The US is not the only country enacting improved clean air standards.  What's the key to meeting of all the standards?  Reliable sulfur detection and sampling.  Here's how SilcoTek® is improving sulfur detection and helping industry meet clean air standards worldwide.

I visited friends in Pittsburgh a few years back.  We toured lots of great places around the city but what struck me the most was a single black and white photo at the inclined plane on Mount Washington.  The photo (taken circa 1940 judging by the cars) was of a vibrant downtown Pittsburgh at what appeared to be early evening.  The cars had their headlights on and the scene was gray, dark and gloomy.  What shocked me was the caption:  Downtown Pittsburgh at 12 Noon!  In those days the air quality was so bad that cars needed to turn on their headlights to avoid collisions.  Forget about blue sky, you were lucky to see where you were going! 

That made me think back to a story my mother told me about growing up in the Pittsburgh area.  If she slept with the window open by morning the window sill would be black with dirt and there'd be black under her nose.  She said my Grandmother had to have the wallpaper cleaned yearly just to keep up with all the black particulates from the near by mills.  I can't imagine growing up in that kind of air pollution.  Unfortunately a good portion of the world's population is all too familiar with this scene.  But things are changing.   

The world is catching on to the benefits of clean air.  China for example has enacted aggressive new standards to improve air quality.  They recognize the benefits of improved health, a stronger economy and a better functioning society.  They realize that fewer air quality related fatalities, less flight cancellations, and fewer pollution related plant shut downs benefit quality of life and the quality of China's economy.  In fact, the world seems to be getting the idea that clean air is important.  Just look at the number of new tighter air standards being enacted throughout the world:

• Tier 3 (US) (related methods include ASTM Method D5453, ISO Method 20846, and ASTM Method D2622)
• National 5 and Beijing 6 (China)
• Bharat Stage 6 (India)
• Euro 5 and Euro 6 (EU)
• Clean fuel projects (Middle East)
• IMO Global Sulfur cap (Global shipping, effective 2020)

What's the primary objective of all these new air quality standards? Reduction of pollution effects through the detection and control of particulates, low level sulfur (SO_x), and NO_X emissions. 

Why control sulfur and nitrogen oxide emissions matters.

Remember that image of Pittsburgh at noon?  Well all that darkness was caused by smog.  The grey haze was formed by sulfur dioxide (SO₂) and to a lesser extent SO₃ as well as oxides of nitrogen (NO_x).  But it's not just the dark cloudy appearance that's a concern, SO_x and NO_x exposure have a real and lasting effect on the environment and humans including:

• Breathing problems and lung disease
• Immune system depression
• Defoliation due to acid rain
• Damage to structures due to acid exposure

Sound bad?  How about this statistic.  In 2015, 9 million deaths world wide were attributable to pollution, mostly due to smog.  In China nearly a third of deaths are caused by poor air quality.  Given the facts, it's not surprising that air pollution control has become a major initiative throughout the developed world. 

What's the key to control of SOx and NOx?  Reliable detection.  Without a way to sample and compare pollution levels, measuring the effectiveness of air pollution controls like scrubbers and clean fuels would be impossible.  Unfortunately sulfur is a tricky element to detect. because it tends to stick to all sorts of metals, glass, and ceramics; which are common materials used in sample flow paths. 

Why is sulfur hard to sample and detect?

Because sulfur and sulfur compounds tend to stick to materials commonly used in sample flow paths.  If the sulfur gets trapped in the flow path, the instrument can't accurately record the data, making control of scrubbers and processes difficult at best.  Here's an example of how sulfur can get lost in a tube.  Shell and O'Brien conducted a study where a sulfur compound was injected into a tube.  Then they waited for the detector at the other end to "see" the sulfur.  They waited... and waited... and finally after 90 minutes some sulfur hit the detector!  Here's a graph of the test results.

The first red line is a graph of the sulfur response when that tube is coated with SilcoNert®.  Under the same test conditions the response is almost immediate!  Virtually no sulfur was lost in the tube.  When all the sulfur makes it to the detector, the plant or refinery can accurately control emissions or their process; making for a better product while minimizing sulfur related air pollution.

Read The Entire Sulfur Detection Study By Shell and O'Brien Analytical

How big a problem is sulfur adsorption?  Well if we look at the US EPA Tier 3 standard, a 10ppm sample will be completely lost in a relatively short length of sample tubing.  If the sample were exposed to a high surface area metal (for example if a sample were filtered through a sintered metal frit), most if not all of the sample would be adsorbed onto the surface.  

Here's an example of how dramatic sulfur loss can be.  A sample of hydrogen sulfide, carbonyl sulfide, and methylmercaptan were injected onto a GC column through a 3 inch long stainless steel liner.  During the brief exposure to the stainless steel liner, the sulfurs adsorbed onto the stainless steel surface.  The adsorption was so complete that the detector was not able to see any hydrogen sulfide (H₂S) or mercaptan (image below).  If we rerun the test using a SilcoNert 2000 coated liner, the H₂S and mercaptan are clearly picked up by the detector. (second graph).

How do SilcoTek® inert silicon CVD coatings improve sulfur sampling and air quality?

