Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MEE 214 > engineering materials > Flashcards

engineering materials Flashcards

1
Q

explain the 3 crystal structures and give 2 examples

include diagram

A
  1. The body-cubic centered structure has atoms arranged so that their centres are positioned on the corners of a cube, with one atom in the centre. Lithium, Sodium, Potassium,
    - it has a packing factor of 0.68
    - has a coordination number of 8
  2. the face centered cubic structure has atoms located at each of the corners and the centers of all the cubic faces. eg. gamma-iron, copper, aluminum ,gold, silver,nickel, platinum.
    - has a packing factor of 0.74
    - 12 coordination number
  3. The hexagonal close packed (HCP) structure helps to explain why different metals have different physical properties. e.g Berryllium, zinc, magnesium
    - 12 coordination number
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Modern use of phase diagram

A
  1. in deciding which composition to use.
  2. A major use of eutectics or near eutectics is in solder. In plumbing, solder is used in joining copper pipes together, producing waterproof seal.
  3. it useful to create phase diagrams which involves three elements, called ternary diagrams to mix several elements in order to improve properties of the materials.
  4. electric solder uses a similar alloy to join parts of an electronic circuit together.
  5. To know the melting point of alloys so as to know what alloy to use.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

phase transition with examples

A

the crossing of any two-phase curve in a phase diagram is called a transition.
melting is a process of solid transitioning to a liquid, and freezing is a process of liquid transitioning to a solid.
vaporization is when liquid transit to a gaseous or vapour phase.
condensation is a vapour transitioning to a liquid. sublimation is when a solid transit from the solid state to a vapour state, without passing through the liquid state. and deposition denotes a vapour transitioning to a solid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

polymorphism

A

is the ability of a solid to exist in more than one crystal form. also known as allotropy e,g diamond and graphite are allotropes of carbon.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Steel

A

steel is an Iron-Carbon alloy that has its carbon composition up to 1.5%, but not exceeding 2.06%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

phase composition of the iron-carbon alloys at room temp

A
  1. hypoeutectoid steels: … has carbon content from 0 to 0.83%. has beteween 0.025% and ….less than the eutectoid point.
  2. eutectoid steels: has a carbon content of 0.83%
  3. hypereutectoid steels: has carbon content from 0.83 to 2.06%
  4. cast irons: has carbon content from 2.06% to 4.3%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

the eutectic concentration of carbon at 4.3% is known as

A

ledeburite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

atomic difffusion and the condition at which active diffusion occurs

A

atomic diffusion is a material transport by atomic motion. active diffusion occur if the temperature is high enough to overcome energy barriers to atomic motion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

note on viscosity

A

It is the measure of the resistance of a fluid deforming by either shear or tensile stress. The relationship between shear stress and velocity gradient is also known as viscosity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

note on metals

A

a metal is a chemical element that is a good conductor of both electricity and heat and forms cations and ionic bonds with non-metals.
T hey are characterized by the following:
-they are strong and can be formed easily into useful shapes
- they have characteristics metallic lust
-they are good conductors of electrical current
- they can be deformed, allowing them to yield to sudden and severe loads.
Mechanical properties of metals: SEPTEMBER SCHD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

stress-stress diagram

A

it expresses a relationship between a load applied to a material and the deformation off the material, caused by the load. stress-strain diagram is determined by tensile testing.

  1. ultimate strength
  2. yield strength
  3. fracture
  4. strain hardening region
  5. necking region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

