Engineering Materials Flashcards
Refers to the group of materials that are used in the construction of manmade structures and components.
Engineering Materials
Selection of Materials for Engineering purposes (3)
Availability, Sustainability, and Cost
is the smallest unit of matter that retains all of the chemical properties of an element. Combine to form molecules, which then interact to form solids, gases, or liquids.
Atom
Atom consists of three basic particles
proton (positive charge), neutron (no charge), electron (negative charge)
describes the orbitals occupied by electrons on the atom.
Electron Configurations
states that each successive electron occupies the lowest energy orbital available and dictates how electrons are filled in the atomic orbitals of an atom in its ground state.
Aufbau Principle
states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.
Pauli’s Exclusion Principle
Every orbital in a sublevel is singly occupied before any orbital is doubly occupied. All of the electrons are singly occupied orbitals have the same spin.
Hund’s Rule
are formed by the joining of two or more atoms. is the physical phenomenon of chemical substances being held together by attraction of atoms though sharing
Chemical Bonding
involve sharing of a pair of valence electrons by two atoms
Covalent Bonds
For atoms with the largest electronegativity differences (such as metals with nonmetals)
Ionic Bonds
typically represented as being transferred from the metal atom to the nonmetal.
Valence Electrons
is the sharing of many detached electrons, where the electrons act as a glue giving the substance a definite structure.
Metallic Bonds
conduct heat well because of delocalized electrons. The electrons drift slowly through the structure as the metal is heated. As the metal heats up, the electrons move faster.
Conductivity of Metals
energy is created by electrons in motion Because the valence electrons in metals are relatively free to move about when you apply a negative charge to the end of a piece of metal and a positive charge to the other end.
Electrical Conductivity of Metals
The delocalized electrons of the metallic bond in the “sea” of electrons allow the metal atoms to roll over each other when stress is applied.
Malleability and Ductility
Physical Properties of Metal
appearance, color, size and shape, luster, weight, density, melting point, and boiling point.
are those associated with the ability of the material to resist mechanical forces and load
Mechanical Properties of Metals
is the ability to resist externally applied forces without breaking or yielding
Strength
ability of a material to resist deformation under stress
Stiffness
is the property of a material to regain its original shape after deformation when the external forces are removed. Desirable for materials used in tools and machines.
Elasticity
property of material that retains the deformation produced under load permanently.
Plasticity
Is the property of a material enabling it to be drawn into the wire with the application of tensile force.
Ductility
is the opposite of Ductility. Property of breaking of a material with little permanent distortion.
Brittleness
special case of ductility which permits materials to be rolled or hammered into thin sheets.
Malleability
is a property of a material to resist a fracture due to high-impact loads like hammer blows.
Toughness
is the property of a material which refers to a relative case with which a material can be cut.
Machinability
is the property of a material to absorb energy and to resist shock and impact loads
Resilience
When a part is subjected to constant stress at high temperature for a long period of time.
Creep
is subjected to repeat stresses, it fails at stresses below the yield
Fatigue
it is a very important property of the metals and has wide variety of meanings.
Hardness
Hardness of a metal may be determined by (4)
Brinell, Rockwell, Vickers, Shore Scleroscope
Thermal Properties of Metals
Thermal conductivity, Expansion coefficient, Resistivity, Thermal shock resistance, and Thermal diffusivity.
Electrical Properties of Metals
Conductivity, resistivity, dielectric strength, thermoelectricity, superconductivity, and electrical hysteresis.
Chemical Properties of Metals
Reactivity, Corrosion resistance, polymerization, composition, acidity, and alkalinity
Optical Properties of Metals
Reflectivity, Refractivity, absorptivity, transparency, opaqueness, color, and luster.
Metallurgical Properties of Metals
Grain size, heat treatment done/required, anisotropy, and hardenability
Classification of Engineering Materials
Metal, Composite, Ceramic, Polymer
Systematic Arrangement or Division of Materials
General Properties, Nature of Materials, Applications
most commonly used class of engineering material, formed by combining a metal with one or more other metallic and/or non-metallic materials.
Metals
containing a high proportion of the element iron. The strongest materials available are used for applications where high strength is required at a relatively low cost
Ferrous Metals
have iron as the base element. Mos common metal alloys in use due to the abundance or iron.
Ferrous Alloys
is an important alloying element in all ferrous alloys. Higher level of carbon increase strength and hardness, and decreases ductility and weldability
Carbon
basically just mixture of carbon and iron
Carbon Steel
contains between 0.30% carbon. Low strength but high ductility. Very weldable and is inexpensive to produce.
Low-Carbon Steel
contains between about 0.30% to 0.70% carbon.
Medium-Carbon Steel
contains between 0.70% to 1.40%
High-Carbon Steel
commonly called alloy steels, contains less than about 8% total alloying ingredients. Typically stronger than carbon steels and have better corrosion resistance.
