K型热电偶检定过程中的测量不确定度评定

依据JJG 351-1996《工作用廉金属热电偶检定规程》对某K型(镍铬-镍硅)热电偶进行了检定,在测量热电动势的基础上,系统分析了该法测量及换算温度误差的不确定度来源,并对热电偶温度误差的测量不确定度进行了评定和总结。     

一等铂铑10-铂热电偶校准K型廉金属热电偶测量不确定度评定

热电偶是温度测量中最常用的传感器之一,被广泛地应用在工业测量中。而K型热电偶是最常见的一种,对它的的校准是采用比较法中的双极法。本文详细论述了用一等铂铑10-铂热电偶校准K型廉金属热电偶时不确定度评定的详细过程,对校准廉金属热电偶工作具有一定的指导意义。     

工作用廉金属热电偶测量不确定度的评定

介绍了工作用廉金属热电偶测量结果的不确定度评定方法,分析了影响工作用廉金属热电偶检定的因素,计算合成不确定度和扩展不确定度,为实际计量工作提供了参考。     

工作用廉金属热电偶的测量不确定度评定

以工作用廉金属热电偶测量结果为研究对象,论述了工作用廉金属热电偶测量值的误差来源及其测量不确定度的分析。     

校准短型廉金属热电偶相关问题的研究

短型廉金属热电偶是一类电极长度较短的可拆卸式廉金属热电偶和廉金属铠装偶的统称。传统的测量设备和测量方法在高温温区往往无法准确测量其示值偏差。通过实验找到其测不准的原因,设计研发接线端恒温器解决这一问题,降低了短型偶示值偏差的扩展不确定度。     

廉金属热电偶示值误差的不确定度评定

JJG 351-1996《廉金属热电偶检定规程》,通过分析计算检定中对热电偶示值误差有影响的各分量的值,并进行有效合成,详细阐述了热电偶示值误差测量不确定度的评定过程和方法。     

廉金属热电偶示值误差的不确定度评定

JJG351—1996《廉金属热电偶检定规程》,通过分析计算检定中对热电偶示值误差有影响的各分量的值,并进行有效合成,详细阐述了热电偶示值误差测量不确定度的评定过程和方法。     

工业热电偶测量结果的不确定度分析

介绍了工作用廉金属热电偶测量方法,并且对测量结果进行了不确定度评定,评价了影响测量结果的因素。     

基于蒙特卡罗法的K型热电偶测量不确定度评定

根据ISO/IEC发布的《Guide 98:测量不确定度》补充件1规定,采用蒙特卡洛法(MCM)对K型热电偶测量不确定度进行了评定。利用MATLAB软件对测量电动势概率密度函数进行蒙特卡洛随机采样并采用JJG 351—1996《工作用廉金属热电偶》检定规程所建立的数学模型进行数据分布传递,确定了输出量温度误差的概率密度函数,从而计算出温度误差的估计值、标准不确定度以及指定包含概率下的包含区间,实现了测量不确定度的评定。     

Ⅰ等K型热电偶示值误差测量不确定度评定

文章针对使用温度自动测量系统检定Ⅰ等K型热电偶,依据JJG 351—1996《工作用廉金属热电偶》检定规程,采用直接测量法,得到热电偶的示值误差,测量结果进行测量不确定度分析,从而判定该系统是否满足测量要求。     

Assessment of Temperature Measurements Using Thermocouples at NIS-Egypt

Thermocouples are increasingly used in industry and research. For many industrial heating processes, particularly those carried out at high temperatures, a thermocouple is the most convenient and simple instrument for temperature measurement. In some instances, it is the only feasible method. The aim of this study is to select and recommend the best thermocouples from both base and noble metals to users in industrial and scientific institutions. Different types of thermocouples and calibration methods are described. From this work, the Nicrosil–Nisil thermocouple has been proposed as the best base metal thermocouple and the Au/Pt thermocouple is the most recommended as a substandard up to 1,000 °C.     

Evaluating the Inhomogeneity of Thermocouples Using a Pressure-Controlled Water Heat Pipe

There exists various research reports concerning the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples; however, the universal method is still waiting to be established. This article considers the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples based on comparison between results of two measurement methods. The first method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a fixed-point furnace during its realization. The second method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a heat-pipe furnace with a long uniform region. A pressure-controlled water heat-pipe furnace with an immersion depth of 1000?mm is developed to enable this work. It overcomes the technical difficulties that existed in applying conventional sealed heat pipes to such applications. From the immersion characteristics of a thermocouple measured by the above two methods, we have introduced three measurement parameters. Estimating the measurement uncertainty due to the inhomogeneity from our measurement results as examples is discussed.     

Study of the Interface between Steel Insert and Aluminum Casting in EPC

The effective surface treatment method for steel insert composited with Al base metal by expendable pattern casting （EPC） process and the bonding interface between steel insert and Al base metal were investigated.It was found that Zn plating on steel insert was effective on improving the bonding property between steel insert and Al base metal in EPC process.Zn is thought to promote the formation of diffusion layer.But almost none content of Zn was observed in the boundary which had been plated on the steel insert.A diffusion layer consisting of Al,Si and Fe was formed at the insert/alloy interface and its hardness was higher than the steel insert as matter of course Al base metal.This layer turned out to be intermetallic compounds of Al-Si-Fe system.Higher pouring temperature promoted the diffusion of Fe into Al alloy,so Fe content in intermetallic layers increased at higher pouring temperature.The layer nearest to steel disappeared due to applied pressure.     