Our inert CVD coating, SilcoNert®, provides a barrier between the sample and the reactive stainless steel surface.  That allows the sulfur or NO_x sample to pass right through the flow path without interacting with the surface, delivering the entire sample to the detector.  Our inert coating benefits include:

• Improved sensitivity
• Better sample system reliability
• Better repeatability and precision
• Improved corrosion resistance and moisture resistance

Sometimes it's not about how fast you can deliver the sample but how long you can hold the sample.  When field operations staff take a grab sulfur sample (be it from the well or from the refinery hydrotreater) they can run into sulfur adsorption problems.  The stainless steel sample cylinder surface will adsorb sulfur starting the second the sample enters the cylinder.  That means time is of the essence when trying to accurately assess if the well is sweet or sour or if the hydrotreater is running to spec.  Sulfur stability in a stainless steel cylinder can be measured in minutes or hours.  After that, it's likely the sample is not indicative of field conditions.  Conversely; SilcoNert® coated stainless steel sample cylinder stability is measured in days or weeks.  That means rather than rushing a sample back to the lab, field technicians can grab and hold a sample for 30 days or more with confidence that the sample is the same as when it was pulled from the field. 

Precise and fast sulfur response allows the plant to better control pollution emissions and avoid plant upsets or regulatory compliance issues.  Improved sulfur, and NO_x sampling flow paths give the plant operator the tools to achieve those tighter clean air standards worldwide.  Want to lean more about analytical sampling and how surface science can improve results?

Did you know that you can buy SilcoTek CVD coated products directly from the manufacturer?  Do you care?  Well you should because it could save you time and money in the long run.

Our network of Approved Partners offer SilcoTek® coated products directly off the shelf to help simplify your supply chain.  We don't sell finished products (only coating services), so we work with leading OEMs and re-sellers to make the purchasing process easier for you.  Now you can buy CVD coated parts for sulfur, ammonia, mercury, or H2S testing directly from the manufacturer.

Lots of customers send in parts for CVD coating application.  Our manufacturing lead time averages about 5 business days for most coatings.  We're fast and offer a great product but there is one drawback.  Parts need to be disassembled before sending them to SilcoTek for coating service. 

Why do I have to disassemble parts? 

In order to coat a part, the surface must be exposed to our coating gases.  We don't need much space (we can penetrate and coat a sintered metal frit for example) but we do need some space.  Areas that are not exposed, like seals or internals of assembled parts may not get a consistent exposure to our process gases.  Surfaces also can't be inspected or adequately prepared for coating so there's a risk of inadequate coating.  As we noted before lots of customers send in their disassembled parts but others really don't want the headache.  It's one thing to take a fitting apart but it's can get sketchy for a novice to take apart a valve or a regulator.  Then there's the time factor.  Some companies or individuals have the resources and knowledge to assemble and disassemble parts but others have to either become fast learners or must pay to have someone properly assemble the part.  That's where our OEM Partner program comes in handy.

No more assembly, Buy CVD Coated Products Directly From The Manufacturer.

We've partnered with some of the best manufacturers in the industry to offer SilcoTek® coated products.  They recognize our coatings are the best in the industry and want to improve the performance of their products (here are just a few case studies for example).  Our coatings offer an additional dimension in performance, be it analytical sulfur inertness, corrosion resistance, anti coking, or moisture resistance.  For the customer it means you don't have to take the time and effort to send in parts, just order them already coated from the manufacturer!  What can I buy?  Lots of things.  Here's list of components you can get directly from the OEM manufacturer. 

• Fittings & Valves
• Sample Cylinders
• Process Sample Probes
• Regulators & Flow Control
• Filters & Separation
• SST Tube, Tubing & Heat Trace
• OEM & Instrumentation

The cost

Just do a Google search on the cost of placing and processing a PO and you'll see a wide range of estimates.  PO costs can range from about $60 per order to over $700 for some oil and gas applications.  That's just the administrative cost associated with order processing.  Now add in the handling cost at shipping and receiving and you're talking a fair amount of money invested in sending in a part for coating.  That's why it's worth a look into specifying our coatings when purchasing parts from the component or equipment manufacturer.  Depending on the OEM stock situation, the lead time may or may not be longer but from a cost perspective it'll be worth it to add our coating when specifying and purchasing the part.  Are you an OEM?  Become a partner and improve your products.

The logistics

From a logistics and SKU perspective it also makes sense to consider purchasing coated parts.  A typical purchasing cycle can entail the following:

• Specify coating
• Source uncoated part or component.
• Disassemble part
• Place coating PO
• Ship part to SilcoTek
• Status order
• Receive coated part from SilcoTek
• Reassemble part
• Process invoice

With good planning, the entire purchasing cycle can be eliminated by specifying our coating when placing an order for the uncoated part at the OEM level.  That will go a long way toward getting home a little earlier from work or greatly reduce the complexity of the order process!

Click here to go to our OEM partner directory.  The directory will take you to specific products and vendor purchasing information.

Want something that's not on our list?  Contact us and we'll do our best to work with your vendor to get us added as an option.

Did you know the base material can have an impact on the performance of CVD coatings?  We tested the compatibility of most metals and other materials commonly used in analytical testing.  Here's what we found out.

