Kalemci, M. | Arifovic, N. | Bağçe, A. | Aytekin, S.O. | Ince, A.T.

Article | 2015 | International Journal of Thermophysics36 ( 8 ) , pp.1968 - 1979

TUBITAK UME Temperature Laboratory initiated a new study which focuses on the construction of a tin freezing-point cell as a primary temperature standard. The design is an open-cell type similar to the National Institute of Standards and Technology design. With this aim, a brand new vacuum and filling line employing an oil diffusion pump and two cold traps (liquid nitrogen and dry ice) was set-up. The graphite parts (crucible, thermometer well, etc.) have been baked at high temperature under vacuum. Each cell was filled with approximately 1 kg of high-purity tin (99.9999 %) in a three-zone furnace. Then several melting and freezing . . .curves were obtained to assess the quality of the home-made cell, and also the new cell was compared with the existing reference cell of the laboratory. The results obtained are very close to the reference cell of UME, indicating that the method used for fabrication was promising and satisfactory and also seems to meet the requirements to have a primary level temperature standard. © 2015, Springer Science+Business Media New York Daha fazlası Daha az

Kalemci, M. | Bağçe, A. | Ince, A.T. | Arifoviç, N.

Article | 2018 | International Journal of Thermophysics39 ( 9 ) , pp.1968 - 1979

The Temperature Laboratory at TUBITAK UME initiated a study which focused on the construction of freezing point cells of ITS-90 as primary temperature standards. The first cell constructed within the scope of this study was an open tin freezing point cell and the results were in good agreement with the reference tin fixed point cell of UME. The second set of cells constructed was two open zinc freezing point cells. The design of these cells is similar to the tin freezing point cell. After construction, all the home-made cells were evaluated by analyzing their melting and freezing curves. Finally comparison measurements were performe . . .d between the current laboratory reference zinc cell and all newly constructed cells. © 2018, Springer Science+Business Media, LLC, part of Springer Nature Daha fazlası Daha az

Torun, M.K. | İnce, A.T.

Article | 2011 | International Journal of Thermophysics32 ( 11.12.2020 ) , pp.2370 - 2378

Liquid baths are the main calibration equipment to directly affect the measurement uncertainty in temperature calibrations. Therefore, the characteristics of baths need to be well investigated and understood. The temperature profile and stability of liquid baths are one of the most important contributions to the calibration uncertainty of platinum resistance thermometers, digital thermometers, liquid-in-glass thermometers, and thermocouples. Commercial baths only present stability and uniformity data in two dimensions in general; however, thermometers and thermocouples are immersed into the body of the bath, so the depth or z-axis i . . .s also very important. In this study, a measurement system has been designed using three-stepper motors and a data acquisition system (DAS). The DAS is developed using object-oriented algorithms to form a three-dimensional (3-D) scanning system. The 3-D scanning system is home-made and used in conjunction with a reference platinum thermometer. The temperature profiles and stability of several types of baths: water, oil, and salt were obtained in the temperature range from 30°C to 450°C. Therefore, this contributed toward a more accurate uncertainty budget evaluation. © 2011 Springer Science+Business Media, LLC Daha fazlası Daha az

Oguz Aytekin, S. | Ince, R.

Article | 2018 | International Journal of Thermophysics39 ( 10 ) , pp.2370 - 2378

In this work, a Raman spectroscopic study of nanoporous silicon sensor samples demonstrated its use as a method of gauging the sensor potential via quantitative data it provides on the sensor nanostructure dimensions. This special property of the Raman spectroscopy technique also showed its potential to determine mechanical stability of the samples over 3 months. This work also shows that the Raman spectroscopy technique is sensitive to step changes in relative humidity in all the sensor samples via its measurement of the strain-free crystalline silicon (c-Si) Raman peak. Since the Raman technique is non-destructive and senses remot . . .ely on the fragile nanoporous sensor samples it will be the ideal replacement of the presently used electrical capacitance techniques as the primary determination of relative humidity. © 2018, Springer Science+Business Media, LLC, part of Springer Nature Daha fazlası Daha az

Aytekin, S.O. | Ince, R.

Article | 2015 | International Journal of Thermophysics36 ( 12 ) , pp.3421 - 3439

This work describes a porous, silicon-based humidity sensor operating under the capacitive transduction principle. One of the aims of this work is to determine the main parameters such as sensitivity, linearity, hysteresis, and time response to step humidity changes of four samples via measurements of their capacitance. The parameters gauged by capacitance measurements were used to explain the dynamics of its operation. The most sensitive sample caused changes in relative humidity of 74nF·%rh-1. Hysteresis of at least 3.6 % to 4.6 % was found to occur. Humidity sensor samples synthesized from nanoporous silicon were also analyzed by . . . scanning electron microscopy, image processing, and Raman spectra red shifts. As a result of these measurement and analysis of this work, the best synthesis conditions and nanopore surface and sub-surface diameters for producing high performing humidity sensors were identified. Another aim of this work is to find the optimal pore size from the analysis of image processing and Raman spectra. The optimal porous sizes in relation to the analyzed sensor’s characteristics were found to be between 4 nm and 26 nm. The novelty of this work is to establish the relationship between the capacitance measurements with image processing of SEM images and Raman spectral measurements. The mechanical stability of the samples was also gauged over 3 months utilizing both capacitance and Raman spectral measurements. © 2015, Springer Science+Business Media New York Daha fazlası Daha az