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VpCI Chemistry 101

VpCI Chemistry 101. Kristy Gillette Cortec Corporation. CORROSION. Natural process as natural as water flowing downhill. Corrosion. Corrosion inhibitors. Outline. Corrosion Corrosion Prevention Corrosion Inhibitors Vapor-phase Corrosion Inhibitors (VpCI) Cortec’s VpCIs Conclusions.

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VpCI Chemistry 101

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  1. VpCI Chemistry 101 Kristy Gillette Cortec Corporation

  2. CORROSION • Natural process • as natural as water flowing downhill

  3. Corrosion Corrosion inhibitors

  4. Outline • Corrosion • Corrosion Prevention • Corrosion Inhibitors • Vapor-phase Corrosion Inhibitors (VpCI) • Cortec’s VpCIs • Conclusions

  5. Corrosion Cost in the US • (Billions of Current Dollars) • 1975 1998 • All Industries •   Total 82.5 276.0 • Avoidable 33.0 83.7 • Motor Vehicles •   Total 31.4 23.4 • Avoidable 23.1 7.0 • Aircraft •   Total 3.0 2.2 • Avoidable 0.6 0.6 • Other Industries •   Total 47.6 253.4 •  Avoidable 9.3 76.0 • Sources: Economic Effects of Metallic Corrosion in the United States, 1978. Cost of Corrosion and Preventative Strategies in the United States, 1998.

  6. Defining Corrosion • Definition: • The destruction, degradation or deterioration of material due to the reaction between the material and its environment • For metals, this is a natural process by which a metal attempts to revert back to its original state by releasing energy. • Natural iron is oxidized, we add energy when we mine it - iron wants to return to a natural, low energy state • Examples of Corrosion: • Cavities in teeth • Batteries • Red rust, white rust, metallic corrosion…

  7. Corrosion Appearance • Classification by appearance (8 categories)

  8. CorrosiveEnvironments • Moist air is more corrosive than dry air • Hot air is more corrosive than cold air • Hot water is more corrosive than cold water • Polluted air is more corrosive than clean air • Acids are more corrosive than bases (alkalies) • Salt Water is more corrosive than fresh water • Stainless steel will outlast ordinary steel • No corrosion will occur in a vacuum, even at very high temperatures, etc.

  9. The Corrosion Cell Current Flow Oxidation Reduction Anode Cathode Electronic Path

  10. Corrosion Prevention • Materials selection (more resistant metal) • Coatings (metallic, organic) • Design (eliminate dead spaces, crevices) • Cathodic and anodic protection (potential) • Alteration of environment • Corrosion inhibitors

  11. Benefits of Corrosion Control • Reduce corrosion costs • lower maintenance and repair costs • extended useful lives of equipment and buildings • reduction of or reduced product loss from corrosion damage

  12. Benefits of Corrosion Control • Lower risk of failure • safety • product liability • avoidance of regulation • loss of goodwill

  13. Corrosion Inhibitors

  14. Corrosion Inhibitor Classification • Anodic (nitrites) • Cathodic (arsenic, bismuth, antimony) • Precipitation (silicates, phosphates) • Organic/Filming (amines, sulfonates) • Vapor-phase

  15. Vapor-Phase Corrosion Inhibitors • Definition: • Vapor-phase corrosion inhibitors condition an enclosed atmosphere with a protective vapor that condenses on all metal surfaces (including recessed areas, cavities) • A multi-metal corrosion inhibitor that protects in 3 phases- contact, vapor and interphase • Practical: • Prevents corrosion, even if not in direct contact allowing cost effective, easy application, use and disposal. Clean, dry and effective protection.

  16. Vapor-Phase Corrosion InhibitorsHistory • Late 1900s Discovery • Late 1940s US Navy (boilers, piping systems) • 1950s Begins New Research • 1977 Start of the Cortec Corporation

  17. Process Industry Construction Electronics Transportation Military Steel Industry Vapor-Phase Corrosion InhibitorsApplications

  18. How Do VpCIs Work? • Corrosion inhibiting molecules are emitted from their source • Molecules naturally diffuse from the source toward the metal • Molecules are adsorbed forming a protective film on metal • Film protects metal from corrosion

  19. VpCIs Effectiveness Factors • Vapor Pressure • Diffusion • Evaporation/Sublimation Rates • Chemical Composition • Environmental Factors • Temperature, Air Flow, Humidity, Cleanliness

  20. Vapor Pressure • Definition: • The pressure exerted when a solid or liquid is in equilibrium with its own vapor. The vapor pressure is a function of the substance and of the temperature

  21. Vapor Pressure Explained Vapor pressure reflects HOW MUCH of a substance is required to reach saturation  low VP means a small amount is required  high VP means a large amount is required VpCI vapor pressure is lower than water, therefore, given a specific air space (package or enclosure), only a small quantity of VpCI is required to counteract the effects of a relatively large quantity of moisture vapor.

