脉冲加热-红外法测定超细二硅化钼粉末中氧

本文建立了用TC-600氧氮分析仪测定超细二硅化钼粉末中氧的分析方法.针对二硅化钼超细粉末和高温难熔的特点,对加热功率、助熔剂和进样量等测试条件进行优化,选择最佳测定条件.本方法简便、快速,测定结果准确.氧的回收率为 98.9%～102.0%,相对标准偏差为1.68%.     

Sm_2Fe_(17)型合金氮化工艺的研究进展

具有优异磁性能的Sm_2Fe_(17)N_x材料在制备过程中,氮化工艺是极其重要的环节。对Sm_2Fe_(17)型合金氮化的晶体结构、扩散反应等基本原理进行了总结,分析了氮化压力、时间、温度等因素对氮化工艺的影响,若氮化时间较短则氮化不完全,而氮化时间过长则导致氮分布不均匀等;指出了现有氮化工艺在固态粉末条件下进行渗氮处理时,存在氮化程度不均一、氮化效率低等问题;提出了高压条件下实现液态或固态合金直接氮化制备钐铁氮合金粉体的新展望。     

惰气熔融-热导法测定氮化铌纳米粉体中氮含量

氮化铌是一种难熔化合物,熔点为2 300℃.在氨解法制备立方相氮化铌纳米粉体中[1],对不同氨解温度、氨解时间合成的氮化铌纳米粉体,一般用X射线衍射、透射电镜、氮含量分析等方法进行表征.氮化铌中氮的质量分数通常在10%～13%之间.用常规碱熔-中和滴定的化学法测定氮化铌中氮[2],分解试样时间长,操作繁琐;特别对纳米粉体样品,称样量多,堆积体积大,所需熔剂量成倍增加,空白值也高.本工作采用惰气熔融-热导法测定氮化铌纳米粉体中氮含量.该方法操作简便、快速、分析数据准确可靠.     

脉冲加热-红外吸收/热导法同时测定碳化硅粉末和纤维中氧和氮

采用脉冲加热-红外吸收、热导法,通过选择合适的助熔剂、确定分析功率和称样量,建立了同时测定碳化硅粉末和碳化硅纤维中的氧和氮含量的方法。经优化后,称取碳化硅粉末20～100 mg,碳化硅纤维7～10 mg,将粉末或纤维放入0.5 g镍囊中,加1 g镍篮后,在分析功率5.5 k W下进行测定。采用碳化硅和氮化硅标准物质测得氧和氮的校准曲线;碳化硅粉末中氧和氮检出限0.0135%和0.0018%,回收率95.8%和95.6%,相对标准偏差(RSD)均小于2%;碳化硅纤维中氧和氮检出限0.0386%和0.0051%,回收率104.2%和99.7%,RSD均小于5%。本方法同时适用于碳化硅纤维和粉末中氧和氮含量的检测。     

红外吸收法测定碳化铪粉末中的氧含量

应用氧氮分析仪建立碳化铪粉末中氧的测定方法。针对碳化铪熔点极高的特性,对加热功率、称样量和空白值等测定条件进行探讨,选择适合的助熔剂和高温石墨坩埚,确定了最佳测试条件。将该方法用于实际样品测定,测定结果的相对标准偏差小于2.0%(n=9),样品的加标回收率为98.1%～102.6%。     

脉冲熔融-红外/热导法测定钛合金粉末微注射成形脱脂坯中氧氮氢

准确测定钛合金粉末微注射成形脱脂坯中氧氮氢含量对钛合金的粉末微注射工艺改进有很大指导作用。采用工业镍板经过表面打磨、酸洗、加工成固定质量的镍粒来代替市售的镍助熔剂,通过自制镍粒预先加入设备预脱气减少空白影响的方式建立了脉冲熔融-红外/热导法测定钛合金粉末微注射成形的脱脂坯中氧氮氢含量的方法。试验表明：镍粒助熔剂与石墨坩埚经二次脱气,可确保镍粒助熔剂的空白降至极低值以代替市售的镍篮、镍屑等助熔剂。钛合金粉末微注射成形脱脂坯采用振动磨形式加工至80目以下,镍粒的加入量为1.5 g,分析功率为5300 W时,可以获得稳定准确的结果。采用实验方法对脱脂坯实际样品进行测定,其相对标准偏差(RSD,n=6)分别为0.08%~0.47%、0.2 %~1.32%和1.6 %~2.02%;采用加入钛合金标准样品进行加标回收试验,氧氮氢回收率分别在 99%~10%、97%~99%及 97%~ 103%之间。方法满足脱脂坯中的氧氮氢快速检测要求的同时极大降低了分析成本。     

