Materials ( 110101j ) Flashcards
Brittleness in a metal is what?
The ability to withstand distortion materials like glass, cast iron are considered brittle as they will shatter easily
How is a metal conductive?
Most metals are good conductors when they permit the flow of heat or electricity through them easily
What is metal ductility?
A metal that has the ability to withstand stretching, bending or twisting past its elastic limit without breaking or losing any other mechanical properties
What is metal elasticity?
Elasticity is the tendency of a metal to return to its original shape after it has been deformed
What is hardness in a metal?
Hardness is the ability of a metal to resist forces that tend to push the molecules apart
When a metal is malleable how is it described?
It can easily be drawn out by hammering or when forces are applied
What is strength of a metal?
The amount of high, steady stress a metal can withstand before it yields
What are 3 categories of heat treating?
Annealing
Quenching
Tempering
What is annealing?
A process used to release internal stresses in a hardened metal
What is quenching?
Quenching is a process that involves rapid cooling of a metal that is heated by immersion in a medium such as water or oil
What is oxidation?
The result of a metal that is exposed to oxygen in the atmosphere
What is a ferrous metal?
Metal that contains iron contents like mild steel
What is a non ferrous metal?
Metal that does not have iron in it
Like aluminum or copper
What are some pure metals?
Gold, silver, aluminum these metals are pure
What is an alloy?
Alloy metals are combination metals that have 2 or more metals
What is expanded metal?
Metal that is formed from slitting and expanding diamond shapes
What is perforated metal?
Solid sheets with holes punched in.
The holes can be round, square, or other patterns
What is most common name for hardware cloth?
Birdscreen, it is a wire mesh to cover openings against the entry of unwanted pests
What is galvanic action?
This is a corrosive process that results when dissimilar metals come into contact with an electrolytes such as moisture
What is one way to prevent galvanic action?
To provide a barrier between the two metals
What is the gauge of metal?
The thickness
What metal must not be used on any food equipment?
Zinc coated metal because the zinc and its compounds are poisonous
What is galvalume used for?
The outer wall of B-vent and L-vent chimney and fittings
What is an advantage of stainless steel?
A high resistance to heat and corrosion
What is a disadvantage of stainless steel?
Because of their high tensile strength they are more difficult to work with.
What is one advantage of aluminum?
It is lightweight weighing about one third the weight of steel
What are some common uses of aluminum?
Aluminum has many uses including automotive, aerospace and marine industries.
Aluminum foil in the packaging industry as well as soda cans and cooking utensils
What is copper?
A reddish brown metal that is considered an element.
It hardens when it is cold worked and is extremely tough
What are some advantages of copper?
It is an excellent conductor of heat and electricity. Because it’s oxides protect it from further oxidation it is a long lasting metal
What are advantages of brass?
Brass is highly malleable and are easily cast, forged, rolled and pressed.
What are two basic categories of plastics?
Thermosetting
Thermoplastic
What are thermosetting plastics?
Thermosetting plastics harden under heat such as vulcanized rubber, silicone
What are thermoplastic materials?
Materials that soften when heated and solidify when cooled
Where is PVC pipe used?
To vent high efficiency furnaces.
For corrosive fume exhaust systems
What is toughness in a metal?
The ability to withstand an impact load
What is no 4 stainless steel?
A stain finish on one side used for restaurant, kitchen etc
How is aluminum obtained?
From an ore called bauxite
What is the formula for an inside diameter measurement?
Add 20 percent of the material thickness to the side of the bend line
( in add 20)
What is the formula for an outside diameter measurement?
Subtract 80 percent of the metal thickness on all sides of the bend
( out sub 80)
How is copper gauged?
By the weight in ounces per square foot