Zn—48.48Al—1.65Cu—0.03Mg合金液表面氧化膜微细特性

利用Ｘ射线光电子能谱（ＸＰＳ）和Ｘ射线衍射等,研究了Ｚｎ－４８．４８Ａｌ－１。６５Ｃｕ－０．０３Ｍｇ合金液表面氧化膜微细特性。除Ａｌ２Ｏ３外,氧化膜内还有相当数量的ＺｎＯ和金属Ｚｎ存在,少量的ＭｇＯ和ＭｇＡｌ２Ｏ４明显富集在膜表面,少量金属Ｃｕ滞留于氧化膜中,氧化膜中金属离子明显过剩,计算及生产实践表明,这种氧化结果导致合金Ｚｎ和Ｍｇ含量减少,Ａｌ和Ｃｕ含量反而增加。     

铸造SiCp／Mg（AZ81）复合材料界面

用ＴＥＭ对铸态ＳｉＣｐ／Ｍｇ（ＡＺ８１）复合材料界面进行了研究。结果表明，ＳｉＣ颗粒与α－Ｍｇ界面光滑，无界面化学反应。Ｍｇ１７Ａｌ１２相及Ｃｕ５Ｚｎ８相能在ＳｉＣ颗粒表面形核长大，且它们之间的位向关系为：［１１－０１］ＳｉＣ‖［１１－１］Ｍｇ１７Ａｌ１２，（０１１－１）ＳｉＣ‖（１１０）Ｍｇ１７Ａｌ１２和［１００］Ｃｕ５Ｚｎ８‖［２１－１－０］ＳｉＣ，（００１）Ｃｕ５Ｚｎ８‖（０００１）ＳｉＣ。     

Si对Zn-Al合金性能的影响

研究了Ｓｉ对ＺｎＡｌ２７Ｃｕ２Ｓｉｘ和ＺｎＡｌ２７Ｍｇ０．０２Ｓｉｘ两类合金力学性能和耐磨性的影响。研究发现,随着Ｓｉ含量的增加,这两类合金的抗拉强度、硬度和耐磨性都提高,而耐塑性下降;含Ｓｉ量在４％左右时,这两类合金的抗拉强度都达到最大值,ＺｎＡｌ２７Ｓｉ４Ｍｇ０．０２和ＺｎＡ２７Ｓｉ４Ｃｕ２合金的抗拉强度分别为４００ＭＰａ和３６７ＭＰａ;当Ｓｉ量为２％～４％时,这两类合金的耐磨性最好。     

γ射线辐照－水热处理法制备纳米金属粉末SCIEI

用γ射线辐照－水热处理法制备出８ｎｍＡｇ粉、１６ｎｍＣｕ粉和１０ｎｍＰｄ粉．研究了实验条件对Ａｇ粉粒径的影响．确定了制备纳米Ｃｕ粉的工艺参数，发现用ＥＤＴＡ络合Ｃｕ离子，有利于制备粒径较小的纳米Ｃｕ粉，在不同条件下可获得球形和针形的纳米Ｃｕ粒子．     

航空结构用高纯高韧性铝合金的进度

综述了美苏等国为适应现代航空工业发展的需要，不断开发新型高纯高韧性飞机结构用铝合金．介绍了一系列高纯高韧性Ａｌ－Ｃｕ－Ｍｇ系合金和Ａｌ－Ｚｎ－Ｍｇ－Ｃｕ系合金的成分和特性．以供我国开展航空工业用新型铝合金的开发和生产工作中参考．     

铸态稀土铝合金中元素分布与枝晶偏析

本文研究了稀土对铝合金中不同合金元素的分布和枝晶偏析的影响。研究表明，当合金中稀土加入量较少时，合金中的稀土没有富集现象；当加入量较多时，合金中的稀土主要与合金元素作用形成化合物。稀土的加入增加了与工业纯铝中杂质元素、Ａ１－Ｃｕ和Ａ１－Ｃｕ－Ｌｉ合金中Ｃｕ等元素形成化合物的趋势和能力，增大了这类元素的枝晶偏析；减少了Ａ１－Ｚｎ－Ｍｇ合金基体中Ｚｎ、Ｍｇ等合金元素形成化合物的趋势和能力，而对其枝晶偏     

