Composites Flashcards
considered to be any multiphase material that exhibits a significant proportion of the properties of both constituent phases such that a better combination of properties is realized.
Composite
It is a multiphase material that is artificially made, as opposed to one that occurs or forms naturally.
Composite
According to this principle, better property combinations are fashioned by the judicious combination of two or more distinct materials
PRINCIPLE OF COMBINED ACTION
Two Phases of Composite Materials
Matrix phase
Dispersed phase
which is continuous and surrounds the other phase
Matrix phase
the one that is being surrounded by the matrix.
Dispersed phase
means the shape of the particles and the particle size, distribution, and orientation;
Dispersed phase geometry
are multilayered and designed to have low densities and high degrees of structural integrity.
Structural composites
two subclassifications of particle-reinforced composites
Large-particle and dispersion-strengthened composites
The term _____ is used to indicate that particle–matrix interactions cannot be treated on the atomic or molecular level; rather, continuum mechanics is used.
large
Some polymeric materials to which fillers have been added are
large-particle composites
modify or improve the properties of the material and/or replace some of the polymer volume with a less expensive material
Filler
composed of cement (the matrix) and sand and gravel (the particulates).
Cement
predict that the elastic modulus should fall between an upper bound & lower bound
rule-of-mixtures equations
Large-particle composites are used with all three material types
(metals, polymers, and ceramics
composed of extremely hard particles of a refractory carbide ceramic such as tungsten carbide (WC) or titanium carbide (TiC) embedded in a matrix of a metal such as cobalt or nickel.
cemented carbide
consists of very small and essentially spherical particles of carbon, produced by the combustion of natural gas or oil in an atmosphere that has only a limited air supply.
Carbon black
a common large-particle composite in which both matrix and dispersed phases are ceramic materials
Concrete
The two most familiar concretes are those made with
Portland and asphaltic cements
widely used primarily as a paving material
Asphaltic concrete
employed extensively as a structural building material.
Portland cement concrete
act as a filler material to reduce the overall cost of the concrete product because they are cheap, whereas cement is relatively expensive
aggregate particles
major material of construction, primarily because it can be poured in place and hardens at room temperature and even when submerged in water
Portland cement concrete
The strength of Portland cement concrete may be increased by additional reinforcement. This is usually accomplished by means of _________ which are embedded into the fresh and uncured concrete.
steel rods, wires, bars (rebar), or mesh
serves as a suitable reinforcement material because its coefficient of thermal expansion is nearly the same as that of concrete
Steel
Another reinforcement technique for strengthening concrete involves the introduction of residual compressive stresses into the structural member; the resulting material is called
prestressed concrete
Another technique, in which stresses are applied after the
concrete hardens, is appropriately called
posttensioning
