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Microporosity and delamination mechanisms in thermally sprayed borosilicate glass coatings
- Source :
- Surface and Coatings Technology. 304:195-202
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- Conventional enamelling requires both the feedstock powder and the substrate component to be heated one or more times in a furnace at 800–900 °C. The process can degrade the substrate and limit the size of the component to the furnace dimensions, which are serious restrictions on the technology. This study concerns the use of combustion- flame spraying as an alternative technique for enamelling. In this process, the heat source (the flame) is separated from the substrate, which enables much lower substrate temperatures and avoids thermal damage. It also removes the need for furnace treatment and opens up the possibility of on-site enamelling and repair. However, experimental trials showed that thick flame-spray coatings delaminated during cooling and had high microporosities due to quenching stresses at the glass-steel interface and inadequate splat flow of small feedstock particles. The research shows that these adverse mechanisms could be overcome by pre-heating the substrate surface to the dilatometric softening temperature and removing fines from the feedstock powder. The control of these two parameters was found to double the adhesion strength, provide coatings of very similar hardness and fracture toughness to conventional enamel aswell as deposit coatings of over 1mmin thickness for heavy-duty corrosion protection. Thermal spraying is well established for ceramic and metal coatings but the fundamentally different structure of glasses requires a different approach. An advantage of combustion flame spraying shown up by this research is that the high energy of the flame accelerates the particles to a high velocity and the resulting impact forces promote the flow of the glass. As a result, lower substrate temperatures may be used with reduced risk of degradation or higher viscosity glasses may be deposited with enhanced properties. The influence of the type of thermal-spray technique on coating quality is also discussed
- Subjects :
- Materials science
Gas dynamic cold spray
02 engineering and technology
engineering.material
Combustion
01 natural sciences
Corrosion
Coating
0103 physical sciences
Materials Chemistry
Ceramic
Composite material
Thermal spraying
010302 applied physics
Quenching
Borosilicate glass
Metallurgy
Surfaces and Interfaces
General Chemistry
021001 nanoscience & nanotechnology
Condensed Matter Physics
Surfaces, Coatings and Films
visual_art
engineering
visual_art.visual_art_medium
0210 nano-technology
Subjects
Details
- ISSN :
- 02578972
- Volume :
- 304
- Database :
- OpenAIRE
- Journal :
- Surface and Coatings Technology
- Accession number :
- edsair.doi...........fe3a3fae48712938e812c7cb36863a08