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Chapter 30-31

Chapter 30-31. Inorganic Finishing Processes. Converted Surfaces and Coatings. http://www.duncanamps.co.uk/metal/black_oxide.php. Surface Prep. Mechanical Abrasive cleaning Tumbling & Vibrating Media Blasting Burnishing Brushing Chemical Pickling (in acid) Alkaline Cleaning

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Chapter 30-31

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  1. Chapter 30-31 Inorganic Finishing Processes

  2. Converted Surfaces and Coatings http://www.duncanamps.co.uk/metal/black_oxide.php

  3. Surface Prep • Mechanical • Abrasive cleaning • Tumbling & Vibrating • Media Blasting • Burnishing • Brushing • Chemical • Pickling (in acid) • Alkaline Cleaning • Vapor degreasing • Electrochemical • Electropolishing • (the part is the anode)

  4. Finishing Processes

  5. Combinations of Inorganic Coatings on Base Materials • Metal on metal • Metal on plastic • Ceramic on ceramic • Ceramic on metal

  6. Phosphate Conversion Coatings • Creates a phosphate layer on the surface • Requires part to be clean first • Provides a base for painting, oiling, or waxing surface • Reduces friction (e.g., for processing)

  7. Chromate Coatings • Used on Aluminum, Zinc, Cadmium coated steel. Also used on Mg and Sn coated steel. • Provides a decorative appearance • Used as a base coat for paint • May contain a dye to color the converted coating zinc chromate (silver) zinc dichromate (gold)

  8. Oxide Coatings • Immersion of parts in hot caustic soda and nitrite or nitrate solution

  9. Anodic Conversion Coatings • Anodizing • Used on Al and Mg • Creates a protective oxide coating

  10. Metallic Coating Finishing • Electroplating • Electroless and Immersion Plating • Dipping • Metalizing • Diffusion Coatings

  11. Electroplating • Provides attractive surface finish • Improves wear resistance • Increase thermal conductivity • Improve materials ability to be soldered • Build up worn areas

  12. Electroless Plating • Metal is deposited by chemical means • Used to deposit nickel, gold, tin, copper, cobalt and zinc to • Copper, aluminum, steel and plastic

  13. Dipping • Base metal is cleaned • Dipped in flux • Molten metal bath • Excess metal drips off

  14. Metallizing • Wire Metallizing or flame spraying • Plasma-arc spraying • Vacuum metalizing

  15. Vacuum Metallizing • Vaporized coating material using tungsten filaments • Vaporized metal floats in the vacuum and deposits on rotating parts • Used to coat automotive trim, reflectors, hardware, jewelry, etc. • Deposits high purity metal

  16. Ceramic Coating Finishes • Porcelain Enamels • Glasslike material bonded to base metal • Fired from 1-2000 deg. F. • Durable, scratch resistant, easy to clean, resists chemicals and heat • Glazes • Glasslike material applied to ceramic material • Refractory Ceramic Coatings • High heat resistance

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