La、Ce掺杂对水热法合成镍锌铁氧体的影响

采用水热合成法制备镍锌铁氧体粉体,以稀土元素La、Ce进行掺杂,利用SEM和XRD 等手段对样品进行表征.结果表明,La3+、Ce3+掺杂后,La3+、Ce3+离子掺杂进入镍锌铁氧体晶格后,会产生一定的晶格畸变,造成晶粒常数的增大,但对晶体的形貌影响不大.除存在少量大颗粒,立方尖晶石相Ni0.35Zn0.65Fe1.9...     

酒石酸-硝酸盐低热固相反应制备Ni_(0.18)Cu_(0.2)Zn_(0.62)O(Fe_2O_3)_(0.98)铁氧体

以酒石酸和金属硝酸盐为原料,采用低热固相反应方法合成了Ni0.18Cu0.2Zn0.62O(Fe2O3)0.98尖晶石型铁氧体,并应用FT-IR,DSC-TG,XRD,TEM以及SEM等技术对低热固相反应过程和样品进行了研究和表征。FT-IR研究表明,酒石酸和金属硝酸盐在研磨30min后发生了低热固相反应,生成金属酒石酸盐前驱体。FT-IR和XRD分析表明,前驱体经不同温度焙烧后得到单一尖晶石相的NiCuZn铁氧体粉。依据谢乐公式计算和TEM表征,证明干凝胶在350℃分解1h后的粒径约为20～30nm,将此粉体在750℃下焙烧2h后,粒径增大到100～150nm。铁氧体于900℃烧结为陶瓷体后,晶粒约为2～4μm,烧结致密。随着烧结温度由850℃提高到900℃,NiCuZn铁氧体的矫顽力Hc有所下降,但饱和磁化强度Ms有所升高。磁谱测量表明,900℃烧结样品的磁导率为170,截止频率为32MHz,样品的磁性主要来源于畴壁位移的贡献。     

Ni0．5Zn0．5La0．05Fe1.95O4铁氧体的制备与吸波性能研究

采用高分子凝胶法制备了Ni0．5Zn0．5La0．05Fe1.95O4铁氧体。当煅烧温度为600℃时,立方晶系尖晶石结构的Ni0．5Zn0．5La0．05Fe1.95O4相初步形成。掺杂稀土La后,Ni0．5Zn0．5La0．05Fe1.95O4铁氧体的吸波性能显著提高,吸收峰向高频移动,其电磁波反射率小于～10dB的频宽可达2．7GHz,最小反射率为-15．6dB。     

Preparation and magnetic properties of Cu0.4Zn0.6Cr0.5Sm0.06Fe1.44O4/polyaniline nanocomposites

A self-propagating combustion synthesis (SPCS) method, citrate SPCS method, was used to synthesize Cu0.4Zn0.6Cr0.5SmxFe1.5-xO4 (x=0-0.1) nanosized powders at relatively low temperature. Polyaniline/Cu0.4Zn0.6Cr0.5Sm0.06Fe1.44O4 (CZCS0.06FO) nanocomposites were prepared by in situ polymerization of aniline in the presence of CZCS0.06FO ferrites. The structures, morphologies, and ferromagnetic properties of ferrite powders and nanocomposites were characterized by powder X-ray diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). The results indicated that ferrite powders were coated effectively by polyaniline, which reduced the agglomeration of ferrite particles to certain extent, and was helpful to the decentralization and stabilization of nanoparticles. The nanocomposites with core-shell structure under applied field exhibited hysteresis loops of the ferromagnetic nature. The nanocomposites were fit for being used as soft magnetic material because of their lower coercivity than that of pure ferrites.     

Synthesis of ZnFe2O4 nanosized powders by pulsed wire discharge

Nanocrystalline zinc ferrite (ZnFe₂O₄) powders have been synthesized successfully by high-power short-pulse electric discharge of Fe and Zn wires in oxygen gas. The powders were characterized by X-ray diffraction and transmission electron microscopy (TEM). Mean size of the obtained particles determined by both BET and TEM was 12 to 56 nm depending on the oxygen pressure. X-ray analysis showed that the zinc ferrite spinel was clearly obtained. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(450), pp. 3–6, July–August, 2006.     

