ut-battelle oak ridge national laboratory u.s. department of energy aluminum soldering performance...
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UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Aluminum Soldering Performance Testing of H13 Steel as Boron Coated by the
Cathodic Arc Technique
James M. Williams, C.C. Klepper, R.C. Hazelton and E.J. YadlowskyHY-Tech Research Corporation, Radford, VA 24141
Gail LudtkaM & C Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Background for this Study• Preliminary deposition studies
demonstrate that boron can be used for the corrosion protection of steel
• Thermodynamic calculations indicate that boron has a negative affinity for aluminum
• This presentation describes the experimental results of a set of dip tests of B coated H13 pins in molten aluminum
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Cathodic Arc Vacuum Technology
Benefits– A fully ionized plasma is
produced out of solid feedstock
– Deposition rates exceed other plasma-discharge methods
– Fully ionized plasma stream allows:
• Substrate biasing to guide ions to coat irregular geometries
• The potential to control of the energy with which ions impinge onto the substrate
Challenges / Drawbacks– Macro-particles require
filtering – Vacuum coatings require a
higher cost than some sprayed and fused cermet coatings
File: SVC paper_all.ppt UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Illustration of Typical Cathodic (Vacuum) Arc Deposition with 90o Bend Magnetic Duct to Filter
out Debris from Solid Cathode
A curved solenoid help prevent debris/ macro-particles from depositing on the substrate
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Advantages of Boron Deposition Using Advantages of Boron Deposition Using Cathodic Vacuum Arc TechniqueCathodic Vacuum Arc Technique
• Very high current density (10-100 MA/cm2) where the arc contacts the cathode results in a non-stationary hot spot that efficiently vaporizes and ionizes materials such as boron, which have very high boiling points (>2000 C).
• Plume is fully ionized and can be guided with the aid of a magnetic solenoid.
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Coating Material Selection Criterion
• Thermodynamic calculations suggest that boron is an excellent candidate for a non-wetting coating for iron-based substrates
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Illustration of the Thermodynamics - Heats of Formation - for Relevant Alloy Systems
-50
-40
-30
-20
-10
0
10
20
30
0 0.2 0.4 0.6 0.8 1
Fraction of Boron or Aluminum
En
tha
lpy
of
Fo
rma
tio
n (
kJ
/g-a
tom
) B in Al
B in Fe
Al in FeB is attracted to steel
B has a repulsive chemical reaction with aluminum
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Schematic of Automated “Dipper”* Testing Set-up to Simulate Die Casting Conditions
*A variant of the dunk tester including programmable, computer controls thus enabling control of the dipping cycle and process cycle parameters (i.e., temperature of molten aluminum and of the lubricant, the dipping time in aluminum, in the lubricant, and in the air spray).
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Soldering Test Set-up and Die Pin Schematic of Pin for Solder Testing
0.1875
Thermocouple
2.0000
0.2500
0.5000
0.7500 0.0625
0.03125
Automated, molten aluminum testing apparatus Dimensions are in inches
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Examples of Soldering Trials Data on Coated vs. Bare H13 Pins
0
100
200
300
400
500
600
700
800
0 100 200 300 400 500 600 700
DB103501 Hy-Tech H13
Series 2
Series 3
Series 4
Series 5
Time (sec)
0
100
200
300
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500
600
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800
0 500 1000 1500 2000 2500
DB103501 Hy-Tech H13-B28-4
Series 2
Series 3
Series 4
Series 5
Time (sec)
0
100
200
300
400
500
600
700
800
0 100 200 300 400 500 600 700
DB103501 Hy-Tech H13-B28-3
Series 2
Series 3
Series 4
Series 5
Time (sec)
Experimental Data indicating the onset of Soldering
Experimental Data indicating No Soldering
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
H13 without coating after 16 cycles exhibits soldering
The experimental conditions are as follows,
(1) Temperature of melt aluminum (Tmelt): 700oC
(2) Temperature of lubricant (Tlubricant): 21oC(3) Dipping time in aluminum(t1):10 s(4) Time in lubricant(t2):3 s(5) Time in air spray(t3):5 s
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Boron-coated H13 Steel Pin Exhibits
No Soldering After 50 Cycles* in Molten Aluminum
End view of die casting pin
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Boron Concentration as a Function of Depth derived from original RBS Data
All the B has reacted/diffused inward to yield a 0.5 micron thick reaction layer.
UT-BATTELLE
Oak Ridge National LaboratoryU.S. Department of Energy
Summary• Experimental results support the primary hypothesis that,
based on thermodynamic based predictions, cathodic arc deposited boron coatings resist aluminum wetting.
• These coatings strongly adhere to the steel substrate, while resisting wetting by aluminum as predicted by thermodynamic calculations.
• Macroparticle management is the biggest challenge for this technology, but preliminary conceptual equipment designs indicate that this is solvable.
• Boron shows promise as a life-extension coating for aluminum casting steel dies.
• Further R&D would provide an industrially robust coating solution for the prevention of soldering and thermal fatigue of aluminum die casting dies.