辉光光谱法测定合金铸铁中硼的不确定度评定

合金铸铁试样碳元素、硅元素质量百分含量比较高,基体比较复杂。合金铸铁中的硼元素百分含量的测定目前常用电感耦合等离子体发射光谱法(ICP-AES)和火花源原子发射光谱法进行分析。采用电感耦合等离子体发射光谱法分解试样费时且困难。采用火花源原子发射光谱法由于基体复杂分析能力受到限制。通过辉光光谱法对合金铸铁中硼测定不确定度的评定,分析辉光光谱法测定过程中不确定因素,进行分量计算,找出影响分析的最大因素。计算结果表明该方法满足分析要求。     

辉光放电质谱仪测定不锈钢中微量元素的不确定度分析

本文以不锈钢中铁(Fe)元素作为内标,采用辉光放电质谱仪测定不锈钢中锰(Mn),硅(Si),硫(S),磷(P),镍(Ni),铬(Cr),钨(W),钒(V),钼(Mo),铝(Al),钛(Ti),铜(Cu)等12种元素。讨论了测试过程中由测量重复性、样品不均匀性和标准样品本身不确定度等因素所带来的不确定度分量,计算出测定不锈钢中的12种元素百分含量的合成不确定度及扩展不确定度。研究结果表明,采用辉光放电质谱仪测定不锈钢中的12种元素含量的扩展不确定度均小于0.01%。     

直读光谱仪检出限的测量不确定度评定

主要介绍了直读光谱仪分析测量碳素钢和中低合金钢中各元素含量的方法。由试验结果重复性引入的不确定度分量,直读光谱仪校准误差引入的不确定度分量,光谱标准块引入的不确定度分量,计算出试样的各元素含量。不确定度的评定对准确地分析钢材料中各元素含量,避免分析过程中存在的不利影响因素等具有现实意义。     

光电直读光谱仪测定中低合金钢中碳的不确定度评定

依据标准JJF 1059—1999对光电直读光谱分析仪测定中低合金钢中碳的不确定度的来源进行分析,并对碳含量测定结果的不确定度进行了评定。     

光电直读法测定中低合金钢元素含量不确定度的分析

本文系统地分析了光电直读法测定中低合金钢元素含量不确定度的影响因素,对其影响程度进行了评定,并以本实验室Si、Mn、Ni、Cr、Cu等元素检测为例,对其不确定度做了详细分析,结果表明:在用光电直读光谱仪对元素含量分析过程中,标准物质与样品间基体含量的差异对测量结果的准确度影响最大,其次为标准曲线的线性因素影响及样品本身的物理性能及均匀程度的影响.     

电感耦合等离子体原子发射光谱法(ICP-AES)测定柴油中硫含量的不确定度评定

采用电感耦合等离子体发射光谱法(ICP-AES)对SRM 2724b柴油标准物质中的硫元素含量进行测定。以硝酸/过氧化氢为溶剂,使用钢衬聚四氟乙烯罐高压消解样品,建立了以无机标准物质制作标准曲线测定柴油中硫元素的ICP-AES方法,确定了测量过程中五个主要的不确定度来源,包括测量重复性、天平称量、消解过程、标准溶液配制和标准曲线的变动性引入的不确定度,并对各个不确定度分量进行评定,计算出测量结果的合成标准不确定度和扩展不确定度。     

化妆品中有害元素含量测定的不确定度评估

本文通过采用电感耦合等离子体发射光谱(ICP-AES)法测定化妆品中有害元素含量,并对测量过程中各项不确定度的来源以及评定方法进行分析,建立起一种分析实验室不确定度的评定方法,使实验结果更具客观性和准确性。     

变色酸光度法测定钢中钛含量的不确定度评定

通过对变色酸光度法测定钢中钛含量的整个实验过程可能引入的不确定度进行分析,不确定度来源主要有测量重复性、标准工作曲线用标准溶液的浓度、由校准曲线求得的样品中钛含量浓度、量器体积、质量,通过简化并计算了测定过程中的不确定度分量,得出了变色酸光度法测定钢中钛含量,达到了对其测试过程测量不确定度合理评定的目的。     

ICP-AES法测定原油中镍含量及不确定度评定

采用电感耦合等离子体发射光谱法(ICP-AES)定量分析原油中金属镍元素的含量,建立了测定镍含量不确定度的分析方法.从4个方面评定了不确定度分量的贡献,分别计算其相对标准不确定度,最终得到合成标准不确定度和扩展不确定度.通过分析计算表明,当原油中镍元素含量为19.64 mg/kg时,其扩展不确定度为0.20mg/kg(...     