冷喷涂Zn-Ni复合涂层形貌及性能

利用冷喷涂制备了Zn-15%Ni复合涂层。应用扫描电镜(SEM)、EDS和XRD对涂层的形貌、成分、孔隙率进行分析,并研究了喷涂前对基体材料进行前处理和喷涂后对涂层进行后处理对涂层形貌、孔隙率和结合强度的影响。结果表明:制备出Zn-15%Ni的复合涂层,涂层主要是以Zn和Ni的单质相形式存在,无新的第二相形成,锌和镍均保持了原本的结构;复合涂层致密,孔隙率低、硬度高、结合力好;喷涂前对基体材料进行喷丸后再吹砂的前处理,有利于提高涂层的结合强度;喷涂后对涂层进行喷丸处理,可使涂层平整、致密。     

电炉粉尘预处理对其合成Ni-Zn铁氧体性能的影响

摘要：尖晶石型铁氧体MFe2O4（M=Ni、Zn、Mn和Mg等）由于其良好的稳定性和优越的磁电性能,在磁电领域受到广泛应用。以电炉粉尘为原料,先利用NaOH溶液对电炉粉尘进行预处理,然后加入不同含量的NiCl2·6H2O,通过水热方法直接合成具有尖晶石结构的Ni-Zn铁氧体（(Ni,Zn)Fe2O4）,最后详细探讨了不同浓度的NaOH预处理除硅和配入不同量NiCl2·6H2O对合成(Ni,Zn)Fe2O4磁性能的变化规律。结果表明,当NaOH浓度从0增加到10mol/L时,预处理后电炉粉尘中SiO2质量分数从6.85%降低到1.49%,合成的Ni-Zn铁氧体的饱和磁感应强度从19.5A·m2/kg升高到32.3A·m2/kg;而预处理后电炉粉尘与NiCl2·6H2O的质量比从1∶0.7降低到1∶0.9时,所得样品的饱和磁感应强度从28.4A·m2/kg增长到32.3A·m2/kg。该工艺不仅简化了电炉粉尘的处理工艺流程,而且实现了其高附加值利用。     

Improving the plasticity of ferrite powders

Conclusions The character of the relationship between the coefficient of plasticity of a ferrite powder and its specific surface is determined by the particle shape and size of the powder. Because of this, such curves can be employed for undirectly assessing the morphological characteristics of ferrite powders. The addition of polyvinyl alcohol has been found to have a marked deleterious effect on the plasticity of ferrite powders. The character of the relationship between the coefficient of plasticity of a ferrite powder and its water content has been established. Stability of water content is shown to be an important factor, ensuring high quality of compacts, minimizing waste due to cracking, and decreasing the rate of wear of die sets.Translated from Poroshkovaya Metallurgiya, No. 11(203), pp. 6–9, November, 1979.     

固溶处理对超低碳奥氏体不锈钢00Cr24Ni13铸坯δ-铁素体转变的影响

研究了1000～1200℃ 1～3 h固溶、淬火或空冷对超低碳奥氏体不锈钢00Cr24Ni13(/%:≤0.02C、23～25Cr、13～14 Ni)200 mm×1 250 mm铸坯8铁素体转变的影响。结果表明,随固溶温度升高和保温时间延长铸坯中δ铁素体量减少;随固溶温度的升高,铸坯中的连续网状δ铁素体断开并且长大,空冷则会促使高温下长大的δ铁素体向小尺寸颗粒状组织转变;当铸坯试样在1 200℃保温3 h空冷后,网状δ铁素体完全转变成弥散分布的小于10μm的颗粒状铁素体组织,δ铁素体相比例也由14.3%降至7.3%。相对于颗粒状铁素体,网状δ铁素体的奥氏体-铁素体两相界面在轧制中更容易产生裂纹。     

氧压力对自蔓延高温合成Ni-Zn铁氧体粉体的影响

在自蔓延高温合成（SHS）Ni-Zn铁氧体粉体的研究中，以XRD、TEM分析， 考察了氧压力对燃烧温度、燃烧波速度以及产物微观相组成和形貌的影响，并结合理论分析，确定了以SHS方法合成Ni-Zn铁氧体粉体的最佳氧压力值。     