铝合金铸锭析出退火处理的进展

对变形铝合金铸锭采取析出退火处理可以提高挤压时的极限允许流动速度。Ａｌ－Ｍｇ，Ｓｉ，Ａｌ－Ｃｕ－Ｍｇ和Ａｌ－Ｚｎ，－Ｍｇ－Ｃｕ系合金的铸锭采取这种处理都有明显的效果。在合金基本组元于铝中固溶稳定性最低的温度下进行析出退火处理，不仅处理时间短，而且可在较低挤压力下实现高速挤压。     

航空结构用高纯高韧性铝合金的进展（2）

航空结构用高纯高韧性铝合金的进展（２）张君尧（东北轻合金加工厂黑龙江哈尔滨市１５００６０）２７ＸＸＸ系高纯铝合金在ＡＩ—Ｚｎ—Ｍｇ—Ｃｕ系合金中，由于存在Ｆｅ、Ｓｔ杂质，可能生成（ＦｅＣｒｈｓｉＡｌｌ。、（Ｆｅ，Ｍｎ，Ｃｕ）Ａｌｅ、Ｃｕ。ＦｅＡＩ，和...     

PREPARATION OF NANOCRYSTALLINE METAL POWDERS BY γ-IRRADIATION-HYDROTHERMAL TREATMENT METHOD

用γ射线辐照－水热处理法制备出８ｎｍＡｇ粉、１６ｎｍＣｕ粉和１０ｎｍＰｄ粉．研究了实验条件对Ａｇ粉粒径的影响．确定了制备纳米Ｃｕ粉的工艺参数，发现用ＥＤＴＡ络合Ｃｕ离子，有利于制备粒径较小的纳米Ｃｕ粉，在不同条件下可获得球形和针形的纳米Ｃｕ粒子．     

γ射线辐照－水热处理法制备纳米金属粉末

用γ射线辐照－水热处理法制备出８ｎｍＡｇ粉、１６ｎｍＣｕ粉和１０ｎｍＰｄ粉．研究了实验条件对Ａｇ粉粒径的影响．确定了制备纳米Ｃｕ粉的工艺参数，发现用ＥＤＴＡ络合Ｃｕ离子，有利于制备粒径较小的纳米Ｃｕ粉，在不同条件下可获得球形和针形的纳米Ｃｕ粒子．     

移动消毒防疫机器人设计与导航实现

基于新冠疫情之下消毒防疫的需求,设计一款具有减振缓冲移动底盘的消毒防疫机器人。集成紫外线和喷雾消毒功能的消毒模块可自动升降,以满足不同高度区域的消毒需求。移动底盘可完成地图构建和自主导航,消毒模块可以满足消毒彻底、不留死角和较高位置消毒的需求。分析并建立移动消毒防疫机器人速度运动模型;搭建仿真环境,得到仿真环境地图,并在该环境下进行自主导航实现。结果表明：所设计的导航系统安全、可靠,可以实现室内空间消毒的绿色化和自动化。     

A theoretical analysis of zero-field splitting parameters of Mn doped dicadmium diammonium sulfate Cd2(NH4)2(SO4)3 single crystal

The superposition model (SPM) and crystallographic data are utilized to determine the zero-field splitting (ZFS) parameters (ZFSPs) for Mn²⁺ ions in Cd₂(NH₄)₂(SO₄)₃ single crystal, assuming that the Mn²⁺ ions locate at either Cd²⁺ or NH⁴⁺ site. The SPM results has been verified by the fourth-order perturbation formulae analysis. Experimental suggestions about Mn²⁺ ions substituting at Cd²⁺ sites have been confirmed theoretically for the first time.     

Phase and structural transformations in the alloy on the basis of the orthorhombic titanium aluminide

Phase and structural transformations in the Ti-24.3 Al-24.8 Nb-1.0 Zr-1.4 V-0.6 Mo-0.3 Si (at %) alloy that take place during heating in the temperature range of 700–1050°C have been investigated. The temperature ranges of existence of the O + β, O + β + α₂, β + α₂, and β phase fields have been established. A scheme of the relationships between the volume fractions of the O, β, and α₂ phases depending on the temperature of heating of the alloy have been investigated. The formation of an ordered incommensurate ω (V _ω) phase has been revealed in the alloy during quenching from 900°C. The existence of a correlation between the hardness properties and changes in the phase composition and morphology of particles precipitating in the alloy has been shown.     

