General Information

Restek passivation and surface protection layers are deposited using a chemical vapor deposition (CVD) process in which the item to be treated is heated under vacuum in a large oven. Our current capacity enables us to treat items up to 6 feet long, or continuous lengths of coiled tubing exceeding 2000 feet (600 meters). Items that can be evacuated, such as gas chambers, can have a volume of up to 43 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. 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 in the layer. By controlling the variables in the process, we control the layer type and thickness. Layer thickness ranges from 0.03µm to 30µm, controlled to our specifications.

Restek?s surface treatments are:

The surface of a system component might be made inert to reduce adsorption or to eliminate the potential for catalyzing reactions. Traditionally, glass linings have been employed to reduce surface activity. Problems with preparing a glass-lined system include the need for careful handling and the difficulty of coating corners, weld seams, and bends, with consequent occurrence of coating flaws. Operating a system with glass-lined components introduces other difficulties, not the least of which is fragility.

Restek offers two treatments, Siltek® and Silcosteel®, that are ideal alternatives to glass linings for passivating many types of surfaces. A Siltek® or Silcosteel® layer provides complete surface isolation while maintaining all the ruggedness of the untreated component. These layers are applied over the entirety of the surface, using a chemical vapor deposition process that does not depend on line-of-sight; corners, bends, and seams are uniformly coated.

In most situations Siltek® treatment is the ideal choice for ultimate inertness. The Siltek® layer is applied at a thickness of up to 0.12µm. At this thickness even parts-per-billion levels of reactive materials will be stable during storage or transfer. A Silcosteel® layer provides equivalent protection for parts-per-million levels of reactive materials.

A selection of Silcosteel®- and Siltek®-treated tubing and fittings are available from stock. All coatings are applied to customer supplied items on a custom basis?see Custom Coating Services.

In many purity-critical applications the potential for contamination created by contact of the process stream with sample transfer components such as tubing, fittings, and valves is a major concern. For example, the slightest contamination in gases used in manufacturing semi-conductor devices can create high failure rates in end products.

Siltek®, Sulfinert®, or Silcosteel® treatment can eliminate interactions between process gases and transfer system components. Our extensive evaluations in the
fields of passivation, corrosion resistance, and ultra-high vacuum show that these treatments eliminate outgassing of impurities into the sample stream and will not react with process stream components.