NAVAIR 01-1A-509-1, Ch. 3 Flashcards
Aluminum and magnesium form corrosion products that are white oxides or what else?
Hydroxides
What is the most common type of corrosion (and the one that can be most effectively treated by maintenance personnel)?
Electrochemical
What is the smallest unit of an element, made up of a positively charged nucleus surrounded by a system of negatively charged electrons?
Atom
There are over how many elements?
100
What is a negatively charged subatomic particle called?
Electron
What cannot move through metal conductors?
Ions
What is a liquid (usually water) solution containing ions called?
Electrolyte
Which branch of science is concerned with chemical reactions at surfaces in contact with electrolytes?
Electrochemistry
How many conditions must exist before metal corrosion can occur?
4
What is corroding metal called?
Anode
When corrosion products form, they often precipitate onto the corroding surface as a what?
Powdery deposit
Since corrosion products occupy more volume than the original metal, the paint surfaces may become blistered, flaked, chipped, or appear in which way?
Lumpy
Which stage is the best time to prevent corrosion?
Design
Aluminum, steel, titanium, along with which other type of metal are the most commonly used in aircraft construction?
Magnesium
Most alloys are made up entirely of small crystalline regions called what?
Grains
Which form of corrosion are many alloys used in aircraft construction sensitive to?
Stress corrosion cracking
Which type of corrosion is probably the most common type?
Uniform surface
Which type of corrosion occurs when different metals are in contact with each other and an electrolyte?
Galvanic
What is a form of extremely localized attack that results in holes in the metal?
Pitting
Which type of metals are most susceptible to pitting damage?
Stainless steels
Which type of corrosion is an attack on the grain boundaries of the metal?
Intergranular
What is an advanced form of intergranular corrosion where the surface grains of a metal are lifted up by the force of expanding corrosion products occurring at the grain boundaries?
Exfoliation
Which type of corrosion occurs because the environment of the local area is very different from the larger environment?
Crevice
Which type of corrosion is a form of crevice corrosion which occurs on metal surfaces having a thin (~4 mils) organic protective coating?
Filiform
Filiform corrosion occurs when the relative humidity of the air is between 65- 90%, and the air temperature is between which temperatures?
70°- 100°F
Which type of corrosion is the increase in the rate of attack on a metal due to the action of a corrosive fluid against the metal surface?
Erosion
Which type of corrosion is the intergranular or transgranular cracking of a metal caused by the combined effects of constant tensile stress (internal or applied) and corrosion?
Stress
Aluminum alloy can fail by stress corrosion cracking when subjected to a stress which is only what percent of its rated strength?
10%
What is the cracking of metals known as that is caused by the combined effects of cyclic stress and corrosion?
Corrosion fatigue
Which type of corrosion occurs at contact areas between materials under load subject to repeated vibration?
Fretting
What are the most widely used materials for aircraft construction?
Aluminum and aluminum alloys
Since pure aluminum is more corrosion resistant than most alloys, aluminum sheet stock is often covered with a thin layer of nearly pure aluminum called cladding or what else?
Alclad
What is the electrochemically applied oxide coating called which is used to protect some aluminum parts?
Anodize
What are the lightest structural metals used for aircraft and missile airframes?
Magnesium alloys
Which type of metals are used for gears, bearings, and high strength bolts, and for mountings, racks, brackets, and hardware in avionic systems?
Stainless steels
Titanium and titanium alloys find numerous uses in aircraft, engines, and missiles up to which temperature?
1000°F
What is used as a coating to protect steel hardware, such as bolts, washers, and screws, and as plating on electrical connectors?
Cadmium
What is used as a protective plating?
Chromium
When added to stainless steel alloys, the stress corrosion resistance increases with nickel contents above what percentage?
10%
Which type of alloys are generally used in avionic systems as contacts, springs, leads, connectors, printed circuit board (PCB) conductors, and wires?
Copper and copper based
Which type of material is used as a plating material over copper in waveguides, miniature and micro- miniature circuits, wires, contacts, high frequency cavities, tank circuits, and RF shielding?
Silver
What is used on printed circuits, semiconductors, leads, and contacts and is traditionally considered the best coating for corrosion resistance and solderability?
Gold
Which brittle gold-aluminum compound is formed when bonding gold to aluminum?
Purple plague
Which material has the best combination of solderability and corrosion resistance of any metallic coating?
Tin
Graphite or carbon fiber composites are materials which consist of reinforcing fibers in a matrix made of organic resin, usually what?
Epoxy
What in addition to conformal coatings are used to envelop an avionic component, module or assembly?
Encapsulants
Which type of compounds are used to encase a part or component, such as in an electrical connector?
Potting
Rubbers along with what else are used for insulation, seals, gaskets, caps, tubing, films, and coatings?
Elastomers
What is present in air as a gas (water vapor) or as finely divided droplets of liquid (mist or fog)?
Moisture
What formation results from condensation of moisture?
Electrolyte
What percentage of the ocean is salt?
3.5-3.9%
Up to how many pounds of seasalt per cubic mile of air can normal sea winds carry?
100
What is a particularly active form of oxygen which is formed naturally during thunderstorms, by arcing in electrical devices, and by photochemical reactions in smog?
Ozone
The two ranges of solar radiation most damaging to materials are ultraviolet (the range that causes sunburn) and which other range that makes sunlight feel warm?
Infrared
Most fungus growth is inhibited by temperatures above which temperature?
104°F
Which type of environments is most military equipment intended for service in?
Low pressure (high altitude)
Some of the least recognized contributors to corrosion are sand, dust, and what else?
Volcanic ash
In arid regions such as deserts, small sand particles are often blown as high as how many feet by the siroccos (hot, dust laden winds)?
10,000’
Nonmetallic materials suffer the most damage from the hot desert climates, where air temperatures during the day may reach what?
124°F
The greatest challenge to the aircraft industry is the design of equipment that is protected from corrosion and deterioration in the heat and humidity that prevails in which region?
Tropics
The tropical environment is sustained by long periods of heavy rainfall, during which as many as how many inches of rain may fall?
100”
Which type of attack includes the action of bacteria, fungi, or molds?
Microbial
Bacteria may be either aerobic or what else?
Anaerobic
Which type of bacteria require oxygen to live?
Aerobic
Ideal growth conditions for most fungi and bacteria are temperatures between 68° and what?
104°F
What is intended to protect equipment or components against corrosion, deterioration, and physical damage during transportation and storage?
Packaging
Equipment should be properly packaged in accordance with which standard to minimize damage during shipment?
MIL-STD-2073-1
How many hours per day in flight operations do most front-line combat aircraft average?
1-2
