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UV+PVD:CORROSIONANDDURABILITY … · • Mul7#stage#or#mul7ple#layers#of#PVD#create#...
Transcript of UV+PVD:CORROSIONANDDURABILITY … · • Mul7#stage#or#mul7ple#layers#of#PVD#create#...
UV+PVD: CORROSION AND DURABILITY ALTERNATIVES TO TRADITIONAL ELECTROPLATING
26 February 2013
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Outline • Corrosion • Chrome pla7ng as an inhibitor of corrosion Overview of process and downsides
• UV coa7ngs and Physical Vapor Deposi7on as an alterna7ve to chrome pla7ng Overview of process and upside
• Weatherability Durability of UV coa7ngs and PVD
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Corrosion • Corrosion is degrada7on of materials’ proper7es due to interac7ons with their environments
• Corrosion of most metals (and many materials for that maGer) is generally inevitable.
• While primarily associated with metallic materials, all material types are suscep7ble to degrada7on. 4
Corrosion cont. • There are different categories of corrosion:
• uniform corrosion that takes place across the exposed surface
• local corrosion (e.g. piPng, crevice, selec7ve), take place at specific places on the surface
• stress corrosion cracking, observed on material exposed to a constant tensile stress in a corrosive environment 5
Chrome Plating – traditional corrosion protection
• Hard Chrome Plating (functional) • Metal Substrates • Chrome Thickness > 1 mil • Applications include hydraulic cylinder rods, piston rings, thread guides, gun bores
• Nickel Chrome Plating (decorative) • Plastic Substrates • Chrome Thickness 250 Å – 1000 Å • Applications include automotive interior & exterior, appliances, general purpose applications.
Chrome Plating Process • Cleaning, rinse,
condition, neutralize to prepare the substrate
• Hydrochloric acid • Rinse • Copper Plating • Rinse • Nickel Plating • Rinse • Nickel Plating (2-‐3
more times) • Rinse • Chrome Plating (Total time >2 hours)
Downside to Chrome Plating • The nickel and copper adhesion layers are susceptible to corrosion
• Extreme Health Hazard – Though a powerful inhibitor of corrosion, it is carcinogenic
• Environmentally Hazardous • Heavily Regulated by EPA – Costly
• Quality Problems • Safety Issues For Some Component Parts
Why Chrome helps corrosion resistance • Passiva7on – being less affected by environmental factors such as air or water. It involves a shielding outer layer of corrosion which can be applied as a micro-‐coa7ng 9
Corrosion -‐ pictorial examples
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UV Coatings / PVD Process as an alternative to Chrome Plating
Substrate
UV Basecoat
PVD Metal Layer
UV Protec7ve Topcoat
Provides protec7on of the metal layer and
performance proper7es
Seals substrate, provides (leveling) and an ultra smooth surface, adhesion proper7es
Coating Options to encapsulate PVD
• Thermal Cure • Longer Processing Times (90 min)
• Lower Cross-‐Link Density
• Post Cure Effect • Pot Life
• Thermal Powder • Longer Processing Times
• Temperature Constraints for Plas7c
• UV Curable • Quick Processing (20 min) • High Cross-‐Link Density – Variety of PVD Metals
• Low Temperature – Large Substrate Selec7on
• One Component, Poten7al Reclaimability
• Unlimited pot life
Physical Vapor Deposition (2 common methods)
• Thermal evapora7on
• Deposi7on of metal via thermal vaporiza7on • Individual components of alloys vaporize at different temperatures, resul7ng in individual layers being deposited
• Most common for deposi7ng elemental metals such as aluminum
• Not durable enough for high end automo7ve applica7ons 13
Physical Vapor Deposition (2 common methods) cont. • SpuGering
• Deposi7on of metal via bombardment by high energy ions.
• This allows for Alloys to be created / deposited uniformly as you can bombard mul7ple metal targets simultaneously
• Coa7ngs are generally chemically iden7cal to target material (Al, Cr, SS, etc)
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Not all PVD equipment and systems are created equal • All PVD coa7ngs have micro pores
• Lesser PVD coa7ngs have more defects
• Defects– allow a direct path for a corrosive electrolyte to access the PVD layer, bc layer, or the substrate 15
• Type of metal spuGered and parameters under which it is spuGered effect the porosity of the deposited film • Ex. – CrN is generally finer and denser than TiN (its less porous)
• Higher energy spuGer Cr leads to denser films
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Not all PVD equipment and systems are created equal
Using PVD to eliminate corrosion • Mul7 stage or mul7ple layers of PVD create a denser, less porous metal layer than that of a single stage coa7ng
• The surface of some metal layers (Zr, Cr, Ti) are protected from uniform corrosion by a thin oxide that forms naturally
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Fortifying PVD against corrosion
• Applica7on of protec7ve coa7ngs • The addi7on of chemical species in chamber barrier coats -‐ HDMSO
Addi7ve to UV topcoat to inhibit corrosion • Altera7on of the alloy chemistry to make the layer more resistant to corrosion
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Automotive – Performance Criteria
• Adhesion • Water Soak • Humidity • Resistance Testing • Impact Testing • Scratch & Mar
• Chip Resistance • Thermal Shock • Oven Aging • Artificial Weathering • Natural Weathering • Salt Spray/Filliform
Testing for corrosion and durability
20 UV basecoat / PVD Cr / UV topcoat
Testing for corrosion and durability
21 UV basecoat / PVD Al / UV topcoat
Testing for corrosion and durability – PVD wheels
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168hrs CASS
3yrs Florida exposure, field validation
Upside to PVD Coating Technology • Environmentally Friendly Hex-‐Chrome Free
• Minimizes need to outsource (esp. overseas)
• Increases Quality Control • Smaller Footprint
• Reduced Cycle Time
• Increased Throughput • Increased Design Flexibility
• Variety of Substrate • Improved Consumer Safety
• Cost Savings per piece
Design Flexibility • Appearance
• Color Varia7on • MaGe Finishes
• Func7onality • RF Transparency • Day/Night Design • Transparency/Backlight • Can be laser etched
Questions?
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Thank you!
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Jason T. Eich Red Spot Paint and Varnish Co., Inc.
1107 E. Louisiana Street
Evansville, IN 47711 USA [email protected]
+1 812 428 9174
Durability • A func7on of the topcoat yes, but really an outcome of a balanced bc -‐PVD –tc system • Basecoat adhesion to mul7ple plas7c substrates
• PVD adhesion to the basecoat
• Topcoat adhesion to the PVD layer 27
Appliances – Performance Criteria
• Taber Abrasion • MEK Solvent Rub • Grease Resistance • Stain Resistance • Humidity Testing
• Heat Resistance • Artificial Weathering • Water Immersion • Detergent Immersion • Salt Spray