电感耦合等离子体发射光谱法测定二次电池废料中锂、镍、钴、锰的含量

采用HCl-HNO 3溶解样品,使用电感耦合等离子体发射光谱(ICP-OES)法直接测定二次电池废料中含量低于20%的锂、镍、钴和锰的含量。选用元素最佳分析谱线和仪器合适的工作条件测定实际样品,实验结果表明共存元素对测定结果基本没有影响。相对标准偏差(n=11,RSD<2%)。通过不同方法的测试结果对比,同一样品的不同测定结果基本吻合,结果表明,方法操作快速简便,分析结果准确,能够满足二次电池废料中20%以下的锂、镍、钴和锰的测定。     

电感耦合等离子体发射光谱（ICP-OES）法测定二次电池废料中锂、镍、钴、锰的含量

采用HCl-HNO_3溶解样品,使用电感耦合等离子体发射光谱(ICP-OES)法直接测定二次电池废料中含量低于20%的锂、镍、钴和锰的含量。选用元素最佳分析谱线和仪器合适的工作条件测定实际样品,实验结果表明共存元素对测定结果基本没有影响。相对标准偏差(n=11,RSD<2%)。通过不同方法的测试结果对比,同一样品的不同测定结果基本吻合,结果表明,方法操作快速简便,分析结果准确,能够满足二次电池废料中20%以下的锂、镍、钴和锰的测定。     

电感耦合等离子体发射光谱（ICP-OES）法测定二次电池废料中锂、镍、钴、锰的含量

采用HCl-HNO_3溶解样品,使用电感耦合等离子体发射光谱(ICP-OES)法直接测定二次电池废料中含量低于20%的锂、镍、钴和锰的含量。选用元素最佳分析谱线和仪器合适的工作条件测定实际样品,实验结果表明共存元素对测定结果基本没有影响。相对标准偏差(n=11,RSD2%)。通过不同方法的测试结果对比,同一样品的不同测定结果基本吻合,结果表明,方法操作快速简便,分析结果准确,能够满足二次电池废料中20%以下的锂、镍、钴和锰的测定。     

高氮含量MCM-41的制备及其对Knoevenagal缩合反应的催化性能

 采用二次合成法制备了含氮MCM-41分子筛,系统考察了氨气流速、氮化温度和氮化时间等因素对分子筛氮含量的影响,并通过X射线衍射、 N2吸附、透射电镜、 X射线光电子能谱和 29Si MAS NMR等方法探测了氮化后分子筛的物理化学特性. 结果表明,氨气流速和氮化温度是影响分子筛氮含量的主要因素. 氨气流速为400 ml/min时, 950 ℃下经12 h氮化后的MCM-41分子筛氮含量(质量分数)可达26.0%, 并较好地保持了原有分子筛的骨架结构. 由于氮化温度相对较低,对分子筛的结构破坏较小,而氮含量高、氮化后的MCM-41分子筛对Knoevenagal缩合反应具有很高的碱催化活性.     

Determination of nitrogen in an aluminium-killed steel by an isotope-dilution method using Al(15)N

Nitrogen in an aluminium-killed steel was determined by an isotope-dilution method using synthesized aluminium nitride enriched with (15)N. The results were in agreement with those obtained by chemical determination, whereas the vacuum fusion method with iron and platinum baths, and the isotope-dilution method using gaseous (15)N-enriched nitrogen, did not give accurate results.     

Manganese Dioxide Graphite Composite Electrodes Formed via a Low Temperature Method: Detection of Hydrogen Peroxide,Ascorbic Acid and Nitrite

Manganese dioxide modified carbon powder was prepared via a wet impregnation method from the solution of permanganate salt. After heating at 120 °C over night in air, the formation of manganese oxide was confirmed by cathodic stripping voltammetry. The synthesized material was used for fabrication of composite electrodes and their potential application in the field of electroanalysis investigated. The composite electrodes based on the manganese dioxide modified carbon powder proved to be useful as electrodes for detection of hydrogen peroxide, ascorbic acid and nitrite ions.     