2 what is tensile testing/tension testing

  1. how tensile testing is useful (3 reasons)
  2. 3 xctics that are directly measured via a tensile test.
  3. 4 measurement that can be derived from the xstics above
A
  1. tensile testing is a fundamental materials science test in which a sample is subjected to uniaxial tension until failure occurred.
  2. to select a material for an application, for quality control, to predict the reaction of a material under other types of forces.
  3. ultimate strength, maximum elongation, and reduction in area.
  4. young’s modulus, Poisson’s ratio, yield strength, and strain-hardening xctics.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  1. what is load?
    - ways in which loading can be applied to a material (types of load) 4.
    - types of forces acting on materials with diagramatic explanation.
    - define compressive stress & compressive strain.
A
  1. load is defined as any external force acting upon a material or machine part.
  2. dead or steady load: the load does not change in magnitude or direction
    - live or variable load: it changes continually
    - suddenly applied or shock loads:…a load is suddenly applied or removed
    - impact lad: it is applied with some initial velocity.
  3. Tensile stress: when a body is subjected to two equal and opposite axial pulls F (also called tensile load), then the stress induced at any section of the body is called tensile stress.
    - tensile strain: when a tensile load is applied to a body there is a decrease in the cross sectional area and an increase in the length of the material. the ratio of the increase in length to the original length is known as tensile strain.
  4. Compressive stress: when a body is subjected to two equal and opposite axial pushes F (also called compressive load or load in compression), then the stress induced at any section of the body is called compressive stress.
    - compressive strain: when a tensile load is applied to a body there is a decrease in the cross sectional area and an increase in the length of the material. the ratio of the decrease in length to the original length is known as compressive strain.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is a lattice?

list with examples the 7 lattice systems( from least to the most symmetric).

Tecno, mobile, Refurbished, HOTC

A
  1. a lattice is a mathematical abstraction that describes the way the atoms or groups of atoms are repeated in space.
    triclinic: k2s208, monoclinic ( kno2), rhombohedral ( sb, hg), hexagonal (zn), orthorhombic ( Ga), tetragonal ( nacl), cubic ( nacl)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

elasticity with diagram

A

it is the property of a material to regain its original shape after deformation when the external forces are removed. this property is desirable for materials (metals) used in tools and machines. it is noteworthy that steel is more elastic than rubber. reversible elasticity in metals can be described by Hook’es law of restoring forces where the stress is proportional to strain. forces lager than the elastic limit may cause permanent/irreversible deformation of the material. i.e plasticity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

plasticity with diagram

A

plasticity is the property of a material to undergo significant permanent deformation without undergoing fracture, when subjected to a stress.this happens to elastic materials when the stress exceeds a certain limit, known as the yield strength or point for that material. plasticity is as a result of bond breading and bond reforming. normally, plastic materials undergo large deformation for a relatively small stress. a perfectly plastic material shows no tendency to revert to its original shape once it has been subjected to a stress. hence, plasticity is a property of a material which retains the deformation produced under load permanently.. this property of the material is necessary for forgings, in stamping images on coins and in ornamental work.
diagram: punch, die; bending force, plastic deformation,: remains bent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

tensile properties

A

tensile properties indicate how the material will react to forces being applied in tension. tensile tests are used to dertermine the modulus of elaticity, elastic limit, ….

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

stiffness

A

is the ability of a material to resist deformation under stress. the modulus of elasticity is the measure of stiffness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

elastic limit

A

is the highest stress a material can withstand without any measurable permanent strain remaining on the complete release o the load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

strength

A

is the ability of a metal or material to resist the externally applied forces without breaking/fracturing or yielding.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

ultimate tensile strength

A

is the maximum engineering stress reached in a tension test

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

yield strength

A

is the stress required to produce a small-specified amount of plastic deformation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

malleability with diagram

Hint: definition, reason for malleability, examples of materials…

A

is a special case of ductility which permits materials to be rolled or hammered into sheets and to be able to retain the deformation without fracturing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

ductility; usefulness stress strain graph of a ductile and brittle material; eg of ductile materials

A

the ductility of a material is a measure of the extent to which a material will deform before fracture. it is the ability to deform before breaking. this property of a material enables it to be drawn into wire with the application of a tensile force.
it provides an indication of how visible overload damage to a component might become before the component fractures. it is also used for quality control meausre to assess the level of impurities and proper processing of a material.
diagram: fig. 8.18
e.g copper, aluminium, tin, lead, zinc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

brittleness

A

it is the property of breaking of a material with little permanent distortion. it is the property of a material opposite to ductility. brittle materials when subjected to tensile loads snap off without giving any sensible elongation. e.g cast iron, glass. materials that easily get fractured are called brittle materials.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

machinability:

A

it is the property of a material which refers to a relative ease with which a material can be cut or machined. brass is machinable than steel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

note on creep

A

creep is the permanent deformation that a material experiences when it is subjected to stresses below the yield strength for extended periods of time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

fatigue

A

It is the inability of a material to return to its original shape after being subjected to repeated stresses

29
Q

toughness with e.g

A

It is the ability to absorb large amounts of stress, deforming plastically before breaking. polythene and steel are examples

30
Q

resilience

A

is the property of a material to absorb energy and to resist shock and impact loads elastically.

