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Metal Parts and Products Coating

Metal Parts and Products Coating

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Metal Parts and Products Coating

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  1. Metal Parts and Products Coating

  2. AREA DESIGNATION FOR STATE AMBIENT AIR QUALITY STANDARD OZONE Legend Attainment Non-Attainment Unclassified Ozone Concentration Map Northeast Plateau North Coast Sacramento Valley Mountain Counties Lake Tahoe Lake County San Joaquin Valley San FranciscoBay Area Great Basin Valleys North CentralCoast SoutheastDesert South CentralCoast South Coast San Diego

  3. Visibility

  4. Who Cares? Ozone Causes: Alveolar injury leading to pulmonary inflammation and permanent lung damage Respiratory discomfort to sensitive populations $330 Million in crop damage each year Damage & failure of paints and rubber parts

  5. Why Paint? Corrosion protection Restore factory color Change color or make uniform Restore protection to repaired spot Reduce wear

  6. Ion Exchanges Galvanic Corrosion Occurs between dissimilar metals

  7. Coatings What is a Coating? A thin film of organic material applied to a mechanical device to protect it from corrosion or assault by its environment. Consequently the color, and texture of the surface are also altered.

  8. Coatings The Four Components of any Coating • Binders or Resin • Solvents, Thinners and Diluents • Pigments & Extenders • Additives 200-9

  9. Coatings Binder A soluble solid capable of hardening into a thin film

  10. Coatings Common Binders/Resins Acetates Latex Acrylics Nitrocellulose Alkyds Polyurethanes Asphaltics Silicone Epoxies Vinyls

  11. Coatings Curing Air dry Thermoset/ Thermocure Thermoplastic Radiation

  12. Coatings Curing Lacquer - cures by the evaporation of the solvent Enamel - cures by an irreversible chemical reaction involving various components or atmospheric water or oxygen

  13. Coatings Solvents, Diluents and Thinners Liquids added to reduce viscosity, promote flow and permit drying by evaporation

  14. Coatings Organic Solvent Types Terpenes pine tree extract Hydrocarbons Aliphatic (mineral spirits) Naphthenic, Aromatic (Toluene & Xylene) Oxygenated Alcohols, Esters & Ketones Furans Tetrahydrofuran for polyvinyl chloride Chlorinated Trichloroethane, Methylene chloride

  15. Coatings Pigments are small, hard particles added for : 1) mechanical strength 2) UV protection 3) color (see additives)

  16. Coatings Some Common Pigments Titanium Dioxide Powdered Metals Zinc Oxide Stainless Steel Flake Antimony Trioxide Bronze, Zinc AluminumPara RedCarbon BlackIron Oxide Graphite Toluidine Red Black Iron

  17. Coatings Extendersare less expensive pigments with poorer hold out Calcium Carbonate Talc (Magnesium Silicate) China Clay (Aluminum Silicate) Calcium Silicate Silica Mica Gypsum (Calcium Sulfate) Barytes or Blanc Fixe (Barium Sulfate)

  18. Coatings Additives A chemical added for a specific effect on either the wet or dry film. examples: luster enhancer, drying speed, hardness, anti fish eye Normally totals less than 5% of liquid volume

  19. Coatings Additives Skinning agents methyl ethyl ketoxime, Wetting agents (for pigment) anionic, cationic and nonionic soya lecithin, anti-foaming(usually water-borne) silicone and non-silicone, coalescing (latex emulsion) , thickening (water borne) methyl cellulose, microbicides mercurial & nonmercurial examples: luster enhancer, drying speed, hardness, anti fish eye

  20. Coatings Water as a Diluent water organic solvents cosolvent solvents solids solids x grams of solids covers area y x grams of solids covers area y

  21. A Coating System Topcoat Compatability Intercoat 1 to 5 mils each Powder Primer/sealer/surface Substrate: Steel, Plastic or other

  22. Coatings ROG Control Strategies for Coatings Use Reduction • Use of Exempt Solvents • Use of Water-Borne Products • Increased Solids Contents • Increased Transfer Efficiency Retrofit Control Devices • Capture and Reuse • Capture and Destroy