直读光谱仪分析法测定钢中碳、硅、锰、磷、硫的不确定度评定

直读光谱仪分析法检测钢中各元素含量已经在各炼钢、铸造、机械制造等部门广泛应用。本文对直读光谱仪分析法测定不确定度的产生原因进行了分析,并对钢材料中碳、硅、锰、磷、硫五种元素的不确定度进行了评定。     

直流辉光和磁控增强放电等离子体的空间分辨发射光谱技术

光学发射光谱(OES)方法是等离子体诊断的有力工具之一,可以定量地给出等离子体的多种重要参数,如等离子体中的物种成分、粒子能态分布、激发温度、粒子相对密度等.本文介绍了一种用于电子回旋共振(ECR)微波等离子体磁控溅射靶附近的增强放电和直流辉光放电等离子体空间分辨诊断的发射光谱装置.其特点是光学收集系统的位置可以水平精细移动,因而可以对放电区域进行空间分辨发射光谱测量.作者利用这套装置对氩气的ECR微波等离子体和直流辉光放电等离子体进行诊断.在ECR微波等离子体的下游区内氩离子谱线的发射强度很弱,主要是高激发态原子的辐射.在磁共振增强放电区,离子谱线强度有所增加但仍比原子谱线弱,类似于直流辉光放电正柱区的光发射特性.     

Influence of deep cryogenic treatment of high speed steel substrate on TiAlN coating properties

Deep cryogenic treatment in combination with classic heat treatment shows a significant improvement in wear resistance of high speed steel tools. The aim of this research was to investigate how the microstructure of the substrate tool steel material, which was altered by deep cryogenic treatment and plasma nitriding, influences the properties of TiAlN coating. The microstructure, topography and composition of the TiAlN coating were investigated using field‐emission scanning electron microscope, atomic force microscopy, XRD, and glow discharge optical emission spectroscopy. The coating adhesion was measured using the scratch test. The sliding wear resistance and the force required to break the coating were determined with the ball‐on‐flat method. Resistance to microabrasion was measured by free ball abrasion test. The results show that deep cryogenic treatment combined with plasma nitriding influence the adhesion of the TiAlN coating to the high speed steel substrate. Wear resistance tests show better wear resistance of deep cryogenic treated samples in comparison with conventionally heat treated ones.     

The analyses of an SiF4 plasma in an R.F. glow discharge for preparing fluorinated amorphous silicon thin films

The measurements of plasma parameters, such as an electron energy and an electron energy distribution function using a probe method, and of the optical emission spectroscopy for observing the chemical reactions in a plasma were studied for characterizing the glow discharge SiF₄ plasma. The probability of a basic dissociation process of the SiF₄ molecule by the electron impact was supported by the optical emission and also by the electron energy in the plasma. The discussions as to the electron energy distribution function in an r.f. glow discharge plasma suggest that a mean electron energy obtained by a double-probe method may not be very critical.The contribution of atomic hydrogen radicals and the probable reactions responsible for the deposition in the gas phase and/or on the substrate surface are also discussed.     

Influence of CO2-laser mixture composition on the distribution of energy in nitrogen spectrum

The DC glow discharge has been studied for mixtures of helium, nitrogen and carbon dioxide - these mixtures are widely used in CO₂ lasers, which are classified as discharge lasers.Analysis of the bands of the nitrogen molecule (the first and the second positive system - B³Π_g → A³Σ_g, C³Π_u → B³Π_g respectively) in an emission spectrum of the glow discharge was used to deduce an energetic balance and a vibrational temperature.The vibrational temperature of dinitrogen was determined by means of optical emission spectroscopy from the second positive system of the nitrogen molecule for various discharge currents and pressures. The dependence of the vibrational temperature on the nitrogen ratio in the mixture was also investigated.A connection between an occurrence of discharge instabilities (often called striations or ionization waves) and the composition of the gas mixture was observed - the less nitrogen was put in the mixture (in favor of helium), the larger part of positive column was subject to standing ionization waves. Ionization waves observed in the positive column of the glow discharge were investigated using optical emission spectroscopy, which showed sinusoidal profile of the vibrational temperature along the axial direction of the ionization waves.     

不锈钢表面渗铜扩散复合处理合金层的抗菌性能研究

采用等离子表面合金化及辉光轰击热扩散复合处理技术在不锈钢表面进行了铜合金化处理. 利用薄膜密贴法对改性层的抗菌性能进行了测试. 通过扫描电子显微镜(SEM)、辉光放电光谱分析仪(GDOES)和X射线光电子能谱(XPS)等手段, 研究了铜合金层的微观组织、化学成分分布及抗菌前后表面铜的价态变化. 结果表明, 铜合金层对大肠杆菌(E. coli)和金黄色葡萄球菌(S. aureus)都展现了优良抗菌性能; 合金层表面铜约为5.7wt%, 合金层厚度约2.7 µm; 表面铜合金化不锈钢与菌液接触后, 不锈钢表面的铜元素以铜离子析出, 并且与试验菌种发生作用, 杀灭试验细菌.     

