X射线荧光光谱法测定不锈钢渣样中多元素含量

以Li2B4O7作熔剂,采用熔片法制样,建立了不锈钢渣样中SiO2、CaO、MgO、Al2O3、TiO2、P2O5、MnO、Fe2O3、Cr2O3的X射线荧光光谱分析方法,本方法采用国家标准样品及人工合成标准样品绘制了工作曲线,进行了精密度和准确度试验,其测定值与化学验证值相符,并有良好的精密度,完全满足生产检验要求。     

X射线荧光光谱法测定硅、磷、铬、锰、铁

以[ KNO3+NaNO3+Sr( NO3)2]为氧化剂,Na2CO3为助熔剂,Li2B4O7作熔剂,采用熔片法制备样片,建立了高碳铬铁、碳素铬铁、炉料级铬铁中硅、磷、铬、锰、铁的X射线荧光光谱分析方法,本方法采用国家标准样品和分析试样绘制了工作曲线,进行了精密度和准确度试验,其测定值与标准值相符,并有良好的精密度,完...     

Phantom standards with temperature- and field-independent relaxation rates for magnetic resonance imaging

RATIONALE AND OBJECTIVES: For use as magnetic resonance imaging reference standards, the optimal set of phantoms should cover a wide range of T1 values, with each phantom having a T1 that is stable over time and is independent of temperature and magnetic field strength. To date, no set of phantoms fulfilling these four requirements has been prepared. In the current work, the construction of such optimal phantom standards is attempted. METHODS: Two linear gadolinium DTPA polymers are used: the first with relaxivities that are independent of temperature and magnetic field strength, and the second with relaxivities that are independent of magnetic field strength, but have an opposite temperature dependence from that of the 1/T1 of the diamagnetic matrix (agarose gel or water). Depending on the desired T1, either one or a combination of the two agents is used. RESULTS: Phantom standards were constructed with 1/T1 values that are independent of temperature (20-35 degrees C) and magnetic field strength (0.47-1.2 T) over a wide range of 1/T1 values (> or = 0.95 s-1). Phantom standards prepared in water were found to be stable with respect to 1/T1 for at least 18 months. CONCLUSIONS: Stable phantoms standards have been constructed covering a wide range of T1 values, where the T1 of any particular phantom is independent of temperature and magnetic field strength for magnetic resonance imaging conditions.     

X射线荧光光谱法测定镁质耐火材料中多元素

以Li2B4O7作熔剂,采用熔片法制样,建立了镁质耐火材料中SiO2,CaO,MgO,Al2O3,P2O5,Fe2O3的X射线荧光光谱分析方法,本方法采用国家标准样品及人工合成标准样品绘制了工作曲线,进行了精密度和准确度试验,其测定值与标准值相符,并有良好的精密度,完全满足生产检验要求。     

铝质耐火材料中多元素的X射线荧光光谱分析

以Li2B4O7作熔剂,采用熔片法制样,建立了铝质耐火材料中SiO2、CaO、MgO、Al2O3、TiO2、Fe2O3的X射线荧光光谱分析方法,本方法采用国家标准样品及人工合成标准样品绘制了工作曲线,进行了精密度和准确度试验,其测定值与标准值相符,并有良好的精密度,完全满足生产检验要求。     

锰矿中多元素的X射线荧光光谱分析

以Li2B4O7作熔剂,采用熔片法制样,建立了锰矿物料中SiO2,CaO,MgO,Al2O3,TiO2,P2O5,MnO,BaO,Fe2O3的X射线荧光光谱分析方法,本方法采用国家标准样品及人工合成标准样品绘制了工作曲线,进行了精密度和准确度试验,其测定值与标准值相符,并有良好的精密度,完全满足生产检验要求。     

影响压延取向粘结磁体性能的因素

从分析压延取向对粘结磁体矫顽力等的机制入手,通过扫描电镜、图象仪等工龄研究了影响磁粉形貌及磁体性能的因素,结果表明：磁粉颗粒的径厚比（D／H）是影响磁体性能的关键因素,合适的径厚比能使 粉在取向过程中获得最大有效的取向力矩,同时又能使该应力所引起的晶格畸变最小,获得综合性能优越的磁体;还他磁粉预烧温度、混料方式、预烧助溶剂以及磁体压延取向工艺的混炼温度对磁体性能的影响,为制造磁粉和磁体提供工艺依据。     

水雾化Fe69Ni5Al4Sn2P10C2B4Si4非晶合金粉末及其磁粉芯的性能

 Fe69Ni5Al4Sn2P10C2B4Si4合金具有强的非晶形成能力，可以通过水雾化方法获得粒度小于75 μm的非晶态合金粉末。用粒度45~75 μm的水雾化粉末制备的磁粉芯具有优异的磁性能，磁导率大于60，良好的频率特性、高的品质因数和低的损耗。该磁粉芯与磁导率相等的韩国MPP磁粉芯产品相比，其综合性能更优越。     

