Typical alloy proportions are 90:10 or 70:30 (Pt:Ir). These have the chemical stability of platinum, but increased hardness. The Vickers hardness of pure platinum is 56 HV while platinum with 50% of iridium can reach over 500 HV.[1][2] This improved hardness has also been considered as beneficial for use in platinum jewellery, particularly watch cases.
Owing to their high cost, these alloys are rarely used. They have been used for spinnerets in the manufacture of synthetic fibres.[3]
The other extremely widespread use for Pt/Ir alloy is fabrication of metal microelectrodes for electrical stimulation of nervous tissue[4] and electrophysiological recordings.[5][6][7] Pt/Ir alloy has an optimal combination of mechanical and electrochemical properties for this application. Pure iridium is very difficult to pull into small diameter wires; at the same time, platinum has a low Young's modulus which makes pure platinum wires bend too easily during insertion into nervous tissue. Additionally, platinum–iridium alloys containing oxides of both metals can be electro-deposited onto the surface of microelectrodes.[8]
Referencesedit
^Darling, A. S. (1960). "Iridium Platinum Alloys" (PDF). Platinum Metals Review. 4 (l): 18–26. Bibcode:1960Natur.186Q.211.. doi:10.1038/186211a0. Retrieved 2008-10-13.
^Biggs, T.; Taylor, S. S.; Van der Lingen, E. (2005). "The Hardening of Platinum Alloys for Potential Jewellery Application". Platinum Metals Review. 49 (1): 2–15. doi:10.1595/147106705X24409.
^Egorova, R. V.; Korotkov, B. V.; Yaroshchuk, E. G.; Mirkus, K. A.; Dorofeev N. A.; Serkov, A. T. (1979). "Spinnerets for viscose rayon cord yarn". Fibre Chemistry. 10 (4): 377–378. doi:10.1007/BF00543390. S2CID 135705244.
^Cogan, SF; Troyk, PR; Ehrlich, J; Plante, TD (September 2005). "In vitro comparison of the charge-injection limits of activated iridium oxide (AIROF) and platinum-iridium microelectrodes". IEEE Transactions on Bio-Medical Engineering. 52 (9): 1612–4. doi:10.1109/tbme.2005.851503. PMID 16189975. S2CID 19297044.
^Cogan, Stuart F. (August 2008). "Neural Stimulation and Recording Electrodes". Annual Review of Biomedical Engineering. 10 (1): 275–309. doi:10.1146/annurev.bioeng.10.061807.160518. PMID 18429704.
^Stein, Richard B.; Charles, Dean; Gordon, Tessa; Hoffer, Joaquin-Andres; Jhamandas, Jack (November 1978). "Impedance Properties of Metal Electrodes for Chronic Recording from Mammalian Nerves". IEEE Transactions on Biomedical Engineering. BME-25 (6): 532–537. doi:10.1109/TBME.1978.326287. PMID 744599. S2CID 7973265.
^Malagodi, Mark S.; Horch, Kenneth W.; Schoenberg, Andrew A. (July 1989). "An intrafascicular electrode for recording of action potentials in peripheral nerves". Annals of Biomedical Engineering. 17 (4): 397–410. doi:10.1007/BF02368058. PMID 2774314. S2CID 23762187.
platinum, iridium, alloy, alloys, platinum, group, precious, metals, platinum, iridium, international, prototype, kilogram, artifact, standard, platinum, iridium, alloy, that, defined, having, mass, exactly, kilogram, typical, alloy, proportions, these, have, . Platinum iridium alloys are alloys of the platinum group precious metals platinum and iridium The international prototype of the kilogram IPK is an artifact standard of platinum iridium alloy that was defined as having a mass of exactly one kilogram Typical alloy proportions are 90 10 or 70 30 Pt Ir These have the chemical stability of platinum but increased hardness The Vickers hardness of pure platinum is 56 HV while platinum with 50 of iridium can reach over 500 HV 1 2 This improved hardness has also been considered as beneficial for use in platinum jewellery particularly watch cases Owing to their high cost these alloys are rarely used They have been used for spinnerets in the manufacture of synthetic fibres 3 Their well known use is in metrology where they are used to make the international prototypes used by international standards bodies for mass standards such as the international prototype of the kilogram and the international prototype of the metre although both have been superseded during the 2019 redefinition of the SI base units The other extremely widespread use for Pt Ir alloy is fabrication of metal microelectrodes for electrical stimulation of nervous tissue 4 and electrophysiological recordings 5 6 7 Pt Ir alloy has an optimal combination of mechanical and electrochemical properties for this application Pure iridium is very difficult to pull into small diameter wires at the same time platinum has a low Young s modulus which makes pure platinum wires bend too easily during insertion into nervous tissue Additionally platinum iridium alloys containing oxides of both metals can be electro deposited onto the surface of microelectrodes 8 References edit Darling A S 1960 Iridium Platinum Alloys PDF Platinum Metals Review 4 l 18 26 Bibcode 1960Natur 186Q 211 doi 10 1038 186211a0 Retrieved 2008 10 13 Biggs T Taylor S S Van der Lingen E 2005 The Hardening of Platinum Alloys for Potential Jewellery Application Platinum Metals Review 49 1 2 15 doi 10 1595 147106705X24409 Egorova R V Korotkov B V Yaroshchuk E G Mirkus K A Dorofeev N A Serkov A T 1979 Spinnerets for viscose rayon cord yarn Fibre Chemistry 10 4 377 378 doi 10 1007 BF00543390 S2CID 135705244 Cogan SF Troyk PR Ehrlich J Plante TD September 2005 In vitro comparison of the charge injection limits of activated iridium oxide AIROF and platinum iridium microelectrodes IEEE Transactions on Bio Medical Engineering 52 9 1612 4 doi 10 1109 tbme 2005 851503 PMID 16189975 S2CID 19297044 Cogan Stuart F August 2008 Neural Stimulation and Recording Electrodes Annual Review of Biomedical Engineering 10 1 275 309 doi 10 1146 annurev bioeng 10 061807 160518 PMID 18429704 Stein Richard B Charles Dean Gordon Tessa Hoffer Joaquin Andres Jhamandas Jack November 1978 Impedance Properties of Metal Electrodes for Chronic Recording from Mammalian Nerves IEEE Transactions on Biomedical Engineering BME 25 6 532 537 doi 10 1109 TBME 1978 326287 PMID 744599 S2CID 7973265 Malagodi Mark S Horch Kenneth W Schoenberg Andrew A July 1989 An intrafascicular electrode for recording of action potentials in peripheral nerves Annals of Biomedical Engineering 17 4 397 410 doi 10 1007 BF02368058 PMID 2774314 S2CID 23762187 Platinum Group Coatings Retrieved from https en wikipedia org w index php title Platinum iridium alloy amp oldid 1198782702, wikipedia, wiki, book, books, library,
