Вимірювальна техніка та метрологія

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Subject: search.filters.subject.Thermocouple

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    Criteria of materials metal glasses selection for thermometry
    (Видавництво Львівської політехніки, 2023-02-28) Skoropad, Pylyp; Lihnovskyi, Ihor; Hamula, Pavlo; Mastylo, Rostyslav; Lviv Polytechnic National University; Technical University of Ilmenau
    In the current paper, there are considered the criteria for estimating the thermoelectric properties of metal glasses (MG) on suitability for thermometry. It is revealed that a principle of choice of thermoelectric materials based only on criteria is not quite efficient. It needs to examine also their mechanical durability, thermal, radiating, and anticorrosive properties, etc. More complete consideration proves that the use of MGs in thermometry is rather expedient.
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    The measuring channels calibration in the industry
    (Lviv Politechnic Publishing House, 2021) Sulyma Oleg; Mykyichuk Mykola; Zinchuk Iryna
    The trend of development of measuring equipment in particular measuring systems and technological processes leads to the need of measuring the temperature without dismantling the primary transducers and stopping the technological process in a very wide range and with high accuracy. The choice of methods and means of measurement depends on such factors as the value of measured temperature, necessary accuracy of measurement, conditions of measurements, and operation of the investigated object. The topicality of the problem is that industrial metrology operates the temperature measuring systems, transducers of which are deployed in such a way that their dismantling is impossible due to the specifics of the process or dangerous for operators’ life (nuclear power plants). Such measuring systems, due to the specifics of their application, are not metrologically provided in the periods between major repairs of controlled objects, thus violating the unity of measurements.
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    Thermometry: from sensitive material to thermoelectric thermotransducer
    (Видавництво Львівської політехніки, 2005-02-24) Stadnyk, Bohdan; Skoropad, Pylyp; Yatsyshyn, Svyatoslav; Lviv Polytechnic National University
    The hard operation conditions of temperature thermotransducers which involve their thermal cycling require special attention to the study of processes occurring in structural elements, in particular in thermometric materials. Operation impacts cause the drift of thermometric characteristics due to the influence of the few factors main of which seem to be the thermo structural stresses. Therefore, different kinds of sensitive elements were studied. Since traditional polycrystalline thermoelectrodes of thermocouples are inherent in the well-known drawback linked with recrystallization, there were investigated the liquid metals as the thermometric substances, melts, single-crystal materials, and metallic glasses. The need for metal glasses application in thermometry is substantiated, which allows eliminating thermally activated gradients of internal stresses in thermocouples ensuring high reproducibility and low drift of their thermo-EMF comparing to traditional materials. The analysis of sources of the instability of thermocouples’ drift is carried out. It demonstrates the density of heat and electric flows in stressed thermoelectrodes depends not only on temperature and electric potential gradient but also on the stresses’ gradient. This causes the dependence of thermometric parameters of both poly- and single-crystal substance of thermoelectrodes on the value and nature of stresses occurring within the operation cycle.