Info & Support
Recommended Care of Treatment Layers
Since 1987, the Restek Performance Coatings Team has been offering leading edge passivation and barrier coating
technology to the scientific, analytical, and process markets. You may have questions regarding the appearance,
performance, and maintenance of the treated surface. Here are a few tips to keep your treated products working
at peak performance.
Appearance
Layer appearance and surface finish can vary from lot to lot. Small variations in surface thickness (measured
in angstroms) can impact layer appearance. The surface finish should be bright and free of defects, but original
surface condition can have a major impact on final surface quality.
Your parts are cleaned after treatment; however, the surface may contain some trace silicon (black particles) as
a byproduct of the treatment process. Residual silicon can be removed by rinsing with a solvent or by sonication
in water.
General thickness ranges are:
|
Product
|
Coating thickness
|
Color
|
|
Silcosteel®
|
300Å–350Å
|
Blue
|
|
Siltek®, Sulfinert®, Silcosteel®-AC
|
1200Å–2500Å
|
Rainbow
|
|
Silcosteel®-CR, Silcosteel®-UHV
|
5+ µm
|
Gray
|
|
Colors associated with layer thickness are:
Thick depositions used in our Silcosteel®-CR and Silcosteel®-UHV processes are 5µm to 20µm
deep and have a silver/metallic grey appearance. The photos below show colors created by Sulfinert®
(left) and Silcosteel®-CR (right) deposition.
Cleaning
When cleaning a treated part, rinse with a solvent compatible with the contaminants you intend to remove (i.e., use nonpolar
solvents with hydrocarbon surface contaminants, more polar solvents with more active contaminants). Do not use
basic solutions with pH>8.
Avoid using cleaners containing abrasives as they can scratch the layer. Mild sonication may assist in contaminant
removal, but do not oversonicate—this could damage the layer.
Avoid steam cleaning of components and lines as this can damage the layer.
Galling
As with any threaded fitting, galling may occur when assembling two treated parts. To prevent thread damage, use
a thread lubricant or Teflon® tape. Galling potentially can be reduced when assembling a treated part and an
untreated part.
Troubleshooting
Under normal use, your treated items should deliver outstanding performance for years to come. However, effective
lifetime is dependent on the severity of the environment. Factors that can impede performance are:
|
Contamination
|
Failure to properly clean the surface can allow increased surface activity. If performance changes,
thoroughly clean the surface and inspect the layer for damage.
|
|
Erosion
|
Contact with abrasives can accelerate surface wear.
|
|
Bases
|
Contact with a base (pH 8 or higher) can accelerate deterioration of the layer.
|
|
Surface finish
|
Surface finish and color should stay consistent throughout the life of the product. Changes in the
finish or color may indicate a partial loss of the layer. To prevent further loss, ensure no exposure
to bases or abrasives.
|
For additional information about Restek Performance Coatings e-mail
us, or contact our technical service department at 800-356-1688.
Restek Surface Treatment Processes
Restek passivation and surface protection layers are deposited using a chemical vapor deposition (CVD) process.
In the process, the item to be treated is heated under vacuum in a large convection oven. Our current capacity
enables us to treat items up to 6 feet in length. Evacuated items, such as gas chambers, can have a volume of
up to 3.5 cubic feet.
When the item has been heated to the appropriate temperature, the reacting gases that form the protective surface
are introduced, depositing a durable, amorphous layer that grows and overlays itself multiple times. By
controlling the variables in the process, we control the layer type and thickness. Layer thickness ranges from
0.03µm to 20µm.
The reaction layer penetrates into the lattice of the treated piece and binds solidly. Consequently, it is
possible to work a piece, such as bending a length of treated tubing, without creating cracks, flakes, or other
flaws which would compromise the layer.
Restek surface treatment processes do not rely on line-of-sight deposition. The chemical vapor deposition process
ensures all surfaces are treated uniformly—even at corners, holes, and machined ridges.
About Us
Restek’s involvement with surface coatings began in 1987, when we developed a treatment that made stainless
steel surfaces inert to low-level reactive organic compounds. Since this initial project, Restek’s coatings
experts have developed a family of surface treatments to address other specific needs and thereby enhance the
performance of system components. These treatments are:
| 
