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PDF 5 Flashcards

1
Q

——- : The capatciy to absorb energy better than other classes of materials.

A

Toughness

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2
Q

——–: An alloy of iron containing from 0.02% and 2.11%

carbon by weight

A

Steel

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3
Q

Steel alloys can be grouped into four

categories:

A
  1. Plain carbon steels
  2. Low alloy steels
  3. Stainless steels
  4. Tool steels
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4
Q

Fill the blank :
Strength of plain carbon steels ——- with
carbon content, but ductility is ———-

A

İncreased

Reduce

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5
Q

Fill the blank :
10XX, where
10 indicates ——————-, and XX indicates
——– % in hundredths of percentage points

A

plain carbon steel,

carbon

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6
Q

What are the applications of low carbon steel

less than 0.20% C

A

Applications: automobile sheetmetal parts, plate

steel for fabrication, railroad rails

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7
Q

What are the applications of medium carbon steel

between 0.20% and 0.50% C

A

Applications: machinery components and engine

parts such as crankshafts and connecting rods

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8
Q

What are the applications of high carbon steel

- greater than 0.50% C

A

Applications: springs, cutting tools and blades,

wear-resistant parts

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9
Q

Fill the blanks:
AISI-SAE designation uses a 4-digit number system:
YYXX, where YY indicates ———- ———- and XX
indicates ———% in hundredths of % points

A
  • alloying elements

- carbon

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10
Q

——-:Highly alloyed steels designed for corrosion

resistance

A

Stainless Steel

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11
Q

Types of Stainless Steel:

A
  1. Austenitic stainless - typical composition 18% Cr
    and 8% Ni
  2. Ferritic stainless - about 15% to 20% Cr, low C,
    and no Ni
  3. Martensitic stainless - as much as 18% Cr but no
    Ni, higher C content than ferritic stainless
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12
Q 
-------: A class of (usually) highly alloyed steels designed for 
use as industrial cutting tools, dies, and molds
A

Tool Steels

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13
Q

Fill the blank:

Tools Steels are ———–

A

heat treated

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14
Q

——-: Iron alloys containing from 2.1% to about 4%

carbon and from 1% to 3% silicon

A

Cast Iron

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15
Q

Types of Cast Iron:

A
  • Gray cast iron
  • Ductile iron
  • White cast iron
  • Malleable iron
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16
Q

Fill the blank:
-Grey cast iron has -% silicon and -% carbon
-The
silicon in grey cast iron causes the carbon to change
into ———. With less silicon, the carbon in white
cast iron changes to ———– (Fe3C).

A
  1. 3 , 2

2. graphite , cementite

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17
Q

——–: Metal elements and alloys not based on iron

A

Nonferrous Metals

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18
Q

Types of Nonferrous Metals :

A

aluminum, copper, magnesium,

nickel, titanium, and zinc, and their alloys

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19
Q

NOTE:
Although not as strong as steels, certain nonferrous
alloys have strength-to-weight ratios that make them
competitive with steels in some applications

A

NOTE:
Many nonferrous metals have properties other than
mechanical that make them ideal for applications in
which steel would not be suitable

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20
Q

Fill the blanks:
1. Aluminum (Al) and magnesium (Mg) are —— metals
NOTE:
Both elements are abundant on earth, aluminum on
land and magnesium in the sea
Neither is easily extracted from their natural
states

A
  1. light
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21
Q

PROPERTIES OF ————–
High electrical and thermal conductivity
Excellent corrosion resistance due to formation of a
hard thin oxide surface film
Very ductile metal, noted for its formability
Pure aluminum is relatively low in strength, but it
can be alloyed and heat treated to compete with
some steels, especially when weight is taken into
consideration

A

Aluminum

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22
Q

————–:
Lightest of the structural metals
Available in both wrought and cast forms
Relatively easy to machine
In all processing of magnesium, small particles of the
metal (such as small metal cutting chips) oxidize
rapidly
Care must be exercised to avoid fire hazards

