High-Performance Al2O3 Coating by Hybrid-LVOF (Low-Velocity Oxyfuel) Process

Tailor, Satish; Vashishtha, Nitesh; Modi, Ankur; Modi, S. C.

doi:10.1007/s11666-020-01033-6

Cited by 13 publications

(20 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…BDS measurements of different thermally sprayed alumina coatings have been reported in a number of studies 23–25,49–52 . HVOF spraying and air plasma spraying (APS), were reported to fabricate alumina coating with BDS values of 29.2 V ac /µm 3 and 13.5–16.5 V ac /µm, 17 correspondingly.…”

Section: Resultsmentioning

confidence: 99%

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

Bajgiran

Rad

McDonald

et al. 2021

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

In coating‐based resistive heating systems applied on an electrically conductive substrate, an intermediary dielectric layer is required to minimize or eliminate leakage of current from the heating surface to the substrate. Aluminum oxide has widely been used for electrical insulation purposes. In this study, alumina was deposited onto carbon steel substrates by using suspension plasma spraying and flame spraying processes. Then, Ni‐20Cr, as the heating element, was deposited on the alumina layer by using air plasma spraying. The resultant microstructure and phase composition of the alumina layers were evaluated by using scanning electron microscope images, X‐ray diffraction analysis, and Raman spectroscopy. The breakdown voltage of alumina layers was measured independently and within the heating system. It was found that the dielectric properties of alumina layers were significantly affected by its microstructural features. It was observed that penetration of metal topcoat into the alumina layer decreased the overall breakdown voltage of the system.

show abstract

Section: Resultsmentioning

confidence: 99%

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

Bajgiran

Rad

McDonald

et al. 2021

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

show abstract

“…However, as-sprayed coating consists of both α and γ -Al 2 O 3 phases as shown in Figure 3(b). The α -phase is associated to un-melted sprayed powder particles or to the molten particles cooled at a lower rate, while the nucleation of the metastable γ -phase from the liquid occurred because of the high quenching rate of the molten splats at the substrate surface (Tailor et al , 2020).…”

Section: Resultsmentioning

confidence: 99%

“…The micro-hardness value of as-sprayed coating is in context with hardness values reported in the literature. Tailor et al (2020) reported an average Vicker hardness value of 712Hv ± 80Hv for plasma sprayed Al 2 O 3 coating. Yin et al (2008) reported that the as-sprayed Al 2 O 3 coating deposited by using plasma technique showed the average micro-hardness value of 870 Hv 0.2 ± 60 HV0.2.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, they need to be finished to get a desirable surface roughness. However, it is difficult to machine the ceramic-based coatings because of the fragile nature of the coating and less fracture toughness value (Tailor et al , 2020). In the present work, the average surface roughness (Ra), maximum roughness (Rz) and root mean square (Rq) roughness of as-sprayed coatings were measured as per the method discussed in Section 2.4.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

High temperature erosion behavior of plasma sprayed Al₂O₃ coating on AISI-304 stainless steel

Prashar¹,

Vasudev

2021

WJE

View full text Add to dashboard Cite

Purpose In the present study, Al2O3 coatings were deposited on stainless steel AISI-304 material by using atmospheric plasma spraying technique to combat high temperature solid particle erosion. The present aims at the performance analysis of Al2O3 coatings at high temperature conditions. Design/methodology/approach The erosion studies were carried out at a temperature of 400°C by using a hot air-jet erosion tester for 30° and 90° impingement angles. The possible erosion mechanisms were analyzed from scanning electron microscope (SEM) micrographs. Surface characterization of the powder and coatings were conducted by using an X-ray diffractometer, SEM, equipped with an energy dispersive X-ray analyzer. The porosity, surface roughness and micro-hardness of the as-sprayed coating were measured. This paper discusses outcomes of the commonly used thermal spray technology, namely, the plasma spray method to provide protection against erosion. Findings The plasma spraying method was used to successfully deposit Al2O3 coating onto the AISI 304 substrate material. Detailed microstructural and mechanical investigations were carried out to understand the structure-property correlations. Major findings were summarized as under: the erosive wear test results indicate that the plasma sprayed coating could protect the substrate at both 30° and 90° impact angles. The coating shows better resistance at an impact angle of 30° compared with 90°, which is related to the pinning and shielding effect of the alumina particle. The major erosion wear mechanisms of Al2O3 coating were micro-cutting, micro-ploughing, splat removal and detachment of Al2O3 hard particles. Originality/value In the current study, the authors have followed the standard testing method of hot air jet erosion test as per American society for testing of materials G76-02 standard and reported the erosion behavior of the eroded samples. The coating was not removed at all even after the erosion test duration i.e. 10 min. The erosion test was continued till 3 h to understand the evolution of coatings and the same has been explained in the erosion mechanism. The outcome of the present study may be used to minimize the high temperature erosion of AISI-304 substrate.

show abstract

“…Another study with a newly developed technology named hybrid low-velocity oxy-fuel (hybrid-LVOF) revealed a finer microstructure and higher gamma to alpha ratio compared to conventional plasma spraying. Hence, this spray technology could be considered as alternative to plasma spraying (Ref 19 ). Since suspension spraying and hybrid-LVOF are still at the beginning of their industrialization and HVOF spraying is not significantly cheaper in direct comparison with plasma spraying, these processes are currently excluded as an economical alternative with regard to the planned industrial application.…”

Section: Introductionmentioning

confidence: 99%

Use of Different Process Gases for Manufacturing Isolating Alumina Coatings by Flame Spraying with Cords

et al. 2021

View full text Add to dashboard Cite

Besides conventional industrial demands, thermally sprayed coatings are increasingly used for innovative products. Such an application is the additive manufacturing of electrical components in automotive engineering. In particular, heating units are currently manufactured by a combination of various spray technologies. At present, simpler spraying processes like flame spraying are investigated with regard to their suitability as a future cost-effective alternative for fabricating isolating alumina coatings. In the present study, alumina cords were flame-sprayed using compressed air and argon as atomizing gases. The results demonstrate finely dispersed microstructures and a more regular and partially even higher surface and volume resistivity compared to past investigations in the literature as well as conventionally plasma-sprayed coatings despite a significantly reduced coating thickness. The content of alpha phase is clearly higher than for plasma-sprayed coatings, regardless of the atomizing gas used. Moreover, flame-sprayed coatings using argon reveal a higher resistivity in comparison to coatings sprayed with air. While the atomizing gas is found to mainly influence the ideal stand-off distance, the phase composition is not changed severely. In addition to the phase composition and kinematics, it can finally be concluded that humidity plays a major role in the coating properties.

show abstract

High-Performance Al2O3 Coating by Hybrid-LVOF (Low-Velocity Oxyfuel) Process

Cited by 13 publications

References 19 publications

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

High temperature erosion behavior of plasma sprayed Al₂O₃ coating on AISI-304 stainless steel

Use of Different Process Gases for Manufacturing Isolating Alumina Coatings by Flame Spraying with Cords

Contact Info

Product

Resources

About

High-Performance Al2O3 Coating by Hybrid-LVOF (Low-Velocity Oxyfuel) Process

Cited by 13 publications

References 19 publications

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

Microstructure, phase and dielectric strength of thermally sprayed alumina layers in coating‐based heating systems

High temperature erosion behavior of plasma sprayed Al2O3 coating on AISI-304 stainless steel

Use of Different Process Gases for Manufacturing Isolating Alumina Coatings by Flame Spraying with Cords

Contact Info

Product

Resources

About

High temperature erosion behavior of plasma sprayed Al₂O₃ coating on AISI-304 stainless steel