillion barrels of bitumen, of which over 175 billion are recoverable with current technology, and 315 billion barrels are ultimately recoverable with technological advances. A major problem of operating machinery and equipment in the oil sands is the unpredictable failure from operating in this highly aggressive environment. One of the significant causes of that problem is premature material wear. An approach to minimize this wear is the use of protective coatings and, in particular, a cermet thin coating. A high level of coating homogeneity is critical for components such as bucketwheels, draglines, conveyors, shovels, heavyhauler trucks etc. that are subjected to severe degradation through abrasive wear. The identification, development and application of optimum wear solutions for these components pose an ongoing challenge. Nanostructured cermet coatings have shown the best results of achieving the degree of homogeneity required for these applications. In this study, WC-17Co cermet powder with nanocrystalline WC core encapsulated with 'duplex' Co layer was used to obtain a nanostructured coating. To apply this coating, high velocity oxy-fuel (HVOF) thermal spraying technique was used, as it is known for producing wear-resistant coatings superior to those obtained from plasma-based techniques. Mechanical, sliding wear and microstructural behavior of the coating was compared with those of the microstructured coating obtained from spraying WC-10Co-4Cr cermet powder by HVOF technique. Results from the nanostructured coating, among others, showed an average of 25% increase in microhardness, 30% increase in sliding wear resistance and a significant increase in the dry sand abrasion wear resistance when compared with the microstructured coating.

Numerical modeling the bonding mechanism of HVOF sprayed particles

During high velocity oxy-fuel (HVOF) thermal spraying, most powder particles remain in solid state prior to the formation of coating. A finite element (FE) model is developed to study the impact of thermally sprayed solid particles on substrates and to establish the critical particle impact parameters needed for adequate bonding. The particles are given the properties of widely used WC-Co powder for HVOF thermally sprayed coatings. The numerical results indicate that in HVOF process the kinetic energy of the particle prior to impact plays the most dominant role on particle stress localization and melting of the particle/substrate interfacial region. Both the shear-instability theory and an energy-based method are used to establish the critical impact parameters for HVOF sprayed particles, and it is found that only WC-Co particles smaller than 40 μm have sufficient kinetic and thermal energy for successful bonding.

Surface properties and tensile bond strength of HVOF thermal spray coatings of WC-Co powder onto the surface of 420J2 steel and the bond coats of Ni, NiCr, and Ni/NiCr

Micron-sized WC-Co powder (powder) was coated onto an 420J2 steel substrate and the bond coats (BCs) of Ni, NiCr, and Ni/NiCr using high-velocity oxy-fuel thermal spraying to study the surface properties, friction behavior, and tensile bond strength of the WC-Co coating (WC-Co) on the 420J2 substrate (sub) and the BCs of Ni, NiCr, and Ni/NiCr. During the spray coating, a small portion of WC decomposed to the less-hard W 2C, W, and free carbon above its decomposition temperature of 1250 °C, decreasing hardness and increasing porosity. The surface hardness of 1120 ± 100 Hv (10,980 ± 980 MPa) depended strongly on the spray parameters. It was three to four times harder than metals and alloys, but less than one-half the hardness of binder-less pure WC (2400 Hv). Free carbon reacted with the sprayed oxygen gas and formed carbon oxide gases, resulting in a coating of 4.3 ± 1.0% porosity. The friction coefficient of the coating increased about 17% with increasing surface temperature: 0.65 ± 0.03 at 25 °C to 0.76 ± 0.06 at 500 °C because of the increased local cold-welding of the asperities at the higher temperature of 500 °C. Sub/WC-Co, sub/Ni/WC-Co, sub/NiCr/WC-Co, and sub/Ni/NiCr/WC-Co had tensile bond strengths of 9600 ± 300 psi (66.2 ± 3.4 MPa), 6300 ± 200 psi, 6000 ± 200 psi, and 7500 ± 200 psi, respectively. The fracture locations of all coatings were at interfaces with the WC-Co coating, indicating that the adhesion of the WC/Co inside coating was higher than 9600 ± 500 psi and that the adhesion of WC-Co on the substrate (9600 ± 500 psi) was much higher than the adhesion on the BCs.

Microstructure and microhardness characterization of a Fe-based coating deposited by high-velocity oxy-fuel thermal spraying

Based on the merits of high-velocity oxy-fuel (HVOF) thermal spraying, hardness and cavitation erosion resistance of steel were improved with a Fe–Cr–Si–B (5.8 wt.% B) alloy coating applied to stainless steel (1Cr18Ni9Ti) substrate by HVOF thermal spraying. The microstructures and microhardness of the coating were investigated. It was found that the morphologies of the coating were of well-flattened splats (containing some un-melted borides), semi-molten particles, featureless structures and a small amount of pores. The average Vickers microhardness of the coating reached 9.9 GPa, about four times that of the substrate (2.8 GPa). From the substrate to coating, the indentation marks or the corresponding microhardness values changed gradually. The higher microhardness values of the substrate near the coating can be attributed to work hardening resulting from the impact of the melted or semi-molten particles and grit sand on the substrate. The microhardness of the well-flattened splats (10.8 GPa) is higher than that of the semi-molten particles (about 6.2 GPa) and the featureless regions (6.4 GPa), and the microhardness of the featureless regions is higher than that of the semi-melted particles. This suggests that the fully molten state of the feedstock can result in the formation of featureless structures and well-flattened splats (containing some un-melted borides) present high microhardness.