A

Magnesium

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23
Q

NOTE:
As a pure metal, magnesium is relative soft and
lacks sufficient strength for most engineering
applications
However, it can be alloyed and heat treated to
achieve strengths comparable to aluminum alloys
In particular, its strength-to-weight ratio is an
advantage in aircraft and missile components

A

NOTE: Designation Scheme for
Magnesium
Three-to-five character alphanumeric code
First two characters = letters that identify
principal alloying elements (up to two elements)
Followed by a two-digit number that indicates,
respectively, the amounts of the two alloying
ingredients to nearest percent
Example: AZ63A – aluminum 6%, zinc 3%,
magnesium 91%

24
Q

———-:
One of the oldest metals known to mankind
Low electrical resistivity - commercially pure
copper is widely used as an electrical conductor
Also an excellent thermal conductor
One of the noble metals (gold and silver are also
noble metals), so it is corrosion resistant

A

Copper

25
Q

Copper Alloys:

A

Bronze - alloy of copper and tin (typical ∼ 90%
Cu, 10% Sn), widely used today and in ancient
times
Brass - alloy of copper and zinc (typical ∼ 65%
Cu, 35% Zn).
Highest strength alloy is beryllium-copper (only
about 2% Be), which can be heat treated to high
strengths and used for springs

26
Q

———–:
Similar to iron in some respects:
Magnetic
Modulus of elasticity ≅ E for iron and steel
Differences with iron:
Much more corrosion resistant - widely used as
(1) an alloying element in steel, e.g., stainless
steel, and (2) as a plating metal on metals such as
plain carbon steel
High temperature properties of Ni alloys are
superior

A

Nickel

27
Q

NOTE:

A

Alloys of nickel are commercially important and are
noted for corrosion resistance and high temperature
performance
In addition, a number of superalloys are based on
nickel
Applications: stainless steel alloying ingredient,
plating metal for steel, applications requiring high
temperature and corrosion resistance

28
Q

——–:
Coefficient of thermal expansion is relatively low
among metals
Stiffer and stronger than Al
Retains good strength at elevated temperatures
Pure Ti is reactive, which presents problems in
processing, especially in molten state
At room temperature Ti forms a thin adherent oxide
coating (TiO2
) that provides excellent corrosion
resistance

A

Titanium

NOTE:
In the commercially pure state, Ti is used for
corrosion resistant components, such as marine
components and prosthetic implants
Titanium alloys are used as high strength
components at temperatures ranging up to above
550°C (1000°F), especially where its excellent
strength-to-weight ratio is exploited
Alloying elements used with titanium include
aluminum, manganese, tin, and vanadium

29
Q

———–:
High-performance alloys designed to meet
demanding requirements for strength and
resistance to surface degradation at high service
temperatures
Many superalloys contain substantial amounts of
three or more metals, rather than consisting of one
base metal plus alloying elements
Commercially important because they are very
expensive
Technologically important because of their
unique properties

A

Superalloys

30
Q

Why Superalloys are Important

A

Room temperature strength properties are good but
not outstanding
High temperature performance is excellent -
tensile strength, hot hardness, creep resistance, and
corrosion resistance at very elevated temperatures
Operating temperatures often ~ 1100°C (2000°F)
Applications: gas turbines - jet and rocket engines,
steam turbines, and nuclear power plants
(systems that operate more efficiently at high
temperatures)

31
Q

Three Groups of Superalloys

A
  1. Iron-based alloys - in some cases iron is less than 50%
    of total composition
    Alloyed with Ni, Cr, Co
  2. Nickel-based alloys - better high temperature strength
    than alloy steels
    Alloyed with Cr, Co, Fe, Mo, Ti
  3. Cobalt-based alloys - ∼ 40% Co and ∼ 20% chromium
    Alloyed with Ni, Mo, and W
    Virtually all superalloys strengthen by precipitation
    hardening
32
Q 
--------:
 Defined as an inorganic compound consisting of a metal 
(or semi-metal) and one or more nonmetals
 Important examples:
 Silica - silicon dioxide (SiO2
), the main ingredient 
in most glass products
 Alumina - aluminum oxide (Al2O3
), used in various 
applications from abrasives to artificial bones
 More complex compounds such as hydrous 
aluminum silicate (Al2Si2O5
(OH)4
), the main 
ingredient in most clay products
A

