改善30Cr2MoV钢大锻件冲击韧性及晶粒度的研究

通过模拟试验及生产试验,对改善30Cr2MoV钢锻件冲击性能及晶粒度进行了分析研究,找到了较为有效的热处理方法,可使用的FATT达到20℃以下,晶粒度达到6级以上。     

高原型交流接触器介绍

CJX4-dG系列高原型交流接触器可适用于海拔高度至5000m高原地区，本文针对高原适应性这一特点分析了高海拔对交流接触器的影响因素，介绍了产品改进后的功能和主要技术性能。     

High-temperature sulfidation of Fe-Nb alloys

The sulfidation behavior of Fe-Nb alloys containing up to 30 w/o Nb was studied over the range of 600–900°C in 0.01 aim. S₂ vapor. All alloys were two-phase, consisting of an Fe-rich solid solution and Fe₂Nb, and followed the parabolic rate law at all temperatures. Scales consisted of two layers-an outer layer of FeS and an inner, complex layer which contained some FeS, FeNb₂S₄ (possibly some FeNb₃S₆), NbS₂, and intermetallic particles which were either completely or only partially sulfidized. Platinum markers were located always at the interface between the two layers, which corresponded to the original metal surface. Activation energies were 18±3 kcal/mol in close agreement with the 19.8 reported for pure iron. The sulfidation rate decreased markedly with increasing Nb content of the alloys. The decrease is attributed to increasing amounts of Fe₂Nb with increasing Nb, the net effect being that the diffusion path for outward iron diffusion through the inner layer is reduced as the Nb content increases. An analysis of the structure of NbS₂ reveals that it is easily intercalated with Fe between loosely bonded layers of S-Nb-S. The S-Nb-S layers are covalently bonded which results in very low diffusivities of either S or Nb in pure NbS₂. Although intercalated Fe tends to change the Van der Waal's type bonding between layers to more ionic or covalent, Fe diffuses readily between the layers in NbS₂. Intercalation of Fe also increases the concentration of sulfur defects in NbS₂, which in turn increases the diffusivity of sulfur. Nb was observed to be immobile. Thus, it is thought that either outward iron diffusion or inward sulfur diffusion in the inner layer is the rate-controlling step, in spite of the close agreement of activation energies with that of the sulfidation of pure iron.     

Taxonomy for protective ability of rust layer using its composition formed on weathering steel bridge

For a quantitative evaluation of the protectiveness of a rust layer formed on a weathering steel bridge, the relationship between the corrosion rate of the bridge and the composition of the rust layers formed on the girders was first investigated. These corrosion rates were clearly classified by the protective ability index (PAI) of α/γ^∗ and (β + s)/γ^∗, where α, γ^∗, β and s are the mass ratio of crystalline α-FeOOH, the total of γ-FeOOH, β-FeOOH and the spinel-type iron oxide (mainly Fe₃O₄), β-FeOOH and spinel-type iron oxide, analyzed by XRD, respectively. The inequality of the former index α/γ^∗ > 1 expressed the protectiveness criterion of the rust layer, while that of the latter index, (β + s)/γ^∗< 0.5 or > 0.5, classified the corrosion rate of the non-protective rust layer. The PAI is useful for a quantitative evaluation of the protectiveness of a rust layer formed on a weathering steel bridge and is an important item for the corrosion assessment of the bridge.     

低电压氧化锌压敏电阻器的研究

研究了一种制造低电电压氧化锌压敏电阻器的方法。在基本成分的基础上适当加入二氧化钛可降低梯度电压（Ｖ１ｍＡ／ｍｍ），适量掺硼和改进热处理工艺可减小元件的漏电流和提高其稳定性。     

高温钎料PdCu-Ti在氧化铝陶瓷上的润湿性及界面反应

本文采用座滴法试验研究了合金系统ＰｄＣｕ－Ｔｉ在Ａｌ２Ｏ３上润湿性的变化规律，探讨了界面冶金及结合等行为，运用热力学理论对结果进行了分析，随Ｔｉ含量的增加及Ｐｄ含量的减少润湿角逐渐降低，Ｔｉ的加入使界面发生了一个双重变化；液相侧富氧，钛吸收层的生成及随后的固相侧氧化钛的生成，只有界面上生成一氧化钛，才能有较好的润湿行为和较强的结合力。     

Stannate and permanganate conversion coatings on AZ31 magnesium alloy

The formation of stannate and permanganate–phosphate conversion coatings on AZ31 magnesium alloy was investigated in situ by EIS measurements and their protective performances were studied by different electrochemical techniques in diluted (0.05 M) sodium sulphate solution.The influence that short or long treatment times exert on the performances of such conversion coatings is discussed. While permanganate–phosphate baths always built layers characterized by penetrating cracks, long stannate baths produced layers without interconnected porosity, but were defective. This accounted for the initial greater protectiveness achieved with the stannate treatment; nevertheless, the easy penetration of the electrolytic solution through such a layer quickly decreased its corrosion resistance.     

氧化钒制取碳化钒的热力学分析

采用热力学的方法对以五氧化二钒为原料制取碳化钒的工艺过程进行了分析,分析表明:钒氧化物的转化过程中遵守逐级还原理论。钒氧化物碳化过程中,不转化为金属钒,直接转化为碳化钒。在钒氧化物的转化过程中,应尽可能使其转化为二氧化钒。若采用气相还原碳化的方法,可通过调节气体的流量、配比、还原与碳化工艺参数进行质量控制。     

凝胶燃烧法合成LiCoO2超细粉体的研究

以LiNO3和Co(NO3)2@6H2O为原料,柠檬酸为燃料.采用凝胶低温燃烧技术合成了LiCoO2超细粉体.并利用各种分析技术对柠檬酸和硝酸盐形成的凝胶及凝胶燃烧合成的粉体进行了研究柠檬酸硝酸盐凝胶在350-400℃之间发生燃烧反应,得到黑色疏松粉体X射线衍射分析表明.适当提高柠檬酸在凝胶中的含量.燃烧后得到的粉体晶粒尺寸显著减小未经燃烧的粉体中除含有LiCoO2外.还有CoO,Li2CO3等杂质相.但在450℃下经短时间煅烧后.杂质相消失,其晶相为层状岩盐结构的高温LiCoO2相扫描电镜和透射电镜观察发现.随着煅烧温度的提高.LiCoO2粉体的粒径有所增大.但远小于在相同煅烧条件下用固相反应法制备的LiCoO2粉体.这表明采用燃烧法更适于合成具有单一相结构的,可在低温条件下烧结的超细LiCoO2粉体.     

Study on structure and magnetic entropy changes of Ce2-xPrxFe16.5Co0.5 alloys

A series of Ce2-xPrxFe16.5Co0.5 alloys were preparedby arc melting under purified argon atmosphere. The structure and magnetic entropy changes in Ce2-xPrxFe16.5Co0.5 alloys were investigated by means of X-ray diffraction pattern and MPMS XL-7 magnetometer. The experimental results show that the crystal structure of Ce2-xPrxFe16.5Co0.5 alloys keeps in TH2Zn17-type rhombohedral, and the Curie temperature of Ce2-xPrxFe16.5Co0.5 alloys can be shifted to room temperature around by a composition adjustment. The magnetic entropy changes (-ΔSM) in Ce2-xPrxFe16.5Co0.5 alloys are relatively large, and a platform of magnetic entropy changes appearsnear the temperature TC. Ce2-xPrxFe16.5Co0.5 alloys are the potential working media for magnetic refrigeration with their stable chemical properties and especially low price.