硅对铁基磁粉芯性能的影响研究

分别从磁滞回线、损耗、磁导率及直流偏置特性来分析硅对铁基磁粉芯性能的影响。结果表明:随着硅含量的增加,磁粉芯的饱和磁感应强度降低,纯铁粉芯的饱和磁感应强度最大;磁粉芯损耗随着硅含量的增加而逐渐减小,纯铁粉芯的损耗最大,FeSi6.5的损耗最小;纯铁粉芯的磁导率要高于铁硅磁粉芯,但随着硅含量的增加,磁导率又缓慢上升;随着硅含量的增加,磁粉芯的直流偏置特性DC-bias稳定性降低。     

润滑剂对温压FeSiAl磁粉芯性能的影响

采用温压成形工艺将水雾化Fe Si Al粉末制备成磁粉芯;用X射线衍射对原始粉末和经过绝缘包覆及热处理的粉末进行物相分析;采用软磁交流测试仪测量磁粉芯的磁损耗;利用精密磁性元件分析仪测量样品的磁导率。混合不同质量分数的硬脂酸锌和聚乙二醇(PEG)作为温压润滑剂,并研究其对Fe Si Al磁粉芯性能的影响。结果表明,1 100 MPa/100℃的温压成形条件下,当硬脂酸锌和PEG质量比为2:3,添加温压润滑剂的质量分数为1.3%时,磁粉芯生坯密度达到最大值5.75 g/cm3,热处理后为5.74 g/cm3。660℃×1 h热处理后,100 k Hz下,相应的有效磁导率?e达到137.9;350 k Hz/50 m T下磁损耗Ps为81.78 W/kg。     

Magnetic Properties of FeSiBC Amorphous Alloy Powder Cores Using Mechanical-crushed Powder

The FeSiBC amorphous powder cores were fabricated using powders of the FeSiBC amorphous ribbons which were mechanically crushed for a short time, and the relationship between magnetic properties and powder particle sizes was evaluated. The saturation magnetization Bs of the amorphous Fe82Si2B15C1 alloy was 1.62 T, which provided a superior dc-bias property for the powder cores. Meanwhile, a stable permeability up to high frequency range over 10 MHz and the low core loss of 400 kW/ma at f=50 kHz and Bm =0.1 T were obtained. These excellent high-frequency magnetic properties of the FeSiBC amorphous powder cores could be attributed to the effective electrical insulation between the FeSiBC amorphous powders made by mechanical crushing.     

Manufacture of pure iron powder by the electrolysis of fused salts

Summary A new method is described for preparing pure iron powder from pig iron and iron sponge by the electrolysis of fused salts at a temperature of 850–900°C. The article deals with the main variables and technical and economic parameters of the process, composition of the resulting iron powder, relative density of compacts produced at various compaction pressures, apparent density of the powder, and maximum magnetic permeability of Dynamaxalloys prepared on the base of pure iron obtained by the authors and on the base of other grades of iron.Translated from Poroshkovaya Metallurgiya, No. 6 (66), pp. 1–7, June, 1968.     

Sintering of iron—silicon—boron magnetically soft steels

An investigation of structure formation in multicomponent magnetically soft powder metallurgy steels was carried out. A model for the homogenization of Fe?Si-0.06% B alloys over a wide range of silicon concentrations is proposed. The optimal processing regime was determined. Highest magnetic induction was obtained in a 1% Si alloy, and highest permeability in a 6.5% Si alloy (both are sintered at 1300°C for 6 h).     

抗EMI用铁硅铝磁粉芯磁性能的研究

采用纳米TiO2对铁硅铝粉体包覆制备复合磁粉芯,研究了制备的复合磁粉芯的性能。结果表明:纳米TiO2在铁硅铝颗粒表面包覆形成一层绝缘膜,降低复合磁粉芯的磁导率,提高磁粉芯的品质因数,改善直流叠加特性,降低功率损耗;成形压力(<2 200MPa)增大,磁导率增加,功耗降低,继续增大时,功耗增加,磁导率基本不变;提高热处理温度,磁粉芯的磁导率增加而功耗降低,当温度超过690℃时,磁粉芯性能恶化。     

The measurement of quality of care in public sector psychiatric services based on consumer expectations

In this study the expectations of consumers of public sector psychiatric care in South Africa were identified, and formulated in the form of 13 standards, each with a set of criteria. During this phase input from the literature was incorporated, and expectations were validated with different groups of consumers, so that rural/urban, ethnicity and regional differences were taken into account. Based on the comprehensive set of standards and criteria, four instruments were developed to measure attainment of these standards. These included a questionnaire to consumers and one to the Director of Mental Health. It also included two schedules to be filled in by observers during site visits to hospital units and clinics. The observer teams included community members and consumers. The content validity of the instruments was established by setting out the items measuring each criterium, and validating that with a group of experts. The instruments were then tested in one province. The inter-rater reliability of the site visit schedules was calculated as 0.94, and the coding of the Director questionnaire by different coders was also tested. The average performance on all criteria was calculated, using items from all four data collection instruments. In the process items were revised, coding instructions developed, and criteria adjusted.     

