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Temperature is one of the most measured parameters within industry. Thermocouple is an extremely versatile device widely used in industry for critical high temperature, achieving extremely high accuracy with a thermocouple can be more difficult because of their inhomogeneity. Temperature drift in thermocouple is a common problem that affects the accuracy of a measurement system. Due to prolonged usage of thermocouple under different conditions causes changes in the properties of the thermocouple and in turn degrade the thermocouple which is followed by drift. Hence it is important to analyze the rate of degradation of the thermocouple material. In this work, material analysis using scanning electron microscopy by an energy dispersive X-ray (SEM-EDAX) has been performed on the thermocouple, due to change in temperature gradient at different insertion positions.

Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si – 95:2:2:1 by wt.) and chromel (Ni:Cr – 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

We developed a method to determine the absolute pressure effect on thermocouple electromotive force (EMF), based on a single wire method using Kawai-type multi-anvil apparatus. In this method, pressure conditions along the wires were evaluated based on in situ X-ray diffraction using synchrotron X-ray radiation. The pressure effect of the Seebeck coefficients of chromel and alumel was determined up to 7 GPa and 600°C by the analyses of single wire EMFs and pressure-temperature profiles along the wires. The temperature correction for the type K thermocouple was calculated to be from 0°C to –3°C in the studied conditions. Since the multi-anvil apparatus is capable of achieving much higher pressure and temperature, the method presented in this study promises to reveal absolute temperature correction for thermocouples over a wide range of pressure and temperature conditions.

The objective of the current investigation is to find out temperature distribution regimes in a horizontal pipe when condensation process is happened. The research was conducted at Pusat Studi Ilmu Teknik Universitas Gadjah Mada. The experiment apparatus consists of an inner annulus pipe made from copper (din = 17.2 mm, do = 19 mm) with the length of 1.8 m. The outer annulus pipe is a galvanized iron pipe (din = 108.3 mm, do = 114.3 mm) with the length of 1.6 m. Thermocouples type K 36 TT OMEGA with chromel (+) and alumel (-) materials were used as temperature sensors, to detect the spread of temperature in radial or axial direction along the pipe. The measurement ranged from -50 to 260 oC, with an accuracy of 0.01 °C. A data logger of RX 40 serial (OMRON, 20 Channels) was used to read and record temperature data with the sampling rate of 5 Hz. In the experiment, the water (H2O)was heated using a boiler to generate steam which was then flowed and condensed inside the annulus pipe to form a steam-condensate two-phase flow in horizontal pipe. On the other hand, the water was used as a coolant in the outer of annulus pipe. The results indicated that the temperature distribution regimes are influenced by axial posisition.The farther distances from the inlet the lower the temperatures being recorded which indicate the increase of film condensate thickness. Such phenomena can affect slugging in the location.

K-type thermocouples are fabricated using a chromel wire and an alumel wire of 50 m by the non-contact discharge welding method. The welding is carried out at six different butt angles. The size of the hot junction tends to decrease with an increase in butt angle, when the butt angle is larger than 1.4 rad. The response rate is measured and it is almost proportional to the reciprocal of the size of the hot junction. It is shown that the size of the hot junction is an important factor for the response rate. Wire diameter is another important factor for temperature measurement of small objects. When temperature is measured at the same point by a thermocouple under the conditions that only the hot junction and its vicinity are heated, the output of electromotive force, i.e. indicated temperature, will depend on the wire diameter. As the metal wire is a good thermal conductor and the rate of heat transport is proportional to the area of the wire cross section, deviation from the true value increases with an i...

Novel multi-junction thermocouple architecture was developed and simulated to in-situ monitor the temperature distribution over a Solid Oxide Fuel Cell (SOFC). This thermocouple architecture requires only {N+1} number of wires for N number of independent temperature measuring points. Therefore, N+1 architecture can independently measure temperature at multiple points simultaneously with much less number of wires than a set of thermocouples require for the same number of independent temperature measurements. Requiring less number of external wires is a distinct advantage, particularly, in constrained environments such as those within SOFC stacks. A thermocouple array having 4 independent temperature measuring points with 5 thermo-elements was simulated in MATLAB. Alumel (Ni:Al:Mn:Si – 95:2:2:1 wt) and Chromel (Ni:Cr – 90:10 wt) were chosen as thermo-element materials because of their wide applicability in the industry as K-type thermocouples. The junctions were considered to be spot welded. Three sets of simulations were performed to investigate two aspects: validation of the multi-junction thermocouple concept and investigation of the effect of the heat affected zone created in spot welding to the temperature measurement. Simulation code generates random temperature values for each junction within a pre-defined range. Temperatures at the boundaries of heat affected zones were also generated randomly according to a pre-defined criterion. The change of Seebeck coefficients within the heat affected zone was set as a percentage change of their corresponding materials Seebeck coefficient. The temperature gradient induced emf values for each sensing point were calculated from Seebeck coefficients. The calculated emf was then mapped back to temperature using ASTM approved inverse conversion function. These mapped temperatures were then compared with the set temperatures for each junction and they were in very good agreement.

