The name Système International d'Unités (International System of Units)) with the international abbreviation SI is a single international language of science and technology first introduced in 1960. SI is a coherent system based on the seven independent physical quantities (base units) and derived quantities (derived units). Note that since 1995 supplementary units have been abandoned and moved into the class of derived SI units.
|Basic SI |
|amount of substance||n||mole||mol|
|SI Unit Name||Unit Symbol||Expression in SI base units|
|plane angle||α , β , γ , θ , Φ||radian||rad||m m-1|
|solid angle||ω , Ω||steradian||sr||m2 m-2|
In addition to the thermodynamic temperature (symbol T) there is also the Celsius (symbol t) defined by the equation t=T-T0 where T0=273.15 K. Celsius temperature is expressed in degree Celsius (symbol C). The unit 'degree Celsius' is equal to the unit 'kelvin', and a temperature interval or a difference of temperature may also be expressed in degrees Celsius. (The word degree and the sign o must not be used with kelvin or K).
When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles or specified groups of such particle.
In this definition, it is understood that the carbon 12 atoms are unbound, at rest and in their ground state.
The radian and steradian were classified as supplementary units.
At the time of the introduction of the International System, the question of the nature of these supplementary units was left open. Considering that plane angle is generally expressed as the ratio between two lengths and solid angle as the ratio between an area and the square or a length, it was specified that in the International System the quantities plane angle and solid angle should be considered as dimensionless derived quantities. Therefore, the supplementary units radian and steradian are to be regarded as dimensionless derived units which may be used or omitted in the expressions for derived units.
Since October , 1995, the class of supplementary units as a separate class in the SI has been removed. Thus the SI now consists of only two classes of units: base units and derived units, with the radian and steradian, which were the two supplementary units, moved into the class of SI derived units.Si Units:
|SI Base Units|
|SI Derived Units|
|expressed with special names|
|expressed in terms of SI base units|
|expressed in terms in terms of SI units with special names|
|SI Unit Prefixes|
|accepted by SI|
|currently accepted by SI|
|derived CGS units with special names|
|other non-SI units|
|Glossary of Units|
MPa - GPa
Bits and Bytes
Alternative Site Recommended for Users of Microsoft Internet Explorer
Nature of Thermal Spray Coatings
Surface Engineering Forum
Thermal Spray Gun Repair Service * Plasma Consumable Parts * Thermal Spray Powder Supplies
Applications: Thermal Spray Coatings on Carbon and Glass Fibre Reinforced Polymers * HVOF Coating of Paper Making Roll * Abradable Coatings*
Photomicrographs: Plasma Sprayed Coatings * Plasma Sprayed Chromium Oxide Coatings * Plasma Sprayed Chromium Oxide Coatings 2 * Combustion Sprayed Coatings * HVOF WC/Co Thermal Spray Coatings * HVOF WC/CoCr Thermal Spray Coatings * HVOF WC/CrNi Thermal Spray Coatings * HVOF NiCrMo (625) Thermal Spray Coatings * HVOF NiCrMoWFe (HastelloyC) Thermal Spray Coatings * HVOF Chromium Carbide Thermal Spray Coatings * Plasma Sprayed WC/Co Coatings * WC/NiCrBSi Thermal Spray Coatings * Thermal Spray Coatings Rogues Gallery * Thermal Spray Coatings Rogues Gallery 2 * Thermal Spray Coatings on Composite Substrates * Thermal Spray Coatings on Composite Substrates 2 * Effect of Metallographic Preparation Technique on Thermal Spray Coatings * Effect of Thermal Spray Coating Process and Powder Size 1 * Effect of Thermal Spray Process and Powder Size 2 * Thermal Spray Abradable Coatings * Combustion Wire Sprayed Coatings * Arc Sprayed Coatings * Arc Sprayed Coatings 2 * Thermal Spray Ceramic Coatings * HVOF Self-fluxing NiCrBSi Coating (not fused) *
Thermal Spray Processes: Combustion Wire Thermal Spray Process * Combustion Powder Thermal Spray Process * Arc Wire Thermal Spray Process * Plasma Thermal Spray Process * HVOF Thermal Spray Process * Detonation Thermal Spray Process * Plasma Flame Theory *
Cold Spray Coating Process *
Wear and Use of Thermal Spray Coatings
Corrosion and Use of Thermal Spray Coatings
Glossary of Thermal Spray and Surface Engineering Terms
Image Directory for Thermal Spray Coatings
Plasma Gas Flow Information
Plasma Gas Flow Correction Calculator
Links to other interesting sites related to thermal spray and surface engineering * Reciprocal Links
Periodic Table of the Elements
SI Units * Calculators for Conversion between Units of Measurement
Surface Engineering Message Board Archive
Surface Engineering Message Board Archive Index
Search This Site