Surface treatment / Coating deposition
Thermal spray (plasma spray)
Thermal spraying is a surface treatment that heats metals, ceramics or other materials to a molten or semi-molten state and sprays them onto a substrate to build a coating. Plasma spraying uses a high-temperature plasma jet as the heat source and can deposit coatings of high-melting-point materials such as ceramics. Coatings add wear, heat and corrosion resistance or electrical insulation.
How it works
"Why it works"Spray material in the form of powder, wire or rod is melted by a heat source and propelled at high speed onto the substrate. The particles flatten on impact and pile up into a layered coating.
Depending on the heat source, methods include flame spray, arc spray, plasma spray and high-velocity oxy-fuel (HVOF). Cold spray, which deposits particles in the solid state without melting them, is a related technique.
Plasma spraying uses a plasma jet of ionized gas such as argon, exceeding 10,000 °C, and can spray ceramics such as alumina and zirconia.
The substrate is roughened by blasting to ensure adhesion. The substrate itself heats up relatively little during spraying, which helps avoid thermal distortion and changes in material properties. Because coatings contain pores, sealing is applied for some applications.
Main effects
- Higher wear resistance
- Heat resistance and thermal insulation (thermal barrier coatings)
- Higher corrosion resistance
- Electrical insulation
- Dimensional restoration of worn or damaged parts (repair)
Definitions
- Plasma spray
- A thermal spray method that melts the spray material in a high-temperature plasma jet of ionized gas and sprays it onto the substrate. Suited to high-melting-point ceramics.
- HVOF (high-velocity oxy-fuel)
- A thermal spray method that accelerates particles with a high-velocity flame from burning fuel and oxygen. It readily produces dense coatings and is widely used for carbide (e.g. WC-based) coatings.
- Sealing
- A post-treatment that fills the pores of a sprayed coating with resin or similar material to improve corrosion resistance or insulation.
Applications
"Where it is used"| Field | Examples |
|---|---|
| Aircraft and gas turbines | Thermal barrier coatings on turbine parts |
| Semiconductor equipment | Plasma-resistant ceramic coatings on chamber parts |
| Paper and steel | Wear-resistant coatings on rolls |
| Industrial machinery | Repair of worn shafts and parts |
Typical process conditions
"Under what conditions"These are general guides. Actual conditions are set by the supplier for each part, material and specification.
| Item | Typical |
|---|---|
| Coating materials | Metals and alloys, ceramics (alumina, zirconia, etc.), cermets (WC-based, etc.) |
| Thickness | Generally tens of μm to several mm |
| Substrate | Mainly metals |
| Coating density | Varies by method |
| Post-treatment | Sealing, grinding and polishing |
| Related standards | ISO 14917 (thermal spraying terminology and classification), etc. |
FAQ
"Direct answers"What is the difference between plasma spray and HVOF?
Plasma spraying uses high-temperature plasma and can spray high-melting-point materials such as ceramics. HVOF gives faster particles and denser coatings, so it is widely used for carbide wear-resistant coatings.
What is the difference between thermal spraying and plating?
Plating builds a thin metal film electrochemically. Thermal spraying sprays molten material, so thicker coatings are easier and the choice of materials, including ceramics, is wider.
Can only part of a component be sprayed?
Yes; masking to limit the sprayed area is standard practice. Specify the area and thickness on the drawing.
Which companies in Japan offer Thermal spray?
Among the companies listed on FactoryMatch, Plasma Giken Kogyo Co., Ltd. offer Thermal spray (based on each company's published information). See the supplier comparison table for minimum lots and overseas support.
Suppliers
"Who to ask"Based on the listed companies' published information.
| Company | Location | Relevant technology | Minimum lot | Overseas support |
|---|---|---|---|---|
| Plasma Giken Kogyo Co., Ltd. | Yorii, Saitama | Plasma spraying, HVOF (high-velocity oxy-fuel spraying), Contract coating (thermal spraying) | — | — |