Term
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Definition
| A chemical or electrochemical action which takes place inside a metal or on its surface |
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| Most metals exist in nature as a chemical compound such as.... |
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Definition
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| Corrosion is a process wherein metals return to.... |
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| What type of "metal" appears as surface pitting and etching often combined with grey or white powdery dust |
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Definition
| Aluminum alloys and magnesium |
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| Results from direct exposure of a bare surface to a caustic liquid or gaseous agents |
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Definition
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| Takes place when two metals having a different level of chemical activity are touching or are in close proximity in the presence of moisture |
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Definition
| Electrochemical corrosion |
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| The earlier a metal appears, the more easily it gives up electrons, and is referred to an anodic metal |
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Definition
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T or F:
Anodic metals corrode easily |
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Definition
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T or F:
Cathodic metals give up electrons easily |
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Definition
False
Cathodic metals do not corrode as easily as anodic metals, therefore they do not give up electrons as easily |
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Term
| The 4 requirements for corrosion |
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Definition
1) presence of a metal that will corrode
2) presence of a dissimilar conductive material (cathode) which has less tendency to corrode
3) presence of a conductive liquid (electrolyte)
4) electrical contact between the anode and cathode (usually metal to metal contact, or a fastener) |
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Term
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Definition
1) Oxidation (Aluminum oxide, iron oxide)
2) uniform Surface
3) pitting
4) galvanic
5) concentration cell (oxygen, metal ion, active-passive)
6) filiform
7) intergranular
8) exfoliation
9) stress
10) fretting |
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| Commonly referred to as dry corrosion |
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Definition
Oxidation corrosion
When a metal is exposed to a gas containing oxygen, a chemical reaction takes place on the surface between the metal and the gas |
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Term
| Film is unbroken, and once it has formed, further reaction with oxygen slows dramatically |
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Definition
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| Forms a porous, interrupted film, which allows the metal to continue to react with oxygen until the metal is completely eaten away |
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Definition
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| Best way to protect from oxidation... |
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Definition
Keep oxygen away from the surface
Temporary= apply a covering to the surface with oil or grease
Permanent= painting surface |
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| Aluminum alloy can be protected from oxidation by the formation of an oxide film on the surface. This film insulates the aluminum from any electrolyte, and prevents further reaction with oxygen |
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Definition
| Cladding (Aclad) aluminum |
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Term
| When an area of unprotected metal is exposed to an atmosphere containing battery fumes, exhaust gasses, or industrial contaminants, a uniform attack over the entire surface occurs. |
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Definition
| Uniform surface corrosion |
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Term
| Appearance of uniform surface corrosion |
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Definition
Dulling of the surface is caused by microscopic amounts of the metal being converted into corrosion salts.
Sometimes spreads under the surface, and cannot be detected, but the paint over the surface starts to blister |
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Term
Likely a result of uniform surface corrosion that has been left untreated.
Usually detected by the appearance of clumps of white powder on the surface |
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Definition
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| Occurs any time two dissimilar metals make electrical contact in the presence of an electrolyte. |
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Definition
Galvanic corrosion
(Two dissimilar metals skins are riveted together
Aluminum inspection plates are held on with steel screws.) |
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Term
Sometimes referred to as crevice corrosion
Is corrosion of metals in a metal to metal joint, corrosion at the edge of a joint, even though the metals are identical, or corrosion of a spot on a metals surface covered by a foreign material |
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Definition
| Concentration cell corrosion |
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Term
Forms when water covers the surface of the aluminum aircraft skin and seeds into the cracks between lap joints.
This type of corrosion attacks the areas where there is no oxygen, under the bolt heads, loose fittings, marking tape |
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Definition
| Oxygen concentration cell corosion |
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Term
| Forms due to the electrode potential within a metal. |
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Definition
| Metal ion concentration cell corrosion |
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Term
| Usually attacks metals which depend on a tightly bonded passive film, such as an oxide or corrosion protection. |
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Definition
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Term
A form of oxygen concentration cell corrosion which occurs on metal surfaces having an organic coating system.
