Managing Change
A Supplier’s Perspective on Qualifying LHE Zinc-Nickel as a
Cadmium Replacement For Aerospace Applications
MINASF, March 28th 2015
Dipsol of America
The Pace of Change in Surface Finishing
• Typically, it doesn’t happen quickly,
• More often, it can be measured in years….
Accelerating Change
Each industrial sector is pressured by many of the
same factors, but the rate at which they adopt the
change varies.
Some familiar factors that can initiate change...
REGULATIONS
REGULATIONS
SPECIFICATIONS
REGULATIONS
SPECIFICATIONS
NEW
TECHNOLOGY
COST REDUCTION
Technology Tradeoff /
Increase in Health &
Safety Costs
Imp
lemen
tation
REGULATION – Often initiates the change ahead of
market driven innovation
Material/Fo
rmu
la
Co
ntro
l
Hazard
/Disp
osal
Regulations Take Flight
DoD Directives for Complying with Environmental Restrictions on Cadmium & Hex Chrome
• Cadmium solutions contain cyanide and cadmium salts.
• EPA – Targeted for reduction under Industrial Toxics & Chemicals of Concern (COC)
• OSHA – Worker (PEL) limits.
• RCRA – Disposal of Hazard Materials from plating and wash down.
• REACH
Phasing out the Exemptions and Waivers
What Took So Long? Aerospace is a very risk averse industry
Cadmium & Hexavalent Chromate:
• relatively inexpensive & simple to operate, very good
corrosion resistance, adhesion to high strength steel, low
hydrogen embrittlement...etc..
• No single alternative was necessarily going to check all of the
right boxes.
In use for decades – all the infrastructure and knowledge was
embedded for supporting and maintaining this process
application, very much a tried and true process.
If It’s Not Broke....
Several Finishes Were Investigated For Landing Gear Applications
However, none were just right.
• Zinc – voluminous corrosion products.
• Sn-Zn – lower temperature resistance.
• Ti-Cd – still toxic.
• Early low nickel Zn-Ni formulas –
hydrogen embrittlement issues.
Some Examples:
Some Were Qualified
IVD – Line of sight only for O.D.
areas. Expensive to maintain.
Aluminum Sputtering –
Complex & Expensive to
operate.
Aluminum Plating – very limited
supplier base.
But still had limitations...
A Timeline of Investigation & Testing
1996-2000
Boeing developed
Acid ZnNi
Alkaline ZnNi –
Low Ni (5-8%)
2003-2005
LHE Alkaline ZnNi
– High Ni (12-15%)
2006-2007
Prototype
Installation,
Qualification
Testing
2007-2009 2009-2013
Additional
Prototype
Installations, &
Continued
Qualification
Testing
Process Qualified,
Large Scale Plating
Installations
2013 Continued Conversion
away from Cadmium.
Assessing Cobalt Free
Passivates
Phase I, II, III... Testing Verifications
The Journey – Some of the Qualification Requirements For LHE ZnNi Over High Strength
Steel 1. Adhesion (ASTM B571)
2. Corrosion (ASTM B117)
3. Fatigue (ASTM E466)
4. Hydrogen Embrittlement (ASTM F519 & USAF DWG)
5. Liquid and Solid Metal Embrittlement (ASTM F519)
6. Brush Plating for Repair of Damage (ASTM B117, B571 and F519)
Adhesion Testing
Impact at 70 in-lbs
Impact Testing
The following two slides
demonstrate that SEM
analysis shows no loss
of adhesion with the Zn-
Ni plated high strength
steel coupons.
Performance matched
that of cadmium.
