Transcript VpCI Chemistry-101 WSM2009

VpCI Chemistry 101
Kristy Gillette
Cortec Corporation
CORROSION
Natural process
as natural as water flowing
downhill
Corrosion
Corrosion inhibitors
Outline
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Corrosion
Corrosion Prevention
Corrosion Inhibitors
Vapor-phase Corrosion Inhibitors (VpCI)
Cortec’s VpCIs
Conclusions
Corrosion Cost in the US
(Billions of Current Dollars)
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All Industries
Total
Avoidable
Motor Vehicles
Total
Avoidable
Aircraft
Total
Avoidable
Other Industries
Total
Avoidable
1975
1998
82.5
33.0
276.0
83.7
31.4
23.1
23.4
7.0
3.0
0.6
2.2
0.6
47.6
9.3
253.4
76.0
Sources: Economic Effects of Metallic Corrosion in the United States, 1978.
Cost of Corrosion and Preventative Strategies in the United States, 1998.
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…
Corrosion Appearance
 Classification by appearance (8 categories)
Corrosive Environments
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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.
The Corrosion Cell
Current Flow
Oxidation
Anode
Reduction
Cathode
Electronic Path
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
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
Benefits of Corrosion Control
 Lower risk of failure
 safety
 product liability
 avoidance of regulation
 loss of goodwill
Corrosion Inhibitors
CORROSION INHIBITORS DEMAND*
(million dollars)
Item
Corrosion Inhibitors Demand
Transportation Equipment
Metal Containers
Water Treatment
Petroleum
Machinery & Equipment
Industrial Maintenance
Heat Transfer Fluids & Other
*The Fredonia Group, December 1997
1987
3651
1365
524
340
563
215
371
273
1996
5010
1758
740
612
530
458
601
311
2001
6140
2075
900
835
585
620
780
345
2006
7455
2355
1100
1150
645
820
1000
385
Corrosion Inhibitor Classification
 Anodic (nitrites)
 Cathodic (arsenic, bismuth, antimony)
 Precipitation (silicates, phosphates)
 Organic/Filming (amines, sulfonates)
 Vapor-phase
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.
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
Vapor-Phase Corrosion
Inhibitors
Construction
Applications
Process Industry
Electronics
Transportation
Military
Steel Industry
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
VpCIs Effectiveness Factors
 Vapor Pressure
 Diffusion
 Evaporation/Sublimation Rates
 Chemical Composition
 Environmental Factors
 Temperature, Air Flow, Humidity,
Cleanliness
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
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.
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
VpCIs Effectiveness Factors
Vapor Pressure
 Diffusion
 Evaporation/Sublimation Rates
 Chemical Composition
 Environmental Factors
 Temperature, Air Flow, Humidity,
Cleanliness
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
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.
VpCIs Effectiveness Factors
Vapor Pressure
Diffusion
 Evaporation/Sublimation Rates
 Chemical Composition
 Environmental Factors
 Temperature, Air Flow, Humidity,
Cleanliness
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.
VpCIs Effectiveness Factors
Vapor Pressure
Diffusion
Evaporation/Sublimation Rates
 Chemical Composition
 Environmental Factors
 Temperature, Air Flow, Humidity,
Cleanliness
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
VpCIs Effectiveness Factors
Vapor Pressure
Diffusion
Evaporation/Sublimation Rates
Chemical Composition
 Environmental Factors
 Temperature, Air Flow, Humidity,
Cleanliness
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
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
Vapor-Phase Corrosion Inhibitors
Benefits
 Cost effectiveness (VpCI vs. barrier bags +
desiccants)
 Ease of use (recessed areas)
 Cleanliness (thin layer)
 Safety/Environment (LD50)
Toxicity
Chemical
LD 50 (mg/kg-rat)
Table Salt
(Sodium Chloride)
3000
Food
Preservative/Cor.Inh
(Sodium Nitrite)
85
Shell VPI-260
284
Cortec VCI-309
2100
* LD50 =mg of chemical per kg of rat weight which kills 50% of the population
Cortec’s VpCIs
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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)
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
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Accelerated
QUV, etc…)
corrosion testing (humidity, salt spray,
VIA Test
Razorblade Test
SO2 Test
F12 Test
Important Parameters Of Use
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Surface cleanliness
Surface finish
Conditioning
Contaminants
Source exhaustion
Others
Defining Performance
 Protection
 Long/short term
 Distance from source
 Conditions
 Humidity
 Temperature
 Corrosive agents, contaminants
Conclusions
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Corrosion
Corrosion prevention
Corrosion inhibitors
Vapor-phase corrosion inhibitors
Cortec’s VpCIs