Appears as puffiness under the paint film and his first noticed around rivet head and a long lap joints. |
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Definition
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| Corrosion which attacks along the grain boundaries of a material |
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Definition
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Term
An extreme case of intergranular corrosion.
Occurs along grain boundaries and causes the material to separate, or delaminate |
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Definition
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| Occurs when a metal is subjected to a tensile stress in the presence of a corrosive environment. |
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Definition
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| When two surfaces fit tightly together, but can move relative to one another. |
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Definition
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Corrosive agents (2)
Form effective electrolytes as they react with metals to form metallic salts |
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Definition
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Term
| Basic tools for visual inspection |
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Definition
1) mirror
2 magnifying lens
3) flashlight
4) borescope
5) fiberoptic scope
6) video scope |
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Term
| Small lens mounted on extension with built-in light source |
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Definition
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Term
| Small lens mounted on extension with built-in light source, has flexible articulating probe, uses glass fibers to transmit light from light source |
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Definition
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Term
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Definition
| Similar to fiber optic scope but electronically made image , easily allows pictures, video, and other features |
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Term
| Weld inspection parameters (6) |
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Definition
1) uniform width
2) even ripples
3) smooth taper of bead into base metal
4) no burn marks or signs of overheating
5) no oxide present within 1/2 inch of the weld
6) should be free of gas pockets, porosity, and inclusions |
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Term
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Definition
1) lap
2) butt
3) fillet or t-joint
4) edge
5) corner |
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Term
| Penetration of a butt weld |
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Definition
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Term
| Penetration of a fillet weld |
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Definition
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Term
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Definition
1) too much acetylene (causes metal to boil- bumps in center, cratered edge)
2) cold weld (lack of penetration, irregular edges)
3) too much heat (long pointed ripples, pitting on edges)
4) rapid cooling (cracking near edges of weld) |
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Term
T or F
If poor welds are detected you may not ground out and reweld them |
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Definition
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Term
| Liquid penetrant inspection |
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Definition
| Used to inspect for cracks and surface irregularities |
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Term
| Liquid penetrant inspection process |
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Definition
Area in question is covered with low viscosity low surface tension penetrating liquid
Allowed to stand on surface so it can be whipped into surface faults
Excess is then washed from service
Developer is then applied to surface |
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Term
| Two types of liquid penetrant inspections |
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Definition
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| Magnetic particle inspection |
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Definition
-Most often used for inspection of parts made of iron or iron alloys.
-Part is magnetized an oxide containing magnetic particles is poured or sprayed on parts surface.
-Discontinuous use create disruptions in parts service.
-Magnetic particles aligned with disruptions |
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Term
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Definition
Uses sound waves.
Requires access to only one side.
Detects surface and subsurface faults |
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Term
| List four types of non destructive inspection |
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Definition
1) visual
2) liquid penetrant
3) magnetic particle
4) eddy current
5) ultrasonic
6) xray |
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Term
| What type of material does eddy current work on |
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Definition
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Term
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Definition
Exposed film.
Develop film.
Interpret the results |
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Term
| What fluid is carried in the line identified by the color code Red? |
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Definition
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| List the three classes of fluid lines |
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Definition
1) pipes (rigid fluid lines)
2) tubes (semi-rigid fluid lines)
3) hoses (flexible fluid lines) |
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Definition
Wall thickness
O.D. (1/16th of an inch increments) |
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Definition
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| List three materials used to manufacture tubes |
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Definition
1) aluminum
2) copper
3) corrosion resistant steel
4) titanium |
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| Where are hoses normally installed? |
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Definition
| Where stationary parts are connected to moveable parts or areas of vibration |
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| How should hoses be stored? |
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Definition
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Term
| What is the cone angle for a flare on aviation tubing and fittings? |
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Definition
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