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While porosity is inherent in die casting manufacturing, its presence may lead to component failure where pressure integrity is a critical characteristic. Porosity may take on several forms from interconnected micro-porosity, folds, and inclusions to macro porosity visible on the part surface.
Sintering is generally considered successful when the process reduces porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity. In some special cases, sintering is carefully applied to enhance the strength of a material while preserving porosity (e.g. in filters or catalysts, where gas ...
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.
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 ...
Dye penetrant inspection (DP), also called liquid penetrate inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to check surface-breaking defects in all non-porous materials (metals, plastics, or ceramics).
A chill is an object used to promote solidification in a specific portion of a metal casting mold.Normally the metal in the mould cools at a certain rate relative to thickness of the casting.
However, there is also a concept of closed porosity and effective porosity, i.e. the pore space accessible to flow. Many natural substances such as rocks and soil (e.g. aquifers, petroleum reservoirs), zeolites, biological tissues (e.g. bones, wood, cork), and man made materials such as cements and ceramics can be considered as porous media ...
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.