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Published byGillian Dalton Modified over 9 years ago
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Like SHS, is loose powder ignition a key process within mechanochemical reactions (ball milling), or is it just an anomaly for Cu 2 O? J. Zeck, Dr. Takacs, and Dr. Bakhshai Goucher College Baltimore, MD
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Stainless Steel Milling Vials What exactly is ball milling? SPEX 8000 Mixer Mill 3CuO + 2Al Al 2 O 3 + 3Cu 2CuO + Ti TiO 2 + 2Cu example reactions:
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Ignition time (seconds) Vial temperature (Celsius) Trends in Temperature When Ignition Occurs in Individual Samples
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Ignition Trends from Summer 2001 Work
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New material systems that have been investigated: Bi 2 O 3 + 2Al Al 2 O 3 + 3Bi 3Ag 2 O + 2Al Al 2 O 3 + 6Ag 3CuS+ 2Al Al 2 S 3 + 3Cu 3Cu 2 S + 2V V 2 S 3 + 6Cu 3CuS + 2V V 2 S 3 + 3Cu 3ZnO + 2Al Al 2 O 3 + 3Zn Ignition No ignition 3CuO + 2Al Al 2 O 3 + 3Cu 2CuO + Ti TiO 2 + 2Cu 3PbO + 2Al --> Al 2 O 3 +3Pb
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Cu Oxide Ignition Trends; as previously looked at Comparison of CuO System’s Ignition Times as mixed with Aluminum and Titanium Powders
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6CuO + 2Al 3Cu 2 O + Al 2 O 3 3Cu 2 O + 2Al Al 2 O 3 + 6Cu 3CuO + 2Al Al 2 O 3 + 3Cu Instead of single step: A two step reaction: may contribute to additional transitory region ΔH= 287.7 kcal/mol ΔH= 304.8 ΔH= 270.6
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3CuO + 2Al Al 2 O 3 + 3Cu
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Is it just the copper that is causing the transitory regions? a look into bismuth... Bi 2 O 3 + 2Al Al 2 O 3 + 3Bi
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Would the ignition affects of ductile silver compare with copper? 3Ag 2 O + 2Al Al 2 O 3 + 6Ag
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How do the ignition times of lead oxide compare? 3PbO + 2Al --> Al 2 O 3 +3Pb
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Is the anomaly just unique to the copper oxides or does it apply more generally to other copper compounds as well? 3CuS+ 2Al Al 2 S 3 + 3Cu
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Examples of Relative Linearity of Temperature Changes due to Ignition in various systems
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Atomic Force Microscopy Investigation: CuO/Al 2 Gram Powder Sample—Layer Study
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Atomic Force Microscopy Investigation: CuO/Al 5 Gram Powder Sample—Layer Study
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Conclusions … Alternate process to established SHS Isolated case–exhibited only in Copper Oxides Cu2O– critical mass transition only CuO– critical mass and exponential decay transitions
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