  23. Coatings 1994 Coating Consumption by type Type Million Gallons Percent Water 586 50.9 Hi-Sol 110 9.6 Powder 70 6.0 Radiation Cure 6.4 0.5 Non Comp High VOC 378 32.9 1149.6 100

  24. Coatings Exempt Solvents Vary by District Have a Variety of Human Health Effects Including Anesthesia and Intoxication Stratospheric Ozone Depletion Sometimes Incompatible with Aluminum or Water 200-12

  25. Coatings Waterborne Pro and Con • reduced air emissions increased water and HAP emissions • reduced fire hazard pretournament more critical • low cure temps drying time controlled more by • easy clean up weather than by additives • higher air pressure means lower TE • rust proof equipment required 200-11

  26. Coatings Cosolvent aka coupling agent a solvent that causes two immiscible liquids to mix may comprise up to 30% of the liquid in a waterborne coating

  27. Coatings For information on Waterborne solutions: Waterweb: http:/www.waterweb.com or call (602) 948-3555

  28. Coatings High Solids Pro and Con reduced air emissions increased viscosity reduced storage reduced storage & handling stability

  29. Coatings Powder Coatings Thermoplastic or thermoset No on-site color mixing Faraday cage Electrostatic application required 200-12

  30. Common MP&P Coatings VOC Contents of baked air dry Prefab Arch. 275 g/l 420 Metallics 350 g/l 420 Masks &Lubs 800 g/l 800

  31. Process Coating steps and points of emission sanding/depainting surface clean and prep primer & topcoat application flash off/drying cure touch up equipment clean up 200-2

  32. Points of VOC Emission 90% of VOC Emission Storage Application Cleanup Mixing Drying & Prep.

  33. Application Techniques Dip Flow Roll Spray } Electrodeposition Autodeposition Airless Air HVLP/Electrostatic }

  34. Process Autodeposition aka autophoresis no electrical current used; waterborne; an acid bath releases iron cations from steel that react with negatively charged latex polymer to precipitate coating solids onto surface

  35. Process Electrodeposition aka Electrophoresis Coating solids and part are given opposite charges. Coating particles are drawn magnetically to part. similar to Electroplating

  36. Plating Listed Hazardous Materials found in Coatings Benzene Lead 1,3-Butadiene Methylene Chloride Carbon tetrachloride Perchloroethlene Chromium VI Toluene Ethylene dibromide Trichloroethylene Ethylene dichloride Vinyl chloride Glycol ethers Xylene 700-2,3

  37. Plating How it Works A direct current is passed through a Chromic acid bath causing positive chromium and hydrogen ions to migrate to the cathode and negative oxygen ions to migrate to the anode.

  38. Plating Percent of Cr6 Consumed by type Percent Type Normal Thickness 60% Hard plate -tools, crankshafts10-300 microns 30 % Decorative - plumbing, auto parts 0.25 microns 10% Anodizing - Al and Mg parts none 700-3

  39. Plating TAC exposure The bubbles breaking the surface of the acid bath emit Cr6vapors and aerosol.

  40. Plating Control Strategies 1. Increase the surface tension of the acid bath 2. Add a layer of foam or ping pong balls 3. Substitute Cr3 for Cr6 4. Capture and reuse 700-4

  41. Plating With mist inhibitors

  42. Cr6 Control Mist Eliminators 1. a mesh pad that captures emissions by inertial impaction 2. a series of chevroned baffles 700-4

  43. Cr6 Control Mesh pad scrubber

  44. Cr6 Control Rule Requirements 1. 95% control 2. record keeping 3. permit conditions which might include: periodic source test specified pressure drop across the control device and instrumentation amp-hour meter and records 700-4

  45. Control ROG Control Strategies for Coatings Use Reduction • Use of Exempt Solvents • Use of Water-Borne Products • Increased Solids Contents • Increased Transfer Efficiency Retrofit Control Devices • Capture and Reuse • Capture and Destroy

  46. Transfer Efficiency (T.E.) the ratio of the amount of solids adhering, to the amount of solidsapplied 200-17

  47. Process Spray Application Airless Air Atomized High Volume, Low Electrostatic Pressure Air-Assisted Turbobell

  48. Spray Gun Wing Port Air path

  49. Spray fan pattern is compressed by air from the spray cap wing ports.