Transcript Aluminum Soldering Performance Testing of H13 Steel as Boron Coated by the Cathodic Arc Technique James M.

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. Yadlowsky
HY-Tech Research Corporation, Radford, VA 24141
Gail Ludtka
M & C Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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:
Challenges / Drawbacks
– Macro-particles require
filtering
– Vacuum coatings require a
higher cost than some
sprayed and fused cermet
coatings
• Substrate biasing to guide
ions to coat irregular
geometries
• The potential to control of
the energy with which ions
impinge onto the substrate
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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/ macroparticles from depositing
on the substrate
Oak Ridge National Laboratory
U.S. Department of Energy
File: SVC paper_all.ppt
UT-BATTELLE
Advantages of Boron Deposition Using
Cathodic 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.
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
Coating Material Selection Criterion
• Thermodynamic calculations suggest that
boron is an excellent candidate for a nonwetting coating for iron-based substrates
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
Enthalpy of Formation (kJ/g-atom)
Illustration of the Thermodynamics - Heats of
Formation - for Relevant Alloy Systems
30
B has a repulsive chemical
reaction with aluminum
20
B in Al
10
0
-10
-20
Al in Fe
B is attracted to steel
-30
B in Fe
-40
-50
0
0.2
0.4
0.6
0.8
1
Fraction of Boron or Aluminum
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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).
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
Soldering Test Set-up and
Die Pin Schematic of Pin for Solder Testing
Automated, molten aluminum testing apparatus
Oak Ridge National Laboratory
U.S. Department of Energy
Dimensions are in inches
UT-BATTELLE
Examples of Soldering Trials Data on
Coated vs. Bare H13 Pins
DB103501 Hy-Tech H13
Experimental Data
indicating the onset of
Soldering
DB103501 Hy-Tech H13-B28-3
800
800
700
700
600
600
Series 2
Series 3
Series 4
Series 5
500
400
500
400
300
300
200
200
100
100
0
Series 2
Series 3
Series 4
Series 5
0
0
100
200
300
400
500
600
700
0
100
200
Time (sec)
300
400
500
600
700
Time (sec)
DB103501 Hy-Tech H13-B28-4
Experimental Data
indicating No Soldering
800
700
600
500
400
300
200
Series 2
Series 3
Series 4
100
Series 5
Oak Ridge National Laboratory
U.S. Department of Energy
0
0
500
1000
1500
Time (sec)
2000
2500
UT-BATTELLE
H13 without coating after 16 cycles exhibits
soldering
The experimental conditions are as follows,
(1)
(2)
(3)
(4)
(5)
Oak Ridge National Laboratory
U.S. Department of Energy
Temperature of melt aluminum (Tmelt): 700oC
Temperature of lubricant (Tlubricant): 21oC
Dipping time in aluminum(t1):10 s
Time in lubricant(t2):3 s
Time in air spray(t3):5 s
UT-BATTELLE
Boron-coated H13 Steel Pin Exhibits
No Soldering After 50 Cycles* in Molten Aluminum
End view of die casting pin
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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.
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE
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.
Oak Ridge National Laboratory
U.S. Department of Energy
UT-BATTELLE