SST Cold Spray Applications and Coating Use
The SST Cold Spray™ process is enabling a broad range of coating and metal consolidation applications, including many that may not been previously possible or commercially practical. If your operation uses coatings for any of the applications outlined on our Coating Use section below please contact us to learn how the unique process attributes of SST Cold Spray ™ can satisfy your needs.
The following coating use descriptions are provided to identify existing commercial applications, as well as to stimulate future application development.
SST Coating Use
The user is ultimately responsible to ensure that their application of the process is not the subject of pending or issued intellectual property protection. The specific application must be evaluated to ensure the suitability of the SST Cold Spray™ process to achieve the desired results.
EXISTING COMMERCIAL USECorrosion-Resistant Coatings
Protect surfaces from major sources of corrosion failures including: pitting, crevice, intergranular, and stress corrosion by sealing the surface or establishing a preferential galvanic reaction. Reliable metal coatings require minimal preparation, no drying time and can exceed the reliability of chemical coatings.
- The robust passive oxide film on aluminum can be exploited to greatly reduce the complexity of implementing magnesium components.
- Cover welds and other seams with zinc-base coatings that provide a moisture barrier and act as a sacrificial anode to add galvanic protection.
- Fill friction stir welds in aluminum with aluminum to make the weld disappear and prevent stress corrosion cracking.
- Isolation of materials that interact with the working environment.
The absence of process-induced oxidation yields coatings of optimum conductivity. Localized application of coatings can be used to form copper grounding pads on materials such as steel or aluminum, or circuit traces on materials such as glass or ceramics. Electrorestrictive or magnetorestrictive materials can be sprayed to form sensors right where you want them.
Quick and easy coating of seams can be used to ensure that there is no possibility of electromagnetic field leakage or intrusion.
Thick coatings can be used to fill surface discontinuities such as voids and depressions and to conceal welded joints. SST has formulated economical powder compositions to optimize cost and mechanical properties. Sheet metal repair and construction is ideal for aircraft, automobile, marine applications. The very low porosity simplifies post coating processes such as painting since solvents will not be trapped to later volatize through drying paint.
Coatings can be applied to increase surface friction. Some of these coatings include entrained cermets for aggressive engagement.
Entrained lubricants and ductile materials can be applied to reduce friction. Anti-seize coatings can be selectively applied.
Surface repair is a great application because the coating is very effective in a wide range of thicknesses. There is no need to feather the coating beyond the repair site. The metal of the repair can match the substrate or provide enhanced properties. The low heat input of the process means that the substrate will not be changed by the process so expensive aluminum injection molds for all types of plastic can be resurfaced to provide for redeployment. Kirksite forming dies can be restored and improved for making short-run stampings. Engine heads and piston crowns can be repaired and/or modified to yield customized operating performance.
With little effort, cosmetic surface repairs can restore components to their original condition. Since the coating material can match the substrate, applied patina, and finishes can be seamlessly applied to make the restoration disappear.
The bond strength of the coating, along with its low porosity and gas permeability, make the coatings ideal for preventing liquid or gas migration. The coatings can be applied to seal pressure vessels and piping for both high and low temperature service. The metal seal is ideal for cryogenic applications and for sealing joints between dissimilar materials. Sensors can also be embedded inside solid materials to make them inconspicuous or vandal proof.
Thermally Conductive Coatings
The intimate bond between substrate and coating ensures maximum heat transfer. It is possible to spray copper heat sinks directly on stainless steel or ceramics.
Transition coatings are widely used to:
- Reduce galvanic corrosion by isolating the material interface from moisture and/or the atmosphere required to support electrochemical corrosion process.
- Provide an interface between materials with large differences in thermal expansion.
- Optimize thermal energy transmission.
Coatings that wear preferentially to the substrate.
Substrates that are prone to wear can be restored using selective application of more resistant materials. An example is our ability to apply surfacing on Kirksite, a moderate strength zinc-base alloy, used primarily as a prototype or low production forming tool alloy.
IN DEVELOPMENT APPLICATIONS FOR COMMERCIAL USEAbradable Coatings
Increase the efficiency of pumps, turbines, turbochargers, and other such devices by applying a coating that will minimize the part clearance and resulting blow-by. These coatings are designed to wear preferentially so that there is a shape conforming seal between precision-made components. The coating material can be a composite to tailor the wear mechanism and properties as desired.
Apply or maintain ductile coatings on carbon steel tools and surfaces to eliminate the possibility of creating sparks in hazardous environments.
Spot application of material can be used to balance rotating parts such as shafts, wheels, and rotors. The coating can match the substrate such as aluminum on an aluminum drive shaft or wheel, or it could be a different material selected for its density or color.
Bearing materials can be sprayed in place or spray formed onto a mandrel. The bearing can be sprayed in place and then finished machined to size - eliminating the need for multiple setups or assembly tolerance stack-ups.
Don't scrap your casting if it has minor porosity, shrinkage, or dimensional (pattern) defects. Localized coatings can be applied to salvage castings of aluminum, brass, bronze, cast-iron, magnesium, and steel to name a few. The coating can be applied to fill or seal defects without negative impact on the substrate. In one instance for large thermoform tooling a machine was located next to the milling machine so that if a void was encountered it could be repaired on the spot with minimal interruption of cutting. The aluminum repair exactly matched the thermal properties of the casting so that the tooling performed flawlessly.
Apply metal coatings to similar or different metal substrates or materials such as glass, ceramic or stone. There is no need for patterns or other complex preparation so the coating can be adapted for each unique project and can be finished quickly. There is no casting shrinkage and minimal material compatibility issues to deal with when making complex media projects.
The cold gas-dynamic process can be used to create near net shape parts of almost any description and size. Form solids of metal composites, dissimilar metals, and nanostructured materials. The composition can be varied throughout the fabrication or expensive materials can be selectively applied. Thick coatings can be used to build up electroformed parts to their desired mass or thickness. Fabrications can be subjected to a variety of post treatments such as hot isostatic compaction, ultrasonic consolidation, laser sintering, and heat treating.
While cold gas-dynamic spray is not promoted as a joining method it can be an enabling technology for mechanical joining methods. One method is to use the coating as a mechanical stop or key. A benefit is that the coating can simultaneously serve as a hermetic seal.
Thick resilient coatings can be applied to hard surfaces to provide a measure of resilience.
Placement of Materials
Pre-placement of solder or brazing filler materials, including deposition of a primer coat on difficult to bond substrates. Deposition of material blends to create metal foams.
The as-sprayed coating can be applied to add texture to rolls and flat surfaces.
Spot application of coating to add mass to the substrate. Such mass may be desired for example to balance aluminum wheels or drive shafts, or the rotors in electric motors.
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