The occurrence of an error due to the thermoelectric inhomogeneity of thermocouple electrodes, acquired during prolonged use, is considered, and the properties of this error are formulated. A mathematical model of the error of chromel and alumel electrodes is constructed, the error in measuring the temperature is estimated, and the most dangerous mode of operation of the thermocouples is revealed.

International audience; This paper presents a dynamic characterization setup to calibrate transient surface temperature sensor in radiative conditions. The temperature sensor is a K type (Chromel/Alumel) wire microthermocouple which hot junction is obtained from a layer deposition by PVD process. Three different metallic layers are used (Tungsten, gold and chromium) with two thin film thicknesses (0.4 μm and 0.8 μm). The aim of this work is to develop a dynamic characterization with a radiation source from a laser focused onto the thermocouple's hot junction. The dynamic performance of the sensor is obtained by measuring its unit-impulse response function (Yag laser) and its periodic response under a chopped continuous laser beam (Argon laser). Experiments are realized at atmospheric pressure. The best results are obtained with deposited probes with gold junction of 0.4 μm thickness. The rise-time and decrease-time are equal to 10 μs and 80 μs respectively (Yag laser).

Base-metal thermocouples play a significant role in industrial measurements, and among the many varieties and formats, bare-wire Type K is often preferred. The reason for this preference is its low cost, durability and tolerance of high temperature. Unfortunately, Type K, like all base-metal thermocouples, is made based on a temperature-to-emf relationship and not on a specific metallurgical formulation. The original Hoskins Chromel/Alumel couple was simple in composition, and it had known thermal drift characteristics associated with reversible crystallographic changes and irreversible oxidation, and these two drift mechanisms led to large instabilities in use. To improve the stability of Type K, most modern manufacturers now adopt compositions with alterations that can depart significantly from those of the original formulation. These alterations are usually made to improve the stability and/or manufacturing processing of their wire. So, although the wire is made to meet the limits of error and tables, this is only true at the time of manufacture. As soon as the wire is exposed to temperatures above $$150~{^{\circ }}\hbox {C}$$ , the supplier-dependent alloys can exhibit a wide range of drift behaviors that depend on composition and even the batch of the wire. This study investigates the change in Seebeck coefficient as a function of temperature for Type K bare-wires from different suppliers by using a linear-gradient furnace and a high-resolution homogeneity scanner. Wires were exposed to temperatures over the range $${\sim }20~{^{\circ }}\hbox {C}$$ to $$950~{^{\circ }}\hbox {C}$$ for time periods between 24 h and 500 h. The results show that most wires have very different drift behaviors, which the end user could not realistically predict or correct.

The Seebeck coefficient, in combination with electrical and thermal conductivity, enables the evaluation of thermoelectric performance of the functional materials. A compact thermopower measurement set up, capable of carrying out the measurements in the mid-temperature range (300–700 K), has been designed, developed and fabricated in-house. The set-up is calibrated first by performing the measurement of thermopower of constantan, alumel, and chromel specimen (reference material) at 313 K. The two data sets obtained on the sample of CaMnO3 in the temperature range of 300–700 K, using the presently developed set-up and a commercial set-up (M/s LINSIES, Model LSR 3), are in fair agreement. The error in the measurement of Seebeck coefficient in the presently developed apparatus is estimated to be less than 5% in the entire temperature range. The instrument design and method of data acquisition have been presented in detail.