Effect of additives on the properties of phosphate conversion coating on electrogalvanized steel sheet

Ni²⁺ and Mn²⁺ ions have been added separately to the phosphate solution to minimize the porosity of the phosphate conversion coating on electrogalvanized steels. Results showed that the Ni²⁺ or Mn²⁺ in the solution reduced the grain size and porosity of the phosphate coating; thereby, the corrosion resistance was enhanced. However, Ni²⁺ and Mn²⁺ played a different role in the coating formation. Ni²⁺ in the solution was reduced by Zn to form Ni, which enhanced the dissolution of Zn to promote the nucleation of hopeite grains. Mn²⁺ in the solution facilitated the nucleation by increasing the impingement of reacting species.     

Combustion synthesis of long-persistent luminescent MAl2O4: Eu2+, R3+ (M = Sr,Ba, Ca,R = Dy,Nd and La) nanoparticles and luminescence mechanism research

Eu²⁺, R³⁺ co-doped alkaline earth aluminates MAl₂O₄: Eu²⁺, R³⁺ (M = Sr, Ba and Ca; R = Dy, Nd and La) nanoparticles with high brightness and long afterglow have been prepared by solution-combustion synthesis at 600 °C without a post-annealing process for the first time. The morphologies and the phase structures of the products have been characterized by transmission electron microscopy and X-ray diffraction. The excitation and emission spectra of the products have been measured by an Edinburgh FLS920 spectrometer at room temperature. The characteristic luminescence of the as-prepared sample has been evaluated, and the reason why the wavelength changed from yellow-green to blue-green and then to blue-purple in visible range when the composition changed from SrAl₂O₄: Eu²⁺, Dy³⁺ to BaAl₂O₄: Eu²⁺, Nd³⁺ and then to CaAl₂O₄: Eu²⁺, La³⁺ has been explained. Furthermore, a new persistent luminescence mechanism was proposed in this article.     

Melting characteristics of magnesium—lithium alloys

Mg-Li-Al alloys containing 4–14 wt% Li and 1.5 wt% Al have been prepared by melting Mg/Mg-Al master alloy and Li separately under MgCl2 + KCl + MgO + CaF₂ and LiCl + LiF flux covers, respectively, and mixing the two together. The observed lithium loss and the pick-up of impurity elements in the melt have been correlated with various physico-chemical phenomena occurring during melting. The effect of holding time on melt composition was also examined. The results indicate that it is possible to control the alloy composition within specified limits by the selection of proper melting fluxes and crucible materials and by restricting the holding time to the minimum possible. These findings suggest that flux-cover melting is a viable route for the production of sound cast ingots of highly reactive magnesium—lithium alloys.     

Optical properties of Yb-doped phosphate laser glasses

Ytterbium-doped phosphate glasses have been prepared and studied their spectroscopic properties through absorption, emission and Fourier transform infrared (FTIR) spectral studies and time-resolved luminescence decay curves. The absorption cross-section has been found to vary with the variation of Yb₂O₃ concentration. The results of the FTIR spectra show that the OH⁻ content is increasing with increase of the Yb₂O₃ concentration in these glasses. The decay curves of the ²F_5/2 level of Yb³⁺ ions exhibit a single exponential nature for all the concentrations. The lifetimes of the ²F_5/2 level of Yb³⁺ ions decreases from 1.04 to 0.27 ms when the Yb₂O₃ concentration is increased from 0.1 to 6.0 mol%. The quenching of lifetimes has been found to vary directly with the inter-ionic distance between the Yb³⁺ ions. The concentration quenching of the lifetime has been analyzed using different energy transfer processes and no evidence of cooperative luminescence of Yb³⁺ ions has been found in these glasses, which reveals that the present glasses are useful for photonic device applications. The laser performance properties have also been evaluated for these glasses and compared with those of other reported Yb³⁺-doped glass systems.     

