Using Chemical Vapor Deposition Processes to Enhance the Corrosion Performance of Steel Substrates
SilcoTek CorporationGary Barone
Topics
• About Us• Products and Applications• Product Performance• Conclusion/Future Product Development
APPLICATION AREAS• SilcoNert™: Inertness
• Silcolloy™:Anti-Corrosion
• SilcoKlean™: Anti-Coking
• SilcoGuard™: Ultra-High Vacuum
MARKET AREAS
AnalyticalPharmaceuticalEnvironmental
PetrochemicalChemicalProcess
Automotive
Semiconductor/Research
Basic Manufacturing Process
• Receive items• Document – digital, customer contact• Clean
– Standard: caustic ultrasonic bath, 2 systems– Custom: solvation via other means
• Chemical Vapor Deposition (CVD) Process– Vacuum– 400ºC– silicon-based deposition
• Clean• Document – digital, customer contact• Pack, ship
Product Characterization
• Amorphous silicon CVD coating• Density: 2.33 g/cm3• Melting point: 1410oC• Max operating temp.
• 600oC to 1000oC: Silcolloy; SilcoNert 1000; SilcoGuard
• 450oC SilcoNert 2000
• 1200A to 5um thickness, minimal smoothing of surface
Coating Cross Section
316 SS316 SS
Auger Depth Profile
Coating Capabilities: Substrates
• Tubing:– 0.004” to 0.5” ID– 2000+ ft. continuous lengths
• Complex geometry parts (inside and out)– Fittings, valves, frits– Block manifolds, sample vessels – custom parts
Sizes of reaction chambers• “Standard” vessels:
– 12” diameter cylinder w/ 56” height– 6” diameter cylinder w/ 72” height– 10” diameter cylinder w/ 18” height– 21” diameter cylinder w/ 42” height
• Large processing oven:– 27” diameter x 26” deep
• Walk-in Oven:– 4 feet by 4 feet by 5 feet– 6 feet by 4 feet by 5 feet
Substrates Which Coat Well
• 300 and 400 grade stainless steel
• High carbon steel
• Titanium
• Ceramics
• Borosilicate glass
• Inconel®
• Hastelloy®
Substrates with Issues
• Nickel / Nickel plating• Aluminum*• Monel®• Copper• Brass• Gold and Silver plated components • Chrome Plated components• Magnesium• Elastomers
*heat-dependent
Corrosion Resistance of Coatings
Silcolloy™Corrosion Resistance:
• Stainless steel surfaces susceptible to attack from in chlorinated environments and acidic exhaust environments.
• Corrosion resistant deposition is insoluble in hydrochloric acid and unaffected in salt water environments.
Corrosion Resist studies
• External Evaluation– Certified corrosion
engineers (Matco)– Spectroscopic
analysis– Mechanical testing– Electrochemical
Cyclic Polarization in neutral, acidic, alkaline– Atmospheric corrosion
• ASTM moisture condensation• Salt spray ASTM B117
– Stress corrosion cracking (MgCl2; ASTM G36)
ASTM G48 B Data: Pitting and Crevice Corrosion
• ASTM G48 method B; Pitting and Crevice Corrosion– 6% Ferric Chloride solution – 72hrs, 20ºC– 316L Stainless samples w/Gasket wrap
Sample InitialWeight (g)
FinalWeight (g)
WeightLoss (g)
Weight Loss(g/m2)
Silcolloy™ Sample 17 10.4105 10.3710 0.0395 19
Silcolloy™ Sample 28 10.1256 10.0743 0.0513 25
Silcolloy™ Sample 47 10.1263 10.0742 0.0521 25
Bare Sample 27 10.0444 9.5655 0.4789 231
Bare Sample 34 10.1265 9.6923 0.4342 209
Bare Sample 37 10.1007 9.6276 0.4731 228
ASTM G48 B (cont.)
• Bare 316L Stainless Steel coupon showing severe crevice corrosion
ASTM G48 B (cont.)
• Corrosion resistant treated sample showing no crevice corrosion and slight pitting corrosion
ASTM G61 Data: Cyclic Polarization
• ASTM G-61; Cyclic Polarization Electrochemical Corrosion Testing– Acid, neutral, basic aqueous solutions with varying Cl- ion
concentrations (100, 3000, 5000ppm)– EG&G VersaStat System, 23ºC– 316L vs. Silcolloy™ on 316L & 304L
Neutral solution;3000ppm Cl-
Sample Ec, mV Ic, uA/cm^2 Eb, mV CR, mpy
316 L -418 0.096 370 0.04
Silcolloy™ 316 L -533 0.002 1460 0.0009
304 L -435 0.145 361 0.06
Ec = corrosion potentialIc = current density at EcEb = pitting potentialCR = corrosion rate
-CR vs 316L Raw: 50x improvement
ASTM B117 Data: Salt Spray
• ASTM B 117 – “Practice for Operating Salt Spray (Fog) Apparatus.” – 4000 hour exposure– 100 degree Fahrenheit– 3.5% by weight sodium chloride
• Reproduces exposure to marine environments.
ASTM B117 Data (cont.)
• Silcolloy™ treated samples showed no signs of bleeding, rusting, or pitting corrosion
ASTM B117 Data (cont.)
• The non-treated samples showed some light surface rusting, but no signs of pitting corrosion.
ASTM D4585 Data: Condensing Humidity
• ASTM D 4585, “Practice for Testing the Water Resistance of Coatings Using Controlled Condensation.” – 1000 hour study– 100 degrees Fahrenheit– Distilled water
• Reproduces exposure to atmospheric conditions
ASTM D4585 (cont.)
• Silcolloy™ treated samples showed no signs of bleeding, rusting, or pitting corrosion
Silcolloy™ Advantages• Longer Life:
– Extend lifetimes of equipment exposed to corrosive environments and/or process streams
• Protection:– Protection of high value equipment in corrosive
environments
• Inert:– Provide enhanced corrosion resistance to analytical
equipment while maintaining inert sample pathway
• High Temperature:– High temperature stability up to 1000c
Silcolloy™ Applications• Manufacturing/Chemical
– Process streams containing HCl
• Environmental– Continuous Emissions Monitoring exposed to stack gases
from coal fired plants and incinerators
• Automotive– Equipment used in Automotive Exhaust testing and catalytic
converter studies– Diesel EGR & Turbo systems
• Marine– Some preliminary evaluation of coating in marine
environments (offshore platforms)
Conclusions/Future• Continual process improvement and new product
development for coatings:– Improving the hardness of coatings– Improved corrosion resistant coatings– Hydrophobic surfaces for moisture sensitive
applications– Protection of high nickel alloys such as Hastelloy®
and Inconel®– Hydrogen embrittlement resistance.
QUESTIONS ?