A Seebeck coefficient measurement apparatus has been designed and developed, which is very effective for accurate characterization of different type of samples in a wide temperature range (80 - 650K) simultaneously covering low as well as the high-temperature regime. Reducing the complexity of the technical design of sample holder and data collections has always been challenging to implement in a single instrument when samples are in different geometrical shape and electronic structure. Our unique design of sample holder with pressure probes covers measurements of different samples shapes (wires, thin films and pellets) as well as different resistivity ranges (metals, semiconductors and insulators). It is suitable for characterization of different samples sizes (3-12 mm). A double heater configuration powered by a dual channel source meter is employed for maintaining a desired constant temperature difference across the sample for the whole temperature range. Two K-type thermocouples are used for simultaneously reading of temperatures and Seebeck voltages by utilizing different channels of a multichannel digital multimeter. Calibration of the system has been carried out using constantan, chromel and alumel materials and recorded data is found to be very accurate and consistent with earlier reports. The Seebeck coefficients of standard samples of constantan (wire) and GaN (thin film) have been reported, which shows the measurement capability of designed setup with versatile samples., Comment: 16 PAGES, 5 FIGURES

Heat exchange of a blunt cylinder in a hypersonic (M = 6) air flow are studied numerically. Calculations are carried out in ANSYS Fluent, taking into account the conjugate heat transfer between the external flow and the solid model under steady and transient incoming flow conditions. As a result of the calculations, the fields of temperature and other external flow parameters were obtained. The heating regimes are defined for the steel model and the heat transfer sensor installed in the frontal part of the model. Results of the analysis of gas temperature measurement are presented at change of the temperature from 1400 K to 2000 K in an impulse wind tunnel with operation time up to 160 ms. The total temperature was measured by chromel -alumel thermocouples with the junction sizes of 0.05, 0.1 and 0.2 mm. Deconvolution method was used for the solution of convolution integral equation. Thermocouples calibration was done by measurements of temperature step-function. Deconvolution method allows obtaining dist...

This paper investigates the corrosion behaviour of type K thermoelements and their thin films, and compares the performance of chromel–alumel thin film thermocouple with its wire counterpart before and after exposure to 5% NaCl medium. Potentiodynamic polarisation tests reveal that chromel and alumel films are more “noble” than their respective wires. Alumel corrodes faster when coupled with chromel in films than as wires. Secondary electron micrographs and electrochemical impedance spectroscopy measurements suggest that chromel shows localised corrosion while alumel undergoes uniform corrosion. Corrosion adversely affects the thermocouple output and introduces an uncertainty in the measurement.

A different to conventional monitoring systems sensor equipped tools give the possibility to gain information about the process status directly from the contact zone between tool and component to be machined. For example this can be realized by the integration of small temperature sensors into grinding wheels. The transmitting of the process data is performed by a telemetric unit attached to the grinding wheel's core. In this paper, the development of a new thin film thermocouple sensor concept is described. The unique feature of this sensor is the continuous contacting of the thermocouple through the grinding process inherent wear which leads to smearing of the thermoelectric layers and thus forming the measuring junction of a thermocouple. The system was used in OD grinding processes aiming to detect grinding burn and process instabilities. By reducing the volume of the sensors a fast response and high time resolution can be obtained. By this way, observance of the key parameters of the practical operation as closely as possible to the cutting area is enabled and so observance of process efficiency and tool status independent from workpiece machining conditions can be realized. All sensors used are thermocouples of type K, a combination of Chromel (NiCr) and Alumel (NiAlMnSi) material. The maximum temperature to be measured by this sensor is about 1350 °C, which ensures the applicability in the grinding process. Telemetry components to amplify and send the thermovoltage signals are adjusted to this type of thermocouple. The ability of the set-up to detect thermal influences was demonstrated in grinding processes with a continuously increasing specific material removal rate. The approach serves to measure temperatures between fast sliding surfaces in harsh environments (fluids, high pressure, heat), similar to the grinding process. Therefore their application is not limited to tools but also applicable for other rotating components such as bearings, gears and shafts in powertrains.

This article deals with an experimental investigation into the different cutting factors which influence the machinability factors such as cutting force, cutting temperature, and tool life during high speed turning of superalloy Inconel 718. Also the article aims to study the relationship of cutting parameters with respect to the tool-chip contact length and chip microstructure. A standard K-type (alumel/chromel) thermocouple was embedded in to the top shim of the tool holder to measure temperature during turning. The test results show that there exist a close relationship between the cutting parameters and tool-chip contact length, thermal loading equivalent, and chip microstructure. In particular, it was observed that by the proper selection of cutting parameters the cutting force, cutting temperature and tool life can be controlled to the great extent. Also by selecting the proper cutting parameters, the tool-chip contact length can be controlled effectively so as to reduce the temperature which is responsible for rapid tool wear (flank wear) and plastic deformation of the cutting edge. The cutting parameters greatly affect the microstructure grain orientation of the chip.

