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 ?