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## Ignore words

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Physical properties
BEHAVIOUR OF MATERIAL IN RESPONSE TO PHYSICAL FORCES other than mechanical ones, properties such as thermal and electrical conductivity, transparency, density.
Density
WEIGHT PER UNIT VOLUME OF A MATERIAL. Density is influenced by the atomic number of the element and other factors, such as the atomic radius and atomic packing. {ρ}
Specific gravity
Relative density of material relative to the density of water.
Strength-to-weight ratio
Tensile strength divided by density.
Thermal expansion
INCREASE OF MATERIAL'S VOLUME DUE TO A RISE IN TEMPERATURE. Change in material volume can be calculated by coefficients of thermal expansion.
Melting and freezing points
Temperature at which material, usually pure metal, transforms from solid to liquid is a melting point, the freezing point occurs when material turns solid again. >>> SPECIFIC TEMPERATURES AT WHICH A PURE METAL MELTS AND FREEZES.
Solidus and liquidus points
Unlike pure metals alloys don't have a melting point, instead melting begins at a certain point: Solidus, continuing until it completely converts to a liquid state at a Liquidus temperature. >>> ALLOY STARTS MELTING HERE AND TURNS INTO LIQUID THERE.
Heat of fusion
Amount of heat required to change phase of a unit mass >>> Ice to water, water to vapour.
Specific heat
Quantity of heat required to raise the temperature of a unit mass of the material by one degree.{C}
Volumetric specific heat
Heat energy to raise a temperature of unit volume of material by one degree { ρ*C }
Thermal conductivity
Capacity of a material to transfer heat energy through itself by thermal movement only (no mass transfer).{k}
Thermal diffusivity
Thermal conductivity divided by the volumetric specific heat { K = k/ρC}, can be used to calculate cutting temperatures in machining. THE ABILITY OF A MATERIAL TO CONDUCT THERMAL ENERGY RELATIVE TO ITS ABILITY TO STORE THERMAL ENERGY. { K = k/ρC}
Mass diffusion
MOVEMENT OF MOLECULES OR/AND ATOMS BETWEEN THE BOUNDARY OF TWO MATERIALS IN CONTACT. According to Fick's first law, mass diffusion depends on the diffusion coefficient of the material, which increases rapidly with temperature (so temperature could be listed as an important variable), concentration gradient, contact area, and time. >>> DIFFUSION( COEFFICENT, TEMP, CONCENTRATION, CONTACT AREA, TIME)
Resistivity
CAPACITY OF MATERIAL TO RESIST THE FLOW OF ELECTRIC CURRENT. Depends, in part, on temperature. Metals are better conductors because of metallic bonding, which permits electrons to move easily within the metal. Ceramics and polymers have covalent and ionic bonding, in which the electrons are tightly bound to particular molecules, thus having a higher resistivity. superconductors have zero resistivity. IN METALS RESISTIVITY DEPENDS ON TEMPERATURE.
Dielectric
MATERIAL THAT DOES NOT CONDUCTS DIRECT CURRENT. If placed between electrodes, the material will not conduct current, but if the current is high enough, the current can suddenly pass through the material, in a form of an ark, for example.
Dielectric strength
Electrical potential required to break down the insulator per unit thickness [volts/in].
Electrolysis
PASSING A CURRENT THROUGH AN ELECTROLYTE, an ionized solution capable of conducting electric current by movement of the ions, in order to achieve some goal, such as decomposing water to hydrogen and oxygen, electroplating a part, in a process of electrochemical machining, removing material from a part.
Ion
A CHARGED ATOM OR MOLECULE. It is charged because the number of electrons do not equal the number of protons in the atom or molecule. An atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.