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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.
Sintered copper may be used as a wicking structure in certain types of heat pipe construction, where the porosity allows a liquid agent to move through the porous material via capillary action. For materials that have high melting points such as molybdenum , tungsten , rhenium , tantalum , osmium and carbon , sintering is one of the few viable ...
Micro CT of porous medium: Pores of the porous medium shown as purple color and impermeable porous matrix shown as green-yellow color. Pore structure is a common term employed to characterize the porosity, pore size, pore size distribution, and pore morphology (such as pore shape, surface roughness, and tortuosity of pore channels) of a porous medium.
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 ...
At the microscopic and macroscopic levels, porous media can be classified. At the microscopic scale, the structure is represented statistically by the distribution of pore sizes, the degree of pore interconnection and orientation, the proportion of dead pores, etc. [4] The macroscopic technique makes use of bulk properties that have been averaged at scales far bigger than pore size.
The average size and density of the pores can be controlled during the manufacturing process. An aerogel material can range from 50% to 99.98% air by volume, but in practice most aerogels exhibit somewhere between 90 and 99.8% porosity. [ 12 ]
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.
Open-cell metal foam CFD (numerical) simulation of fluid flow and heat transfer on an open cell metal foam. Open-celled metal foam, also called metal sponge, [3] can be used in heat exchangers (compact electronics cooling, cryogen tanks, PCM heat exchangers), energy absorption, flow diffusion, CO 2 scrubbers, flame arrestors, and lightweight optics. [4]