skip to main content

Title: Towards the development of high temperature comparison artifacts for radiation thermometry

This paper describes the methodology and first results of the development of high temperature fixed point artifacts of unknown temperature suitable for scale comparison purposes. This study is being undertaken at the Thermal Metrology Division of Inmetro, Brazil, as part of PhD studies. In this initial phase of the study two identical cobalt carbon eutectic cells were constructed and one doped with a known amount of copper. This was an attempt to achieve a controlled change in the transition temperature of the alloy during melting. Copper was chosen due to the relatively simple phase diagram it forms with carbon and cobalt. The cobalt, in powder form, was supplied by Alfa Aesar at 99.998 % purity, and was mixed with carbon powder (1,9 % by weight) of 99.9999 % purity. Complete filling of the crucible took 6 steps and was performed in a vertical furnace with graphite heating elements, in an inert gas atmosphere. The temperature measurements were performed using a KE LP3 radiation thermometer, which was previously evaluated for spectral responsivity, linearity and size-of-source effect (SSE). During these measurements, the thermometer stability was periodically checked using a silver fixed point blackbody maintained in a three zone furnace. The main purposemore » of the first part of this study is to dope a series of Co-C blackbody with differing amounts of copper, in order to alter their temperatures whilst still retaining good melting plateau performance. The long-term stability of the adjusted transition temperatures will also be investigated. Other dopants will be studied as the research progresses, and thermo chemical modeling will be performed in an attempt to understand the change in temperature with dopant concentration and so help select suitable dopants in the future. The overall objective is to construct comparison artifacts that have good performance, in terms of plateau shape and long-term temperature stability, but with unknown temperatures. These can then be used as comparison artifacts with no participant, except the pilot, knowing the temperature a priori.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Inmetro, Duque de Caxias, RJ (Brazil)
  2. NPL, Teddington (United Kingdom)
  3. PUC-Rio, Rio de Janeiro, RJ (Brazil)
Publication Date:
OSTI Identifier:
22218023
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1552; Journal Issue: 1; Conference: 9. international temperature symposium, Los Angeles, CA (United States), 19-23 Mar 2012; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BLACKBODY RADIATION; COBALT; COBALT ALLOYS; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; COPPER; COPPER ALLOYS; DOPED MATERIALS; EUTECTICS; GRAPHITE; MELTING; PHASE DIAGRAMS; POWDERS; SILVER; TEMPERATURE MEASUREMENT; THERMOMETERS; TRANSITION TEMPERATURE