Frequently Asked Questions

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SilcoTek Frequently Asked Questions

SilcoTek CVD coatings are uniquely tailored to solve tough material problems in a variety of industries and applications.  We offer over 20 custom coatings that solve challenging material problems found in process, analytical, semiconductor, gas, oil and wherever a durable inert surface is needed.  We call our patented CVD coatings silcod technologies because they can be tailored to meet your specific application.  To learn more about SilcoTek's intellectual property and how we improve performance, please visit  www.silcotek.com/ip.

Have questions about SilcoTek® coatings?  Learn about our people, products and processes.  View our "About SilcoTek" video then explore the topics below to find answers to several frequently asked questions.  Can't find the answer you're looking for?  Contact our Technical Service Team:

Ordering

SilcoTek does not sell anything besides our coating services, but our Channel Partners work with us to stock their products with our coatings to help your supply chain.  Click here to see product listings.

Click here to request a quotation for custom surface deactivation of sample pathway components, inlet liners, etc. Please forward a scaled drawing or photograph detailing the product to be treated. Upon receipt of this completed worksheet, SilcoTek's Technical Staff will contact you with a quotation, typically within 1 business day or less.

When you are ready to send items to SilcoTek for treatment, contact technical support at 814-353-1778 or email SilcoD@SilcoTek.com to request a sales order number.

When submitting parts for treatment, remember that parts must be completely dissembled, and components that cannot withstand the high (400°C) temperatures associated with the process (rubber o-rings, brass, etc.) must be removed. Note that SilcoTek cannot assume liability for damaged parts due to process heat.

See your quote for specific disclaimers.

The following definitions explain the various treatments currently available and their recommended applications:

  • SilcoNert® 1000 (Silcosteel®)
    A general-purpose passivation layer for steel and stainless steel.

  • SilcoNert® 2000 (Siltek®/Sulfinert®)
    The ultimate passivation of treated surfaces, from glass to high nickel alloys of steel. A required treatment for metal components when analyzing for parts-per-billion levels of organo-sulfur compounds, mercury, and other reactive chemicals.

  • Silcolloy® 
    A corrosion resistant layer that increases the lifetime of system components in acidic environments containing hydrochloric acid, nitric acid, or seawater.  Also a tremendous oxidation-resistant barrier.

  • SilcoKlean® 
    Dramatically reduces carbon coke buildup on stainless steel components.

  • SilcoGuard® 
    Greatly reduces outgassing from components of ultra-high vacuum systems.

  • Dursan®  
    Our most versatile coating.  Ideal for corrosion resistance in pH 0-14 environments but also highly inert for low-level (ppm) sampling.  Ideal for harsh processing or analytical environments, Dursan also offers 2x the wear resistance of bare 316 stainless steel.

  • Dursox®
    A ceramic-like silicon oxide (SiO) film.  Ideal for protecting parts when the carbon content of Dursan is not desirable.  

Coating Properties

The different colors of the coating can be attributed to angstrom-level thickness variations across the surface.  All SilcoTek coatings have a thickness of <1.5µm.

Certain coating processes (e.g. Silcolloy, SilcoGuard) result in a thicker layer and have a silver/matte gray appearance, while thinner coatings (e.g. SilcoNert) exhibit the ‘rainbow’ colors

Coupon Color Image 2 12 13 resized 600

In general, temperatures should not exceed the recommendations below in order to maintain the coatings' specified performance properties, but coated parts can be used at higher temperatures under certain conditions.  Heat treatment of parts at the application's temperature will ensure the best results if exceeding the temperature limits suggested below. Please contact technical support at 814-353-1778 or by clicking here for additional information or to discuss your application.

SilcoTek® coatings are stable to the following temperatures in an inert atmosphere:
*The values below reflect limits of the coating material itself and assume that the base substrate is stable at these temperatures.

SilcoNert® 2000
SilcoNert® 1000
Silcolloy®
SilcoGuard®
SilcoKlean®

Dursan®

Dursox

450 °C; 400 °C (oxidative atmosphere)
1410 °C 
1410 °C
1410 °C
1410 °C

500 °C; 450 °C (oxidative atmosphere)

500 °C

There are several variables that determine thickness, but all SilcoTek coatings in current production are deposited at < 3µm thicknesses.  Please contact us to discuss thickness specifications.

