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A.     Bakhshai, G.S. Dengler, and A.R.Torosyan

Micro-Hardness Characteristics and Morphology of Cr-Coating formed due to Mechanical Alloying. A.     Bakhshai, G.S. Dengler, and A.R.Torosyan. Department of Physics, Goucher College, Baltimore, Maryland 21204. What is Ball Milling?. How Does the Reaction Propogate?.

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A.     Bakhshai, G.S. Dengler, and A.R.Torosyan

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  1. Micro-Hardness Characteristics and Morphology of Cr-Coating formed due to Mechanical Alloying A.     Bakhshai, G.S. Dengler, and A.R.Torosyan Department of Physics,Goucher College, Baltimore, Maryland 21204

  2. What is Ball Milling?

  3. How Does the Reaction Propogate? • Increase in Surface to Volume Ratio • Increase in Heat as a result of the Kinetic energy of the milling balls • Cold Welding of the Powder to substrate

  4. Key Variables • Milling Time • Number and Size of Milling Balls • Powder Mass • Powder Mass to Ball Ratio

  5. Initial Experimental Problems • Downward Curvature of the Substrate • pressure gradient • Solution: Insertion of a small hole in substrate prior to milling

  6. Obtaining A Uniform Coating • Ring Formation • Uniformly coated substrate

  7. Atomic Force Microscopy:Uniform Cr coating on Steel

  8. Atomic Force Microscopy: Non-uniformity of the Cr-on-steel Sample

  9. Effect of Mass of Cr Powder on Steel Substrate

  10. Milling Time: Effects on Surface Morphology

  11. Heat Treatment

  12. Further Investigations: Cr Coating on Al substrate • Studied: Powder mass in relationship to microhardness • Displayed increase in microhardness with increase in powder mass • Produced same characteristic curve as steel substrate • Atomic Force Microscopy also showed increases in surface morphology with increased powder mass

  13. Physical Properties of the Coating Powder

  14. Anomaly: Cu Coating on Al Substrate • No noticeable coating obtained under equivalent reaction conditions • Alcohol, Acetone, Silicon oxide were used in an effort to stimulate reaction • Copper coating obtained by shortening of milling time to 2 minutes

  15. Conclusion

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