1. Kristy Gillette Cortec Corporation
VpCI Chemistry 101
Kristy Gillette
Cortec Corporation

2. as natural as water flowing downhill
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)  
All Industries    
  Total
  Avoidable
Motor Vehicles    
  Total
  Avoidable
Aircraft    
  Total
  Avoidable
Other Industries    
  Total
  Avoidable
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: Examples of Corrosion:
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. Corrosive Environments
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 Oxidation Reduction Current Flow 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 Inhibitors History
Late 1900s Discovery
Late 1940s US Navy (boilers, piping systems)
1950s Begins New Research
1977 Start of the Cortec Corporation

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

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

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

21. 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

22. 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.

23. 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

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

25. 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

26. 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.

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

28. 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.

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

30. 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

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

32. 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

33. 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

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

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

36. 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)

37. 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…)

38. VIA Test
SO2 Test
Razorblade Test
F12 Test

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

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

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