A highly sensitive ten junction thermopile sensor comprising of twenty K type thermocouples (Alumel/Chromel)with the thermo power of 0.040002 mv/°C fabricated on a barrier terminal with terminal lugs of speciic material havingthickness of 25.4 mm. The developed sensor can measure the temperature difference ΔT (°C) up to 0.01°C. An errorof 15.73% recorded when the thermopile sensor junction is placed under high humidity and the relative humidity (RHvalue) goes to 100%. The generation of humidity is through the Marcet boiler steam process and control with gatevalve. High temperatures have no significant effect on the junction of thermopile sensor

Oscillatory behaviour during methane oxidation over a cobalt foil has been studied using on-line mass-spectrometry and video recording of the colour of the catalyst surface. It was demonstrated that during oscillatory behaviour, periodic transitions of the catalyst surface from an oxidised state (dark colour) to a reduced state (light colour) occurred together with the variation of the catalyst temperature. Oscillations over the cobalt foil appeared at higher temperatures (860–950 °C), and had longer periods, in comparison with oscillatory behaviour which was observed earlier over a nickel foil. The application of TGA in combination with TPR experiments revealed the differences in nickel and cobalt redox properties which are responsible for the variation in the properties of the oscillations. Forced oscillations could be obtained in a low temperature region (700–860 °C), if bare chromel and alumel wires were spot-welded separately to the cobalt foil. It was shown that in this case the chromel wire induced oscillatory behaviour of the whole cobalt foil. Complicated mixed mode oscillations detected at higher temperatures were shown to be the result of the coupling of high frequency oscillations produced by the unshielded chromel–alumel thermocouple and low frequency oscillations appearing over the cobalt foil.

Metallic coils (in most cases Cu coils) are often used in high-pressure experiments to protect thermocouple wires. In this paper we show that these coils have important influences on thermocouple EMF and therefore on the temperature measurements. We tested this effect by measuring EMF from Cu coiled single wires of chromel and alumel, and, further, we conducted experiments to compare the EMF from W5Re-W26Re thermocouples with and without Cu coils attached to them. The results show systematic differences in thermocouple readings; the EMFs from W-Re thermocouples with Cu coils give systematically lower values than EMFs from thermocouples without Cu coils. The results were analyzed using a simple model. The difference in thermocouple EMFs between thermocouples with and without protection coils is given by \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[{\Delta}\mathit{E}\_{TC}\ =\ \frac{\mathit{E}\_{2}\ {-}\ \mathit{E}\_{1+}}{1\ +\ \frac{\mathit{R}\_{2}}{\mathit{R}\_{1+}}}\ {-}\ \frac{\mathit{E}\_{2}\ {-}\ \mathit{E}\_{1{-}}}{1\ +\ \frac{\mathit{R}\_{2}}{\mathit{R}_{1{-}}}}\] \end{document} where E i and R i are the EMF and the electrical resistance of metal i in the portion of the Cu coil, and the subscripts 1+, 1–, and 2 indicate positive thermocouple metal, negative thermocouple metal, and coil metal, respectively. The addition of a coil with different metal has a large effect — the Δ E TC will be close to –( E 1+ – E 1–) > R 2 and therefore thermocouple readings with a Cu coil will lead to underestimation of the real temperature. Under common experimental conditions with a multi-anvil apparatus, the error in the temperature estimate caused by Cu protection coils is ~100–150 K for a peak temperature of 1600–2000 K.

A chromel-alumel thermoelectric flow sensor using thermal isolation membrane was fabricated. Temperature coefficient of resistance of thin film Pt-heater was about , and Seebeck coefficient of chromel-alumel thermocouple was about . The sensor showed that thermoelectric voltage decreased as thermal conductivity of gas increased, and -flow sensitivity increased as heater voltage increased or the distance between heater and thermocouple decreased. When heater voltage was about 2.5 V, -flow sensitivity and thermal response time of the sensor were about and 0.18 sec., respectively. Linear range in flow sensitivity of the flow sensor was wider than that of Bi-Sb flow sensor.