Selective electroless and electrolytic deposition of metal for applications in microfluidics: fabrication of a microthermocouple

This paper describes a general strategy for the fabrication of a microthermocouple based on the spatially defined electroless deposition of metal, followed by annealing and electroplating. We present scanning electron microscopy and atomic force microscopy characterizations of the deposition and annealing process, as well as the performance of the microfabricated Ni-Ag thermocouple. The temperature-voltage curve for this Ni-Ag microthermocouple is linear over the range 0-50 degrees C with a slope of 61.9 degrees C mV(-1). The sensitivity of our temperature measurement, which is limited by the uncertainty of our calibration curve, is approximately 1 degrees C. The optimum figure of merit (Z(opt)) is 1.0 x 10(-5) for this type of Ag-Ni thermocouple. We have fabricated microthermocouples ranging in size from 50 to 300 microm. The microthermocouple was integrated into microchannels and used to measure the in-channel temperature rise caused by the following: (1) a simple acid-base reaction, HCl + NaOH --> H2O + NaCl, and (2) an enzyme-catalyzed biochemical reaction, H2O2 + catalase --> H2O + 1/2 O2. We have also profiled the temperature increase in the presence of electroosmotic flow for a 100-, 200-, and 300-microm channel.     

Development and Realization of Iron–Carbon Eutectic Fixed Point at NPLI

The concept of metal–carbon eutectic temperature fixed point has been introduced in 1999 and is extensively being investigated by thermometry researchers to cover the high-temperature range above copper fixed point. Metal–carbon eutectic fixed points also helped to provide direct traceability with reduced associated uncertainty in the high temperature range for thermometry and radiometry applications. In view of this, CSIR-National Physical Laboratory, India (NPLI) has developed iron–carbon (Fe–C, 1153 °C) eutectic fixed point cell in the graphite crucible and realized by using the noble metal thermocouples. The preparation parameters such as design and fabrication of a graphite crucible, Fe:C eutectic composition and filling procedure, furnace profile, melting and freezing plateau measurements, heat flux immersion, inhomogeneity, etc. have been optimized and presented in this paper. The measurement uncertainty of the Fe–C eutectic cell realized with Type-S thermocouple was estimated to be 3.04 μV (0.25 °C) at coverage factor k = 2.     

铠装热电偶分流误差模型与实验

铠装热电偶在高温使用时,常出现电分流而影响测量精度,本工作进行了以下研究：（１）热电偶分流模拟实验;（２）分流误差数学模型及计算公式;（３）影响分流误差因素分析。     

Evaluating Uncertainties in Interpolations Between Calibration Data for Thermocouples

Two methods for evaluating thermocouple calibration uncertainty over the temperature range of the calibration are presented, when the thermocouple is calibrated at only a few temperatures. The evaluation of the uncertainty at fixed-point temperatures is well established, but it is often not clear how the uncertainty arising from interpolation between fixed points can be determined. We present a conventional method, based on that described in the “Guide to the expression of uncertainty in measurement” (GUM), and a numerically-based Monte Carlo method, for quantifying the calibration uncertainty arising from the use of an interpolating polynomial defined by calibration data. The two methods are compared and found to be in excellent agreement, but the Monte Carlo method is, in general, more flexible, e.g., when measurements are described by non-normal distributions.     

基于连续激光加热法测量金属材料的比热容

提出了一种基于连续激光加热测量金属材料比热容的方法。建立有限尺寸试样在连续加热条件下的传热和准稳态测量模型,使用COMSOL Multiphysics仿真软件进行数值模拟验证。考虑实际测量过程中金属试样存热损失,对模型进行了热损失修正,仿真验证了在试样表面综合传热系数小于80W/(m2·K)的情况下,修正后的测量模型偏差小于±0.81%。使用532nm连续激光器作为加热源,加工了TC4钛合金、316L不锈钢、45钢、7075铝合金和T2紫铜等金属试样并在试样上打微孔,对受热面喷涂石墨,使用极细K型热电偶对试样内部温升进行测量,并使用T2紫铜的参考值对系统参数进行标定。实验结果表明,在常温下实验装置的测量重复性优于0.91%,各金属试样测量结果平均值与数据手册参考值的相对偏差均小于±3.1%。测量结果相对扩展不确定度为U=3.66%(k=2)。     

Establishment of the Co-C Eutectic Fixed-Point Cell for Thermocouple Calibrations at NIMT

In 2015, NIMT first established a Co-C eutectic temperature reference (fixed-point) cell measurement capability for thermocouple calibration to support the requirements of Thailand’s heavy industries and secondary laboratories. The Co-C eutectic fixed-point cell is a facility transferred from NPL, where the design was developed through European and UK national measurement system projects. In this paper, we describe the establishment of a Co-C eutectic fixed-point cell for thermocouple calibration at NIMT. This paper demonstrates achievement of the required furnace uniformity, the Co-C plateau realization and the comparison data between NIMT and NPL Co-C cells by using the same standard Pt/Pd thermocouple, demonstrating traceability. The NIMT measurement capability for noble metal type thermocouples at the new Co-C eutectic fixed point (\(1324.06\,{^{\circ }}\hbox {C}\)) is estimated to be within \(\pm 0.60\,\hbox {K}\) (\(k=2\)). This meets the needs of Thailand’s high-temperature thermocouple users—for which previously there has been no traceable calibration facility.     

洛氏硬度测量不确定度的评定

通过在金属洛氏硬度试验中对不确定度的分析与计算，介绍了不确定度的基本原理及其在硬度试验中的实践应用。