Ceramic
A ceramic is an inorganic, non-metallic solid prepared by the action of heat and subsequent
cooling。 Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous
(e.g., a glass). Because most common ceramics are crystalline, the definition of ceramic is often restricted
to inorganic crystalline materials, as opposed to the non-crystalline glasses.
The earliest ceramics were pottery objects made from clay, either by itself or mixed with other materials,
hardened in fire. Later ceramics were glazed and fired to create a colored, smooth surface. Ceramics now
include domestic, industrial and building products and art objects. In the 20th century, new cerami
materials were developed for use in advanced ceramic engineering; for example, in semiconductors.
The word ceramic comes from the Greek word "κεραμικός" (keramikos), "of pottery" or "for pottery", from
"κέραμος" (keramos), "potter's clay, tile, pottery". The earliest mention on the root "ceram-" is
the Mycenaean Greek ke-ra-me-we, "workers of ceramics", written in Linear b syllabic
script. Ceramic may be used as an adjective describing a material, product or process; or as a singular
noun, or, more commonly, as a plural noun, ceramics.
Metal
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.
In chemistry, a metal (from Greek "μέταλλον" - métallon, "mine") is an element, compound,
or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form
positive ions (cations). Those ions are surrounded by delocalized electrons, which are responsible for the
conductivity. The solid thus produced is held by electrostatic interactions between the ions and the
electron cloud, which are called metallic bonds.
Metals are sometimes described as an arrangement of positive ions surrounded by a sea of
delocalized electrons. They are one of the three groups of elements as distinguished by their ionization
and bonding properties, along with the metalloids and non-metals.
Metals occupy the bulk of the periodic table, while non-metallic elements can only be found on the righthand-side of the Periodic Table of the Elements. A diagonal line, drawn from boron (B) topolonium (Po),
separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes
called semiconductors. This is because these elements exhibit electrical properties common to both
conductors and insulators. Elements to the lower left of this division line are called metals, while elements
to the upper right of the division line are called non-metals.
An alternative definition of metal refers to the band theory. If one fills the energy bands of a material with
available electrons and ends up with a top band partly filled then the material is a metal. This definition
opens up the category for metallic polymers and other organic metals, which have been made by
researchers and employed in high-tech devices. These synthetic materials often have the characteristic
silvery gray reflectiveness (luster) of elemental metals.
Glass
Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle, and often
optically transparent.
The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass,
made of about 75% silica (SiO2) plus Na2O, CaO, and several minor additives. Often, the term glass is
used in a restricted sense to refer to this specific use.
In science, however, the term glass is usually defined in a much wider sense, including every solid that
possesses a non-crystalline (i.e. amorphous) structure and that exhibits a glass transition when heated
towards the liquid state. In this wider sense, glasses can be made of quite different classes of materials:
metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications
(bottles, eyewear) polymer glasses (acrylic glass, polyethylene terephthalate) are a lighter alternative to
traditional silica glasses.
Glass, as a substance, plays an essential role in science and industry. Their chemical, physical, and in
particular optical properties make them suitable for applications such as flat glass, container
glass, optics and optoelectronics material, laboratory equipment, thermal insulator (glass wool),
reinforcement materials (glass-reinforced plastic, glass fiber reinforced concrete), and glass art (art
glass, studio glass). Quartz sand or what is known as silica is the main raw material for the production of
glass.
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the
manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may
contain other substances to improve performance and/or reduce costs. Monomers of plastic are either
natural or synthetic organic compounds.
The word plastic is derived from the Greek πλαστικός (plastikos) meaning capable of being shaped or
molded, from πλαστός (plastos) meaning molded. It refers to their malleability, or plasticity during
manufacture, that allows them to be cast, pressed, or extruded into a variety of shapes—such
as films, fibers, plates, tubes, bottles, boxes, and much more.
The common word plastic should not be confused with the technical adjective plastic, which is applied to
any material which undergoes a permanent change of shape (plastic deformation) when strained beyond
a certain point. Aluminum which is stamped or forged, for instance, exhibits plasticity in this sense, but is
not plastic in the common sense; in contrast, in their finished forms, some plastics will break before
deforming and therefore are not plastic in the technical sense.
There are two types of plastics: thermoplastics and thermosetting polymers. Thermoplastics are the
plastics that don't undergo chemical change in their composition when heated and can be moulded again
and again; examples are polyethylene, polystyrene, polyviny
chloride and polytetrafluoroethylene (PTFE). Thermosets can melt and take shape once; after they have
solidified, they stay solid.
The raw materials needed to make most plastics come from petroleum and natural gas.
Fiber
Fiber, also spelled fibre, is a class of materials that are continuous filaments or are in discrete elongated
pieces, similar to lengths of thread.
They are very important in the biology of both plants and animals, for holding tissues together.
Human uses for fibers are diverse. They can be spun into filaments, string or rope, used as a component
of composite materials, or matted into sheets to make products such as paper or felt. Fibers are often
used in the manufacture of other materials. The strongest engineering materials are generally made as
fibers, for example carbon fiber and Ultra-high-molecular-weight polyethylene.
Synthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but
for clothing natural fibers can give some benefits, such as comfort, over their man-made counterparts.