Ceramics

Question 1

An inorganic non-metallic solid made up of either metal or non-metal compounds that have been shaped and then hardened by heating to high temperatures.

Answer 1

ceramic

Question 2

The term ceramic comes from the Greek word ______, which means “burnt stuff”.

Answer 2

keramikos

Question 3

One of the atoms (the metal) transfers electrons to the other atom
(the nonmetal), thus becoming positively charged (cation), whereas the nonmetal becomes negatively charged (anion). The two ions having opposite charges attract each other with a strong
electrostatic force.

Answer 3

ionic bond

Question 4

Nowadays this term has a more expansive
meaning and includes materials like glass, advanced ceramics and some cement systems as well.

Answer 4

ceramic

Question 5

Occurs between two nonmetals, in other words two atoms that
have similar electronegativity, and involves the sharing of electron pairs between the two atoms.

Answer 5

covalent bonding

Question 6

Bonds of ceramics that are responsible for many unique properties of these materials, such as high hardness, high melting points, low thermal expansion, and good chemical resistance, but also for some undesirable characteristics, foremost being brittleness, which leads to fractures unless the material is toughened by reinforcing agents or by other means.

Answer 6

ionic and covalent

Question 7

Some of the common ceramic materials are those in which there are equal numbers of cations and anions. These are often referred to as

Answer 7

AX compounds

Question 8

Perhaps the most common AX crystal structure is the

Answer 8

sodium chloride (NaCl) or rock salt type

Question 9

Structure where the coordination number for both cations and anions is 6.

Answer 9

Rock Salt Structure

Question 10

The coordination number is 8 for both ion types.

Answer 10

Cesium Chloride Structure

Question 11

A third AX structure is one in which the coordination number is 4—that is, all ions are tetrahedrally coordinated.

Answer 11

Zinc Blende Structure

Question 12

If the charges on the cations and anions are not the same, a compound can exist with the
chemical formula ______.

Answer 12

AmXp

Question 13

It is also possible for ceramic compounds to have more than one type of cation; for two types of cations (represented by A and B), their chemical formula may be designated as ________.

Answer 13

AmBnXp

Question 14

The properties of ceramics, however, also depend on their _____________-.

Answer 14

microstructure

Question 15

are by definition natural or synthetic inorganic, non-metallic, polycrystalline materials.

Answer 15

ceramics

Question 16

are formed by multiple crystal grains joined together during the production process.

Answer 16

Polycrystalline materials

Question 17

are grown as one three-dimensional crystal.

Answer 17

Monocrystalline materials

Question 18

Fabrication processes of polycrystalline materials are relatively _______, when compared to single crystals.

Answer 18

inexpensive

Question 19

a familiar group of ceramics; containers, lenses, and fiberglass represent typical applications.

Answer 19

glass

Question 20

Most inorganic glasses can be made to transform from a non-crystalline state into one that is crystalline by the proper high-temperature heat treatment. This process is called

Answer 20

crystallization

Question 21

have been designed to have the following characteristics:
relatively high mechanical strengths; low coefficients of thermal expansion (to avoid thermal shock); good high-temperature capabilities; good dielectric properties (for electronic packaging
applications); and good biological compatibility.

Answer 21

glass-ceramic materials

Question 22

The most attractive attribute of glass-ceramic materials is
the ease with which they may be _______

Answer 22

fabricated

Question 23

are manufactured commercially under the trade names of Pyroceram, CorningWare, Cercor, and Vision.

Answer 23

glass-ceramic

Question 24

One of the most widely used ceramic raw materials is _____. This inexpensive ingredient, found naturally in great abundance, often is used as mined without any upgrading of quality.

Answer 24

clay

Question 25

The salient properties of these materials include the capacity to withstand high temperatures without melting or decomposing and the capacity to remain unreactive and inert when exposed to severe environments.

Answer 25

refractories

Question 26

are marketed in a variety of forms, but bricks are
the most common.

Answer 26

refractories materials

Question 27

are used principally in furnace construction to confine hot atmospheres and to thermally insulate structural members from excessive temperatures.

Answer 27

Fireclay bricks or fireclay refractories

Question 28

For fireclay brick, ______ is not ordinarily an important consideration because support of structural loads is usually not required.

Answer 28

strength

Question 29

The prime ingredient for silica refractories, sometimes termed acid refractories, is

Answer 29

silica

Question 30

These materials, well known for their high-temperature load-bearing capacity, are commonly used in the arched roofs of steel- and glass-making furnaces; for these applications, temperatures as high as 1650 0C (30000F) may be realized.

Answer 30

Silica Refractories

Question 31

The refractories that are rich in periclase, or magnesia (MgO), are termed ________; they may also contain calcium, chromium, and iron compounds.

Answer 31

Basic Refractories

Question 32

Some of these are relatively high-purity oxide materials, many of which may be produced with very little porosity. Included in this group are alumina, silica, magnesia, beryllia (BeO), zirconia (ZrO2), and mullite (3Al2O3–2SiO2). Others include carbide compounds, in addition to carbon and graphite. Silicon carbide (SiC) has been used for electrical resistance heating elements, as a crucible material, and in internal furnace components. Carbon and graphite are very refractory, but find limited application because they are susceptible to oxidation at temperatures in excess of about 800C (1470F). As would be expected, these refractories are relatively expensive.

Answer 32

Special Refractories

Question 33

are used to wear, grind, or cut away other material, which necessarily is softer.

Answer 33

Abrasive ceramics

Question 34

are those in which an abrasive powder is coated on some type of paper or cloth material; sandpaper is probably the most familiar example.

Answer 34

Coated abrasives