Elastomers

Long chain rubber molecules cross linked by sulphur are called elastomers

Decarburization

In decarburization, carbon content is reduced from outer surface. So the surface layer becomes soft which is responsible for lowering of fatigue resistance.

Case Hardening or Carburizing of steel

It is diffusing carbon into surfaces of steel components. This is done when a component should be hard on the outer face but tough inside.

Whiskers

Whiskers are obtained by elongating single crystal into fibrous form. Greatest Strength is usually observed in whiskers of smallest diameter.

Allotropy

Allotropy or allotropism is the property of some chemical elements to exist in two or more different forms, known as allotropes of these elements. An allotropy is polymorphism of metals.

Ploymorphism

Polymorphism is exhibiting different crystal structures at different temperatures and pressures.

Lever Rule

The lever rule is a tool used to determine weight percentages of each phase of a binary equilibrium phase diagram. It is used to determine the percent weight of liquid and solid phases for a given binary composition and temperature that is between the liquidus and solidus.

Lever rule is employed to obtain relative amounts of co-existing phases as a binary system. This rule is not applicable at eutectic or peritectic points as three phases exist in equilibrium at these temperatures.

Peritectoid

Two Solid phases transform into a different solid phase on cooling.

Peritectic

When the melting point of tow components differ too much from each other. Solid liquid phase transforms to a single solid phase.

Eutectoid

A solid phase replaces the liquid phase of eutectic system. Eutectoid reaction involves transformation of a solid phase into two other solid phases on cooling and vice versa

Eutectic phase / point, Hpyoeutectic Alloy, Hypereutectic Alloy

Eutectic: An Eutectic phase diagram is obtained when the melting points of the two components of phase diagram are neither very close nor much different.

Hpyoeutectic Alloy - Alloys to the left of eutectic point
Hypereutectic Alloy - Alloys to the right of eutectic point

Ferrite, Cementite, Pearlite & Austenite

alpha-Iron is Ferrite
Fe3C - Cementite
Ferrite + Cementite is Pearlite
Gamma-phase Iron is Austenite

Graphite

1. Used in Pencil making with a blend of clay.
2. Used as solid lubricant or in a graphited oil 
3. Has directional properties
4. Thermal and electrical conductivity are much higher along the direction of sheet as compared to its perpendicular direction.
5. Can be used as dry powder, as a spray, as a paste, as grease or as a liquid dispersion.
6. Suitable for use at hight temperature and pressure because of its low coefficient of friction.
7. Opaque
8. Grey in color
9. Also used in dry cells
10. Moderator in nuclear reactor

Subcooled Liquid or Compressed Liquid

If the temperature of the liquid is lower than the saturation temperature for the existing pressure,it is called either a subcooled liquid (implying that the temperature is lower than the saturation temperature for the given pressure) or a compressed liquid (implying that the pressure is greater than the saturation pressure for the given temperature).

Saturation Temperature, Saturation Pressure and Vapor Pressure Curve

The term saturation defines a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure.

The temperature at which vaporization (boiling) starts to occur for a given pressure is called the saturation temperature or boiling point. 

 

The pressure at which vaporization (boiling) starts to occur for a given temperature is called the saturation pressure.

The graphical representation of this relationship between temperature and pressure at saturated conditions is called the vapor pressure curve.

Bragg peak

The peak of radiation dosage at the end of the proton's path is known as the Bragg peak.

Charles' Law

The pressure of a gas varies directly with temperature when the volume is held constant, and the volume varies directly with temperature when the pressure is held constant.

Boyle's Law

The pressure of a gas expanding at constant temperature varies inversely to the volume.

Entropy

Entropy is sometimes referred to as a measure of the inability to do work for a given heat transferred.

Absolute Pressure & Gauge Pressure

When pressure is measured relative to a perfect vacuum, it is called absolute pressure (psia).

When pressure is measured relative to atmospheric pressure (14.7 psi), it is called gauge pressure (psig).