Why is it that we can coat most metals but cannot coat some materials like nickel? Furthermore we say that we see excellent results with Hastelloy® (up to 74% nickel) and Inconel (over 70% nickel) but on the other hand Monel (2/3 Nickel & 1/3 copper) is not treatable.  Why is there variation in material compatibility for CVD coatings?  All great questions!  To understand why certain metals perform the way they do we'll need to jump into alloys and how they react with our coatings.

About alloys and why they make a difference in coating results.

An alloy is a mix of a base element metal with another element (or elements).  Metal alloys can often have quite different properties than their base metal.  In the case of alloys, two wrongs can often make a right.  For example aluminum and copper are pretty soft metals, but mix them and you get an aluminum alloy that's stronger. 

The same goes for iron mixed with a touch of carbon.  Carbon's not even a metal but mix a touch of it with iron and you get steel which can have all sorts of benefits like greater strength. Throw in a bit of chromium into the mix and the resulting stainless steel will vastly improve corrosion resistance.    

Alloys have benefits and drawbacks that impact coatability.  We'll use nickel as an example. 

Confused about what we can coat?  Get our latest quick reference Material Compatibility Guide.

How Material Compatibility Can Impact Downhole Sulfur Sampling

Our process is incompatible with pure nickel, because it induces a different growth mode and does not produce the typical nice amorphous (unstructured or non crystalline) coating we see on a stainless steel substrate.  You see silicon is happy to bond and diffuse into all sorts of metals, glass or ceramic surfaces but it preferentially does not bond particularly well with nickel.  In fact after the first few silicon atoms bond to the nickel surface, the remaining silicon atoms prefer to bond to themselves rather than to the nickel.  The result?  Under magnification you'll see lots of silicon columns with deep voids, almost like skyscrapers in a big city.  That's not a good coating because chemicals you're interested in testing (like H2S or other sulfurs) can hide in the valleys, or corrosive chemicals can attack the exposed surfaces.  That's not good for downhole sampling reliability.  The SEM image below is a general example of what columnar growth looks like under magnification.  See?  Kind of like big buildings.  There's alot of space for sulfur to hide or for corrosives to attack the base metal.

Our amorphous coating when applied to stainless steel, glass, ceramics or many metal alloys will bond uniformly to the surface and build a coating layer-by-layer over the entire surface.  It will look something like this SEM image below (note silicon particulates on the surface).

The Auger plot below shows how our silicon barrier coatings bond to the surface.  Auger electron spectroscopy (AES) sputter depth profile analysis quantifies the material composition and diffusion zone characteristic of our silicon coatings (in this case our inert SilcoNert® coating).  The plot shows a layer of approximately 2000 angstroms (200 nm) of silicon.  Note the approximately 500 angstrom diffusion zone between the stainless steel surface and the silicon coating.  An Auger depth profile of a coated nickel part would show areas with little to no coating while other areas would have a much greater depth profile.

Back to alloys.

In cases where nickel is alloyed with other “stabilizing” elements, such as Cr (chromium), Si (silicon), P (Phosphorus) etc., even when nickel (Ni) is the major component base metal, our process coats beautifully over these alloys (e.g. Hastelloy®, Inconel, or typical nickel brazing filler alloys such as Ni-Cr-P or Ni-Cr-Si-P).  In these cases, the coating is able to bond to the "more beneficial' alloy despite the Ni base metal because the alloy characteristics will allow silicon to more easily or preferentially bond to the surface uniformly.  So that's why we can coat superalloys and Ni brazing material.

You can't win them all!

In cases where nickel is alloyed with another difficult to coat element, such as copper, there is no “stabilizing force” or synergy to allow our CVD coatings to bond to the surface.  A copper nickel alloy is usually incompatible with our process. Monel is such an example. Nickel and copper by itself are both incompatible with our process, so when you combine these two into Monel, it is incompatible as well.  

If you want to learn about our coatings and how they benefit your applications, get our webinar:

How To Choose The Right SilcoTek Coating

Have questions about silicon CVD coating material properties?  Go to our Material Property Page and get coating specifications, material data and much more.

We smashed stretched and burned our impact resistant coating.  What we found was alarming, for the other test coupons....

It looks like our R&D staff had some pent-up anger lately.  We set them lose on our Dursan® coating so they could let off some steam (and keep the rest of the the team safe)!  They compared the coating durability, strength and bend resistance of Dursan® in what looked more like a medieval torture chamber than a lab.  Did the coating survive?  Let's find out.*

Wear resistant CVD coatings for Downhole?

CVD coatings are thin but are they wear resistant?  We tested Dursan vs. uncoated stainless steel in a comparative pin-on-disk wear test. We found Dursan was more wear resistant than stainless steel and had higher surface lubricity, making the wear resistant coating ideal for valve components and wear prone surfaces.

Read the wear resistance report.

Want to see more material tests of our coatings?  Here's a great webinar that tests the mechanical properties and material limits of our coatings.  The webinar is focused on semiconductor applications but the data applies to all coating applications.

Mechanical properties of coating.

We tested the tensile strength of an uncoated 316 stainless steel 1in diameter rod and a Dursan coated 316 stainless steel rod.  We pulled the samples to ultimate tensile strength and Bang! Rod failure!  Wow that was cool!  Here's a video of a tensile test, it's not our test, but it does give you a good idea of how the test was performed. 

