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Questions and Answers
Driving force = ______ – elastomer becomes warmer when stretched
Driving force = ______ – elastomer becomes warmer when stretched
entropy
Criteria for polymer to be elastomeric: Not crystallize easily and have ______ rotations relatively free
Criteria for polymer to be elastomeric: Not crystallize easily and have ______ rotations relatively free
chain bind
Vulcanization is a nonreversible reaction involving ______ in which crosslinks are formed.
Vulcanization is a nonreversible reaction involving ______ in which crosslinks are formed.
sulphur
Adjacent lamellae chains ______ past each other and the chain folds become more aligned with the tensile axis.
Adjacent lamellae chains ______ past each other and the chain folds become more aligned with the tensile axis.
Because they are crosslinked, elastomers are ______.
Because they are crosslinked, elastomers are ______.
Whiskers are thin single crystals with large length to diameter ratios and are exceptionally strong with high crystalline perfection, but very ______.
Whiskers are thin single crystals with large length to diameter ratios and are exceptionally strong with high crystalline perfection, but very ______.
The matrix phase generally consists of ______, polymer, or ceramic materials.
The matrix phase generally consists of ______, polymer, or ceramic materials.
Fibre continues deforming ______, while the matrix yields plastically.
Fibre continues deforming ______, while the matrix yields plastically.
The modulus of elasticity in the transverse direction is important for understanding the elastic behavior under ______ loading.
The modulus of elasticity in the transverse direction is important for understanding the elastic behavior under ______ loading.
Fibre materials commonly used in composites include glass, carbon, and ______.
Fibre materials commonly used in composites include glass, carbon, and ______.
The compressive stresses exerted by the rolls results in a reduction of ______.
The compressive stresses exerted by the rolls results in a reduction of ______.
When fibres fracture, the load is transferred fully to the ______.
When fibres fracture, the load is transferred fully to the ______.
During ______, a bar of metal is forced through a die orifice by a ram.
During ______, a bar of metal is forced through a die orifice by a ram.
Composite tensile strength is represented by the stress in the matrix at fibre ______.
Composite tensile strength is represented by the stress in the matrix at fibre ______.
In the drawing process, metal is pulled through a die having a tapered ______.
In the drawing process, metal is pulled through a die having a tapered ______.
Ceramic-matrix composites are ideal for ______ temperature applications.
Ceramic-matrix composites are ideal for ______ temperature applications.
The greatest diversity of applications is seen in ______-matrix composites.
The greatest diversity of applications is seen in ______-matrix composites.
______ processes are heat treatments in which material is exposed to elevated temperatures.
______ processes are heat treatments in which material is exposed to elevated temperatures.
Hybrid composites often combine different fibres, such as glass and ______ fibres in a single matrix.
Hybrid composites often combine different fibres, such as glass and ______ fibres in a single matrix.
Annealing may be accelerated at higher temperatures because ______ is involved.
Annealing may be accelerated at higher temperatures because ______ is involved.
Casting involves pouring molten metal into a mold cavity, and upon solidification, metal assumes the shape of the ______.
Casting involves pouring molten metal into a mold cavity, and upon solidification, metal assumes the shape of the ______.
Process annealing is used to negate the effects of cold work, to soften and increase ______ of previously strain-hardened metal.
Process annealing is used to negate the effects of cold work, to soften and increase ______ of previously strain-hardened metal.
If the rate of temperature change during annealing is too great, internal ______ may occur.
If the rate of temperature change during annealing is too great, internal ______ may occur.
Secondary creep becomes ______ -> rate is constant.
Secondary creep becomes ______ -> rate is constant.
Corrosion is the deteriorative loss of a metal as a result of ______.
Corrosion is the deteriorative loss of a metal as a result of ______.
Oxidation results in the formation of a non-metallic scale or ______.
Oxidation results in the formation of a non-metallic scale or ______.
Stainless steel is highly corrosion resistant in a variety of ______.
Stainless steel is highly corrosion resistant in a variety of ______.
A protective film normally re-forms ______ if it is damaged.
A protective film normally re-forms ______ if it is damaged.
Increasing temperature generally increases the rate of ______ reactions.
Increasing temperature generally increases the rate of ______ reactions.
A galvanic couple involves the connection of two metals in a liquid ______.
A galvanic couple involves the connection of two metals in a liquid ______.
Uniform attack occurs in equivalent intensity over the entire exposed ______.
Uniform attack occurs in equivalent intensity over the entire exposed ______.
Cold working a metal makes it more susceptible to ______.
Cold working a metal makes it more susceptible to ______.
The metal becomes positively charged as it loses ______ electrons.
The metal becomes positively charged as it loses ______ electrons.
Used when the finished shape is large or complicated, recovery and recrystallization are allowed to occur, but heat treatment is usually terminated before grain growth as fine ______ are sometimes preferable.
Used when the finished shape is large or complicated, recovery and recrystallization are allowed to occur, but heat treatment is usually terminated before grain growth as fine ______ are sometimes preferable.
In sand casting, ordinary sand is used as the mold material, and a ______ system is incorporated to expedite metal flow and minimize defects.
In sand casting, ordinary sand is used as the mold material, and a ______ system is incorporated to expedite metal flow and minimize defects.
In die casting, liquid metal is forced into a mold under ______ at a high velocity.
In die casting, liquid metal is forced into a mold under ______ at a high velocity.
Stress relief is used to eliminate residual stresses that developed as a result of machining or ______.
Stress relief is used to eliminate residual stresses that developed as a result of machining or ______.
In annealing of ferrous alloys, normalizing is used to refine the irregular grain shapes produced by plastic ______.
In annealing of ferrous alloys, normalizing is used to refine the irregular grain shapes produced by plastic ______.
Full anneal involves allowing the metal to turn into ______ then cooled in air after reaching a specific temperature.
Full anneal involves allowing the metal to turn into ______ then cooled in air after reaching a specific temperature.
Precipitation heat treating involves heating the supersaturated alpha solid solution to an intermediate ______ within the two-phase region.
Precipitation heat treating involves heating the supersaturated alpha solid solution to an intermediate ______ within the two-phase region.
In precipitation heat treating, diffusion rates become ______ at certain elevated temperatures.
In precipitation heat treating, diffusion rates become ______ at certain elevated temperatures.
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Study Notes
Corrosion
- Corrosion is the deterioration of metals as a result of dissolution due to environmental reactions.
- Oxidation is the formation of non-metallic scale or film.
- Degradation is the deteriorative process that occurs with polymers.
Passivity
- Passivity is the loss of chemical reactivity. Under some environmental conditions, some metals and alloys become extremely inert. This behavior occurs due to the formation of a protective film.
- Passivity is exhibited by Cr, Ni, Ti, and their alloys.
- Stainless steel (Fe alloyed with at least 11% Cr) is highly corrosion-resistant in various atmospheres.
- Passive behavior results from the formation of a thin, adherent oxide film on the metal surface, which acts as a barrier against corrosion.
- If damaged, the protective film usually reforms rapidly.
- Changes in the environment might cause the metal to revert to an active state, leading to increased corrosion rates.
Environmental Effects
- Increasing fluid velocity enhances corrosion due to erosive effects.
- Increasing temperature increases the rate of chemical reactions.
- Increasing corrosion concentration increases the corrosion rate.
- For materials capable of passivation, raising corrosion content may result in a transition from an active to a passive state, significantly reducing corrosion.
- Cold working or plastically deforming a metal makes it more susceptible to corrosion.
Forms of Corrosion
- Uniform attack occurs with equivalent intensity over the exposed surface, often leaving behind a scale or deposit.
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