 

Design, Fabrication and Installation of Coated Parts

Welding will remove the SilcoTek coating ~2-4mm in all directions from the heat affected zone.  SilcoTek can coat over high-quality welds, such as those listed in our material compatibility guide.  For specific questions regarding welding, please call +1 (814) 353-1778 and press 2 for technical service.

SilcoTek offers two processes for coating tubes:

Coiled/Rolled Tubing  Coiled Tubing

  • Coated internally-only 
  • Maximum continuous length: 2500 ft. per coil
  • Maximum coil OD for tubing > 1/16" OD: 36"
  • Maximum coil OD for tubing 1/16" OD or smaller: 18"
  • Must be shipped on a metal spool or bound with metal wire.  No spools made of wood, plastic, or other flammable materials.

Straight Tubing Sticks  Straight Tubes

  • Coated both internally and externally
  • Maximum length: 80"

Click here to read a Technical Insight from SilcoTek's R&D group regarding coating of brazed and soldered components.

We recommend vacuum brazing or welding of joints for best coating quality. Vacuum brazing is a high temperature, flux-free brazing process that results in a contamination-free joint. SilcoTek recommends vacuum brazing services from Solar Atmospheres Inc.

SilcoTek coatings conform to the microstructure of the part surface.  There is minimal filling of voids or change to the overall surface roughness.  Overall roughness measurement may be reduced slightly (1-2 RA reduction), but not a significant change in roughness.  Some SilcoTek coatings have a higher lubricity than stainless steel, so even though surface roughness has not changed, the surface may have a lower friction coefficient.

Yes!  SilcoTek coatings are proven to withstand compression and shear stress common to CF, face seal, and threaded sealing systems.

For more information about SilcoTek coatings and sealing surfaces, click here!

FSEM ImagePre_sealed_surface_2_8_10_15_2

FESEM (Field Emission Scanning Electron Microscopy) image of the coated pre-sealed surface shows the coating conforms to the sealing area.  The raised surfaces of the face seal gland area can be seen.  SilcoTek coatings conform to surface contours and small orifices.

 

FSEM Post_seal_1_8_10_15

After making the metal-to-metal face seal per manufacturers instruction, a second FESEM image of the post sealing surface shows no scarring or scratching, only trace particulate from the silver gasket.

SilcoTek does not recommend coating ferrules as we have found this may lead to leaking problems after coating.

Coating non-Steel Substrates

Virtually all alloys of stainless steel, ceramic, and most glass materials can be treated. Some other metallic materials, such as nickel, brass, and copper, are incompatible with the 400+°C temperatures used in the process, and should not be treated. 

Note: carbon steel, F22 or similar carbon steel, is not recommended for coating in corrosion resistant applications.  Treated carbon steel may rust in corrosive environments.  Avoid corrosive environments when using treated carbon steel in inert sampling applications.

SilcoTek can coat aluminum substrates however there are limitations for components used in high stress applications.  Go to our aluminum coating page to learn more about aluminum coating capabilities.  Contact us to ensure optimal processing of your aluminum parts.

Request re-deactivation of SilcoNert 2000 treated glass liners by contacting SilcoTek's Customer Service department at 814-353-1778. Requesting SilcoNert 2000 re-deactivation of customer supplied liners. A minimum of ten liners is required. Metal inlet liners are designed as inexpensive, disposable products and it is not cost effective to re-treat them. We recommend discarding them when they are no longer serviceable

Maximum temperatures usually will be dictated by the composition of the glass, not by the surface treatment. The SilcoNert 2000 layer is stable at temperatures up to 450°C, but some glasses can soften at lower temperatures. Injection port temperatures normally are well below the SilcoNert 2000 maximum temperature limit, so SilcoNert 2000 treatment is an excellent deactivation for all injection port surfaces.

The color of a surface coating is an expression of the light diffraction qualities and thickness of the layer. The thickness of a SilcoNert 2000 layer determines the degree of darkness, secondary reflectivity, and/or final color of the item. The color can range from light golden-brown (thin coatings) to reflective silver (heavier coatings). We deposit a layer that provides a gold color on liners to aid analysts in inspecting for cleanliness. Chromatographic performance does not depend on the thickness of the layer.

SPECIAL NOTE: Coating of glass fritted liners - SilcoTek would prefer that all glass liners be sent without deactivation (e.g. silanization) since the deactivation layer will prevent our intermolecular coatings from bonding to the surface. For most glass liners, our cleaning process will remove all prior deactivants. However, SilcoTek cannot put fritted liners through our cleaning process without damaging the frit.

