Coatings Flashcards
Is there a chemical change to the resins in a non-convertible coating?
No
How do you determine the WFT through math?
DFT divided by %solids= WFT
What is polymerization?
When 2 chemicals react to make a coating film.
Most coatings are named due to their what?
Their resin.
Which coating has excellent resistance to sulfuric acid?
Phenolic coatings
Should rubber be overcoated by convertible coatings?
Nope!
Should a convertible coating go on top of a solvent-effected coating?
Nope!
What is a common failure in VINYL coatings?
Solvent blistering
Do ACRYLIC coatings have a good resistance to UV?
Yes
What is a common failure for ACRYLIC coatings?
Incomplete cure
Do BITUMINOUS coatings have good UV resistance?
No
Which coating type commonly fails due to applying it too quickly?
ALKYDS
Which coatings should only be used as a primer?
Zinc coatings
What is the most common failure for POLYESTER and VINYLESTER coatings?
Incomplete/failure to cure
Moisture-cured URETHANE is prone to what type of failure?
Incomplete cure because of LOW HUMIDITY
Silicone coatings are often coated over what?… but not always.
INORGANIC ZINC
INORGANIC ZINCs are usually applied at what mils?
.75 mils
ALKYDS react with what to cure?
Oxygen
How do EPOXYESTER coatings cure?
Oxidation
Most marine coatings are ORGANIC or INORGANIC?
Organic
This coating cures by oxidation, cures slowly, and is single packaged.
ALKYDS
What type of lining has great resistance to ozone, gases, acids, and bases?
Neoprene
What is an INTUMESCENT coating?
Fireproof coating
Builds thicker layer with heat
What are the 3 basic coating types?
by how they fight corrosion
Barrier
Inhibitive
Sacrificial
2 examples of oil-based coatings are what?
ALKYDS & EPOXY
What is coalescence cure?
When oxygen is evaporated and THEN chemically fuses the film.
What are the 4 components of a coating?
Pigment
Additive
Binder
Solvent
Describe ALKYD coatings?
Oxidation cure Slow to cure Used on US navy ships Oil-based Single packaged
Describe EPOXY coatings.
2 component Good adhesion Chemical resistance Water resistance Susceptible to chalking
Describe ALIPHATIC POLYURETHANES.
High UV resistance
Excellent gloss
Used for exterior coating
Describe AROMATIC POLYURETHANES.
Tough
Great chemical resistance
Chalks in sunlight
Which types of cures are convertible?
Oxidation
Coreaction
Hydration
Fusion
Explain POLYURETHANE coatings.
2 component
Aliphatic & Aromatic
What general type of coatings DO NOT perform well on zinc primers?
Oil-based
What percentage of zinc is in a zinc rich coating?
75%-95%
How long does powder coating take to cure?
3 minutes
True or false?
2 component epoxies need environmental readings through the curing process.
True
Which process cures rubberized linings?
Vulcanization
Which individual part of a coating changes from a liquid to a solid?
The resin or binder
Describe phenol coatings.
Organic
High resistance to chemicals
What are the 3 types of natural rubber?
Soft
Semi-hard
Hard
Does electrically static- applied coating have a solvent?
No
What does a coating “vehicle” consist of?
Solvent
Binder
Any additive
The coating “vehicle” is synonymous with what?
The coating base
What is dryspray?
In conventional spray, when the pressure is too high.
Can convertible coatings be brought back to their original state?
Nope
Explain 3 things about polyureas
2 component
flexible
very short cure time
Name the 3 test methods for soluble salt contamination
Potassium ferricyanide
Bresel patch
Sleeve test
What percentage of premature coating failures are attributed to surface preparation
75%
Do organic zinc coatings require a topcoat
Yes
At what relative humidity does corrosion rate significantly decrease
50%
Steel contains approximately how much iron
95%
What is the “driving force” in the corrosion process
The potential difference
The anode corrodes in the form of what
Positively charged ions
The method a tape test is for what thicknesses
Anything over 5 mills
how fast is the reaction time for polyureas?
As little as 9 seconds
Are polyaspartic coatings high VOC?
No
Organic coatings have less resistance to THIS in comparison to inorganic coatings.
Heat
What is solvency power?
The ability to dissolve the resin
What is volatility?
The speed at which the solvent leaves the coating film during and after application.
Primers are always this type of coating. (Broad term)
Inhibitive coatings