Ceramics

33
Q

NOTE:

A

Properties of Ceramic Materials
High hardness, electrical and thermal insulating,
chemical stability, and high melting temperatures
Brittle, virtually no ductility - can cause problems in
both processing and performance of ceramic
products
Some ceramics are translucent, window glass (based
on silica) being the clearest example

34
Q

Three Basic Categories

of Ceramics:

A
  1. Traditional ceramics - clay products such as
    pottery, bricks, common abrasives, and cement
  2. New ceramics - more recently developed
    ceramics based on oxides, carbides, etc., with
    better mechanical or physical properties than
    traditional ceramics
  3. Glasses - based primarily on silica and
    distinguished by their noncrystalline structure
35
Q

What is the type of following ceramics:
Based on mineral silicates, silica, and mineral oxides
found in nature
Primary products are fired clay (pottery, tableware,
brick, and tile), cement, and natural abrasives such
as alumina
Products and the processes to make them date back
thousands of years
Glass is also a silicate ceramic material and is
sometimes included among traditional ceramics

A

Traditional Ceramics

36
Q

What is the type of following raw materail :

consist of fine particles of hydrous aluminum
silicate
Mostly based on kaolinite, (Al2Si2O5
(OH)4
)
Mixed with water, clay becomes a plastic substance
that is formable and moldable
When heated to a sufficiently elevated temperature
(firing), clay fuses into a dense, strong material
Thus, clay can be shaped while wet and soft, and
then fired to obtain the final hard product

A

Clay

37
Q

What is the type of following raw materail :
Available naturally in various forms, most important is
quartz
Main source of quartz is sandstone
Low cost
Hard and chemically stable
Principal component in glass, and an important
ingredient in other ceramic products including
whiteware, refractories, and abrasives

A

Silica

38
Q

What is the type of following raw materail :
Bauxite - most alumina is processed from this
mineral, which is an impure mixture of hydrous
aluminum oxide and aluminum hydroxide plus similar
compounds of iron or manganese
Bauxite is also the principal source of aluminum
Corundum - a more pure but less common form of
Al2O3
, which contains alumina in massive amounts
Alumina ceramic is used as an abrasive in grinding
wheels and as a refractory brick in furnaces

A

Aluminia

39
Q

Traditional Ceramic Products :

A

Pottery and Tableware
Brick and tile
Refractories
Abrasives

40
Q

————-:
Ceramic materials developed synthetically over the
last several decades
Also refers to improvements in processing
techniques that provide greater control over
structures and properties of ceramic materials
New ceramics are based on compounds other
than variations of aluminum silicate
New ceramics are usually simpler chemically than
traditional ceramics; for example, oxides,
carbides, nitrides, and borides

A

New Ceramics

41
Q

————–:
Most important ——— ceramic is alumina Al2O3
Although included among traditional ceramics, alumina
is also produced synthetically from bauxite
Through control of particle size and impurities,
refinements in processing methods, and blending with
small amounts of other ceramic ingredients, strength
and toughness of alumina are improved substantially
compared to its natural counterpart
Alumina also has good hot hardness, low thermal
conductivity, and good corrosion resistance

A

Oxide Ceramics

42
Q

Products of Oxide Ceramics:

A

Abrasives (grinding wheel grit)
Bioceramics (artificial bones and teeth)
Electrical insulators and electronic components
Refractory brick
Cutting tool inserts
Spark plug barrels
Engineering components

43
Q

———–:
Includes silicon carbide (SiC), tungsten carbide (WC),
titanium carbide (TiC), tantalum carbide (TaC), and
chromium carbide (Cr3C2
)
Production of SiC dates from a century ago, and it is
generally included among traditional ceramics
WC, TiC, and TaC are hard and wear resistant and are
used in applications such as cutting tools
WC, TiC, and TaC must be combined with a metallic
binder such as cobalt or nickel in order to fabricate a
useful solid product

A

Carbide Ceramics

44
Q

—————-:
Properties: hard, brittle, high melting temperatures,
usually electrically insulating, TiN being an exception
Applications:
Silicon nitride: components for gas turbines,
rocket engines, and melting crucibles
Boron nitride and titanium nitride: cutting tool
materials and coatings

A

Nitrides

45
Q

Important nitride ceramics are:

A 
silicon nitride (Si3N4
), 
boron nitride (BN), and titanium nitride (TiN)
46
Q

Why So Much SiO2

in Glass?