  22. Vapor Pressure Examples • Atmospheric pressure: 760 mm Hg • Water: 18 mm Hg at 68ºF (20ºC) • Typical VpCI: 10-4 mm Hg at 68ºF (20ºC) • Sodium nitrite: ~ nil

  23. VpCIs EffectivenessFactors • Vapor Pressure • Diffusion • Evaporation/Sublimation Rates • Chemical Composition • Environmental Factors • Temperature, Air Flow, Humidity, Cleanliness

  24. Diffusion • Governed by Fick’s Law • Natural process by which VpCI molecules travel from an area of high VpCI concentration to an area of low VpCI concentration until equilibrium is reached • Examples: • In cell biology, diffusion is the main form of transport for necessary materials through cells (amino acids, ion transport, etc…) • Deflation of helium balloon • Aroma of fresh baked cookies diffuses through the kitchen/home

  25. Diffusion Analogies Like an air-freshener in your car, VpCI travels from the “source” where there is a high concentration… to all void spaces (low concentration) until all the air is saturated with VpCI molecules.

  26. VpCIs Effectiveness Factors • Vapor Pressure • Diffusion • Evaporation/Sublimation Rates • Chemical Composition • Environmental Factors • Temperature, Air Flow, Humidity, Cleanliness

  27. Evaporation & Sublimation Rates • Determines how quickly saturation occurs • Evaporation (Liquid  Gas) • Determines how quickly molecules are released. • Different substances will release gaseous molecules at different rates. • Too fast may mean not long enough protection • Too slow may mean no protection achieved • Sublimation (Solid  Gas) • Same as above, but think about VpCI powder, which is a solid, but emits a vapor.

  28. VpCIs Effectiveness Factors • Vapor Pressure • Diffusion • Evaporation/Sublimation Rates • Chemical Composition • Environmental Factors • Temperature, Air Flow, Humidity, Cleanliness

  29. Chemical Composition • VpCI molecules are “polar” meaning they are attracted to metal, rather than just passing past the metal. • VpCI molecules adsorb onto metal surfaces Adsorption = accumulation of atoms/molecules onto the surface Absorption = diffusion of molecules into a liquid or solid

  30. VpCIs Effectiveness Factors • Vapor Pressure • Diffusion • Evaporation/Sublimation Rates • Chemical Composition • Environmental Factors • Temperature, Air Flow, Humidity, Cleanliness

  31. Environmental Factors • Temperature • The higher the temperature, the higher the vapor pressure • Hot air is more corrosive than cold • Air Flow • Accelerates the depletion of VpCIs • Humidity • Moisture is corrosive. • Requires excess VpCI to combat the acts of moisture. • Cleanliness • Contamination causes corrosion • Oils and dirt act as barrier to VpCIs

  32. Putting It All Together VpCI products emit a protective vapor that adsorbs onto multi-metal surfaces, protecting both the anode and cathode. • Quantity to reach saturation = Vapor Pressure • Ability to travel to recessed areas = Diffusion • How quickly molecules go into vapor phase = Evaporation/Sublimation rate

  33. Vapor-Phase Corrosion Inhibitors Benefits • Cost effectiveness (VpCI vs. barrier bags + desiccants) • Ease of use (recessed areas) • Cleanliness (thin layer) • Safety/Environment (LD50)

  34. Toxicity * LD50 =mg of chemical per kg of rat weight which kills 50% of the population

  35. Cortec’s VpCIs • Multi-metal protection (VpCI-126) • Multi-functional (VpCI-125, VpCI-377) • Very low toxicity (VpCI-309) • Environmental friendly (ISO 14001) • Superior quality system (ISO 9001)

  36. Test Methods • Vapor Inhibiting Ability VIA (Fed. Std. 101C) • Razorblade • Half Immersion Test • Electro-Chemical Polarization Resistance, Tafel Plots, etc. • SO2 and F-12 • Others • Accelerated corrosion testing (humidity, salt spray, QUV, etc…)

  37. VIA Test SO2 Test Razorblade Test F12 Test

  38. Important Parameters Of Use • Surface cleanliness • Surface finish • Conditioning • Contaminants • Source exhaustion • Others

  39. Defining Performance • Protection • Long/short term • Distance from source • Conditions • Humidity • Temperature • Corrosive agents, contaminants

  40. Conclusions • Corrosion • Corrosion prevention • Corrosion inhibitors • Vapor-phase corrosion inhibitors • Cortec’s VpCIs

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