31
Q

difference between crystalline solids and amorphous solid

A

crystalline solid:

  • . they have characteristic geometrical shape.
  • they have highly ordered three-dimensional arrangements of particles.
  • they are bounded by planes or faces.
  • planes of a crystal intersect at particular angles.
  • they have sharp melting points and boiling points.
  • e.g includes, NaSO4, diamond, graphite nacl.

amorphous solid:

  • does not have a definite geometrical shape
  • they are randomly arranged in three dimensions
  • they don’t have sharp melting points.
  • they are formed due to sudden cooling of liquid.
  • melt over a wide range of temp
  • e.g include: coal, coke, glass, plastic , rubber
32
Q

difference between material science and engineering materials

A

material science is the branch of science that is basically concerned with the search for basic knowledge about the internal structure, properties and processing of materials.

while engineering materials are simple materials used to produce technical products.

33
Q
  1. heat treatment of steels

2. aim of heat treatment

A

Heat treatment of steel generally means heating alloy to a required temperature, holding it for sometime and cooling it to 25 deg. C without getting it turn into liquid.

  1. to increase the hardness of metals.
    - to relieve the stresses set up in the material after hot or cold working.
    - to improve machinability.
    - to soften the metal
    - to change the grain size.
    - to improve its electrical and magnetic properties.
    - to increase the qualities of a metal
34
Q

note on normalising (main objectives and how it is done)

A
  • to remove strains caused by cold working processes like hammering, rolling, bending, e.t.c., that can make the metal brittle and unreliable.
  • to improve mechanical and electrical properties.
  • to remove dislocations caused in the internal structure of the steel due to hot working
  • to refine the grain structure of the steel to improve machinability, tensile strength, and structure of weld.

process: the process of normalising consists of heating the steel from 30 to 50 degree Celsius above its upper critical temp ( for hypoeutectoid steels) or Acm line ( for hypereutectoid steels). it is held at this temp for about fifteen mins and then allowed to cool down in still air.

35
Q

note on Annealing (main objectives, types, and how it is done)

Soften, rm internal stress, refine grain, rm gases, alter,

A
  • to soften the steel so that it may be easily machined or cold worked.
  • to refine the grain size and structure to improve mechanical properties like strength and ductility.
  • to relieve internal stressess which may have been cause by hot or cold working or by unequal contraction in casting.
  • to alter electrical, magnetic or other physical properties.
  • to remove gases trapped in the metal during initial casting.

types:

a. full annealing. the purpose of full annealing is to soften the metal to refine the grain structure, to relieve the stresses and to remove trapped gases in the metal. the process:
i. heating the steel from 30 to 50 degree Celsius above the upper critical temp for hypoeutectoid steel and by the same temp above the lower critical temp for hypereutectoid.
ii. holding it at this temp for some time to enable the internal changes to take place. the time allowed is approximately 3 to 4 mins for each millimetre of thickness of the largest section, and
iii. cooling slowly in the furnace.

b. process annealing: is used for relieving the internal stresses previously set up in the metal and for increasing the machinability of the steel. in this process steel is heated to a temp below or close to the lower critical temp, held at this temp for some time and then cooled slowly. this may cause complete re-crystallization in steels which have been severely cold worked and a new grain structure is formed. the process annealing is commonly used in the sheet and wire industries.

36
Q

Difference between Eutectic & Peritectic vs Eutectoid & Peritectoid (with diagram)

A

Liquids are involved vs solids are involved.