Results showed the Dursan coating performed at or above the uncoated coupon in ultimate tensile performance; failing at 96,000 psi at ambient temperature.

We tested again at 450ºC to see if the relative tensile test changed.  The ultimate tensile strength dropped as expected, but the Dursan coated rod fared a bit better, with a 20% drop compared to a 23% drop for the uncoated rod.

Read the complete report to compare the yield data and test specifications.

Read The Complete 

Tensile Strength Test Report

The Crush Test...Ouch!

We crushed a coated foil sheet and a stainless steel ball to see if the coating would stay put.  Here's the video of our crush tests.  First we compared a coated stainless steel foil sheet and a painted foil sheet.  We balled them up to see if the coating would flake.  Nope!

Then we got out the press and crushed a coated stainless steel ball to see if we could get the coating to say uncle.  Again we were amazed at the durability of the coating.  Finally we coated a tube to see if the coating failed.  You guessed it, the coated tube bent without a problem.

 OK, Let's Turn UP The Heat!

You guessed it we torched the coating to see if it would burn, flake, oxidize or explode.  I was hoping for explode but no luck!  In fact the coating took the flame test in stride.  Here's the video.  Watch how the surface glows bright red yet after cool down the coating looks unscathed with no oxidation or damage.  The stainless steel coupon was severely oxidized after the heat exposure and the PTFE sample really took it on the chin. 

Want more data about SilcoTek coatings and applications?  Go to our new E-book library and download our easy to read e-books.  You'll get lots of application and coating data and great tips on how to make your process or products better.

* Photo Courtesy of NASA.

We tested our coatings in a wide range of corrosive environments to see just how effective they are in protecting stainless steel from corrosion and preventing rust on stainless steel.  Here's what we learned.

Corrosion can not only compromise analytical system integrity and increase maintenance cost; it can also generate particulates that can result in obstruction and fouling of the system and cause adsorption of reactive compounds. Pitting can also create excellent hiding places for “sticky” molecules, resulting in carryover and false positive results. Passivation and polymeric coatings have been utilized to reduce corrosive attack, but there’s a higher performing alternative that improves both inertness and corrosion resistance of the surface.  But first let's talk about passivation and why it's not an ideal corrosion prevention technique in analytical flow paths.

About Passivation

Nitric acid passivation is commonly used in an effort to remove exogenous iron from surfaces and add an oxide layer in the
hope that the stainless steel flow path will become more corrosion resistant or inert.

Traditional passivation techniques involve the following steps:
• Thorough cleaning of surfaces
• Immersion in nitric or citric acid bath for 30 minutes. (acid concentration and additives are dependent on the grade of
  stainless steel)
• Rinse parts thoroughly in water
• Test part for passivation by placing in a humidity cabinet.

Unfortunately, when applications require the use of aggressive agents like bleach, sulfuric, or hydrochloric acid, no amount of
passivation or electropolishing will prevent corrosive attack.  That's because highly corrosive agents react with the stainless steel protective oxide layer, causing pitting and corrosion of the surface.

Read more on how to effectively prevent corrosive attack. 

Get Our Corrosion Webinar Summary Presentation

An Alternative to Passivation
There's an alternative to passivation that produces better results: change the surface properties of the material by bonding enhanced silicon compounds onto the steel surface via chemical vapor deposition (CVD).  A CVD coating like Dursan®, for example, will improve the corrosion resistance and inertness of the surface, offering a multitude of benefits. The chemical vapor deposition process used to coat stainless steel flow paths will prevent disruption of grain boundaries and act as an inert barrier to aggressive and sticky compounds. Dursan coated analytical flow paths will prevent HCl, sulfuric acid, bleach, and other corrosives from pitting and attacking stainless steel surfaces.  Here are some examples of how Dursan and Silcolloy® can improve corrosion resistance.

Click here to learn more about improving the corrosion resistance and durability of analytical systems.

Dursan offers inertness, durability, fouling, and carryover contamination benefits for process analytical, refinery, downhole, flare and stack sampling applications.  Want to learn how our coatings benefit process and stack analysis and prevent flare sampling corrosion? 

Dursan Corrosion Resistance Data.  How a CVD Coating Can Stop Stainless Steel Corrosion.
Dursan® can increase corrosion resistance by 10x or more through preventing interaction of the analyte or process fluid and the stainless steel surface. Dursan exceeds typical metal passivation capability. Immersion testing in 6M hydrochloric acid (HCl) shows that Dursan coated surfaces prevent surface attack and protect stainless steel from rust by orders of magnitude compared to passivated stainless steel.

Sulfuric acid can form in process analytical sampling systems and stack sampling systems that transport stack emissions or hydrocarbon flare samples. When exposed to water and heat, sulfur compounds commonly found in stack samples can form sulfuric acid and corrode and contaminate sample systems. Inert coatings like Dursan reduce the risk of corrosion, even when exposed to sulfuric acid.

H₂S Corrosion Resistance in Downhole Sampling

Immersion in H₂S saturated acidic brine solution for 30 days per NACE TM0177 shows that the Dursan coated coupons improve corrosion resistance but do show some pitting on the surface.  Note that any coating does not meet NACE MRO175 standard for H₂S exposure.  MRO175 applies to the base metal exposure only.  Dursan, however, can improve H₂S inertness and sample flow path durability in conjunction with MRO175 compliant materials.

