GST 216
INDUSTRIAL MATERIALS
INDUSTRIAL MATERIALS
• Metals – Ferrous and non-ferrous
– Plain and Alloyed
– castings and wrought metals
• Non- Metals
i. plastics thermoplastics, thermosetting , elastomers
ii. Wood soft wood and hard wood
iii. Ceramics
iv. Composites
INDUSTRIAL MATERIALS
• Industrial materials are defined as those used in
the manufacture of “hard” goods, such as more or
less durable machines and equipment produced for
industry and consumers, as contrasted with
disposable “soft” goods, such as chemicals,
foodstuffs, pharmaceuticals, and apparel.
Industrial Materials
• Industrial materials are substances employed in industrial
processes for the creation of goods and artifacts.
• Materials may be classified in different ways: nature of
constituents, usage, etc. In general, they are classified as
metals and non-metals.
Metals
Most metals are solids at room temperature and exist as crystal
lattices with atoms held together by strong metallic bonds.
Metals are grouped into ferrous and non-ferrous materials.
Metals can further be classified as plain or alloy metals.
Plain metals are materials that have a significant composition of a
base element but contain traces of other elements mainly as
impurities.
Alloy metals are materials that have one or more base elements but
contain significant amount of other elements that are used to impact
specific properties.
Metals
An alloy is an element added to a base material so as to modify the
properties of the base material.
An alloyed material is a uniform mixture of the base and alloying
substances.
Metals usually have high melting point, are relatively ductile and
malleable, and are hard with relatively high tensile strength.
They are often good conductors of heat and electricity with high
densities.
Exceptions include mercury which is liquid at room temperature with
a melting point of -39 oC. Sodium and potassium are light and soft
with melting points of 97 oC and 63 oC respectively.
Metals
Metals are used in two forms of castings and wrought metals.
Casting is used to produce ingots or component blanks.
The component blanks or work pieces are processed into finished
forms by secondary manufacturing processes.
Ingots are used as stock materials for producing wrought metals
which are obtained by some secondary manufacturing processes such
as forging, rolling, and extrusion.
Ingots are obtained by casting liquid metal into rectangular and
square cross-sections. The section may be in form of a slab, billet, or
bloom.
. These shapes are further processed through hot rolling, forging or
extrusion, to produce materials in standard form such as plates,
sheets, rods, tubes and structural sections.
Non- METALS
Non-metals exist as covalent molecules where atoms are held
together by weak forces.
Non-metals usually have low melting point, are relatively brittle
and soft with relatively low tensile strength.
They are often bad conductors of heat and electricity with low
densities.
Exceptions include carbon which is extremely hard with high
melting temperature when in the form of diamond and is a good
conductor of heat and electricity when in the form of graphite.
Non- Metals –Plastics
Plastics are solid materials that are mainly hydrocarbon (hydrogen and
carbon) or organic compounds.
They consist of long chains of simple molecules fused together by a
process called polymerization.
During polymerization, simple hydrocarbon molecules are replicated and
linked together to form heavier and more complex hydrocarbon
molecules. Hence they are also called polymers.
As a rule of thumb, a polymer must contain at least 10 simple organic
molecules. The complex molecules from polymerization have physical
properties usually different from the original molecules.
They are capable of retaining their shape and form under ordinary
conditions.
Plastics are manufactured mainly from products of crude oil and natural
gas.
Non-Metals –Plastics
Plastics may be grouped into thermoplastics, thermosets, and elastomers.
Thermoplastics: Thermoplastics are the set of plastics that soften and melt when
heat is applied. They have straight or branched chains of molecules joined by weak
forces. They harden when cooled and are capable of being re-shaped or re-molded
several times. Examples include acrylic, ABS, Nylons, Polyethylene, PVC, etc.
Thermosetting Plastics: Thermosetting plastics or thermosets are the set of plastics
that do not soften and melt when heat is applied. They have chains of molecules in
3-D layout that are joined by strong forces. They are formed by the application of
both heat and pressure. They harden when heated and cannot be reshaped or re-
molded several times. Examples are polyester, phenolics, polyimides, etc.
Elastomers: Elastomers are plastics with high elasticity. They undergo considerable
elongation under load and return to their original shape and size when unloaded.
Examples are rubber, silicones, polyurethanes, etc.
Non-Metals- Wood
Wood is composed of cellulose bonded by lignin and the cellulose is
longitudinal in orientation.
Wood contains a
bout 50% - 60% cellulose and 20% - 35% lignin with other constituents
in small amounts. These other constituents include resins, pentosane,
carbohydrates, gum, and mineral water.
The cellulose is the structural substance in wood and is hollow with
very small diameter.
Wood may be classified into softwood and hardwood.
Wood
Softwood: Softwoods are derived from coniferous trees which have
needle like leaves.
Softwood products are mainly used for building construction and
decorative works. Examples of softwood sources are pine, cedar,
spruce, fir, and redwood. Pine wood is used in building
construction, furniture work, boxes, and molds for manufacturing
processes.
Hardwood: Hardwood is obtained from deciduous trees which shed
their leaves at the end of each growing season.
They are primarily used for furniture and cabinet works. Examples
of hardwood sources are oak, walnut, mahogany, cherry, maple, and
teak. Oak is used for desks, flooring, and boat frames. Walnut and
mahogany are used for desks, tables, and cabinet.
Non-Metals - Ceramics
Ceramics are inorganic compounds that contain metals and non-
metals.
They are corrosion resistant and very hard. However, they are brittle
and have low impact strength.
Clay-based ceramic products include bricks, tiles, clay pipes,
porcelain, stoneware, and earthware. Fire clay, a common refractory
material, is designed to resist high temperatures. Ceramics may be
grouped as oxides, nitrides, carbides, and glasses.
Non-metals -Composites
Composites have two or more constituents that are blended and
held together by mechanical or adhesive bonding.
The constituent materials are usually distinct in chemical properties.
Composites are referred to as engineered materials because they are
designed and manufactured to desired application qualities.
Composites can be a combination of metals, plastics, ceramics,
fibers, etc.
In composites, a filler material or filler materials are dispersed in a
matrix or base material so that the filler(s) reinforce the matrix.
Usually fillers are made from strong and stiff materials while the
matrix has low density.
Composites
The properties of the composite are better than the properties of
individual constituent. Typically, the fillers carry the load while
being held in place by the matrix.
The fillers or reinforcements impart their special mechanical and
physical properties to enhance the matrix properties.
The number of composite materials is increasing rapidly and so are
their applications.
Composite materials are used to make consumer and recreation
products, components for bicycles, vehicles, and aircrafts, electrical
products, and products for building construction and industrial
facilities.
composites
Composites have high strength to weight ratio, can resist fatigue
damage better that steel or aluminum, have high wear resistance,
and can be formulated to provide high toughness and damping.
Composites may be classified into fiber-reinforced, particulates, and
laminates, based on the filler type.
Another classification approach uses the matrix material type:
polymer, metal, and ceramic matrix composites.