高速压制制备高密度纯铁软磁材料

以退火纯铁粉末为原料,采用粉末退火结合高速压制技术的方法制得高密度压坯(7.70 g·cm-3),经烧结后获得高密度高性能的纯铁软磁材料.研究退火粉末的高速压制行为,以及烧结时间和烧结温度对材料磁性能和晶粒大小的影响.结果显示:退火粉末的压坯密度随压制速度的增加而增加,压坯密度最高可达到7.70 g·cm-3,相对密度可达到98.10%.烧结温度为1450℃,烧结时间为4 h时,材料密度达到7.85 g·cm-3,相对密度为99.96%,最大磁导率达到13.60 m H·m-1,饱和磁感应强度为1.87 T,矫顽力为56.50 A·m-1.      

磁粉离合器磁粉特性及其相关参数的关系

本文研究了不同形式磁导仪和磁粉不同填充密度对所测磁粉静态磁感应强度Ｂ值的影响；动态磁感应强度Ｂδ与Ｂ的相对关系。通过数据分析，找出了其间所存在的规律，其研究结果对统一磁粉静态磁性能测试方法、简化磁粉离合器主要参数的设计计算、分析磁粉离合器在使用中出现的问题，具有重要的参考价值     

Routine analysis of proteins by Kjeldahl and Dumas methods: review and interlaboratory study using dairy products

The Kjeldahl and Dumas (combustion) methods were compared in 11 laboratories analyzing samples of milk, skim milk powder, whole milk powder, whey protein concentrate, infant formula, casein, caseinate, 2 reference compounds (glycine and EDTA), and a secondary reference skim milk powder. The comparison was conducted by using international standards where applicable. Overall means were 8.818 g N/100 g by the Kjeldahl method and 8.810 g N/100 g by the Dumas method. No evidence was found for a consistent bias between methods that may be of concern in the trading of dairy produce. A review of more than 10 related trials revealed a lack of consensus in the bias between the 2 methods, suggesting that differences in methodology and sources of systematic error may be contributors. For samples containing > 2 g N/100 g, the Dumas relative repeatability and reproducibility standard deviations were consistently about 0.35 and 0.75%, respectively, whereas the corresponding Kjeldahl values declined generally with N content and were significantly larger. The Dumas precision characteristics may be due to the dominance of Leco analyzers in this trials, and in most other recent trials, rather than an inherent method attribute. Protein determination methods for dairy products need to be reviewed and updated. The Dumas method needs Codex Alimentarius status as a recognized test method.     

陕西某次生岩型红柱石矿的生产流程及产品品质

次生石英型红柱石矿,矿石呈浅红色,矿物颗粒细小,分布均匀,红柱石含量高,实际入选矿石品位多在33%以上,矿石中含有极少量金红石、褐铁矿、黄铁矿等,是精矿中TiO_2和Fe_2O_3的主要来源,通过细磨磁选可以减少精矿中Fe_2O_3含量。实际生产流程为磁选重选联合流程,流程简单,不添加任何化学药剂,也不需要尾矿库,磁机分离的铁矿物和尾矿混在一起都是生产水泥的好原料。生产的产品分粒料和粉料两大类六个品种,以粉料为主,通过多次反复除铁,大大降低了粉料中铁的含量,生产的粉料质量基本符合行业标准。     

Magnetoabrasive Fe-C-W alloy powders

Conclusions With a titanium alloy, the shaping of a surface being polished is linked to a large extent with plastic deformation (work hardening). In the polishing of a harder material (steely cutting plays a more important part. This explains why in the polishing of a titanium alloy surface roughness is reduced more effectively by round than by faceted particles. In the polishing of a titanium alloy with the powders investigated a dominant role is played not by their hardness but by their magnetic properties: In our work the best results were obtained with the powder of lowest tungsten content. With steel, probably because of an increasing role of the hardness of the powder particles, the quality of polishing is best at a higher tungsten content. A slight fall in magnetic properties is apparently compensated, compared with a titanium alloy, by the high magnetic permeability of steel. A magnetoabrasive Fe-C-W alloy powder can be successfully used for polishing titanium alloys, polished surfaces having a finish two or three classes higher than that attainable in polishing with Zh15KT material (15 wt. % TiC-Fe cermet).Translated from Poroshkovaya Metallurgiya, No. 9 (225), pp. 79–82, September, 1981.