 Get more corrosion application information and benefits for your process or products.  Get our corrosion presentation.

Protecting analytical flow paths from rust can revolutionize the reliability of process and analytical sampling.  Contact our technical service team to discuss your application.  Need an inert hydrophobic surface?  How about an anti-fouling surface that's wear resistant?  Our team can help match the best coating for your application.

We discuss the importance of a metal free HPLC flow path in hydrocarbon processing applications.  Here's what we learned.

Separation and characterization of petroleum products using HPLC analytical tools has been a long established method for use in separation of light distillates, kerosene and diesel fuels, aviation fuels, lubricating oils and bituminous products.  Typical HPLC analytical flow paths rely on stainless steel and PEEK for analyte transport and testing.  Unfortunately those surfaces are prone to oil wetting and corrosion which can lead to cross contamination.  Additionally solvent rinsing of PEEK tubing can result in tube swelling and pressure control issues. 

Making petroleum analytical flow paths resistant to oil cross-contamination can be as easy as changing the surface energy.  Applying a corrosion resistant, solvent resistant and oleophobic coating like Dursan® throughout the stainless steel flow path can improve hydrocarbon product test reliability.  

How Dursan® can improve HPLC separation in hydrocarbon processing.

Dursan is a silicon CVD coating that is bonded to stainless steel to enhance surface properties and analytical performance.  Dursan benefits include:

• Oleophobic surface to reduce oil wetting and improve cleaning and prevent cross contamination.
• Coking and fouling resistance improves column and flow path life 
• Corrosion resistant surface prevents pitting and damage to the flow path
• Solvent resistance will not swell or react with solvents, helping to maintain consistent colum pressure.

Why an inert flow path is critical to HPLC applications.

Using non reactive materials (stainless steel is not one of them...) in HPLC sample transfer systems can be summed up in one word, consistency.  There are lots of other, more specific, benefits of a non reactive suface (see the list below) but consistency ties into all of the threads nicely; be it financial consistency, test consistency, or consistency of quality.  Consistency if why an inert HPLC flow path is critical.    

• Reduce costs and downtime
• No need to re-test
• Accurate profile of all components, both reactive and non-reactive
• Trust your results
• Eliminates false negatives
• No additional molecules/ions introduced

The enemy of consistency, stainless steel and PEEK

Stainless steel and PEEK tubing solve a lot of sample transfer problems.  At first blush they appear to be the perfect solution.  Kind of like that Fiat I once had.  It was cheap and got great gas mileage.  So what if the paint blew off the car every time I washed it  Reliability was not it's strong suit, so in the long run it was not a good deal.  Ultimately I could not consistently get to work because of that car.  Well stainless and PEEK are kind of like that Fiat.  At first they appear to be a good solution but take them for a drive for a while and problems begin to become clear.  

Stainless steel: Chemical reactivity, corrosion, and abrasion can all lead to the introduction of molecules and ions that are not in your sample.

Stainless steel issues include:

• Acid corrosion (Halogenated solvents – HCl, HBr)
• Highly reactive toward chelating agents
• Protein Fouling/carryover

PEEK: Solvent damage and temperature limitations can lead to inconsistent pressures, flow problems and potential delamination and failure.

PEEK issues include:

• Temperature limitations (Tg = 148°C)
• Halogenated solvent damage
• THF, Acetone, and other organic solvents cause swelling

Get the scoop on how to improve corrosion resistance and prevent PEEK swelling problems.  Sign up for our special webinar on improving HPLC.

Sign UP For Our Metal Free HPLC Webinar

Dursan® Material Properties

Stainless and PEEK are not perfect but they're a good material choice for many HPLC applications.  Dursan can help improve test consistency under challenging test conditions or when flow paths are exposed to organic solvents that can cause swelling.  So what is Dursan?  

Dursan is a silicon, oxygen, carbon coating that is bonded to stainless steel flow paths by chemical vapor deposition.  Wherever a vapor molecule can get to, we can coat it.  That includes sintered metal frits and inner bores of needles.  That means that you can get all the structural benefits of stainless steel ( ie. heat resistance, high pressure capable, easy to work with, and low cost) and combine that with the non reactivity of a plastic free coating.  Material benefits include:

• High temperature: Stable up to 450°C
• Usable in wide pH range: 0-14
• Molecularly bound to the substrate: Excellent adhesion
• Wear: 2x more resistant than 316 Stainless steel
• Inert to most chemicals

So how can Dursan® make a difference in HPLC flow paths and columns?

Acid corrosion resistance makes Dursan a solution for difficult HPLC coating applications.  Comparative tests of our corrosion resistant HPLC coating, Dursan, VS. uncoated stainless steel show orders of magnitude improvement in corrosion rate.  ASTM G31 hydrochloric acid immersion of test coupons show the stainless steel surface corrodes at a 170x faster rate than the Dursan coated surface.  That means less chance of contamination and improved flow path life.

• ASTM G31 guidelines
• 20% (6M) HCl room temperature immersion 24 hours
• Over 170x improvement with coating

Learn How To Improve Moisture Resistance, Fouling Resistance, and Corrosion Resistance.   

