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。     

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。     

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。     

Ⅱ级工作用廉金属热电偶示值误差测量结果的不确定度评定与表示

本文介绍了检测Ⅱ级工作用廉金属热电偶的示值误差测量结果不确定度的评定与表示.     

短型热电偶测温装置的整体检定

为解决短型热电偶示值检定中 ,因参考端温度补偿难以准确测量 ,给检定结果带来的误差 ,将短型热电偶测温装置进行整体检定 ,从而解决了短型热电偶的示值检定问题。     

加接补偿导线对短型廉金属热电偶的检定

本文从是否使用补偿导线对同一支短型廉金属热电偶进行检定所得的两组数据出发 ,从现有装置的检定原理上具体分析说明了使用现有装置对短型电偶进行检定必须使用相应补偿导线的原因。最后指出热电偶在配合二次仪表实际使用时 ,为了量值的准确可靠也必须使用相应的补偿导线     

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。     

使用延长丝进行工作用短型廉金属热电偶校准/检定

热电偶检定是一项重要工作,它依据国家技术监督局颁布的“热电偶检定规程“来进行。国家计量检定规程《工作用廉金属热电偶》(JJG351-1996)对长度大于750mm 工作用廉金属热电偶的检定进行了规范与要求,但是在实际工作中常常会遇到小于750mm 工作用廉金属热电偶的校准/检定需要。如何对短型廉金属热电偶进行校准/检定,我们经过探索、研究、实验,总结了一套校准/检定方法。     

廉金属热电偶检定中的不确定度分析

本文分析了廉金属热电偶在检定中的不确定度分量及对示值结果的影响,通过分析不确定度可以提高我们的测量结果可信赖度,对检定结果更准确的表达是有帮助的.     

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。     

Life Expectancy Study of Small Diameter Type E, K, and N Mineral-Insulated Thermocouples Above 1000???C in Air

Very little if any current data is available for the life expectancy of very small diameter thermocouples operating at high temperatures, greater than 1000???C. Over the past 10?years significant changes in the supply stream of the materials used to manufacture base metal thermocouples have occurred. In many industrial applications, small diameter thermocouples are the only solution for high-temperature measurements. This study has been undertaken to assess the performance of small diameter magnesium oxide insulated metal sheathed thermocouple sensors at or above 1000???C. Three different American Society of Testing and Materials (ASTM) standard letter designation thermocouple types have been included in this study, Types E, K, and N. Inconel 600 and 316 stainless, for three different sizes, 0.5?mm, 1.0?mm, and 1.5?mm, have been tested for different thermocouple types. Each group of sensors was placed in an equalization block in air for a maximum of 500?h or until failure. The performance of 0.5?mm diameter thermocouples varies widely depending on the thermocouple type, sheath material, and test temperature. Larger diameter Type K and N thermocouples show very little drift up to 500?h at 1100???C. The data for each test was collected at 10?s intervals for the entire duration of the test. Data for the sensor drift and subsequent failure are presented.     

纯铜表面的连续摩擦压扭处理

提出了一种在纯铜表面得到大面积亚微米细晶组织及晶表面硬化处理的新工艺。在T2紫铜表面，利用连续摩擦压扭过程中产生的剧烈的剪切塑性变形，使材料表面形成了一层厚为0．1－0．2mm，晶粒直径200－300nm的亚微米细晶组织，表面硬度比基材提高了1倍，压扭头行走速度和转速对变形区晶粒细化和硬化效果影响显著。理论分析结果表明，在垂直于行走方向上加热能量和变形程度基本均匀。     

Melting Temperature of High-Temperature Fixed Points for Thermocouple Calibrations

Thermocouples can be calibrated at pure metal ingot-based fixed points at temperatures up to the freezing point of copper (1084.62 °C). For Pt/Pd thermocouples, the deviation from the accepted reference function very often takes an approximately linear form up to the copper fixed point. The calibration of Pt/Pd thermocouples may therefore be more amenable to extrapolation than that of Pt/Pt-Rh thermocouples. Here, the melting temperatures of a Co?CC and a Pd?CC eutectic fixed point are determined by extrapolating the deviation functions of several Pt/Pd thermocouples, after the fashion of Edler et al. The results are compared with the melting temperatures measured using non-contact radiation thermometry. The expanded uncertainty (k = 2) of the melting temperatures determined by extrapolation of the Pt/Pd thermocouple calibrations is ±0.32 °C for the Co?CC fixed point, and ±0.49 °C for the Pd?CC fixed point. For both fixed points, these uncertainties are comparable to those of non-contact radiation thermometry measurements. While a number of assumptions are made in performing the extrapolation of the calibrations, the method does appear to offer a useful complement to non-contact radiation thermometry measurements.     