A

Because SiO2
is the best glass former
Silica is the main component in glass products,
usually comprising 50% to 75% of total
chemistry
It naturally transforms into a glassy state upon
cooling from the liquid, whereas most ceramics
crystallize upon solidification

47
Q

Other Ingredients in Glass

A 
Sodium oxide (Na2O)
 Calcium oxide (CaO)
 Aluminum oxide (Al2O3
)
 Magnesium oxide (MgO)
 Potassium oxide (K2O)
 Lead oxide (PbO)
 Boron oxide (B2O3
)
48
Q

Functions of

Other Ingredients in Glass

A

Act as flux (promoting fusion) during heating
Increase fluidity in molten glass for processing
Improve chemical resistance against attack by
acids, basic substances, or water
Add color
Alter index of refraction for optics

49
Q

Advantages of Glass-Ceramics

A

Efficiency of processing in the glassy state
Close dimensional control over final shape
Good mechanical and physical properties
High strength (stronger than glass)
Absence of porosity; low thermal expansion
High resistance to thermal shock

50
Q

Applications of Glass-Ceramics

A 
Cooking ware (e.g., Corning ware)
 Heat exchangers
 Missile radomes
51
Q

————-:
Defined as a compound consisting of long-chain
molecules, each molecule made up of repeating units
connected together
There may be thousands, even millions of units in
a single polymer molecule
The word polymer is derived from the Greek
words poly, meaning many, and meros (reduced
to mer), meaning part
Most polymers are based on carbon and are
therefore considered organic chemicals

A

Polymers

52
Q

Types of Polymers

A
  1. Thermoplastic polymers
  2. Thermosetting polymers
  3. Elastomers
    where (1) and (2) are plastics and (3) are rubbers
53
Q

Reasons Why Polymers are

Important

A

Plastics can be molded into intricate part shapes,
usually with no further processing
Very compatible with net shape processing
On a volumetric basis, polymers:
Are cost competitive with metals
Generally require less energy to produce than
metals
Certain plastics are transparent, which makes them
competitive with glass in some applications

54
Q

Mechanical Properties of

Thermoplastics

A

Low modulus of elasticity (stiffness)
E is much lower than metals and ceramics
Low tensile strength
TS is about 10% of metal
Much lower hardness than metals or ceramics
Greater ductility on average
Tremendous range of values, from 1% elongation
for polystyrene to 500% or more for polypropylene

55
Q

General Properties of

Thermosets

A

Rigid - modulus of elasticity is two to three times
greater than thermoplastics
Brittle, virtually no ductility
Less soluble in common solvents than thermoplastics
Capable of higher service temperatures than
thermoplastics
Cannot be remelted - instead they degrade or burn

56
Q

Why Composites are Important

A

Composites can be very strong and stiff, yet very light in
weight
Strength-to-weight and stiffness-to-weight ratios are
several times greater than steel or aluminum
Fatigue properties are generally better than for common
engineering metals
Toughness is often greater
Possible to achieve combinations of properties not
attainable with metals, ceramics, or polymers alone

57
Q

Classification of

Composite Materials

A
  1. Metal Matrix Composites (MMCs) - mixtures of
    ceramics and metals, such as cemented carbides
    and other cermets
  2. Ceramic Matrix Composites (CMCs) - Al2O3 and SiC
    imbedded with fibers to improve properties
  3. Polymer Matrix Composites (PMCs) - polymer resins
    imbedded with filler or reinforcing agent
    Examples: epoxy and polyester with fiber
    reinforcement, and phenolic with powders

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