Adhesion : Impact Testing of Zn-Ni
Adhesion: Impact Testing of Cadmium
Adhesion Testing
• Adhesion of the LHE Zn-Ni coating to the substrate was tested per ASTM B571
• All adhesion test coupons were manufactured from 1”x 4”x 0.040” 4130 steel sheet
• Results: All Test coupons passed
Overall Conclusions: Zn-Ni has adhesion as good as Cadmium when tested by bend-to-break and impact test methods and passes ASTM B571
Bend to Break Tests On LHE Zn-Ni Test Coupons
Corrosion Performance • Corrosion tests were conducted on LHE Zn-Ni coupons
with Cadmium as the baseline
• Testing was also performed on both cadmium and LHE Zn-Ni coated coupons with a prime/paint topcoat after being scribed (See Table below). All test coupons were 4”x 6”x 0.040” 4130 steel sheet
• All testing was performed per ASTM B117
• Test specimens were both scribed and un-scribed
Test per ASTM B 117
Corrosion Performance – LHE ZnNi
1000 hours
3000 hours
5000 hours
IZ-C
17+
Zn
-Ni w
ith T
rivale
nt C
hro
me C
onve
rsio
n C
oating
Unscribed
–A
ST
M B
117
Fig
ure
4
1000 hours
3000 hours
5000 hours
IZ-C
17+
Zn
-Ni w
ith T
rivale
nt C
hro
me C
onve
rsio
n C
oating
Scribed –
AS
TM
B 1
17
Fig
ure
6
Un-scribed Scribed
Tested per ASTM B 117
Corrosion Performance - Cadmium C
ad
miu
m w
ith
He
xa
va
len
tC
hro
me
Con
ve
rsio
n C
oatin
g
Unscrib
ed
–A
ST
M B
117
Fig
ure
3
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
1000 hours
3000 hours
5000 hours
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
1000 hours
3000 hours
5000 hours
Cad
miu
m w
ith
He
xa
va
len
tC
hro
me
Con
ve
rsio
n C
oatin
g
Scribe
d –
AS
TM
B 1
17
Fig
ure
5
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Test Panel
Removed From
Salt Spray Cabinet –
Excess Amount
of Red Rust
Detected
Un-scribed Scribed
Corrosion Result: (Paint & Scribe)
LHE Cd w/Hex CC
Tested per ASTM B117
LHE Zn-Ni w/Tri CC
Corrosion Results
Corrosion Results
Corrosion – Testing Summary
• Plated and Scribed / Un-scribed (ASTM B-117)
• Cadmium with hex chromate: Failure at 1000 hours
• LHE ZnNi with Tri CC: Passed at 1000 hours
• Acceptable results at 5000 hours
• Plated + Paint and then Scribed (ASTM B-117) • Cadmium/Hex CC + primer + paint then Scribed: Pass at 1000 hours
• LHE ZnNi/Tri CC + primer + paint then Scribed: Pass at 1000 hours
Fatigue Testing
Load-controlled axial fatigue testing was performed to evaluate any service life impacts associated with LHE Zinc-Nickel.
Plated Test Bars Test Cell
Fatigue Validation
Test Conclusions:
LHE Zinc-Nickel was comparable to Cadmium.
200 KSI
180 KSI
160 KSI
30,000
100,000
1,000,000
# o
f Cycle
s
Hydrogen Embrittlement Testing
• V-notch test samples manufactured per ASTM F519 specifications (4340)
• Additional test samples plated and tested at additional dates
• All v-notch samples tested per ASTM F519 passed the 200 hour sustained load tests @ 75% of the tensile notch fracture strength
ASTM F519 Type 1A.1 Test Samples
Testing Equipment
New fixture and Conformal Anode Design
Additional Hydrogen Embrittlement Testing
Original Chain Design
Re-Embrittlement Testing Results
Additional, 3.5% salt water, re-embrittlement testing was conducted on LHE Zn-Ni plated coupons and they all passed the ASTM 519-06 150 hour requirement
Liquid/Solid Embrittlement Testing
• Liquid and Solid Metal Embrittlement (LME and SME) occur when one metal, either as a liquid or solid, intrudes into the structure of another, potentially causing embrittlement in the base metal
• Melting points for the coating metals are as follows:
• Cadmium ~610°F
• Zinc ~787°F
• Nickel ~2650°F
Liquid Metal Embrittlement Test #3
300M Type 1a.1 Plated with Zn-Ni (Lt.) and Cd (Rt.)