Get Our Presentation.

HPLC Inert and Oleophobic Surface

• Tetracycline has a number of potential chelating groups
• Dursan® coated column shows improvement in peak shape.

The comparative chromatograph below tells the story.  The resolution quality of tetracycline on a stainless steel column was compared to a Dursan coated column.  The Dursan coated column significantly improved the peak shape.

Get the most out of our inert coatings and see how SilcoTek can improve HPLC performance.

Make Surfaces Resistant to Oil for Easy Cleaning and Prevention of Contamination

Low surface tension liquids like oil or organic solvents are designed to wet the surface for maximum lubrication or solvation.  But what if you're separating organics or don't want the surface to wet?  Water repelling materials like PTFE aren't effective in repelling oil.  Here's what oil and hexadecane look like when placed on a PTFE surface.

We bonded our new Fluoro coated Dursan material on a rough stainless steel surface to see if the contact angle would increase.  The Fluoro-Dursan material made a big difference in contact angle, making the stainless steel oleophobic surface.

Given the nature of refining or cleaning for that matter, we can expect the surface to be exposed to elevated temperatures.  PTFE is temperature limited and can fail in many high temperature applications.  We exposed the Fluoro surface to elevated temperature (300°C) for several hours to gauge the impact to wettability and contact angle on various surfaces.  The graph below shows consistent contact angle readings over the 90+ hour test.  PTFE would have failed at 250°C. 

The contribution of surface energy and it's relationship to process fluids can have far ranging impacts.  Surface interaction can impact corrosion, fouling, analytical sampling results, filtration and produced water.  So it's important to understand how to manage the energy of critical flow path surfaces.

Get some really informative and helpful tips on ways to prevent fouling, change surface energy, & improve surface performance.

Confused about what coating to use?  Want find out if SilcoTek® CVD coatings are right for your application but don't have time to wade through our website?  Here are some tips on how to get relevant data for your application quickly and efficiently.  

Where to start?  Do I read through the Home page and just pick a coating?  Do I tab through the various solutions or applications to find out if a coating works for me?  How do I find relevant test data quickly?  Ugh, so complicated.  Well no worries, let's take a step-by-step approach and walk through our website.  We'll show you how to research CVD coatings and get the information you need within minutes!

If you're new to SilcoTek

Start with SilcoTek 101.  You'll find it prominently displayed on our home page.  SilcoTek 101 is exactly what it sounds like, it's an introduction to our coatings and a review of coating basics.  You can check it out here.

Now that you've got a basic idea of what our coatings are and what they do, what now?  Go to the navigation bar at the top of the page and work your way from left to right.  That can take a few minutes but by the third tab you'll know what each of our coatings do and how they solve material problems. 

To short cut your way to selecting a coating just go to our coating selection guide.  That will give you an idea of which coating will work for your application. 

Or get our coating properties guide for the short and sweet results about what our coating do.

Then jump on over to our Common Applications guide for a primmer on, you guessed it, applications!

Where can I find these on the SilcoTek website?  Just click on the Learning Center tab.  The coating basics are all listed on the left side of the page.  

Check out our Learning Center if you want to get the latest coating data.

Or you can take the ultimate shortcut and contact our Technical Service Team and discuss your application and desired results.  We'll pick a coating for you.  One email and you'll have a solution that day.

Wait, that day?  You said minutes!  Liar!  OK, that was just one option.  You can have a coating solution in minutes by navigating to our our solutions tab to get a coating recommendation for many material problems such as corrosion resistance, inertness, anti sticking, fouling resistance, carbon coking and purity.  If you don't see your solution that doesn't mean you're out of luck.  It means you'll have to jump over to our learning center to get a more specific application or study. 

If you're data driven and need test results and whitepapers.

There's only one place you need to go for CVD coating data, the learning center tab.  There you'll get a deep dive into whitepapers and data from independent resources.  You can get everything from brochures and whitepapers to videos, webinars, and e-books under that tab.

If you want the source for fastest data, go to presentations and scan through the presentation of choice.  For example go to our corrosion presentation and you'll find all the latest corrosion data.  Need a coating specification?  Go to our Coating Properties & Specifications tab under learning center to get coating specs.

OK so let's take this navigation thing for a test drive and see how long it will take to get data on say hydrochloric acid corrosion.  Follow the example flowchart below:

Success!  From clueless to expert in 11 minutes, not bad.  I wish my calculus class was that easy!  Full disclosure, it may take longer to take a super deep dive into whitepaper data and studies.  Reading through a corrosion whitepaper can take some time but it's worth the time to discover how other scientists and engineers have evaluated our coating in similar applications.  If you want lots of data about a particular subject, go to our new e-book tab under Learning Center.  There are literally volumes of data about our coatings there.  Pardon the pun!

