Copper Feedstock Materials
There are two readily available feedstock materials for copper coatings, water atomized and hydrogen reduced copper powder (0.15% oxygen, 0.02% hydrogen). The same is true for the copper-based alloys.
The best copper powder particle size for HVAF spraying is -45/+22 microns (nothing below 15 microns). The absence of fines in the feedstock powder is essential to avoid the formation of oxides.
The Properties of the Copper Coating
|Apparent metallographic porosity, %||<0.5|
|Bond strength, MPa||>75|
|Oxygen content, wt%||0.30-0.40|
|Electrical resistivity, micro-Ohm x m||0.03|
The coating is near theoretically dense, non-oxidized and exhibits physical properties comparable to bulk (“tough-pitch”) copper. Excellent bonding to steel and aluminum.
A Typical Cross- Sectional Micrograph of a Copper Coating
A Comparison of Copper Deposition by HVAF, HVOF and Cold Spray Technologies
The melting point of Cu is 1,084°C (1,983°F), different brass and bronze alloys melt between 900 and 1040°C (1,650 to 1,900°F).
Spraying copper alloys with an HVOF combustion temperature of 2,800 – 3,000°C (5,072 – 5,432°F) results in material melting and oxidation. And with a boiling point of 2,567° (4,653°F) the vaporization of copper in HVOF spraying is certain.
The Cold Spray approach to deposit cold or warm copper powder prevents oxidation, but the cost of cold spray equipment and process makes this type of coating unbearably expensive for most applications.
HVAF combustion occurs at a temperature of 1,960 – 2,010°C, which is still too high for copper. That is why we have developed a dedicated type of HVAF equipment – Kermetico SL, which keeps the temperature of the copper powder below its melting point.
Copper, brass and bronze powders are being preheated below their melting point, accelerated and delivered to the substrate shrouded by an inert gas. This is how we can spray unoxidized dense coatings at a lower cost than HVOF and Cold Spray.
But that’s not all.
The Kermetico HVAF process provides an efficient method to apply thick, inexpensive copper and Cu-based coatings.
We have deposited up to 6 mm (0.250”) for our clients, but that is not the maximum we can apply.
The Typical Applications of Copper, Brass and Bronze HVAF Coatings
- Heat conductive coating in electronic packaging devices
- Brazing copper layers over aluminum heat sinks
- High electrical conductivity layers on annealing rolls in steelworks
- Restoration of worn parts spraying copper, brass or bronze
Kermetico HVAF Equipment to Spray Copper Coatings
Kermetico has developed a specialized gun to spray Cu and Cu-alloy powders: Kermetico HVAF SL.
You may also be interested in the rest of our HVAF equipment to spray different materials:
- Convertible HVOF and HVAF equipment:
- Multi-purpose HVAF AK systems, with a range of spray guns:
- AK7 – a high power gun for the thermal spray of large parts
- AK6 – a universal gun to spray a balanced mix of parts in a job shop
- AK5 – a compact gun to spray smaller parts, thin walls and complex surfaces
- AK-ID – an 80 mm (3.15”) and larger internal diameter spray gun
- AK-IDR – a rotating ID gun to spray 4” (100 mm) and larger bores
- AK-HH – a handheld gun for on-site coating
- Specialized HVAF S equipment:
- Additional equipment:
Kermetico, Inc. – Material Science Excellence, HVAF and HVOF Equipment Manufacturing and Thermal Spray Coating Services Since 2006
We create equipment that helps material scientists, engineers and business managers achieve their goals.
We have installed more than 60 Kermetico HVAF and HVOF systems in the USA, Europe, Japan and China.
Some of the systems are at work in Universities and National Labs, but most of them work in production thermal spray shops.
We proudly design and produce our thermal spray equipment in California and install it all over the world.
You can visit our R&D center in Benicia, CA to meet our designers and see our HVAF and HVOF equipment in action.
We also deposit HVAF and HVOF thermal spray coatings for customers in North America.