Low-Alloy Steel
primarily used to make tooling for use in manufacturing.
Tool Steel
have good corrosion resistance, mostly due to the addition of chromium as an alloying ingredient.
Stainless Steel
a ferrous alloy containing high levels of carbon, generally greater than 2%. The carbon present in _____ can take the form of graphite or carbide
Cast Iron
Advantages of Cast Iron
Better corrosion resistance, high strength in compression, easy to cast.
Disadvantages of Cast Iron
Very brittle, poor weldability
The carbon is in the form of graphite flakes. Has low tensile strength, high compressive strength, and no ductility. free graphite in its structure acts as a lubricant.
Gray Cast Iron
Resulting material of Gray Cast Iron because the magnesium causes the graphite flakes to form into spherical nodules. has good strength, ductility, and machinability.
Ductile Cast Iron (Nodular Cast Iron)
has carbon in the form of carbide (known as cementite) which is a hard constituent of iron. Primarily used for wear-resisting components as well as for the production of malleable cast iron
White Cast Iron
used for machine parts for which the steel forgings would be too expensive.
Malleable Cast Iron
the purest iron which contains at least 99.5% iron but may contain up to 99.9% iron.
Wrought Iron
materials refer to the remaining metals known as to mankind.
Non-Ferrous Metals
Non-Ferrous Materials Characteristics (4)
Ease of Fabrication, Resistance to corrosion, Electrical and thermal conductivity, and weight
a white metal produced by electrical processes from its oxide (alumina), which is prepared from a clayey called bouxite. Light metal has a specific gravity of 2.7 and a melting point of 658 C. Tensile strength varies from 90 MPa to 150 MPa.
Aluminium
Composed of 95% Aluminium, 4% copper, 0.5% manganese, and 0.5% magnesium.
Duralumin
if the metal is allowed to age for 3 or 4 days, it will be hardened.
Age Hardening
also called copper-aluminium alloy. The addition of 4% copper to pure aluminium increases its strength and machinability.
Y-Alloy
Made by melting the aluminium with 2 to 10% magnesium in a vacuum and then cooling it in a vacuum or under pressure of 100 to 200 atmospheres. Contains about 1.75% of copper.
Magnalium
An alloy of aluminum and magnesium with a small quantity of chromium.
Hindalium
is a group of nickel alloys, primarily composed of nickel (from 52 to 67%) and copper, with the small amounts of iron, manganese, carbon, and silicon.
Monel
is a nickel-chromium alloy that is classified as superalloy because of its high-performance qualities and resistance to corrosion and oxidation
Inconel
is a nickel-molybdenum-chromium superalloy with an addition of tungsten designed to have excellent corrosion resistance in severe environments.
Hastelloy
one of the most widely used non-ferrous metals in industry. Its specific gravity is 8.9 and its melting point is 1083 C. Tensile strength varies from 150 MPa to 400 MPa.
Copper
most widely used copper zinc alloy is brass. Fundamentally a binary alloy of copper with zinc each 50%.
Copper-Zinc Alloys (Brass)
composition of 75 to 95% copper and 5 to 25% tin.
Copper-tin alloys (Bronze)
is an alloy of copper, tin, and zinc. Usually 88% copper, 10% tin, and 2% zinc. Also known as Admiralty gun metal.
Gun Metal
a blush grey metal having specific gravity 11.36 and melting point of 326 C.
Lead
It is used for making important alloys, fine soldier, as a protective coating for iron and steel sheets and for making tin foil.
Tin
These alloys can be casted easily with a good finish at fairly lo temperatures.
Zinc Base Alloys
are widely used in engineering industry on account of their high mechanical strength properties, corrosion resistance.
Nickel Base Alloys
an important alloy of nickel and copper. It has tensile strength from 390 MPa to 460 MPa.
Monel Metal
It consists of 80% nickel, 14% chromium, and 6% iron. Its specific gravity 8.55 gravity and its melting point 1395 C
Inconel Metal
Consists of 65% nickel, 15% chromium, and 20% iron
Nichrome
Consists of 80% nickel and 20% chromium.
Nimonic
These are non- metallic materials that do not exist in nature. They combine good resistance with ease of manufacture, being used for the joining of metallic components.
Synthetic Materials
so diverse that only a few can be listed here to give basic introduction to some applications.
Natural Materials
naturally occurring fibrous composite material used for the manufacture of casting patterns.
Wood
used for hydraulic and compressed air hoses and oil seals
Rubber
This is a hardwearing, abrasion-resistant material with excellent weathering properties.
Glass
widely used in abrasive and is a naturally occurring aluminum oxide.
Emery
produced by baking naturally occurring clays at high temperatures.
Ceramic
can be used for cutting tools for operation at high speeds for metal finishing where surface finish is greater importance.
Diamonds
Used as bearing lubricants, cutting fluids, and fuels.
Oils
used as an alloying element and also for the manufacture of semiconductor devices.
Silicon