EPA Method 325 requires low-level monitoring of benzene at the refinery fenceline via passive sorbent tubes sampling over 2 week intervals.  Compliance will be costly to refineries; but to make the most of the dollars invested and to fully comply with the regulation, operators need to understand the why and how of refinery fenceline monitoring; then make monitors faster and cheaper. * 

Understanding The Why of Refinery Fenceline Monitoring

Rather than acting on a mandated "because I said so" approach.  It's better to understand why EPA is taking action on monitoring benzene and potentially other toxic VOC's at the fenceline.  According to EPA, 85% of benzene emissions from refineries occur from fugitive sources.  Typical emission sources are:

• Process piping leaks 
• Wastewater streams leaks, vents, cooling towers, and drains
• Tank leaks, vents, pump leaks, maintenance related emissions

Emissions are likely to have the highest concentrations at ground level and because monitoring specific sources in the refinery will be impossible, perimeter ground level sampling makes sense and will provide the refinery operator the best data for monitoring and addressing potential benzene emissions. The ultimate payoff of will be protecting and improving the health of area communities.  With next generation monitoring technology it's now more cost effective and faster to meet EPA 325 requirements.

*

How To Get The Most Out Of EPA 325

According to EPA the regulatory objective of refinery fenceline monitoring is to manage benzene and eventually other toxic VOCs.  Monitoring requirements and specifics of the regulation are: 

• Require perimeter monitoring and corrective action upon exceeding trigger of 9 ug/m3 (2.8 ppbv)
• Require sub-3 ppb level monitoring capability for benzene.
• Monitor by Auto-GCs and passive monitoring using thermal desorption tubes.
• Trigger is based on highest concentration modeled at any fenceline.
• Continuous, 2-week sampling periods.
• Complete coverage of fenceline, average concentration over the 2 week period.
• Trigger for Root Cause Analysis / Corrective Action based on annual average concentration.

EPA has mandated that thermal desorption tubes be inert coated to prevent adsorption of active and reactive compounds.  According to EPA the analytical approach will be based on the TO-17 method which specifies pumped sampling into tubes with thermally stable adsorbents.  

Potential sampling related issues with EPA 325 are:

• Interference
  • Other non target VOC's and coelution of sample peaks
  • Sorbent decomposition
  • VOC's not completely cleaned from tubes
• Humidity
• Contamination from sample handling.

SilcoNert^® coating is recognized industry-wide as the leading inert surface that enables refiners to sample their processes reliably with fast response, high accuracy and reproducibility and at lower cost. If left uncoated, even low surface area parts will adsorb compounds of interest and lead to invalid results, causing expensive retesting.

Figure 1: Uncoated surfaces within the GC flow path adsorb benzene, toluene, xylenes
and other target analytes, leading to severe peak distortion and missing peaks.

Benzene, organosulfur compounds, and other hazardous air pollutants (HAPs) that can be measured with Method 325 protocol are known to be highly reactive with bare, untreated stainless steel. SilcoNert^® provides a uniform barrier between substrate and sample while preventing analytes of interest from adsorbing onto the surface, ensuring they reach the analyzer and can be accurately assessed at low levels (ppb or lower).

Figure 2: SilcoNert-coated GC flow paths produce sharp peaks with high resolution, giving refineries superior analytical accuracy and full compliance with EPA regulations.

Coat the entire sample flowpath

To assure complete inertness, coat the entire sample flowpath with an inert coating like SilcoNert^® 2000.  Be sure high surface area internal components are coated:

Fritted filters Screens Tubes Tubing GC Liners Inlet Weldments Fid jets GC columns

 Image courtesy of US EPA.

We put our new Dursox™ metal free coating to the test.  Here's what happened.

There are lots of corrosion resistant coatings out there.  But what if you're concerned about metal contamination and metal leaching?  Or what if you need to protect a precision instrument or flow path that requires high tolerance or high heat resistance and a dry coating technology?  Then your options are limited.  Want a metal free high durability corrosion resistant coating?  Let's test our new Dursox coating and find out if it fits the bill.

Is Dursox™ metal free?

We measured the elemental composition of of Dursox to find out if it is in fact metal free.  We tested the surface by X-ray Photoelectron Spectroscopy (XPS).  Basically we blasted the surface with X-ray energy beams and analyzed the material that came off the surface.  As the X-ray beam penetrates the surface you get a pretty good idea of what's in the material.  The XPS plot below shows the coating consists of oxygen carbon and silicon, no metals.  The amorphous structure of the material allows the coating to flex with the base metal without cracking or failing.  That enables the coating to be used in high stress applications like high pressure cylinders or compression seal fittings.

No metal, check.  But is it corrosion resistant?

Let's look at the data.  ASTM G31 hydrochloric acid immersion testing demonstrates the high purity corrosion resistance of Dursox™.  After 72 hours the coated test sample showed roughly an 80% reduction in corrosion compared to uncoated 316L stainless steel.  

Dramatically less corrosion, but what about ion contamination?  Let's do a visual check and find out.

Here's a photo of the uncoated coupon during the HCl immersion test.  Notice the green liquid?  HCl is clear so why is this beaker green?  That's the result of chloride corrosion of the stainless surface and metals being leached from the coupon.  A great example of metal ion contamination. 

Applications that require high purity, are sensitive to contamination (like semiconductor fabs), analytical testing, or processes where metals can impact yield, this sort of contamination can cost a company in high maintenance, poor product quality or low yields.  

The Dursox™ HCl beaker by comparison is clear.  There's no change in color so no leaching of nickel into the acid solution.  The result?  More accurate test results, improved flow path durability, lower maintenance and better product quality.