37
Q

Eutectoid steel

A

a steel with carbon content of 0.8%

38
Q

Hyper-Eutectoid steel

A

a steel with carbon content between 0.8% &2.06%

39
Q

cast iron

A

C between 2.06 & 4.3%

40
Q

Ferrous metal vs non-ferrous metal

A

metal that has iron as its main constituent (steel, cast iron) vs metal that has metals other than iron as it main constituent (cu, sn, al)

41
Q

Iron ores

A

Magnetite (Fe2O3) black
Hematite Fe3O4) Red
Limonite (FeCO3) Brown
Siderite (Fe2O3 H2O) Brown

42
Q

types of cast iron

A
  • Grey
  • White,
  • Chilled
  • malleable,
  • Mottled,
  • Nodular
43
Q

Effect of impurities on cast iron

SSMP

A
  • Silicon makes it soft and easily machinable.
  • Sulphur makes it hard and brittle
  • Manganese makes it white and hard
  • phosphorus makes it brittle
44
Q

Effect of impurities on cast iron

A
  • silicon makes it harder
  • manganese toughens the metal and increases it critical temperature.
  • phosphorus make it brittle.
45
Q

types of steel

A

Dead mid-steel
Low carbon or Mild steel
Medium steel
High carbon steel

46
Q

What alloys makes up stainless steel

A

Nickel and Chromium

47
Q

Classifications of engineering materials

A

Diagram

48
Q

What are ceramics

A

Ceramics are brittle, inorganic and non metallic materials, composed of more than one element that are commonly used for electrical and thermal insulators

49
Q

Characteristics of ceramics

A
  • They have been subjected to heat treatment
  • They are heat resistant
  • They can sustain large compressive loads at high temp
  • They are hard brittle materials.
50
Q

Types of ceramics

A

White ware
Structural clay
Glass
Refractory materials

51
Q

3 Ceramic forming techniques

A

Hydro plastic forming
Slip casting
Drying and moulding

52
Q

What are abrasives

A

They are hard, mechanically resistant ceramic materials (diamond, AL oxide) used for cutting and grinding.

53
Q

Types and applications of abrasives

A
  1. Diamond : applied in: brick saws, drilling hard rocks, polishing hard carbide metal, glass and ceramics.
  2. Emery: for sand paper
  3. Walnut shells: for cleaning aircraft engine parts
  4. Gamet and flint: for sand papers
54
Q

Types of cement

A 
Portland (artificial) 
Natural
Coloured
Rapid
Low heat
55
Q

Characteristics of polymers

A 
Low density
Good corrosion resistance 
Good mouldability
Economical
Low mechanical properties
Poor tensile strength
56
Q

Polymerization

A

Process of converting a moniker or a mixture of monomers into a polymer

57
Q

Types of polymerization

A

Addition
Copolymerization
Condensation polymerization

58
Q

Alloys of copper

A

Copper-zinc-alloys (brass)

Copper-tin-alloys(bronze)

59
Q

Alloys of aluminum

A

Duralumin (4% cu) : wrought conditions : forging, stamping
Magnalium (1.75% cu) in aircraft engines and astromobile components.
Hindalium for anodized utensil manufacture.
Copper-aluminium: for casting purposes, aircraft engines

60
Q

What is crystallography

A

crystallography is the branch of science dealing with the formation, structure and properties (FSP) of crystals.

61
Q

Applications of crystallography

A

it helps in the identification of unknown materials and reveals the crystal stucture of the sample.

to calc the amount of phases present

62
Q

3 factors to consider when selecting a materials

A
  • availability of the materials.
  • the cost of the materials
  • suitability of the materials for the working conditions in services.
63
Q

with the aid of a diagram differentiate between eutectic & peritectic vs eutectoid & peritectic transformations

A

Eutectic & Peritectic: liquids are involved while

Eutectoid & peritectoid: solids are invoved

64
Q

what is yield point

A

it is the point which the material becomes plastic

65
Q

What is corrosion

A

corrosion is the degradation of a material due to a reaction with it’s environment.

66
Q

Types of corrosion

A

Galvanic corrosion
microbial corrosion
high temp corrosion
passivation

67
Q

methods of corrosion protection

A

Applied coating
reactive coating
cathodic protection
anodic protection

68
Q

classification of engineering materials

A

..note

MEE 214 (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions