Gas and liquid-fuelled HVOF spraying of Ni50Cr coating: Microstructure and high temperature oxidation

Song, Bo; Pala, Zdeněk; Voisey, K.T.; Hussain, Tanvir

doi:10.1016/j.surfcoat.2016.07.046

Cited by 35 publications

(13 citation statements)

References 18 publications

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“…The XRD patterns of the as-sprayed coatings (Fig. 3) showed that the Ni peaks shifted towards shorter lattice parameters (higher 2θ angles) which might be due to the level of residual stresses within the coatings (macrostrain) [15]. The peak broadening of the as-sprayed coatings compared to the powders is due to three primary factors of a) presence of micro-strain due to the plastic deformation during the HVAF spraying process [29], b) reduction in crystallite size, and c) instrumental broadening due to beam size, sample to detector distance, air scatter, etc.…”

Section: Microstructure Of As-sprayed Coatingsmentioning

confidence: 99%

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

et al. 2018

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Chlorine-induced corrosion of HVAF-sprayed Ni21Cr and Ni5Al coatings was investigated in 5 vol.% O2 + 500vppm HCl + N2 with and without KCl at 600°C up to 168 h. Both coatings were protective in the absence of KCl. With KCl, Ni21Cr degraded through a two-stage mechanism: 1) formation of K2CrO4 followed by diffusion of Clthrough the oxide grain boundaries to yield chlorine and a nonprotective oxide, and 2) inward diffusion of chlorine though defects in the non-protective oxide, leading to breakaway oxidation. Cl-/Cl2 could not diffuse through the protective alumina scale formed on Ni5Al, hence the corrosion resistance increased.

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Section: Microstructure Of As-sprayed Coatingsmentioning

confidence: 99%

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

et al. 2018

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“…The microstructure of the coating is typical of the HVOF dense metallic coating with a low degree of porosity. HVOF thermal spraying using a liquid fuel tends to result in a relatively low amount of oxides in the coatings than in gas fuel HVOF [22]. Indeed, no oxides were detected by PXRD on the coating surface (not shown here).…”

Section: As-deposited Microstructurementioning

confidence: 76%

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

et al. 2017

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Laser clads and HVOF coatings from a stellite 6 alloy (Co-Cr-W-C alloy) on 304 stainless steel substrates were exposed both bare and with KCl deposits in 500 ppm HCl with 5% O 2 for 250 h at 700°C. SEM/EDX and PXRD analyses with Rietveld refinement were used for assessment of the attack and for analysis of the scales. The bare samples suffered from scale spallation and the scale was mostly composed of Cr 2 O 3 , CoCr 2 O 4 and CoO, although due to dilution haematite (Fe 2 O 3 ) was detected in the scale formed on the laser clad sample. A small amount of hydrated HCl was detected in bare samples. While the corrosion of the bare surfaces was limited to comparatively shallow depths and manifested by g and M 7 C 3 carbide formation, the presence of KCl on the surface led to severe Cr depletion from the HVOF coating (to 1 wt%). Both inward and outward diffusion of elements occurred in the HVOF coating resulting in Kirdendall voids at the coatingsteel interface. The laser clad sample performed significantly better in conditions of the KCl-deposit-induced corrosion. In addition to the oxides, CoCl 2 was detected in the HVOF sample and K 3 CrO 4 was detected in the laser clad sample. Thermodynamic calculations and kinetic simulations were carried out to interpret the oxidation and diffusion behaviours of coatings.

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“…The method gives promising results regarding allowing the formation of suspension spraying layer [93][94][95]. By introducing the axial powder injection, the new high-velocity suspension lame spraying (HVSFS) process typically would be able to resolve the injection complications [96][97][98].…”

Section: High-velocity Suspension Plasma-sprayingmentioning

confidence: 99%

Hydroxyapatite-Based Coating on Biomedical Implant

Harun¹,

Asri²,

Sulong³

et al. 2018

Hydroxyapatite - Advances in Composite Nanomaterials, Biomedical Applications and Its Technological Facets

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The use of metallic biomaterials for replacement of biomedical implants has been traced back from the nineteenth century. These metallic biomaterials have been declared as clinical success as their mechanical properties that satisfy the prerequisite of the human bone. Nevertheless, critical issues of the materials when they are utilised as implants; including the releasing toxic and harmful metal ions through wear and corrosion processes after longer implantation. Besides that, the bonding strength between bone and implants itself is considered weak due to the diferent components of human bone and metal implants. Hence, developing hydroxyapatite (HAp) coating on metallic biomaterials is expected to overcome the problems faced by biocompatible metallic biomaterials. As far as this, various commercial techniques have been introduced to develop the HAp coating on metallic biomaterials. The techniques are including plasma-spraying method, sol-gel dip-coating, electrochemical deposition and high-velocity suspension plasma-spraying. The formation of HAp coating on metallic biomaterials improved the corrosion resistance together promoting its load-bearing ability and enhanced substrate-coating adhesion.

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Gas and liquid-fuelled HVOF spraying of Ni50Cr coating: Microstructure and high temperature oxidation

Cited by 35 publications

References 18 publications

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

Chlorine-induced high temperature corrosion of HVAF-sprayed Ni-based alumina and chromia forming coatings

Laser Clad and HVOF-Sprayed Stellite 6 Coating in Chlorine-Rich Environment with KCl at 700 °C

Hydroxyapatite-Based Coating on Biomedical Implant

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