The conventional RTD (Resistance Temperature Detective) thermocouples of types B, E, R, K and S are the efficient keys in the temperature sensing applications. These are the combinations of thermoelectric materials like Platinum, Rhodium, Constantan, Chromel, and Alumel which works on the Seebeck theory. The chief objective of this research work is only to explore their energy conversion efficiencies in the temperature range of 330°C by the generations of thermo emf. The present research work is carried out in the two parts; one is for the normal conditions and the other for the applied magnetic field of three different magnitudes i.e. 260Gauss, 360Gauss and 460Gauss. Hence this paper reports about the energy management aspects of RTD materials not only by the direct conversion of heat into electricity but also along with the magnetic field.

Thermoelectric devices have been investigated widely in order to transform a low temperature heat source to the electrical power. In this report, we proposed a knitted wire panel as a thermoelectric power generator. A thermocouple on the knitted wire panel was formed by knitting an alumel wire and a chromel wire (ϕ 0.3 mm). The knitted wire panel was set at a measurement system using a peltier cooling device, and electrical characteristics were measured. Additionally, we discuss here the characteristics of electrical power generation from the panel using an equivalent circuit model. As a result, electrical power from the panel increased linearly with increasing a number of thermocouple formed by wire knitting process on the panel. It ia considered that thermocouples can be formed easily by wires knitting process. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(1): 16–21, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10028

We report on an experimental setup for the simultaneous measurement of the thermoelectric power (TEP) of two samples in the temperature range from 77 K to 500 K using optimum electronic instruments. The setup consists of two rectangular copper bars in a bridge arrangement for sample mounting, two surface mount (SM) chip resistors for creating alternate temperature gradient, and a type E thermocouple in differential geometry for gradient temperature (ΔT) measurement across the samples. In addition, a diode arrangement has been made for the alternate heating of SM resistors using only one DC current source. The measurement accuracy of ΔT increases with the differential thermocouple arrangement. For the calibration of the setup, measurements of TEP on a high purity (99.99%) platinum wire and type K thermocouple wires Chromel and Alumel have been performed from 77 K to 500 K with respect to copper lead wires. Additionally, this setup can be utilized to calibrate an unknown sample against a sample of known absolute TEP.

Surface junction thermocouples are used extensively for transient heat flux measurements, but their accuracy is dependent on the effective thermal product (TP) of the gauge and this can be a function of the time scale of interest. In the present work the response of surface junction k-type thermocouples was investigated experimentally using a water droplet calibration technique (for millisecond times scales) and a small shock tube (for microsecond time scales). Different junctions formed by scalpel blade scratches and abrasive paper were investigated. When scratches from scalpel blades were used to form the junction, the TP identified from the water droplet calibrations consistently differs by approximately 20% depending on whether the junction was made on the chromel or alumel substrate, in accord with existing thermal properties data. However, the shock tube calibrations indicate that for scalpel-scratched junctions there is considerable variability in thermocouple response time due to effective junction depth variations produced during construction. In contrast, junctions formed with abrasive paper produced rise times consistently less than 1s, but the water droplet and shock tube experiments both indicated significant variability in the effective TP for these gauges. The consistency in TP for scalpel-scratched junctions for millisecond time scales and the variability for junctions created with abrasive grit for both the millisecond and microsecond time scales is attributed to the differences in the effective proximity of the junction to the insulation between chromel and alumel substrates. For junctions created with abrasive grit, the effective TP is approximately 30% smaller for microsecond time scales than it is for millisecond time scales.

This paper describes micromachined scanning thermocouple probes that exploit the low thermal conductivity and the high mechanical flexibility of polyimide as a structural material. They are surface micromachined using a low-temperature six-mask process suitable for appending to a CMOS fabrication sequence. The probes are 200-1000-/spl mu/m long, 40-120-/spl mu/m wide, and of varying thickness. They are assembled by a flip-over approach that eliminates the need for dissolving the substrate wafer or removing the probe from it. Temperature sensing is provided by thin-film Ni/W or chromel/alumel thermopiles embedded in the polyimide, which provide Seebeck coefficients of 22.5 and 37.5 /spl mu/V/K per junction, respectively. Modeling results indicate that the low thermal conductivity of polyimide causes the temperature drop along the probe length to be much higher than with other candidate materials such as Si or SiO/sub 2/, which contributes to improved thermal isolation of the sample and higher temperature sensitivity of the probe. However, the response time of the probe is compromised, and the measured -3 dB bandwidth of the probes is /spl ap/500 Hz. A sample scan is presented.