Performance of abrasive wear of WC-12Co coatings sprayed by HVOF

The performance of multimodal and conventional materials in the form of coatings deposited by high velocity oxy-fuel (HVOF) thermal spraying has been studied. WC-12Co coatings were deposited under same conditions using multimodal and conventional WC-12Co powder feedstocks. The phase composition of the feedstock powders and the coatings were analyzed by XRD. Abrasive wear resistances of coatings were carried out on wet sand rubber wheel abrasion tester. The characterizations of spraying feedstock powders, microstructure and surface micrographs of the prophase and anaphase attrition surfaces were performed by SEM. The results indicated the multimodal coating shows slight higher microhardness and better abrasive wear resistance than the conventional counterpart. Also, the thermally sprayed carbide-based coatings have excellent wear resistance with respect to the hard chrome coatings.

Microstructure evolution and thermal stability of an Fe-based amorphous alloy powder and thermally sprayed coatings

High velocity oxy-fuel (HVOF) thermal spraying has been used to produce coatings of an Fe–18.9%Cr–16.1%B–4.0%C–2.8%Si–2.4%Mo–1.9%Mn–1.7%W (in at.%) alloy from a commercially available powder (Nanosteel SHS7170). X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to investigate the powder, as-sprayed coatings and annealed coatings which had been heated to temperatures in the range of 550–925 °C for times ranging from 60 to 3900 min. Microhardness changes of the coatings were also measured as a function of annealing time and temperature. The powder was found to comprise amorphous and crystalline particles; the former had a maximum diameter of around 22 μm. The coating was composed of splat like regions, arising from rapid solidification of fully molten powder, and near-spherical regions from partially melted powder which had a largely retained its microstructure. The amorphous fraction of the coating was around 50% compared with 18% for the powder. The enthalpies and activation energies for crystallization of the amorphous phase were determined. Crystallization occurred in a two stage process leading to the formation of α-Fe (bcc), Fe 1.1Cr 0.9B 0.9 and M 23C 6 phases. DSC measurements showed that the first stage occurred at 650 °C. Annealing the coating gave a hardening response which depended on temperature and time. The as-sprayed coating had a hardness of 9.2 GPa and peak hardnesses of 12.5 and 11.8 GPa were obtained at 650 and 750 °C, respectively. With longer annealing times hardness decreased rapidly from the peak.

Influence of the elementary mixing scale on HVOF-sprayed coatings derived from nanostructured aluminosilicate/mullite feedstock

Aluminosilicate/mullite coatings were prepared from nanosized sources of aluminium and silicon by means of a high velocity oxy-fuel thermal spray process. X-ray diffraction, analytical electron microscopy, differential thermal analysis and Fourier transform infrared spectroscopy were used to characterize the phase composition, elementary distribution, and microstructure in the feedstock and in the coatings. It was revealed that the chemical environment of the alumina component, as well as the inherent elementary distribution in the nanoparticulate aluminosilicate feedstock, showed the greatest influence on the microstructure and the crystallization of nanosized ceramic phases in the sprayed coatings. A uniform distribution of alumina and silica in a short-range ordered monophasic-like nanostructure was the most appropriate physico-chemical conditions of the feedstock to achieve nanosized crystallites of mullite in a monolithic-like aluminosilicate coating. In turn, when using diphasic feedstock, clearly heterogeneous but nanostructured coatings with a good abrasion resistance were obtained. The agglomerated and heat-treated powders were considered as the most suitable type of feedstock for providing nanostructured aluminosilicate coatings.

Processing optimization, surface properties and wear behavior of HVOF spraying WC–CrC–Ni coating

In this work, the optimal coating process (OCP) designed by Taguchi program for high velocity oxy-fuel (HVOF) thermal spraying WC–CrC–Ni powder on Inconel 718 substrate (IN 718) is obtained by optimizing hardness (38 FMR oxygen flow rate, 53 FMR hydrogen flow rate, 25 g/min powder feed rate and 7 in. spray distance). Oxygen flow rate affects hardness mostly. The surface properties such as microstructure, crystalline phase, hardness, and porosity of WC–CrC–Ni coating have been investigated. The phase of coating has been changed during the OCP spraying because a portion of carbides, such as WC, Cr 7C 3, Ni 3C decomposes to W 2C, Cr, Ni and free carbon. Hardness (1150 ± 50 Hv) and porosity (1.2 ± 0.2%) of the OCP coating have been improved by optimization. The friction and wear behaviors of the WC–CrC–Ni coating, electrolytic hard chrome (EHC) plating and IN 718 have been studied comparatively. The lubrication due to free carbon and metal oxide debris results in a decrease of friction coefficients of the WC–CrC–Ni, compared to EHC and IN 718 at both 25 and 450 °C. It is concluded that HVOF WC–CrC–Ni coating performs more excellent anti-wear than others at both temperatures.

