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37 Cards in this Set
- Front
- Back
How many conditions must exist for metal corrosion to occur? |
Four |
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What is the electrochemical deterioration of a material or its properties due to is chemical reaction with the surrounding environment? |
Corrosion |
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What is the most common type of corrosion that results from a direct chemical attack on a metal surface that proceeds over the entire surface area? |
Uniform Surface Corrosion |
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What is the smallest unit of an element, made up of a positively charged nucleus surrounded by a system of negatively charged electrons? |
Atom |
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What occurs when different metals are in contact with each other and an electrolyte and is usually recognized by the presence of a build up of corrosion deposits at the joint between metals? |
Galvanic Corrosion |
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What is a negatively charged subatomic particle? |
Electron |
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What corrosion is extremely localized attack that results in holes in the metal? |
Pitting Corrosion |
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An atom or group of atoms or molecules which has acquired a net electric charge by gaining or losing electrons? |
Ion |
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What corrosion attacks the grain boundaries of the metal? |
Intergranular Corrosion |
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What is a liquid (usually water) solution containing ions whose major components are sodium and chloride ions? |
Electrolyte |
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What corrosion is an advance form of intergranular corrosion where the surface grains are lifted up by a force of corrosion products occurring at the grain boundaries? |
Exfoliation Corrosion |
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Most alloys are made up entirely up of small crystalline regions called? |
Grains |
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What corrosion can occur when stagnant solution is pooled? |
Crevice corrosion |
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What are the four conditions that must exist for metal corrosion to occur? |
1. Anode (metal which can corrode) 2. Cathode (dissimilar conductive material) 3. Electrolyte (conductive liquid) 4. Electrical contact (between anode and cathode) |
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What corrosion is a form of crevice corrosion, which occurs on metal having a thin organic protective coating and is recognized by its wormlike trace of corrosion beneath the coating? |
Filiform Corrosion |
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If the surface area of the _____ is smaller than the surface area of the less active _____, corrosion will be rapid and severe. |
Anode, Cathode |
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What 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 Corrosion |
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What is the intergranular or transgranular cracking of a metal caused by the combined effects of constant tensile stress and corrosion? |
Stress Corrosion |
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Corrosion will occur if the concentration of the _____ on the surface varies from one location to another. |
Electrolyte |
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What is the cracking of metals caused by the combined effects of cyclic stress and corrosion? |
Corrosion Fatigue |
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Higher _____ environments tend to produce more rapid corrosion due to accelerated chemical reactions. |
Temperature |
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What occurs at contact areas between materials under load subject to repeated vibration? |
Fretting Corrosion |
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What does the corrosion product of aluminum alloy look like? |
Aluminum oxide (white to gray powder) |
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What does the corrosion product of magnesium alloy look like? |
White powdery snow-like mounds |
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What is corrosion in the absence of water that can occur at high temperatures, such as those found in turbine engine combustors, turbine sections, and afterburners? |
Hot Corrosion |
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What are the most widely used materials for aircraft construction in addition to its uses inside the aircraft structure? |
Aluminum and aluminum alloys |
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Some aluminum parts are protected with an electrochemically applied oxide coating called? |
Anodize |
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What is the lightest structural metal used for aircraft and missile airframes? |
Magnesium alloys |
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What does the corrosion product of carbon and low alloy steel look like? |
Reddish-brown oxide (rust) |
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What does the corrosion product of stainless steels look like? |
Rough surface, sometimes has red,brown, or back stain. |
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What is subject to growth of whisker-like deposits? |
Tin |
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Dirt, salt, acidic stack gases, and engine exhaust gases can dissolve on wet surfaces, increasing the electrical conductivity of the _____, thereby increasing the rate of corrosion. |
Electrolyte |
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What six types of corrosion affect Aluminum alloy? |
1. Pitting corrosion 2. Intergranular Corrosion 3. Exfoliation Corrosion 4. Stress Corrosion 5. Corrosion Fatigue 6. Fretting Corrosion |
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What does the corrosion product of titanium alloy look like? |
No visible corrosion, colored surface oxides develop at over 700 F. |
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All metals will corrode to some extent in a natural environment. When a metal corrodes, the atoms lose electrons and become positively charged. |
Theory of Corrosion |
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What is it called when corrosion occurs when the concentration of the electrolyte on the surface varies from one location to another? |
Concentration Cell |
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What is it called when some of the electrolyte on a metal surface is partially confined and metal in this confined area corrordes more rapidly than other metal surfaces of the same part outside of this area? |
Oxygen Concentration Cell |