Frequently Asked Questions
Frequently Asked Questions
- What is the arc-plasma spray process?
- What about size limitations?
- Will heat distort the part?
- But won't such coatings flake and peel off?
- How can I benefit from this technology?
- Where can I find more info about Thermal-Spray Technology?
Arc-plasma spray is the method whereby a hot gas plasma is used to melt a particulate material and transfer it to a substrate, at which point the material solidifies to become a coating. The plasma is generated by passing the gas between two concentric electrodes (water-cooled ) where it is heated by a sustained high-current d.c. arc. Temperatures within the chamber reach higher then 30,000° F which causes the gas to expand and issue from the front electrode-nozzle at a very high velocity. At some point downstream from the arc, powder is injected via a carrier gas and mixed with the plasma. The powder melts and is carried at the gas velocity to the substrate where it is quenched and bonds to form a dense coating. Both thermal and kinetic energy in the particles bring about the high bond strength associated with plasma spray coatings.
We have processed films as thin as 2 µm, and as thick as ½ in. on foils and ceramics small enough to be held in tweezers and on castings and fabrications with many hundred square feet of area.
If the substrate will fit within our 10x11 foot door, we can process it in the shop. For those larger parts or ones not easily accessible, we have portable equipment that we can bring to the job.
I.D.'s above 4 inches can be coated internally; below this diameter, we can reach the depth equal to the diameter.
No! The heat input to the substrate is very minimal and even on small substrates, the temperature will normally be held at 250° F. Thus APS processing will not affect the geometry nor the hardness of nearby surfaces which have been finished.
There are several methods for constructing a coating to withstand high loads and even severe impact. Even ceramics have been graded-diffused bonded on aluminum plate and successfully tested as armor plate against 30-06 projectiles. Other coatings have been milled, threaded, ground, and machined--even to feathering against the base substrate.
Easily, by saving time and money! Consider the following suggestions for your use.
Either worn or new mismachined parts. We can bring a worn part back into spec at a fraction of the new cost and most generally within a two week period. The part will outperform a new counterpart in most instances!
And how about those production castings with overbored holes or those shafts with under-size bearing surfaces? Like another chance at machining them to spec?
Use in lieu of distortion-causing heat treats. Or provide a better surface for that bearing... for slides... for seals. How about lining your pumps for improved wear? Mixer bodies? How about a coating with a higher hot hardness than your present part has?
Repair pumps and valves with linings... patch reactor kettles and mixers... rebuild those seals... clad those offending parts.
Saving Material Costs!
Why use that 4000 lbs. of stainless shaft when you can clad a much less expensive material and save up to half the price! Why use an inch-thick Hastelloy® casting when it has to be discarded or rebuilt after 0.050 in. of wear? Use a 0.060 in. coating at less than half the cost. Machining Hastelloy and Inconel expensive? Why not machine a less resistive material and clad for your corrosion protection?
Production line down? Delay in getting those parts?
APS Materials offers a 48 hour turnaround (excluding shipping) to machine, repair, and maintenance departments. This includes coating and finishing the part to spec ready to use!
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