A chromel–alumel thermocouple has been found to catalyse the methane/oxygen reaction, the main products being CO, H2 with some CO2 and H2O. Regular oscillations in both reactants, products and temperature have been observed at temperatures around 700thinspcirC. Similar behaviour has been obtained using nickel wires.

In order to obtain oxide films using catalytic chemical vapor deposition (Cat-CVD), oxidation experiments for catalyzers of Alumel, Al Chrom-O, Chromel, Hastelloy C-276, Kanthal, Kovar, Inconel-600, Inconel-601, Inconel X-750, Iron Chrome 30, Moleculoy, Monel, Ni, Nickel Chrome, Pt, SUS-304, SUS-316, Super Invar, and Ti have been carried out. The electric resistance measured for each metal heated at 900 °C, exposed for 30 min in O 2 atmosphere, have revealed that Alumel, Al Chrom-O, Chromel, Hastelloy C-276, Kanthal, Inconel-600, Inconel-601, Inconel X-750, Iron Chrome 30, Moleculoy, Ni, Nickel Chrome, Pt, SUS-304, and SUS-316 are in resistance to oxidation.

Alkali metal perchlorates are known as oxidizers widely used in propellants, pyrotechnics, catalysts, and other fields [1]. These compounds contain significant proportions of oxygen, so they can also be successfully employed as solid oxidizers in the self-propagating high-temperature synthesis (SHS) of functional oxide materials (ferrites, ferroelectrics, high- T c superconductors, and others) [2]. In the combustion synthesis of complex oxides, the quality of the ultimate product is significantly affected by the degree of coincidence of the peak of perchlorate decomposition with oxygen gas evolution and the peak of metal fuel oxidation [3]. Usually, numerous test-and-trial experiments are needed to solve this problem and to find an optimal batch composition. In this context, it is pertinent to search for means of controlling such processes, especially for distant control means. It was discovered that, for example, strong electric fields generated by a condenser under SHS conditions substantially change the combustion process parameters [4]. The magnetic parameters of some ferrites are substantially modified during SHS in electric fields. To explain the effect of external physical actions on combustion and phase formation during the synthesis of complex oxide materials, it was hypothesized that electromagnetic fields applied to the zone of intense chemical reactions affect the kinetics of the decomposition of solid intrareaction oxidizers [5]. In addition, it cannot be ruled out that such actions affect oxygen exchange during the formation of complex oxides. In order to elucidate possible effects of electric fields, we believed it important to recognize the major SHS stages and to analyze the field effects on each stage. In this context, by way of example we studied the decomposition kinetics in electric fields for pure sodium perchlorate. The experimental setup used to study sodium perchlorate thermolysis (Fig. 1) was a vertical furnace equipped with a kanthal wire heater, with two tubular chambers 20 mm in inner diameter. The furnace was mounted between two copper plates, which were isolated with Teflon liners 1 mm thick and to which voltage up to 25 kV could be applied. Crucibles 18 × 24 mm in size, one containing powdered sodium perchlorate and the other containing a reference (NaCl), were simultaneously inserted into the chambers preheated to the required temperature ( 750°C ). Chromel‐ Alumel thermocouples were embedded beforehand into the powder to a depth of about 3 mm. Thermocouple signals were recorded with a potentiometer equipped with an xy plotter. Sodium perchlorate (99+%) from Acros Organics pounded in an agate mortar with a pestle was used in the experiments.

A transient heating technique, improving the constant-rate-heating technique for the measurements of thermal diffusivities of metals, is proposed. For a physical model of a specimen to be measured, the transient heat-conduction equation was solved with some boundary conditions, and the solution obtained was used as the principle of the present transient heating technique for determining the thermal diffusivity of the specimen. Additionally, a thermal analysis was made to satisfy a boundary condition involved in the principle, that is, the condition of radiative thermal insulation at the two end surfaces of the specimen. To verify the validity of the present technique, the thermal diffusivity of iron, whose thermophysical properties are well-known, was measured with the same apparatus as used in our previous work, and the experimental results are discussed. Moreover, thermal diffusivities of thermocouple materials, namely, constantan, chromel, and alumel, were measured by the technique in the temperature range of 360 to 680 K.