Design and optimisation of a multi-powder feed system for the HVOF deposition process

Currently no specific method exists for the deposition of High Velocity Oxy-Fuel (HVOF) thermal spray functionally graded coatings. This paper investigates the design and optimisation of a multi-powder HVOF thermal spray device in order to deposit aluminium/tool-steel functionally graded coatings. A multi-powder feed device concept was developed. The concept was based on a stand alone two powder chamber device which integrates with common hopper systems to allow the mixing of two powders during thermal spray deposition. This concept was verified by simulation the design of this device for multi-powder flow using Finite Element Analysis (FEA) to arrive at the optimum dual feed design. The FEA model predicted the mixing and flow of two powders of various ratios' of mass flow rate and velocity based on an optimum designed shape and pressure ratios' of nitrogen gas in the chamber to pick-up shaft of 2.25:1. This yielded the best results in terms of carrying the powders from the mixing zone into the nitrogen gas flow path, inside the pick-up shaft and on towards the HVOF gun. Post finite element analysis the device was manufactured for the utilisation within the HVOF process. Optimisation tests of the device included; powder flow bench tests and HVOF thermal spraying of graded deposits. The results revealed a calibration graph for the two powders in question and the compositional variation across the deposit during functionally graded deposition. The composition of the graded deposits were close to that anticipated hence this showed the suitability of the newly designed multi-powder deposition system in mixing two powders for the purpose of producing HVOF graded coatings.

A DTA Study on HVOF Thermally Sprayed WC–M Coatings

Five types of tungsten carbide based powders with different chemical compositions (WC-12Co, WC-17Co, WC-10Ni, WC-10Co-4Cr and WC- 20Cr-7Ni) were deposited onto ST37 mild steel substrate using high velocity oxy fuel (HVOF) spray technique. The feedstock powders and sprayed coatings were studied by using X-ray diffraction (XRD), and differential thermal analyzing (DTA). The results were shown during HVOF thermal spraying, WC-M powders become partially melted before being sprayed on the surface of the substrate with supersonic speed. In these types of coatings, the crystallographic structures are normally non equilibrium, because the cooling rates of the deposited splats are very high due to the cold substrate acting as a thermal sink. These partially melted powders are then rapidly solidified to an amorphous phase. XRD analysis showed that the amorphous phase was existed in all of the as sprayed coatings. The amorphous phase in WC-12Co, WC-17Co and WC-10Ni coatings was transformed to crystalline phases by heat treatment at high temperature. Heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. In cobalt base coatings, the new phases were eta carbide phases like Co6W6C and Co3W3C but in WC-10Ni coating a NiW intermetallic phase was formed. Heat treatment of WC-10Co-4Cr and WC-20Cr-7Ni coatings did not change the amorphous phases in these coatings. Differential thermal analysis of cobalt containing coatings revealed an exothermic reaction at approximately 880°C. This exothermic reaction may be related to the transformation of the amorphous phase to eta phases. On the contrary, DTA analysis of feedstock powders of these coatings showed an endothermic reaction at approximately 1000°C. DTA analyses of nickel containing cermets also showed similar results. Differential thermal analysis of chromium containing cermets did not show any noticeable exothermic or endothermic reactions.

Improved Protection Properties by Using Nanostructured Ceramic Powders for HVOF Coatings

The potential of the high-velocity oxy-fuel (HVOF) thermal spray process for reduced porosity in coatings compared to those produced by other ambient thermal spray processes is well known. The ability to produce high-density ceramic coatings offers potential in high-performance applications in the field of wear, corrosion resistance, and dielectric coatings. However, due to operational limit of the HVOF process to effectively melt the ceramic particles, the process—structure relationship must be well optimized. It has been also demonstrated that benefits from HVOF ceramic coatings can be obtained only if particles are melted enough and good lamella adhesion is produced. One strategy to improve melting of ceramic particles in relative low-flame temperatures of HVOF process is to modify particle crystal structure and composition. In this paper the effect of the powder manufacturing method and the composition on deposition efficiency of spray process as well as on the mechanical properties of the HVOF sprayed are studied. Effect of fuel gas, hydrogen vs. propane, was also demonstrated. Studied materials were alumina-, chromia-, and titania-based agglomerated powders. Coating properties such as microstructure, hardness, abrasive wear resistance, and relative fracture toughness were compared to the coating manufactured by using conventional fused and crushed powders. It can be concluded that powder size distribution and microstructure should be optimized to fulfill process requirements very carefully to produce coatings with high deposition efficiency, dense structure, improved fracture toughness, and adhesion.