Benefits

Dursox™ makes critical surfaces non reactive and corrosion resistant, preventing process contamination and improving yield.  The highly inert CVD coating offers improved stability, delamination resistance and durability over ceramic coatings like yttria.  The coating is ideal for high purity gas transfer flow paths, high purity applications where corrosion is a concern, and whenever improved durability for precision instrumentation is needed.   

Etch High purity coating eliminates ion contamination in corrosive etch gas streams. Atomic Layer Deposition (ALD)        Enhance purity by coating of all chambers and equipment. Reduces carryover, burn-in, and corrosion. Ozone Stabilize flow path to assure ozone purity. Gas Transfer Prevent ion contamination, assure high purity gases. Chemical-Mechanical Planarization (CMP) Increase lubricity, prevent sticking and cut downtime. Epitaxy Significantly reduces contamination and maintenance caused by corrosion.

Dursox™ Specifications

Need a dry coating that will withstand exposure to extreme temperatures or challenging process environment?  Dursox specifications highlight the durability and heat resistance of the coating.  Our CVD coating technology is moisture free and deposits a thin high tolerance silicon coating onto the surface of metal, glass, and ceramics.    Contact our Technical Service Team to discuss your application or to arrange an evaluation with our R&D staff.

Not sure if Dursox™ fits your application?  We've got coatings for a variety of corrosion resistant applications.  Read our corrosion presentation and get relevant data to improve your process.

From our first coating, Silcosteel®, to SilcoNert®, Dursan® and Dursox®, our coatings have helped customers improve flare, stack, downhole and process analytical sensitivity and performance.  Here's what we're talking about this year at Pittcon 2018 in Orlando.  

Spoiler alert!  We're talking about the benefits of our new fluoro based coating as well as how Dursan® can improve bioinert flow paths and prevent biofouling.  You should go to Pittcon to chat with our SilcoTek® staff to learn more about our coatings.  (Not to get a break from the cold weather, who me? Never!)

About our new fluoro coating

We recently developed a new fluoro chemistry based coating that proved to be super hydrophobic with anti fouling or non stick properties. 

To demonstrate the super hydrophobic nature of the new fluoro coating, Dr. Smith (our R&D director) sprayed water on the coating to see if the water wetted the surface.  The water stream bounced off the coated part without getting the surface wet, showing excellent moisture resistance.  Watch our video to see how the new fluoro coating resists moisture.

The low energy of the fluoro surface makes for a super hydrophobic surface, making a 160 degree contact angle.  Because of that low surface energy, we found another application for the coating.

Get more information about

hydrophobic and corrosion resistant coatings.

Hydrophobicity, check, but what else can the coating do?

Well we're not sure about all the potential uses, but we're finding great success in plastic mold release applications.  It turns out the coating promotes better release of product from plastic molds and can prevent fouling in some applications. 

Here are some mold release benefits of Dursan and our new fluoro surface:

• Better wear resistance for higher durability, and erosion prevention.

• Higher lubricity to improve operation of moving cores and slides and improved resin flow for reduced energy cost and wear.

• Prevents contamination by oxidation by products in medical and electronic applications.

• Visual inspection of the surface signals coating loss without precision measurement. 

• Mold complexity does not significantly impact coating price. 

• Eliminate Diamond finish release problems by improving surface lubricity.  

If you want to learn more about fouling prevention and mold release read the latest article in AZOM: 

Improving and Protecting Industrial Applications With Anti-Fouling CVD Coatings

Contact our Technical Service Team and we'll be happy to discuss details about the coating. 

Have another material problem?  Get our applications guide to learn how SilcoTek can improve the performance of your products.

Metal Free Flow Path for Bioinertness

Now you can count bioinertness and biofouling coatings to our list of applications that benefit from our coatings.  This year at Pittcon we're talking metal free flow paths for bio technology benefits.  Did you know you can eliminate many of the problems caused by a metal flow path with inert coatings like Dursan?  In fact, you can improve the bioinertness, anti fouling, and sensitivity of instrumentation and filtration by coating metal flow paths with Dursan.

• Stop biofouling
• Prevent corrosion
• Less maintenance

Dursan^® is a very low surface energy, bioinert coating and anti fouling coating designed to reduce non-specific protein binding and carryover while improving corrosion resistance in biotechnology, filtration or wherever bio growth is a problem .

With the assistance of a non ionic surfactant-containing wash solution, Dursan^® was found to facilitate 100% removal of adsorbed proteins (BSA, mouse IgG and NHP), the same proteins remain adsorbed on the bare stainless steel surface.

Stop Protein Binding And Corrosion On Stainless Steel Surfaces

Dursan^® benefits protein testing 3 ways:

1. Very low protein carryover

• Dursan^® significantly reduced protein binding compared to uncoated stainless steel and an amorphous fluoropolymer.

2. Beneficial to surfactants

• Facilitated 100% removal of tested proteins.  The same wash solution had no effect on protein loading on bare stainless steel.     

3. Corrosion resistance means high purity

• Comparison studies between Dursan^® and stainless steel show the high purity Dursan surface prevented ion contamination and corrosive attack from bleach and other commonly used cleaning agents.

Click here to learn more or visit SilcoTek in booth #2113 to see how we're changing the game in flow path surface technology to create a new standard of performance.