Growth of intragranular ferrite in Fe-Ni-P alloys

Analytical electron microscopy (AEM) techniques were used to study the growth of intragranular ferrite in Fe-Ni-P alloys. The spatial resolution of the AEM was exploited to gather microchemical information regarding elemental redistribution at ferrite/austenite interfaces in order to determine the growth mechanism for intragranular ferrite. In this alloy system, the growth kinetics are dictated by the bulk diffusion of Ni in austenite. Full equilibrium occurs during intragranular ferrite growth with full partitioning of Ni and P between austenite and ferrite, and chemical equilibrium occurs at the α/γ interface in both phases. A numerical model to simulate ferrite growth was developed based on equilibrium growth considerations. The Ni concentrations and precipitate sizes predicted by the model agree well with those measured by AEM techniques in the experimental alloys. The computer model has been extended to predict the thermal histories of iron meteorites and their parent asteroidal bodies.     

直接法制备铁锰锌共沉淀粉的工业试验

在扩大试验基础上,以软锰矿、锌烟灰和铁屑为原料,进行了500t／a锰锌铁共沉淀粉湿法制备工艺工业试验。结果表明,Fe,Mn和zn总回收率分别为97．33％,97．16％和98．66％;Fe,Mn和zn的总直收率分别为83．58％,88．18％和85．57％。共沉淀粉的质量较高,配比非常接近理论值,杂质元素含量低。按单槽共沉粉中的金属质量推算,每槽可产铁氧体粉料（∑MexOy）0．548t,每年铁氧体粉料产量为493t,基本达到设计能力。工业试验中以共沉淀粉制成的铁氧体样环的磁性能,除个别高温高频功耗,其余均达到日本TDK公司PC30产品质量指标。     

pH值对溶胶凝胶自燃法合成纳米镍锌铁氧体的影响

用溶胶-凝胶法制备Ni0.5Zn0.5Fe2O4.研究不同pH值对试样物相的影响.利用差示扫描量热仪对干凝胶热分解行为进行研究.利用X射线衍射(XRD)、透射电子显微镜(TEM)、振动样品磁强计(VSM)对产物的物相、微观结构和磁性能进行研究.结果表明,利用溶胶凝胶自燃法制备的镍锌铁氧体粉末未经热处理得到具有单一尖晶石...     

Effect of physicochemical transformations occurring in compacts during heating on the properties of manganese-zinc ferrites

Conclusions The temperature ranges of the physicochemical transformations occurring during heating in compacts from manganese-zinc ferrite powders produced by different methods have been established. The effect of method of preparation of ferrite powders on the character of processes taking place in compacts during heating is demonstrated. The degree of decomposition of the spinel at a given rate of heating is lower in powders produced by the carbonate coprecipitation method than in powders obtained from an oxide mixture. The reason for this is that the structure of carbonate-grade powders has comparatively few defects. Lowering the rate of heating of specimens in the temperature range 550–650C increases the degree of decomposition of the spinel, ensures a better reproducibility of properties, and improves the quality of ferrite parts.Translated from Poroshkovaya Metallurgiya, No. 10(238), pp. 62–66, October, 1982.     

Numerical Modeling of δ‐Ferrite Dissolution Kinetics in Austenitic Stainless Steels

In the present paper a numerical model that describes the diffusion processes of Ni and Cr between ferrite and austenite in Fe‐Cr‐Ni ternary systems has been developed by using the finite difference method (FDM). The model employed the tie‐line relationships given by Kajihara and Kikuchi. The moving ferrite/austenite interface was determined by solving the mass balance equations using the Newton‐Raphson method. The model has been applied to predicting the dissolution kinetics of ferrite in austenitic stainless steels, which were processed by welding, continuous casting and strip casting, respectively. The accuracy of the model has been confirmed to be quite satisfactory as compared with measured values, with advantages over another numerical model developed by Vitek et al. This model was reproduced in the present work.     

