Search results
Results from the WOW.Com Content Network
Refractory metals have high melting points, with tungsten and rhenium the highest of all elements, and the other's melting points only exceeded by osmium and iridium, and the sublimation of carbon. These high melting points define most of their applications. All the metals are body-centered cubic except rhenium which is hexagonal close-packed.
In most HVAC systems, the use of sacrificial anodes and cathodes is not an option, as they would need to be applied within the plumbing of the system and, over time, would corrode and release particles that could cause potential mechanical damage to circulating pumps, heat exchangers, etc. [5]
"Noble Metals. Gold, Platinum, Silver, and a few rare metals. The members of this class have little or no tendency to unite with oxygen in the free state, and when placed in water at a red heat do not alter its composition. The oxides are readily decomposed by heat in consequence of the feeble affinity between the metal and oxygen." [29]
Gold nuggets do not naturally corrode, even on a geological time scale. The materials most resistant to corrosion are those for which corrosion is thermodynamically unfavorable. Any corrosion products of gold or platinum tend to decompose spontaneously into pure metal, which is why these elements can be found in metallic form on Earth and have ...
High-temperature corrosion is a mechanism of corrosion that takes place when gas turbines, diesel engines, furnaces or other machinery come in contact with hot gas containing certain contaminants. Fuel sometimes contains vanadium compounds or sulfates, which can form low melting point compounds during combustion.
In metallurgy, non-ferrous metals are metals or alloys that do not contain iron (allotropes of iron, ferrite, and so on) in appreciable amounts.. Generally more costly than ferrous metals, non-ferrous metals are used because of desirable properties such as low weight (e.g. aluminium), higher conductivity (e.g. copper), [1] non-magnetic properties or resistance to corrosion (e.g. zinc). [2]
In physical chemistry and engineering, passivation is coating a material so that it becomes "passive", that is, less readily affected or corroded by the environment. . Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build by spontaneous oxidation
Low emissivity (low e or low thermal emissivity) refers to a surface condition that emits low levels of radiant thermal (heat) energy. All materials absorb, reflect, and emit radiant energy according to Planck's law but here, the primary concern is a special wavelength interval of radiant energy, namely thermal radiation of materials.