In this research, uniformity of temperature on wafer in fine scale was investigated. A measurement system has been developed, and a sensor as thin-film thermocouple was fabricated using a lift-off process. To generate EMF voltage by Seebeck effect, Chromel and Alumel materials were used for the thermocouple. The system obtains the micro scale temperature from multi-points on the surface of the wafer and then precisely analyzes thermal distribution. A numerical analysis was performed to compare to the measurement method. The experimental results and the analysis shows the system can be used for thermal measurement in a micro scale.Copyright © 2013 by ASME

Flooding of the reactor cavity is being considered as a cooling strategy to prevent vessel thermal failure in the case of severe core damage accidents in which relocation of core material into lower vessel head occurs. A recent study carried out at UCLA showed that the flooding of cavity could indeed be a viable option. However, one important factor contributing to uncertainty in that study was the internal natural convection heat transfer coefficient. In the present work, experiments were conducted to examine natural convection heat transfer in internally heated hemispherical pools with external cooling. In the experiments, Freon-113 contained in a Pyrex bell jar, was used as a test liquid and the vessel was cooled from the outside with water. The pool was bounded with a rigid wall at the top, and was heated with a 750 W magnetron taken from a conventional microwave oven. The vessel inner wall temperature was not held constant and varied from the stagnation point to the equator. A series of chromel alumel thermocouples was used to measure the pool and wall temperatures at different locations. Experiments were performed for pools with nearly insulated and cold rigid walls at the top. The depth of the pool was varied parametrically. Both local and average heat transfer coefficients based on maximum pool temperature were obtained. The results have been compared with the correlations obtained for pools with free surface.

As the demand of complex and small scale semiconductor devices has been increased, the measurement technologies were developed to meet the accurate requirement in semiconductor manufacturing process. The uniform temperature requirement on the wafer is the major factor related to the semiconductor device yield. It is normally acquired from the thermocouples following the inner wall of the chamber. However, since the temperature difference between the wall of equipment and the surface of wafer is existed, the actual wafer temperature is commonly measured by a thermocouple wafer to calibrate the temperature measurement accuracy of the equipment. However, as the diameter of the commercial thermocouple wires is larger than the recently demanded pattern size, the TC wafer has not been able to measure the micro scale temperature differences on the micro patterned wafer. We, therefore, designed a micro-scale thermal sensor. The developed sensor has 37 sets of the measurement points on a 4-inch silicon wafer. The size of the measurement point is approximate to 16 um2. Two alloys, chromel and alumel which are as same as the materials of the K-type thermocouple are used to generate the thermoelectric voltage. The sensor has the temperature range of −200°C to 1300°C. The commercial K-type thermocouple extension wires are connected to the pads of the sensor array and they transfer the analog voltage data to a data acquisition device (DAQ). The sensor was calibrated by comparing the EMF voltage at different temperatures to the standard thermocouple EMF voltage. With the developed micro-scale thermal sensor system, the temperature distribution of the wafer in the furnace chamber is obtained.Copyright © 2012 by ASME

The thermal oxidation properties of Al-ion-implanted, Ni-based alloys used for thermocouples of Inconel 600, alumel, chromel and constantan have been studied in humid O2 atmospheres at 970 K for 50 h. The Al ion implantation was performed with doses ranging from 1 × 1016 to 2 × 1017 ion cm-2 at an energy of 50 keV. The depth profiles measured by Auger electron spectroscopy showed that the concentrations of Al and O were higher near the surface of the alloys after implantation. The implanted alumel and constantan exhibited no effect on the suppression of oxidation. However, implantation above a dose of 1 × 1017 Al ion cm-2 significantly slowed the oxidation of the Inconel 600 and chromel alloys containing Cr. The thermoelectric properties of the actual thermocouples modified by Al ion implantation are discussed.

Using a transient calorimetric technique, the specific heat and total hemispherical emissivity of chromel and alumel were measured simultaneously in the temperature range 360–760 K. Two types of specimens for each material were prepared. To obtain reliable experimental values of specific heat and total hemispherical emissivity, an expression for the time history of the temperature of the specimens was developed; this expression is accurate over the whole temperature range. An error analysis is made and the uncertainty (the total error) in the values of specific heat and total hemispherical emissivity is estimated to be 3.1% for the well-designed specimens.