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Glossary of MinSE


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W

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The process of removing surface residues by means of clean water or water containing passivating, wetting or detergent additives.    It may be carried out in running or stagnant water, either hot or cold, by immersion or spraying.

Hungary flag Mosás

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Wavelength dispersive x-ray analysis.  Sometimes available as an "add-on" to a standard SEM.  Formerly known as "electron microprobe analysis" (EPMA).  An electron beam (≈20-30 KeV) is focused onto a conducting surface and among the many surface effects, X-rays, of characteristic wavelength are produced.  The optimal sample-electron beam distance is obtained with the aid of a light-optical microscope; this ensures that the X-rays  are brought to focus at the X-ray counter where they are collimated and diffracted by a crystal spectrometer.   The geometry of the crystal is configured to enable diffraction according to the Bragg equation:

nl = 2 d sinq

where is the X-ray wavelength, d is the inerpanar spacing (of the crystal) and q is the angle of diffraction (Bragg angle).   Accordingly, within a given wavelength range, the crystal is "tuned" to the incoming X-rays by varyingq; this is achieved by rotating the crystal.    Several crystals are needed to cover the range of 6.76 nm for B Ka to 0.013 nm for U Ka1.   In this way, most elements can be detected.   The intensity of the diffracted X-rays is proportional to the amount of a given element in the sample, which can be quantified after applying a "ZAF" correction; i.e., after accounting for the effects of atomic number (Z), X-ray absorbtion (A) and X-ray fluorescence (F).  For quantification it is essential to determine the peak count rate and background count rate for an external primary standard, ideally for the pure element.   Elemental mapping, in conjunction with secondary electron imaging is also a useful feature of this method.    For a recent review see:  M. G. Hall, Surf. Eng., 1993, 9, 205-212.

Hungary flag WDX

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The loss of material from a surface when brought into rubbing contact with two or more other surfaces; usually measured as weight loss, volume loss or dimensional change.    The type and amount of wear is determined by many factors.   The most important are atmosphere, contact stresses, contact speed, direction of contact and presence of third-body particles.   The nature of the wear interface is of crucial importance.  Also see seizure  and lubrication.

Hungary flag Kopás

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Service life in terms of material loss through wear; sometimes expressed as the time required to achieve a critical dimensional change or weight loss.

Hungary flag Kopási élettartam

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A general term denoting the response of any given material to wear.   This should be qualified by specifying the wear environment and the rate controlling wear mechanisms.

Hungary flag  Kopási tulajdonságok

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The ability of a material to endure wear

Hungary flag Kopásállóság

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A technique for laying down very thick (≈1 to 10 mm) layers of wear resistant material.   Various  welding techniques can be used, these include metal-inert gas (MIG), tungsten-inert gas (TIG), plasma transferred arc (PTA), submerged arc and manual metal arc.   The latter, because of its relative simplicity,  is found in widest use.   A very broad range of coating materials can be applied.  They include stellites (Co alloys), martensitic and high speed steels, nickel alloys and WC-Co cemented carbides.   After deposition, it is frequently necessary to finish machine the object to size by metal cutting or grinding.   Also see fusion hard facing alloys.

Hungary flag Felrakóhegesztés

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The extent to which a solid surface is wetted by a liquid; usually expressed as wetting angle.  A zero degree wetting angle corresponds to complete wetting, while a high angle of 70 or 80° corresponds to poor wetting.

Hungary flag Nedvesíthetőség vagy nedvesítés

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The ability of a surface engineered material to endure in-service wear, corrosion or fatigue.   The same meaning as durability.

Hungary flag Működési jellemzők


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