Welding of Small Parts Using

Nanocomposite Thermites

Ann Cannella New Jersey Institute of Technology

Mentor: Dr. Dreizin

Thermites

Compositions of mixed metal (typically Al) and metal oxide

2Al+Fe2O3 → 2Fe+Al2O3+heat.

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

Example of Traditional Welding

http://www.ameco.net/images/products/thermite_welding_tns.jpg

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

Objective

Identify conditions for the thermite welding suitable for joining small parts

VaryCompositionMixture densityScale of mixing between components

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

Tests

Powerstat Variable Autotransformer

Copper plates pressed in copper wedge

Tungsten Wire (diameter .2mm)

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 2Al+3CuO 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

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