Two binary intermetallic compounds PrNi5 and Nd2Ni17 have been tested as getters for reducing the oxygen content in a stream of pure argon. Both the intermetallics used are the Ni richest phase in the respective rare-earth (RE)-Ni phase diagrams. The gettering efficiency has been evaluated through the quantities MTGA and OPPg The former is the minimum temperature of the getter activity, i.e., the temperature at which the gettering action becomes detectable, and OPPg, is the oxygen partial pressure in the gas stream after reaction. The best MTGA values found are 242 and 287 degrees C for PrNi5 and Nd2Ni17, respectively, with OPPg minimum values equal to 1 X 10(-16) and 1 X 10(-15) Pa. Though these values are produced for a relatively short time, the average OPPg values are satisfactory for practical purposes. It has been shown that the oxidation produces the rare-earth oxide (RE2O3) and Ni. The rate-determining step has been found to be the transport of oxygen in the gas phase and its transport constant has been also calculated. (c) 2006 Elsevier Ltd. All rights reserved.
Ni-Re intermetallic oxygen getters / Gozzi, Daniele; Iervolino, M; Latini, Alessandro; Bellucci, A.. - In: VACUUM. - ISSN 0042-207X. - STAMPA. - 80:8(2006), pp. 930-938. [10.1016/j.vacuum.2005.12.004]
Ni-Re intermetallic oxygen getters
GOZZI, Daniele;LATINI, ALESSANDRO;
2006
Abstract
Two binary intermetallic compounds PrNi5 and Nd2Ni17 have been tested as getters for reducing the oxygen content in a stream of pure argon. Both the intermetallics used are the Ni richest phase in the respective rare-earth (RE)-Ni phase diagrams. The gettering efficiency has been evaluated through the quantities MTGA and OPPg The former is the minimum temperature of the getter activity, i.e., the temperature at which the gettering action becomes detectable, and OPPg, is the oxygen partial pressure in the gas stream after reaction. The best MTGA values found are 242 and 287 degrees C for PrNi5 and Nd2Ni17, respectively, with OPPg minimum values equal to 1 X 10(-16) and 1 X 10(-15) Pa. Though these values are produced for a relatively short time, the average OPPg values are satisfactory for practical purposes. It has been shown that the oxidation produces the rare-earth oxide (RE2O3) and Ni. The rate-determining step has been found to be the transport of oxygen in the gas phase and its transport constant has been also calculated. (c) 2006 Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
