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Glossary of MinSE


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G

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An electrochemical cell having two dissimilar electrical conductors as electrodes.

Hungary flag Galván-cella

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A method of hot dip coating whereby steel, typically in sheet from, is immersed into a bath of molten Zn-5wt%Al alloy held at approximately 450°C.   Under optimal processing conditions, a coating free from from massive interfacial intermetallics, is produced.  Instead, a fine lamella microstructure, containing h-Zn (a solid solution of iron in Zn) plus q-FeAl­3 and h-Fe2Al5 intermetallics, is formed throughout the coating.  This method has been developed as an alternative to galvanising.   Also see galvaluming.

Hungary flag galvanizálás

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(i)  A traditional term for flash gold (24 carat) plating of fancy goods, trinkets and giftware sold at the cheaper end of the domestic market. See gold plating.  (ii) The mechanical application of gold leaf (0.076 to 0.127 micrometers thick) to wooden or base metal objects.

Hungary flag bevonás aranyfüsttel

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A relatively recent (circa 1979) optical emission spectroscopy technique that has the capability to analyse a large number of elements.   The design of the sample chamber is based on the Grimm lamp.  The sample is made cathodic with respect to an anular anode (≈ 8mm in diameter) through which a low pressure flow of argon is passed.  A current intensive glow discharge plasma is subsequently created at a pressure ≈ 1.5 torr and material is removed from the sample face by high rate sputtering.   Whilst in-flight the excited sputtered sample atoms emit photons of characteristic wave-length (due to electronic transitions); see diagram.   The light is then focused and passed through a colimating slit into a spectrometer where it strikes a concave holographic grating, splitting the light into its component wave-lengths.  The spectral detection range is ≈110 to 1000 nm. The system must be calibrated against primary standards, but can routinely analyse all the major elements including, hydrogen, nitrogen, carbon, oxygen and boron.  It also has the capability to achieve rapid depth profiling, making the technique of special value for the analysis of ceramic coatings and diffusion zones.   For example, it is possible to analyse 10 elements to a depth of 50 µm in less than 30 minutes.   However, some experiences show that depth resolution would not appear to be better than 0.5µm.

Hungary flag Izzítási optikai emissziós spektroszkópia

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Base metals, like zinc and brass castings, are given a prior bright nickel electroplate deposit.   Gold plating (gilding) is costly and hence electroplating is carried out for very short times (typically ≈5 to 15 seconds).  Hence, the term flash gilding.   For filigree work (delicate ornamental objects made from wire) thicker coatings are needed and electroplating is therefore carried out for 20 to 30 seconds.

Hungary flag bevonás aranyfüsttel

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Any coating whose constitution varies continuously between successive layers, usually enabling a progressive blending of properties between that of the substrate and the outermost layers of the coating.  Coatings of this type can be produced by thermal spraying or plasma assisted PVD methods.

Hungary flag fokozatos bevonatolás

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A process for removing rust, paint or unwanted surface deposits (e.g., flash) from components.   A high velocity air stream is used to propel angular shaped alumina or silicon carbide particles onto component surfaces at high speed.  The flow is directed through a flexible hose and nozzle, enabling manipulation of the flow direction.  Grit blasting is a common preparation stage prior to thermal spray coating.

Hungary flag Homokolás


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