Fritted liners are special because there is no effective way of cleaning glass frits or stripping the coating in case of failure. As we continue to gain experience with glass frits and tailor our processes, we will get better. Our major hurdle is being able to "test" fritted liners prior to coating to ensure they are clean. We continue to work on this aspect of our operation.

Yes, SilcoTek can coat most grades of aluminum alloys.  It is important that customers inform SilcoTek of the exact material grade of aluminum substrates prior to sending parts. Learn more by clicking here

*SilcoTek does not recommend coating cylinders or any other aluminum product that will be pressurized or used in high stress applications.

Liner_image2_23_14

The color of a surface coating is an expression of the light diffraction qualities and thickness of the layer. The thickness of a SilcoNert 2000 layer determines the degree of darkness, secondary reflectivity, and/or final color of the item. The color can range from light golden-brown (thin coatings) to reflective silver (heavier coatings). We deposit a layer that provides a gold color on liners to aid analysts in inspecting for cleanliness. Chromatographic performance does not depend on the thickness of the layer.

Tubing

Tubing coils 10 10 18

SilcoTek’s process for treating coiled tubing results in a uniform coating throughout the interior of the tubing from end to end.  The exterior surface of coiled tubing is not coated, but it will exhibit a change in appearance after being oxidized by the high temperatures of our CVD coating process.  This resulting external appearance will vary based on the specific elemental composition of the tubing substrate. 

SilcoTek offers two processes for coating tubes:

Coiled/Rolled Tubing  Coiled Tubing

  • Coated internally-only 
  • Maximum continuous length: 2500 ft. per coil
  • Maximum coil OD for tubing > 1/16" OD: 36"
  • Maximum coil OD for tubing 1/16" OD or smaller: 18"
  • Must be shipped on a metal spool or bound with metal wire.  No spools made of wood, plastic, or other flammable materials.

Straight Tubing Sticks  Straight Tubes

  • Coated both internally and externally
  • Maximum length: 80"

How tightly can the tubing be bent?

OD
<= 1/16"
1/8"
1/4"
3/8"

Min. Bend Radius
1" (2.5 cm)
2" (5.1 cm)
4" (10.2 cm)
6" (15.2 cm)

Yes!  Our unique chemical vapor deposition process is performed in the gas phase, so even the smallest channels and tightest tolerances will be adequately coated along with the rest of the part.  We also have the ability to coat certain tube configurations internally-only.

We proved this by coating a 1/16" OD, .4mm ID tube with multiple bends both internally and externally.  After coating, the tube was cut open to examine the coating at the center-most point inside the tube.  In addition to the external coating on the tube, a quick visual inspection shows the vibrant purple-colored SilcoTek coating inside the narrow bore.  

 

 

The thickness of the coating throughout the tube was verified by aFilmetrics F40-Series Thin Film Analyzer and it was confirmed to meet our specifications.  SilcoTek coatings are not applied with line-of-sight processes that lead to inconsistent deposition and uncoated areas.  With our process, 100% of your parts are coated, even if the design is complex or the pathways or tortuous.  

Narrow-Tube-Coated-BlowUp.jpg

Corrosion Applications

We recommend all end users test SilcoTek coatings in corrosive applications to better understand the performance and potential lifetime prior to installing coated parts into service.  Since every corrosive application is different, several factors impact the coating's lifetime, and there are potential risks associated with failure, it is nearly impossible for us to provide a realistic estimation.

Our goal at SilcoTek is to partner with you to help you solve your corrosion problems, so we put a priority on helping you evaluate our coatings.  This includes gathering relevant test data, providing samples, coating your test pieces, and putting our technical experts on your project to find a solution that works.  Please contact us to discuss your application and establish a testing and validation plan.

SilcoNert 1000 and SilcoNert 2000 treated materials have improved corrosion resistance, but Silcolloy (formerly Silcosteel®-CR) and Dursan surface treatments are optimized to enhance resistance to many common acids; providing a 10-fold improvement in corrosion resistance, compared to untreated stainless steel, and a 4-fold improvement compared to SilcoNert 1000 coated stainless steel.

Note: carbon steel, F22 or similar carbon steel, is not recommended for coating in corrosion resistant applications.  Treated carbon steel may rust in corrosive environments.  Avoid corrosive environments when using treated carbon steel in inert sampling applications.