Welding of Small Parts Using Nanocomposite Thermites

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Welding of Small Parts Using Nanocomposite
Thermites

• Ann Cannella
• New Jersey Institute of Technology
• Mentor Dr. Dreizin

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Thermites
Example of Traditional Welding

• Compositions of mixed metal (typically Al) and
  metal oxide
• 2AlFe2O3 ? 2FeAl2O3heat.
• Reactions release large quantities of heat,
  molten iron, and aluminum oxide
• Difficult to ignite
• Self-sustaining only for a large amount of
  thermite mixture
• Used traditionally for large scale welding

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Nanocomposites

• Mixture of two or more materials blended on the
  scale of one billionth of a meter.
• Produced by mechanical milling
• Large reactive surface areas
• React more rapidly and more intensely than larger
  sized composites

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Objective

• Identify conditions for the thermite welding
  suitable for joining small parts
• Vary
• Composition
• Mixture density
• Scale of mixing between components

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Nanocomposite Thermites

• Al-CuO prepared using Arrested Reactive Milling
  (ARM)
• Blends of varying ratios of Al-CuO and Al or
  Al-Cuo and Cu prepared in an ultrasonic bath

Shaker Mill
Crest Ultrasonics
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Tests
Tungsten Wire (diameter .2mm)
Copper plates pressed in copper wedge
Powerstat Variable Autotransformer
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Results

• Textolite boards covered by copper foil were used
  as parts to be joined
• A series of experiments with different
  compositions prepared and performed
• ARM powder of 2Al3CuO
• Added Al powder
• Added Cu powder
• Mixed Al and CuO powders
• Bonding of molten copper to the copper foil
  observed in some experiments, but no joining was
  achieved
• Reaction was
• too quick copper boils and vapor repels joining
  parts
• too slow does not propagate

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Future Work

• Press powders into pellets
• Remove porosity
• Reduce reaction temperature to avoid Cu boiling
• Reduce amount of filler by making thin pellets
• Use laser to ignite thermites
• Overcome ignition difficulties for dense pellets