微波消解一电感耦合等离子体发射光谱法测定增碳剂中5种元素的方法研究

建立微波消解-电感耦合等离子体发射光谱法(ICP-AES)同时测定增碳剂中微量元素镍、铜、铝、铬、钼含量的方法.使用硝酸和少量氢氟酸并采用微波消解进行样品溶解,采用高纯物质进行基体匹配,对增碳剂中的微量元素进行测定.对样品溶解方法、酸介质的选择做了相关的试验,采用配制标准溶液系列建立校准曲线,同时进行了一系列的精密度、...     

微波消解-火焰原子吸收光谱法测定磷矿石中铅

采用微波消解技术对磷矿石样品进行预处理,确定了溶样酸介质及其用量、微波消解压力、时间等关键因素,建立了火焰原子吸收光谱法测定磷矿石中铅的方法。实验结果表明,在盐酸、硝酸、硫酸、王水等四种溶样介质中,以王水的溶样效果最好,其适宜用量为每克样品5 mL。采用3步的微波消解程序,消解压力/消解时间依次为:0.3 MPa/60 s,0.5 MPa/360s,1.0 MPa/180 s。与传统酸溶法相比,微波消解的溶样时间短,试样溶解完全。方法的检出限为0.036μg/mL。对磷矿石样品进行分析,相对标准偏差(RSD)在4.1%~6.6%之间,加标回收率为94%~108%。     

探究微波消解-光度法测定镍基合金中镍

对微波消解溶解高温合金试样和使用光度法测定高温合金中镍含量进行了探究。微波消解节省了传统常压下溶样时间;光度法测定镍基合金中镍,保证了结果的准确度和精密度,比传统重量法和滴定法更简便。     

微波消解溶样滴定法测定硅钙合金中的钙

采用微波消解法溶解硅钙合金，溶样完全、操作简单且样品不易损失。本方法有很好的准确度和精密度，工作效率大大提高。     

微波消解溶样技术在冶金化学分析中的应用

微波溶样技术是世界上最先进的样品预处理技术之一.介绍了微波消解溶样技术的基本原理、优点及其在冶金化学分析中的应用.     

悬浮熔融法测定高温合金中氮

高温合金中氮含量的测定通常采用化学分析法,即凯氏法.但是对于氮含量低的试样,采用凯氏法分析则比较困难.因为高温合金的化学成分大多比较复杂,试样不易溶解,尤其是镍基高温合金.为了溶解试样,往往需要用大量试剂,操作手续比较麻烦,溶样时间也很长.这样,溶解试样这一环节不仅费时间,还可能带来相当大的氮空白值,影响低含量氮的测定.脉冲加热法已用于高温合金中氮的测定,但更多的是用于钢     

微波消解溶样技术在冶金化学分析中的运用

文章主要介绍了微波消解溶样技术在冶金化学分析中的应用。首先对微波消解溶样技术进行概述,然后详细阐述了微波消解溶样技术在铅、锌、铜等元素测定方面的研究情况及方法学考察结果,最后通过实际样品加标回收实验来验证该法的准确度和精密度。同时还提出展望,提高工作效率,降低试剂消耗成本,减少环境污染,是一种值得推广使用的新技术。因此,该技术有望成为今后冶金行业分析检测的主流趋势之一。相信随着相关技术的不断进步和完善,微波消解溶样技术将会得到更为广泛的应用和推广。     

低氮增碳剂中氮的检测方法研究

经过试验确定低氮增碳剂的加工方法,利用德国埃尔特公司生产的ON-900分析仪对低氮增碳剂试样中氮的检测条件和参数进行研究,找出最佳的分析方法。结果表明,该方法可得到较高的准确度和精密度,满足炼钢生产中对氮的检测要求。     

微波消解-分光光度法测定钨矿中钨

研究了利用微波消解技术对钨矿石样品进行消解,并采用硫氰酸盐分光光度法测定钨矿石中钨的含量。微波消解溶剂为40 mL NaOH溶液(25 g/L),微波火力为中高火,微波消解时间30 min。对各试剂用量进行了探讨,方法检出限为0.5μg/mL。对钨矿石样品进行分析,测定结果与传统溶样方法的结果相吻合,相对标准偏差小于2.3%。     