Fabrication of nanopore array electrodes by focused ion beam milling

Single nanopore electrodes and nanopore electrode arrays have been fabricated using a focused ion beam (FIB) method. High aspect ratio pores (approximately 150-400-nm diameter and 500-nm depth) were fabricated using direct-write local ion milling of a silicon nitride layer over a buried platinum electrode. This local milling results in formation of a recessed platinum electrode at the base of each nanopore. The electrochemical properties of these nanopore metal electrodes have been characterized by voltammetry. Steady-state voltammograms were obtained for a range of array sizes as well as for single nanopore electrodes. High-resolution scanning electron microscopy imaging of the arrays showed that the pores had truncated cone, rather than cylindrical, conformations. A mathematical model describing diffusion to an electrode located at the base of a truncated conical pore was developed and applied to the analysis of the electrode geometries. The results imply that diffusion to the pore mouth is the dominant mass transport process rather than diffusion to the electrode surface at the base of the truncated cone. FIB milling thus represents a simple and convenient method for fabrication of prototype nanopore electrode arrays, with scope for applications in sensing and fundamental electrochemical studies.     

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.     

The effect of critical operational parameters on the circulation-enhanced electrokinetics

Electrokinetics (EK) is a technique for soil remediation. However, the acid produced due to the water electrolysis at the anode will cause soil acidification, which may destroy the soil constituents, and reduce contaminant removal efficiency. The formation of a base front produced at the cathode will result in the precipitation of metal hydroxides and a concomitant clogging of pore space. In this study, a circulation-enhanced EK (CEEK) system is designed to neutralize the pH of the working solution and soils for avoiding the above problems. Experiments are conducted by controlling different voltage gradients, electrode materials, and electrode emplacement, respectively. According to the experimental results, the CEEK system could effectively stabilize the current and the pH of processing solution at a neutral range. The strength of voltage gradient is proportional to the current magnitude of the CEEK system. The graphite electrode for CEEK is the better choice than the metal electrodes because graphite electrodes can achieve the lower electricity consumption. The electrode installed in the reservoir without attachment on soils can decrease the pH deviation of the soil matrix.     

Precipitation of complex carbonitrides in a Nb–Ti microalloyed plate steel

Complex carbonitrides precipitated in base metal and heat-affected zone (HAZ) in Nb–Ti hot-rolled microalloyed steel plates have been identified to be Ti-rich (Nb, Ti)(C, N). As the reheating temperature is decreased from 1,200 to 1,150 °C, the average particle size in base metal is decreased from 40 to 20 nm. The morphology of complex carbonitrides in the HAZ, however, is transformed from cuboidal to rectangle shape with length of over 500 nm. Reheating at low temperature 1,150 °C may improve the toughness of HAZ by reducing the austenite size at large heat input welding.     

Conditions for complete self-healing breakdown in glow discharge polymerized styrene films

Breakdown patterns of glow discharge polymerized styrene film sandwiched between the top and base electrodes and fabricated on a glass substrate have been observed with a microscope. The breakdown patterns can be classified into three types: a broad ring of partly vanishing top electrode metal occuring around the breakdown hole in the dielectric (type A); a large hole made through the three layers (one dielectric and two metal layers), the dielectric film and the top electrode being folded back together at the periphery of the hole and the base electrode being melted over the hole area (type B); successive breakdown around the periphery of previous breakdown spots (type P). These patterns are interpreted in terms of the action of an arc across an extremely short gap as well as joule heating. Type A is preferable for attaining complete self-healing and the conditions that most favour the occurrence of type A holes are (a) the application of a positive voltage to the top electrode and (b) the top electrode being thin compared with the base electrode.     

A New Panel Test Facility for Effective Thermal Conductivity Measurements up to 1,650°C

A new steady-state panel test facility is presented which has been designed and constructed for effective thermal-conductivity measurements of insulations in the temperature range between 300 and 1,650°C following ASTM C201-93 and DIN V ENV-1094. Square-shaped samples (length of 400 mm) are used, heated from above and settled on a water-cooled calorimeter system to obtain a one-dimensional steady-state temperature field. The heat is supplied by electrical heating elements freely hanging inside a furnace which is completely constructed from ceramic components to withstand temperatures up to about 1,800°C. The calorimeter system consists of a square central measuring zone (length of 100 mm) surrounded by guard loops to avoid heat losses in all directions. The samples, e.g., a number of fiber mats, one on top of the other up to a maximum height of 110 mm, are open to ambient pressure and atmosphere (air). Measurements include the heat flow rate (taken in the central calorimeter), temperature differences across individual layers of the sample (measured by a series of thermocouples which regularly have to be calibrated), and the thickness of the respective layers (before and after the experiment). The thermal conductivities range from 0.025 to 2 W · m⁻¹ · K⁻¹, and both isotropic and non-isotropic materials can be investigated due to the one-dimensional characteristic of the temperature field. Measurements for alumina fiber mats are presented, and good agreement is found with respective results from other methods and test facilities. Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5-8, 2005, Bratislava, Slovak Republic.     

铠装贵金属热电偶测量端位置的确定方法

热电偶测量端位置的准确定位对于热电偶的校准和使用有着重要影响,特别对于铠装贵金属热电偶来说,由于无法通过肉眼准确识别保护管内部热电偶测量端的位置,因此在热电偶检定和使用过程中一般将其外保护管顶部作为测量端所在位置。然而通过现场试验发现,铠装贵金属热电偶测量端一般并不位于保护管顶部,本文提供了一种准确定位铠装贵金属热电偶测量端的方法。