After Being Step Loaded to Failure
Cadmium = 91.5% NFS : Zinc-Nickel = 100% NFS
Fracture Surface of Zn-Ni and Cd After Step Load to
Failure – Cadmium Had Pre-Existing Crack from High
Temp Exposure Under Stress
LHE Zn-Ni and Cad Type 1a.1 Specimens After ISL Test to Determine the NFS After Exposure to 400oF for 200 Hours
Brush Plating Repair • In order for a brush LHE Zn-Ni plating to qualify it
must pass the following tests:
• Hydrogen Embrittlement (HE) testing per ASTM F519
• Bend to break adhesion test per ASTM B571
• Corrosion testing per ASTM B117
• SIFCO recommended procedures to use for plating several sets of HE type 1a.1 coupons, adhesion coupons, and corrosion coupons, using SIFCO 4018 No Bake LHE Zn-Ni brush plating solution
• Brush Plating Repair performed as well as original plated finish.
Test Results Summary
• Passed hydrogen embrittlement testing
• Passed adhesion testing on steel and LHE Zn-Ni plated steel
• Corrosion test performance is excellent
Next Steps: Prototype Implementation
• Customer implemented a tank of approximately 325 gallons for the purpose of demonstrating the LHE Zn-Ni plating process on full sized gear components
• The demonstration tank was used to develop uniform plating thicknesses and process parameters on test coupons and full scale landing gear components
• During the plating operations Quality Assurance testing has been conducted to ensure the alkaline LHE Zn-Ni solution is within proper process limits
LHE Zn-Ni Plating Tank
LHE Zn-Ni Performance Tracking Program (PTP)
• Criteria for part selection • Fixture Completed
• 2 to 3 Parts from each Weapon System
(NLG & MLG)
• Ease of access to component on aircraft
C-130 Main Landing Gear Components
Landing Gear Components
F-15 Platform F-16 Platform
MLG Axle plating in LHE Zn-Ni Solution
Before Plating After Plating
MLG Outer Cylinder
LHE Zn-Ni Conformal Anode and
Fixture Models
Complex Geometries
Field Corrosion
Component Corrosion Evaluation LHE Zn-Ni Plating (Cape Kennedy)
F-15 MLG Lower Drag Brace CAD F-15 MLG Lower Drag Brace Zn-Ni
Parts Placed 10/13/2010, Pictures taken 7/24/2012
Component Corrosion Evaluation LHE Zn-Ni Plating (Cape Kennedy)
C-5 MLG Rotation Collar Zn-Ni C-5 MLG Rotation Collar CAD
Parts Placed 10/13/2010, Pictures taken 7/24/2012
Reaching the Goal 1. Adhesion (ASTM B571) – Passed
2. Corrosion (ASTM B117) - Passed
3. Fatigue (ASTM E466) - Passed
4. Hydrogen Embrittlement (ASTM F519 & USAF DWG) - Passed
5. Liquid and Solid Metal Embrittlement (ASTM F519) - Passed
6. Brush Plating for Repair of Damage (ASTM B117, B571 and F519) - Passed
• Qualified:
• Boeing BAC 5680 & Boeing BAC 5637
• USAF Drawing# 201027456
• UTC Aerospace Systems LGPS 1106 Landing System
• Heroux-Devtex HPS-138
• SAE AMS 2417
• Bell Helicopter #5445
A Change for the Better
• LHE Zn-Ni and trivalent passivate most closely matched and in many cases surpassed the performance requirements of cadmium and hexavalent chromate.
• Provided a process that was more of a “drop-in” replacement compared to other technologies.
• Legacy knowledge and infrastructure was more readily transitioned over to LHE Zn-Ni + trivalent passivate.
• Zinc-Nickel plating continues to be a viable option for existing and new applications that require replacement finishes to meet regulatory or increased performance requirements.
Or Is It?
Successful Change, So...
Nickel? Chrome
Free Cobalt Free
From Hexavalent to
Trivalent Passivates
Staying Relevant
AUTOMOTIVE
Our Industry Continues to Innovate
From Cyanide to
Alkaline Non-Cyanide
Plating
• Regulations will continue to push changes in our industry.
• Timeframes narrow as replacement substances then become future candidates for restriction.
• Competent & willing partners may be needed to share in the costs of developing these alternative technologies.
AEROSPACE
ELV
“When you’re finished changing, you’re finished.”
- Benjamin Franklin
Thank you
Questions or Comments
Dipsol of America