Factors affecting the oxidation mode of stainless steels

Abstract

Studies have been made to investigate what effect different factors have on oxide formation on stainless steels at 600–1,000°C in air. The factors include the effect of microstructure, airflow rate, surface preparations, residual oxides and variations of the dew point of the air. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and light optical microscope (LOM) were used to characterise the oxides.     

Characteristics of pulse-modulated radio-frequency atmospheric pressure glow discharge

In this letter, the electrical and optical characteristics of pulse-modulated radio-frequency atmospheric pressure glow discharge are presented. The 13.56 MHz glow discharge is modulated with pulses at repetition frequency of 100 kHz. It is shown that the discharge during power on has similar characteristics to that of discharge without pulsing, except during the discharge ignition and extinguishment phase. The spatio-temporal evolution of discharge in phases of ignition and extinguishment is studied by time-resolved imaging and optical emission spectrograph.     

Nitrogen uptake by austenitic stainless steels on annealing in N2–H2 atmospheres

Abstract

Laboratory simulation of bright annealing of types 301 and 304L stainless steel has been performed in N₂–H₂ atmospheres. Nitrogen profiles have been quantified by glow discharge optical emission spectroscopy and electron microprobe analysis, whereas transmission electron microscopy has been utilised to characterise the surface phase status after annealing. Systematic variation in the water content of the annealing atmosphere showed that at low water vapour levels, Cr₂N precipitates could coexist with a surface film of silicon oxide or be inhibited by the presence of a metal aluminium silicate, whereas at higher water vapour levels, nitride precipitation was completely suppressed by the formation of a Cr–Mn spinel type oxide. The results are discussed in thermodynamic terms, and kinetic limitations caused by the development of an oxidised surface are considered in some detail. It was found that, in addition to the more obvious variables of alloy content and nitrogen activity, surface reactions and cooling rate are critical parameters controlling the surface nitrogen composition.

MST/1811     

Corrosion behavior of candidate heat exchanger materials in oxidizing and reducing gases relevant to oxyfuel power plants

Abstract

In the present paper, the oxidation behavior of potentially suitable construction materials for heat exchanging components in coal fired power plants was studied in the temperature range 550–700 °C. The selected materials (low alloy steel 13CrMo44, martensitic steel P92, austenitic steel S304HCu and Ni-base alloy 617) were exposed in a simulated atmosphere typical for oxyfuel combustion and the results were compared with the behavior in a test gas simulating oxyfuel gas with addition of CO, thus simulating locally occurring reducing operating conditions which may happen due to incomplete combustion. The oxidation/corrosion behavior was studied by gravimetry in combination with a number of characterization methods such as optical microscopy, scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX) and glow discharge optical emission spectroscopy (GDOES). For the low alloy steel and P92 only minor differences in oxidation rates between the different environments were found. For S304HCu generally smaller corrosion rates were found in the reducing gas, whereas for alloy 617 the effect of gas composition depended on temperature. The obtained results are interpreted on the basis of thermodynamic considerations comparing equilibrium activities of the main species in the gas atmospheres with the thermodynamic stabilities of various possible corrosion products.     

Nitriding behaviour of maraging steel: experiments and modelling

The microstructure and the kinetics of growth of the nitrided zone of a Mo-containing maraging steel were investigated by performing gaseous nitriding at temperatures between 713 K (440 °C) and 793 K (520 °C) and at nitriding potentials up to 0.5 atm^?1/2 for both solution-annealed and precipitation-hardened specimens. The microstructure of the nitrided zone was investigated by means of X-ray diffraction (phase constitution; crystal imperfection). Fine, initially largely coherent Mo₂N-type precipitates developed in the nitrided zone. The elemental concentration-depth profiles were determined employing glow discharge optical emission spectroscopy (GDOES). The nitrogen content within the nitrided zone exceeds the nitrogen content expected on the basis of the molybdenum content and the equilibrium solubility of nitrogen in a (stress-free) ferritic matrix: excess nitrogen occurs. A numerical model was applied to predict the nitrogen concentration-depth profile within the nitrided layer. The model describes the dependence on time and temperature of the nitrogen concentration-depth profiles with, as fit parameters, the surface nitrogen concentration, the diffusion coefficient of nitrogen in the matrix, a composition parameter of the formed nitride and the solubility product of the nitride-forming element and dissolved nitrogen in the matrix. Initial values for the surface nitrogen concentration and the composition parameter were determined experimentally with an absorption isotherm and fitted to the measured nitrogen concentration-depth profiles. The results obtained revealed the striking effects of the amount of excess nitrogen and the extent of precipitation hardening on the developing nitrogen concentration-depth profile.