Development of single-phased copper alloy for seawater applications: As a cost-effective substitute for Cu-10Ni alloy

Cu-10Ni alloy is a standard material for seawater application. Under Indian scenario, where half of copper and whole of Ni (and Cu-Ni) requirement is met by imports, search for a cheaper substitute is obvious. An attempt has been made to develop a single-phased copper alloy containing 10 wt% Ni, 29 wt% Zn, up to 5 wt% Mn and 1 wt% Fe as a substitute to Cu-10wt% Ni-1wt% Fe alloy. Studies on Corrosion resistance of test alloys were carried out in synthetic seawater (ASTM D 114-75) by electro-chemical methods (cathodic and anodic polarization). Corrosion product film formed on alloy containing 5wt% Mn was characterized by SEM and XRD. A film of Cu₂O was found to form on the surface of the alloy, which accords corrosion protection. The test alloys containing 29 wt% Zn and 3 or 5 wt% Mn have exhibited better corrosion resistance in synthetic seawater than Cu-10Ni alloy. The role of Mn and Zn addition has been discussed.     

固溶温度对022Cr22Ni5Mo3N双相不锈钢组织和性能的影响

试验研究了1000℃ 4h和1060℃ 4h固溶处理后022Cr22Ni5Mo3N钢中ϕ75 mm材的组织和力学性能。结果表明,022Cr22Ni5Mo3N钢ϕ75 mm材终锻温度970℃空冷的组织（体积分数)约为铁素体31% ,奥氏体 56%,析出物13%;1 000℃ 4 h固溶后为铁素体38% ,奥氏体60% ,析出物2%;1060℃ 4h固溶后铁素体50%,奥氏体50%,该钢通过釆用1060℃固溶后,拉伸断裂强度731MPa延伸率38%,冲击功AKV(-40℃ ）76~81 J,满足标准要求。     

Particle Deformation and Sliding During Compaction of Spherical Powders: A Study by Quantitative Metallography

Abstract

Fe–Ni heterogeneous alloys were prepared from powders by pressing, sintering, hot rolling, cold rolling, and heat treatment. A composite alloy was produced which consisted of ferrite, martensite, and austenite phases elongated parallel to the rolling direction. The volume fraction of each phase depended on the amount of Ni powder and the annealing temperature. The strength and elongation of the alloy increased with the amount of martensite phase and austenite phase, respectively. Both its yield strength and uniform elongation satisfied a rule of mixtures qualitatively. It was found that inhomogeneous Ni distribution affected the formation of each phase and the mechanical properties of the alloys.     

TEM Studies of Boron-Modified 17Cr-7Ni Precipitation-Hardenable Stainless Steel via Rapid Solidification Route

Commercial grade 17Cr-7Ni precipitation-hardenable stainless steel has been modified by adding boron in the range 0.45 to 1.8 wt pct and using the chill block melt-spinning technique of rapid solidification (RS). Application of RS has been found to increase the solid solubility of boron and hardness of 17Cr-7Ni precipitation-hardenable stainless steel. The hardness of the boron-modified rapidly solidified alloys has been found to increase up to ~280 pct after isochronal aging to peak hardness. A TEM study has been carried out to understand the aging behavior. The presence of M₂₃(B,C)₆ and M₂(B,C) borocarbides and epsilon-carbide in the matrix of austenite and ferrite with a change in heat treatment temperature has been observed. A new equation for Creq is also developed which includes the boron factor on ferrite phase stability. The study also emphasizes that aluminum only takes part in ferrite phase stabilization and remains in the solution.     

高能机械研磨制备铁氧体的研究

通过高能机械研磨的方法直接将ZnO和α-Fe₂O₃混合粉末合成尖晶石型铁氧体粉末,采用高能机械研磨和热处理相结合的工艺,由BaO、ZnO和α-Fe₂O₃制备超细晶的BaZn₂Fe₁₆O₂₇型六角铁氧体,采用X射线衍射（XRD）分析不同研磨时间ZnFe₂O₄和BaZn₂Fe₁₆O₂₇铁氧体形成的化学反应过程,研究发现ZnFe₂O₄反应过程分阶段进行,反应合成的ZnFe₂O₄铁氧体粉末的平均晶粒度小于10nm;通过机械研磨和热处理相结合的工艺可以制取晶粒尺寸为100~200nm的超细晶BaZn₂Fe₁₆O₂₇铁氧体粉末。