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Glossary of MinSE


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O

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The property of some coatings not to transmit rays of a specified wavelength, e.g., the ability to absorb radio waves (radio-opaque).

Hungary flag Fedőképesség

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Coatings developed for enhancing the optical properties of glass.    Such properties include refractive index, infra-red absorbtion and reflectance.  The most common coating materials are vanadium oxide, aluminium oxide, tantalum oxide, silicon dioxide and silicon oxynitride.  These maybe applied singly or as multi-layered, multi-phased coatings, usually using RF plasma assisted PVD or CVD methods.

Hungary flag Optikai bevonatok

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Properties of a coating material which characterize its behaviour in relation to the electromagnetic radiation of the optical range (i.e. visible, infrared and ultraviolet) incident upon it (e.g. reflectance, transmittance, index of refraction).

Hungary flag Optikai jellemzők

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Any coating deposited without chemical reaction with the substrate.

Hungary flag Nem kémiai eljárással készült bevonat

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Thermochemical diffusion treatment in which oxygen is deliberately introduced into the surface layer of an object.  The process is carried out in a controlled atmosphere, or air vented furnace.   Some recent innovations in this area have been the thermal oxidation of zirconium which results in an external layer of zirconia which is highly wear resistant; further it is mechanically supported by a zone of oxygen solutionised zirconium beneath, making it tolerant to point contact loads.  This material is presently being investigated for use in the bearing surfaces of orthopaedic implant materials, e.g.,  by Smith & Nephew Richards of Memphis, USA.  Also see steam treatment  and the nitrotec  group of processes where selective oxidation plays an important role.

Hungary flag Oxidáció

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The ability of a material to withstand degradation by oxidizing atmospheres, e.g., as found in gas turbine applications.

Hungary flag Oxidációval szembeni ellenállólépesség

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A process observed in rolling or sliding contacts whereby oxygen ingresses the contacting surfaces leading to localised oxidation.   The process is stimulated by the ocurance of "hot-spots".   The oxide grows to a critical thickness beyond which it is sheared off and removed.   The kinetics of such dynamic oxidation are generally agreed to be more rapid than for static oxidation.   Many oxidational wear models exist, but the principal theory is attributed to Quinn.    For example, see T. F. J. Quinn, Wear, 1992, 153, 179-200.

Hungary flag Oxidációs kopás

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Thermochemical treatment involving the diffusional enrichment of a ferrous surface with nitrogen and oxygen.  Oxynitriding has been applied to metal cutting tools made from high-speed steel.   The process increases surface hardness;  it is claimed that wear resistance is also improved.     However, this is likely to be at the expense of toughness - a similar scenario takes place after nitriding high speed steel.      Oxynitriding can be conducted at temperatures ≈520-560°C for 0.5-2 hours in a gaseous medium of ammonia and water vapour.  The depth of the treated zone is in the range of 10 to 60 µm.

Hungary flag Nitrogén-oxigén eljárás


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