微波消解-电感耦合等离子体原子发射光谱法测定氧化铁粉中14种元素

提出了微波消解电感耦合等离子体原子发射光谱(ICP-AES)同时测定酸再生氧化铁粉中铝、硅、硫、钙、锰、硼、钛、镁、钾、钠、磷、铬、镍、铜等14种元素的分析方法。采用微波消解技术消解酸再生氧化铁粉,考察了微波消解时间、功率和压力对消解效果的影响,选择了最佳工作参数。通过ICP-AES仪器的FACT软件,选择合适的分析谱线,避免了基体干扰和元素之间的光谱干扰。同时对溶样条件、基体影响的机理等进行了探讨。微波消解方法测量结果的回收率及相对标准偏差(n=6)均优于常规溶样方法。对酸再生氧化铁粉样品的测定结果与传统湿法分析的结果相一致。     

Terminal nitrogen rise

Eighteen-breath nitrogen washouts were performed on eight subjects. Each washout could be simulated by a four-compartment model, each compartment with a different ventilation-to-volume ratio and a variable contribution to expiratory flow. In large breaths initiated near residual volume, a terminal nitrogen rise (TNR) was seen. To account for the TNR with this model, there were relatively small changes in flow from compartments with markedly different nitrogen concentration. Reasons are given for believing these compartments could not be the upper and lower lung. Three of these subjects were studied in the supine, seated, and head-down positions. The TNR was seen at the same lung volume in all positions. At routine bronchospirometry in a second group of subjects, sampling with small catheters during a nitrogen washout showed a TNR in the expirate of lungs, lobes, segments, and subsegments in the upright and supine positions. Apparently a large vertical hydrostatic gradient is unnecessary to produce a TNR. Finally, the TNR was shown to occur at that lung volume where transpulmonary pressure is very small and changing rapidly with volume. This TNR was often followed by a terminal nitrogen fall while the lung was continuing to empty. The TNR occurs when flow from a large poorly ventilated compartment increases relative to the flow from other compartments. A model of lung in which the poorly ventilated compartment develops high specific compliance at low lung volume explains these data.     

Fundamentals of nitrogen transfer in gas-metal bath systems during nitrogen injection

This publication derives basic principles of mass transfer between nitrogen gas and metallic melts. Equilibrium solubility in multi-component alloys can be calculated using known relations. To examine the question of the driving force for mass transfer, we first accept the usual treatment found in literature, namely that the concentration-difference is responsible for mass transfer. In agreement with some earlier studies, it is suggested, however, that the activity difference or difference in chemical potential of nitrogen in co-existing phases should be used to represent the driving force. Both models apply both to diffusion-controlled mass transfer and to mass transfer occurring due to reaction at the interface. Calculated mass transfer for a bubble rising in a metal bath indicates that a very intensive mass transfer may be expected. This is confirmed in industrial practice.     

Fabrication of ultrahigh nitrogen austenitic steels by nitrogen gas absorption into solid solution

For the purpose of fabricating ultrahigh nitrogen austenitic steels (>1 mass pct N), the phenomenon of nitrogen absorption into solid solution was thermodynamically analyzed and applied to Fe-Cr-Mn system ternary alloy. During the annealing of the steel in a nitrogen gas atmosphere of 0.1 MPa at 1473 K (nitrogen absorption treatment), the nitrogen content of the steel was increased with the absorption of nitrogen gas from the material surface and then saturated when the system reached a state of equilibrium. Effect of the steel composition on an equilibrium nitrogen content was formulated taking account of interactions among Cr, Mn, and N atoms, and the condition for fabrication of ultrahigh nitrogen austenitic steels was clarified. The nitrogen addition to ultrahigh content markedly increased proof stress and tensile stress of the austenitic steels without losing moderate ductility. For example, Fe-24Cr-10Mn-1.43N (mass pct) alloy has 830 MPa in 0.2 pct proof stress, 2.2 GPa in true tensile stress, and 75 pct in total elongation. As a result of tensile tests for various nitrogen-bearing austenitic steels, it was found that the proof stress is increased in proportion to (atomic fraction of nitrogen)^2/3.     