Determination of the types of nitrogen in steels containing aluminium or titanium by an extraction method with hydrogen

The extraction method with hydrogen, hitherto used to determine mobile nitrogen in steels over the temperature range 350–450°C, has been employed at higher temperatures to determine nitrogen bound as aluminium nitride, or as titanium nitride or carbonitride. In steels containing only silicon and titanium as deoxidizers, the nitrogen remaining after passage of hydrogen at 600 or 750°C is present as titanium nitride or carbonitride and can be determined by difference. In steels containing only silicon and aluminium as deoxidizers, the nitrogen remaining after passage of hydrogen at 600°C is present as aluminium nitride and can also be determined by difference. This was verified by determining the aluminium nitride indirectly. The nitrogen released from both the aluminium and titanium steels in hydrogen at 600°C probably results from dissociation of submicroscopic particles of manganese silicon nitride.     

AIN纳米微粉的微波合成

Nanometer aluminum nitride powder with purity higher than 98wt% and diameter in the range of 5-80nm has been obtained by microwave heating using α-Al2O3、Al(OH)3、 colloidal Al(OH)3 as the source for aluminum, and phenolformaldehyde resin, char, nanometer carbon black powder as the source for carbon, respectively. The effect of the type of starting materials and synthesis conditions on the purity and the size of the nanometer AlN powder has been analyzed in this paper.     

The determination of manganese by the peroxidisulphate method

The colorimetric determination of manganese according to the periodate method requires a rather long period of heating for the full development of colour, especially in extremely dilute solutions. This fact led the author to investigate the possibilities of the faster peroxidi-sulphate method which for several reasons has been considered as rather unreliable.The extinctions found were compared to those of standard permanganate solutions.The optimum conditions of acidity were fixed. ALTEN AND WEILAND'S statement, that the presence of phosphoric acid prevents the precipitation of manganese dioxide, was verified.The oxidation could be carried out in the presence of chlorides and minute amounts of bromides and iodides if these ions were complexly compounded with mercuric ions. The concentration of the catalysing silver ions can conveniently be kept as low as 10-5 M which will eliminate troubles from silver chloride precipitates.Variation of the concentration of the peroxidisulphate, within wide limits, has no influence on the results.The oxidation may be carried out in the presence of certain amounts of organic matter.The permanganate is stable as long as there is an excess of peroxidisulphate and no reducing compounds are present; the decomposition rate of the peroxidisulphate under the prevailing conditions has been investigated.Amounts of manganese ranging from 100 to 0.1 μmoles (5.5-0.0055 mg) were determined in l00 ml of solution. At the higher manganese concentrations the relative error was about 1 % ; at the lowest concentrations the relative error was larger but the absolute error in no case exceeded 0.01 mmmol.From this investigation it can be concluded that the peroxidisulphate method is at least as accurate as the periodate method. It is more rapid and the fact it can be used in the presence of chlorides and organic matter makes it preferable for several purposes, e.g., for natural waters and soil extracts.     

Structural and phase transformations and hardness of ceramics produced by high-temperature zirconium nitriding

Resistive heating of zirconium in a gaseous nitrogen atmosphere yields ceramics based on zirconium nitride with a heterophase structure. X-ray powder diffraction analysis determined the compositions of phases of the synthesized ceramics. The surface of the material consists of zirconium nitride close in composition to ZrN. In the bulk of the materials, in shallower layers, a nitrogen-deficient nitride phase forms, and in deeper layers, a phase of solid solution of nitrogen in zirconium does. The hardness of ceramics based on heterostructures of the type Zr_{solid solution}/ZrN_1–x /ZrN was studied. Changes in the structure and phase composition during high-temperature nitriding of zirconium foil at 1500 and 2400°C were described.     

FAAS法连续分析测试电池锌粉中镁铁铜铅锰

提出了运用FAAS法连续分析测试电池锌粉中Mg、Fe、Cu、Pb、Mn的含量,给出了Mg、Fe、Cu、Pb、Mn最佳测定条件及线性范围,在测定中对样品中的干扰因素进行了综合考虑.方法具有很好的灵敏度和重现性,步骤简单、操作容易、干扰少.测定样品Mg、Fe、Cu、Pb、Mn含量的相对标准偏差均小于1.0%（n=10）.标准加入回收率均在97.0%-101.5%（n=6）范围内.适用于电池锌粉中Mg、Fe、Cu、Pb、Mn的含量控制分析和样品系统分析.     

氮化钛的制备及表征

以金红石为原料 ,金属铝作还原剂合成氮化钛 ,以X射线衍射、热分析等方法进行测定 ,结果表明该法合成得到的氮化钛纯度较高 ,经济可行。