Abstract:Cermet coatings were fabricated on AA5083 by D gun coating technique using three different combinations of powder feedstock namely WC-Co, WC-Co-Cr, and Cr 3 C 2 -NiCr. The effect of powder combinations on coatings' phase composition, surface morphology, and crosssectional microstructure were investigated using XRD, SEM, and EDS. Major findings revealed that WC-Co and WC-Co-Cr powders produced higher thickness with considerable surface defects compared to a coating that was produced by Cr 3 C 2 -NiCr powders. M… Show more
“…Precise control of the explosive mixture parameters, the location of powder injection point, and the interval between shots allow controlling the particle impact temperature and velocity with high precision [13][14][15]. The detonation spraying could be successfully applied for deposition of single-material metal and ceramic coatings [16][17][18][19][20]. The possibility of manufacturing of gradient coatings was also reported [21,22].…”
The feasibility study of elaboration of metal composite coatings by detonation spray using the blends of iron, nickel, copper, cobalt, and aluminum powders was performed using different spray modes. The numerical simulation of particle parameters showed that the particles formed the coating in solid, semi-molten, or molten state depending on the spraying modes, particle material, and particle size. It was shown that successful formation of the coating containing all powder mixture components could be achieved in case of proper optimization of spraying parameters. Obtained Fe-Co-Ni, Fe-Co-Ni-Cu, and Fe-Co-Ni-Cu-Al coatings had the uniform lamellae structure. However, the composition of the coatings differed from the initial powder mixture composition due to different deposition efficiencies of the powders. It was also found the mutual influence of blend components on bonding. In particular, the deposition efficiency of iron particles was probably affected by copper.
“…Precise control of the explosive mixture parameters, the location of powder injection point, and the interval between shots allow controlling the particle impact temperature and velocity with high precision [13][14][15]. The detonation spraying could be successfully applied for deposition of single-material metal and ceramic coatings [16][17][18][19][20]. The possibility of manufacturing of gradient coatings was also reported [21,22].…”
The feasibility study of elaboration of metal composite coatings by detonation spray using the blends of iron, nickel, copper, cobalt, and aluminum powders was performed using different spray modes. The numerical simulation of particle parameters showed that the particles formed the coating in solid, semi-molten, or molten state depending on the spraying modes, particle material, and particle size. It was shown that successful formation of the coating containing all powder mixture components could be achieved in case of proper optimization of spraying parameters. Obtained Fe-Co-Ni, Fe-Co-Ni-Cu, and Fe-Co-Ni-Cu-Al coatings had the uniform lamellae structure. However, the composition of the coatings differed from the initial powder mixture composition due to different deposition efficiencies of the powders. It was also found the mutual influence of blend components on bonding. In particular, the deposition efficiency of iron particles was probably affected by copper.
“…Then this ignited gas explodes and its detonation wave (high-pressure shock wave) is used to accelerate the powder. Nitrogen gas is also used to avoid backfiring [34]. Thus, the induced hot gases accelerate the powder particles towards the substrate with supersonic velocity to produce the desired coating, as shown in Figure 19.…”
Section: Preventive Measures To Combat High-temperature Degradationmentioning
confidence: 99%
“…Thus, the induced hot gases accelerate the powder particles towards the substrate with supersonic velocity to produce the desired coating, as shown in Figure 19. Figure 19 Schematic diagram of D-Gun spray [34]. …”
Section: Preventive Measures To Combat High-temperature Degradationmentioning
High-temperature corrosion of coal-fired boiler parts such as water walls and superheated tubes poses a serious threat to the efficiency of the thermal power plant. To overcome this, numbers of corrosion control techniques are commonly employed. But, a dense and defectfree coating deposited by the thermal spray technique has shown promising result to combat hot corrosion. Although open or closed porosity in distinct thermal spray coatings can originate from distinct factors such as partial or totally un-molten particles, inadequate flow or fragmentation of the molten particle at impact, non-optimal spray angle and entrapped gas. But, this can still only be prevented by coating post-treatment. Hence, in this paper, authors have reviewed the performance of distinct coatings deposited by diverse thermal spray processes. Then, the effect of distinct process parameters and heat treatments on microstructure and mechanical properties of coatings is described. Finally, the best coatings are suggested to combat maximum hot corrosion of boiler tubes.
“…There are different coating deposition methods which can be applied in order to obtain high characteristics of base material to protect it from corrosion, erosion, wear, ensure some specific properties of surfaces [3][4][5][6] or to increase the service life of parts [7]. Among all methods of thermal coating, cold spraying (CS) has a number of advantages [8], namely the absence of high temperatures, oxidation, phase transformations of coating materials and substrates, and it can be successfully used to form protective and restorative coatings on light alloy parts: magnesium [9], aluminum [10] and titanium [11].…”
The effect of operating gas temperature and powder type on microstructure and mechanical characteristics of cold spraying coatings deposited on EZ33A-T5 magnesium alloy was studied. Three aluminum-based cold spraying powder mixtures Al + Zn, Al + Al2O3 and Al + Zn + Al2O3 were used for the investigation. Deposition was performed using D423 low-pressure cold spray system at operating gas pressure of 1.0 MPa and different temperatures – 300 °C, 450 °C, and 600 °C. The coatings microstructure was investigated with optical and scanning electron microscopy. Mechanical properties of the coatings were characterized through standard test methods for adhesion and cohesion strength, and standard test methods for Vickers hardness of thermal spray coatings. The results demonstrate that with increasing initial gas temperature at spraying nozzle inlet from 300 °C to 600 °C, an increase in the porosity of the coatings of all investigated powder mixtures can be observed. Microstructure characterization showed an increase in porosity from 2.3 % to 4.1 % for Al + Zn powder mixture, from 2.1 % to 3.5 % for Al + Al Al2O3 powder mixture, and from 2.5 % to 5.6 % for Al + Zn + Al2O3 powder mixture. The minimum porosity was obtained at 450 °C for all investigated powder mixtures. Adhesion and cohesion strength and microhardness of coatings were reach their maximum value at 450 °C. The best performance was obtained for Al + Al2O3 powder mixture: coating adhesion – 31.9 MPa (was limited by the bonding strength of the glue), cohesion – 93.5 MPa, microhardness – 81 HV0.15. The influence of Al2O3 particles in the powder mixture on the above-mentioned parameters was also established. The results show that the presence of ceramic particles in powder mixtures can positively affect porosity level and mechanical characteristics.
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