Spectroscopic and 1.06 μm laser properties of Nd-doped K–Sr–Al phosphate and fluorophosphate glasses

Optical absorption, fluorescence and decay curves for the ⁴F_3/2 level of Nd³⁺ ions in phosphate (P₂O₅–K₂O–SrO–Al₂O₃) and fluorophosphate (P₂O₅–K₂O–SrO–Al₂O₃–AlF₃ and P₂O₅–K₂O–SrO–Al₂O₃–BaF₂) glasses doped with three concentrations (0.1, 1.0 and 2.0 mol%) of Nd³⁺ ions have been investigated. The Judd–Ofelt (JO) theory has been applied to the absorption spectra of 1.0 mol% Nd³⁺-doped glasses to derive JO intensity parameters which are in turn used to calculate the radiative properties of the Nd³⁺ ion fluorescent levels. The assigned energy level data of Nd³⁺ (4f³) ions are analysed in terms of a parametrized free-ion Hamiltonian model that consists of 20 interaction parameters of atomic nature. The stimulated emission cross section and branching ratios have been calculated using the emission spectra. The relatively higher branching ratio for ⁴F_3/2 → ⁴I_11/2 transition shows the suitability of these glasses for laser application. It is interesting to note that the measured decay curves of the ⁴F_3/2 level remain nearly single exponential even for higher Nd³⁺ ion concentration but with shortening of lifetime.     

Role of cadmium on corrosion resistance of Zn-Ni alloy coatings

Cadmium (Cd) catalyzed Zn-Ni alloy plating has been accomplished galvanostatically on mild steel (MS) using gelatin and glycerol as additives. The effect of addition of Cd into Zn-Ni bath has been examined in terms of nickel (Ni) content and corrosion resistance of Zn-Ni-Cd ternary alloy coatings. The process and product of electrolysis under different concentrations of additives and Cd have been investigated by cyclic voltammetry (CV). The effects of current density (c.d.) on Ni content of the alloy have been studied by spectrophotometric method, supported by EDX analysis. The deposition has been carried out under different concentrations of Cd ranging from 0.004 to 0.1 M. The corrosion rates (CR) of Zn-Ni alloy coatings have been found to decrease drastically with addition of Cd. It has been also revealed that the CR of binary Zn-Ni alloy coatings decreased with the increase of Cd concentration only up to a certain optimal concentration, i.e., up to 0.02 M, and then remained unchanged. An effort to change the anomalous type of codeposition into normal one by changing the molar ratios of the metal ions, i.e. [Cd²⁺]/[Ni²⁺] as 0.01, 0.05 and 0.25 has remained futile. CV study demonstrated an important role of Cd in mutual depositions of Zn²⁺ and Ni²⁺ ions by its preferential adsorption, thus leading to the increased Ni content of the alloy. The bath composition and operating parameters have been optimized for deposition of bright and uniform Zn-Ni-Cd alloy coatings. Changes in the surface morphology and phase structure of Zn-Ni alloy coatings due to addition of Cd has been confirmed by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) study respectively. Experimental investigations so as to identify the role of Cd in codeposition Zn-Ni alloy coatings have been carried out and the results are discussed.     

Molybdate based conversion coatings for zinc and zinc alloy surfaces: a review

Abstract

The replacement of chromate conversion coatings for Zn surfaces has been necessitated by industry due to the toxicity issues associated with Cr(VI) and the enforcement of 'WEEE' and 'ELV' directives by the European Union. Molybdate conversion coatings have been investigated by many researchers as possible 'non-chromate' alternatives due to their low toxicity. A significant amount of work has been undertaken in this area in the past 20 years and this review tries to bring together findings from this work. Although a direct replacement for Cr(VI) conversion coatings using molybdates does not appear to have been found, limited success has been gained with the addition of synergistic chemical species such as PO₄^3? and Al³⁺. Immersion time, pH, temperature and additives have been investigated by many researchers and the effects of these on molybdate systems have been contrasted. X-ray photoelectron spectroscopy characterisation data are included and shows coatings to contain Mo in the +2, +4, +5 and +6 oxidation states. ASTM B-117 neutral salt spray corrosion data suggests that the best performance of molybdate based coatings is around 24 h without white rust on electroplated Zn surfaces. Molybdate treatments on Zn–Ni alloy surfaces have given times to white rust of up to 360 h. In conclusion, the outlook for molybdate based conversion coatings on Zn surfaces is a promising one; with synergistic additions giving increased efficacy in corrosion tests.