高氮钢制备及焊接过程中氮的溶解与释放

综述了高氮钢制备及焊接过程中氮的溶解与释放规律;论讨了不同制备及焊接工艺下钢中氮溶解度的计算公式、适用条件及影响因素等;指出大气压力下的GTA焊接过程是一个非平衡过程,焊缝处的氮含量与保护气体中的氮分压之间不满足Sievert定律,焊缝处的氮含量主要取决于钢中平衡氮含量和Cr的含量;选择GTA焊接时,在较低的氮分压下,便可对焊缝氮含量进行控制,但由于氮的吸收和释放较快,采用GTA焊接时焊缝氮含量不能精确控制;采用（CO2,YAG）激光焊接时需要考虑焊缝氮的释放;氮质量分数大于1．0％的高氮钢焊接方法亟待开发．     

转炉底吹氮氩切换对氮质量分数影响

为了研究转炉底吹气体对钢水终点氮质量分数影响,研究了迁钢210 t顶底复吹转炉底吹模式对转炉终点氮质量分数的影响,并基于钢液脱氮和吸氮理论对试验结果进行了分析。应用实践结果表明,随着铁水碳质量分数增加以及终点氧质量分数降低,终点氮质量分数逐渐降低;在铁水条件、副原料、转炉终点、底吹流量以及过程操作一致条件下,随着氮氩切换时间节点延长,钢液增氮量逐渐增加。当切换时间节点为吹氧比56%以内,底吹氮氩切换对终点钢水氮质量分数影响较小,当切换时间节点为吹氧比高于56%时,终点钢水氮质量分数增幅较大。     

氮含量对高氮不锈钢硬化和软化特性的影响

 为了研究高氮奥氏体不锈钢的加工硬化和退火软化的现象,设计并冶炼了氮质量分数为0.02%～1.20%的无镍奥氏体不锈钢,通过力学性能测试、SEM、EBSD等显微组织观察,分析氮含量对加工硬化和退火软化影响机理。结果表明,氮元素的添加大幅提升了加工硬化速率,氮质量分数从0增加到1.2%,加工硬化率提高了7.06 MPa/%。氮能够促进再结晶形核,有效细化晶粒尺寸,氮质量分数为0.4%～1.2%时晶粒细化达60%,但会阻碍晶粒动态回复。     

On nitrogen sorption during high energy milling of silicon powders in ammonia and nitrogen

A systematic study on nitrogen sorption during high energy milling of Si powder in NH₃ and N₂ has been conducted. X-ray diffraction (XRD), transmission electron microscopy (TEM), and nuclear magnetic resonance (NMR) have been used to analyze the milled powder and correlate the enhanced nitrogen sorption to the structural change of Si powder during milling. It is found that the amount of the sorbed nitrogen in Si is substantially higher than that predicted by the equilibrium phase diagram. Further, the sorbed nitrogen is primarily present in the amorphous phase. NH₃ is found to be much more effective than N₂ in enhancing the sorption of nitrogen. Mechanisms responsible for these phenomena are discussed based on the structural change of Si powder and mechanical activation induced by high energy milling.     

荧光猝灭法测定空气中二氧化氮和一氧化氮

NO2可被藏红T溶液吸收并转变为亚硝酸根,并且在酸性介质中,亚硝酸根可以使藏红T发生荧光猝灭,据此建立了荧光光度法测定亚硝酸根进而间接测定空气中NO2和NO的新方法。研究了硫酸,藏红T用量,柠檬酸钠用量对测定体系的影响。在最佳实验条件下,NO2-的浓度在0.023~0.276μg/mL范围内与荧光信号的降低值呈良好的线性关系,相关系数为0.9978。该方法用于测定空气中NO2和NO时的检出限分别为0.000 4 mg/m3和0.000 6 mg/m3。该方法简单、快速、检出限低,可为环境评估提供一个参考方法。