Sealing of Thermally Sprayed Coatings

Oksa, Maria; Turunen, Erja; Varis, Tommi

doi:10.1179/026708404225016346

Cited by 21 publications

(8 citation statements)

References 6 publications

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“…They showed that in order to reduce the number of pores and the unevenness of surface morphology, low fusing speed and homogeneous heating were preferable. Surface melting of thermally sprayed metallic coating was examined by Oksa et al [3]. They showed that laser melted coatings had superior corrosion resistance in short term tests.…”

Section: Mathematical Modeling Of Liquid Layer Formationmentioning

confidence: 99%

Laser treatment of HVOF coating: model study and characterization

2007

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HVOF coating is widely used in industry for protective coating of the metallic surfaces. The coating is based on the mechanical anchoring of the splats onto the substrate surface and thermal integration among the splats in the coating is not possible during the spraying process due to the operation temperature, which is lower than the melting temperature of the coating material. This, in turn, results in the formation of non-homogeneous structures and voids in the coating. One of the techniques to avoid such situations is to integrate the spats through the controlled melting. This can be achieved through the laser melting process. In the present study, laser melting of HVOF coating is modeled to determine the melt layer thickness. A lump parameter analysis is introduced in the model study and simulations are carried out in relation to the actual laser melting conditions. The melt layer predicted is compared with the experimental measurements. The microstructural analyses prior and post laser melting process are carried out using SEM and EDS. It is found that the predictions ofthe melt layer are in good agreement with experimental results.

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Section: Mathematical Modeling Of Liquid Layer Formationmentioning

confidence: 99%

Laser treatment of HVOF coating: model study and characterization

2007

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“…They showed that the laser re-melting resulted in a full homogenization of the sprayed structure. Laser heating of HVOF coating and thermally sealing of the coating surface were investigated by Oksa et al (2004). They showed that the thermal sealing provided good corrosion resistance of the surface in short-term tests.…”

Section: Introductionmentioning

confidence: 99%

Effect of WC on the residual stress in the laser treated HVOF coating

Taha-al

Hashmi

Yilbaş

2009

Journal of Materials Processing Technology

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“…One approach towards this end is to use the HVOF process. A cheaper option that is also more easily adaptable to on‐site coating is arc spraying, although it will result in a higher porosity level (<5%) 12–14.…”

Section: Introductionmentioning

confidence: 99%

Optimised selection of new protective coatings for biofuel boiler applications

Tuurna¹,

Varis²,

Penttilä³

et al. 2010

Materials & Corrosion

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Using biofuels in power and CHP boilers can pose a challenge for materials performance. Formation of deposits containing e.g. potassium, sulphur, calcium, sodium, and chlorine can result in severe corrosion of conventional steels and alloys at relatively modest temperatures. Given suitable component design and fabrication facilities, coatings may be considered to protect the fireside surfaces. This paper aims to present a systematic approach to the design and selection criteria for protective coatings of boilers. The approach includes modelling of the process and surface conditions, optimisation of the coating process and structure, and performance validation in the laboratory and plant scales. The applied examples have included iron and nickel based HVOF and arc sprayed coatings subjected to verification field testing in boiler testing under aggressive biofuel conditions. The coatings have shown good corrosion resistance in both laboratory tests and long-term harsh field tests. The paper discusses the used approach for finding a suitable and cost effective coating for biofuel boiler applications. The paper gives test results from microstructural, corrosion resistance and field testing experience for the selected coatings.

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Sealing of Thermally Sprayed Coatings

Cited by 21 publications

References 6 publications

Laser treatment of HVOF coating: model study and characterization

Laser treatment of HVOF coating: model study and characterization

Effect of WC on the residual stress in the laser treated HVOF coating

Optimised selection of new protective coatings for biofuel boiler applications

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