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Porosity is a fraction between 0 and 1, typically ranging from less than 0.005 for solid granite to more than 0.5 for peat and clay. The porosity of a rock, or sedimentary layer, is an important consideration when attempting to evaluate the potential volume of water or hydrocarbons it may contain.
For porosity testing, coatings can be single or multiple layers of any metal that is not corroded and sealed by a self-limiting reaction in the reducing sulfur environment of the FOS test. The simplest recommended technique is to identify any porosity of the coating as revealed by the presence of surface spots.
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This porosity can range in size, from sub-micron to voids greater than 10 mm, depending on the casting. Casting defects caused by porosity can affect the part’s structural integrity, creating a failure point. Porosity can also prevent the part from being pressure tight. This will impact performance if the part is designed to hold gases or ...
The high cost of the material generally limits its use to advanced technology, aerospace, and manufacturing. Fine-scale open-cell foams, with cells smaller than can be seen unaided, are used as high-temperature filters in the chemical industry. Metal foams are used in compact heat exchangers to increase heat transfer at the cost of reduced ...
Nitrogen, oxygen and hydrogen are the most encountered gases in cases of gas porosity. [6] In aluminium castings, hydrogen is the only gas that dissolves in significant quantity, which can result in hydrogen gas porosity. [9] For casting that are a few kilograms in weight the pores are usually 0.01 to 0.5 mm (0.0004 to 0.02 in) in size.
Low porosity The high temperature gradient and solidification speeds can help eliminate shrinkage porosity. Honda used ablation casting to produce the Acura NSX hybrid supercar. Honda chose ablation casting because conventional castings would have been too brittle for the car's crush zones.
They are often utilized in the petrochemical industry for drying gas streams. For example, in the liquid natural gas (LNG) industry, the water content of the gas needs to be reduced to less than 1 ppmv to prevent blockages caused by ice or methane clathrate .