用柠檬酸作释放剂选择性螯合滴定法测定锡

本文提出了测定锡的一个简易、快速螯合滴定法。该方法是先用EDTA螯合锡和其它金属离子，然后用柠檬酸(Cit)解蔽。释放出的EDTA用Pb(NO3)2标准溶液滴定，以XO—CPB为混合指示剂，终点变化相当敏锐。研究了在测定锡时，一般共存离子的干拢。此法已成功地应用于测定电镀铅锡合金溶液和电镀层铅基合金中的锡。     

FeAlMn中Al的测定-强碱出离、氟化释放

试样经盐酸和H2O2溶解后，在强碱性条件下，铝呈偏铝酸钠，其它金属离子呈氢氧化物沉淀而相互分离，用甲酸缓；中控制pH3左右，加入过量的EDTA，在加热至沸的情况下，使EDTA和铝定量络合，用六次甲基四胺控制pH5～6左右，以PAN为指示剂，Zn标准溶液滴定过量的EDTA，用NaF释放与NaF络合的EDTA，再用Zn标准溶液滴定。     

选择性螯合滴定法测定钯

用DL—Methionine(蛋氨酸)为释放剂选择性螯合滴定法测定钯含量。加入过量EDTA螯合Pd^2 和其他金属离子，剩余EDTA在pH5～6时，以Zn^2 标准溶液、XO—CPD为指示剂，进行滴定。然后，加入DL—Methionine分解Pd—EDTA螯合物，释放析出的EDTA(与Pd^2 等摩尔)，再用Zn^2 标准溶液进行滴定，终点颜色变化敏锐、清晰。实验表明，阴阳离子都不干扰，选择性相当高，已成功的用于测定触媒，合金和复杂络合物中的钯，结果十分满意。     

钇铝合金钇、铝联合测定方法

试料经盐酸溶解，40%氢氧化钠溶液调至沉淀出现并过量20 mL,煮沸，碱分离，保留沉淀和滤液。沉淀用盐酸酸化，定容、干过滤，取适量溶液用抗坏血酸还原Fe³⁺,乙酰丙酮掩蔽少量铝干扰元素，pH=5.5时，以二甲酚橙作指示剂，用EDTA标准溶液测定钇的含量。滤液定容，取适量溶液，加入过量EDTA,在pH=5～6时铝与EDTA定量络合。硫酸铜标准滴定溶液滴定过量的EDTA,氟盐取代与铝络合的EDTA,以吡啶基偶氮萘酚(PAN)为指示剂，用硫酸铜标准滴定溶液滴定，计算铝的质量分数。     

偏铝酸锂中铝含量的测定

1　方法提要 试样用氢氧化钠熔融，用水浸取。盐酸酸化，移取部分溶液，加入过量的EDTA，在pH5-6煮沸络合，过量的EDTA以二甲酚橙为指示剂，用铅标准溶液回滴。加入氟化物，煮沸将铝-EDTA络合物中的EDTA置换出来，再由铅标准溶液滴定被释放的EDTA。用消耗的铅标准溶液体积计算AI的含量。     

释放螯合滴定法测定铊

提出以盐酸氨基脲作释放剂选择性螯合滴定铊的一种方法。加入过量的EDTA，而过剩的EDTA在pH5～6下，以XO—CPB为混合指示剂，用Zn^2 标准溶液进行返滴定。然后加入盐酸氨基脲分解Tl—EDTA螯合物、释放出的EDTA，再用Zn^2 标准溶液返滴定。研究了各种阳离子的干扰。实验结果表明，常见金属离子都不干扰测定铊，已用于测定铅铊合金，铊化合物和硫酸铊中的铊，结果相当满意。     

铜合金中Sn Pb Zn的测定

本法是以HCl H_2O_2溶解铜合金,用硫脲掩蔽Cu,然后加入过量EDTA,加热使Sn~(4 )与EDTA定量络合,用六次甲基四胺调节PH=5～6,以XO为指示剂,用P_b盐滴定过量EDTA,然后加入NaF,将Sn-EDTA中析出EDTA,再用P_b盐滴定析出的EDTA,来计算Sn%。一份用硫脲掩蔽Cu,NH_4F掩蔽Sn,以XO为指示剂,用EDTA滴定并过量,然     

氟化物置换EDTA滴定法测定铝土矿中的三氧化二铝

试样经氢氧化钠熔融,水浸取,制成酸性溶液后,以二甲酚橙为指示剂,用Pb(NO3)2标准溶液滴定置换出的EDTA,借此测定铝土矿中三氧化二铝的含量。方法经国家一级标准物质GBW07178、GBW07180验证,分析结果与标准值相符,方法精密度(RSD,n=12)小于0.25%。     

TCH作释放剂螯合滴定钯

本文叙述了在其它金属粒子存在下，钯的螯合滴定法。方法是基于TCH对钯选择性能力，加入过量EDTA，剩余的EDTA在PH5-6，以Pb^2 标准溶液进行滴定，XO-MTB-CPB为混合指示剂，然后加入TCH分解Pd-EDTA螯合物，释放出的EDTA，再以Pb^ 标准溶液进行滴定，终点颜色变化格外敏税。曾对多种阳离子可能存在的干扰作了研究。一般常见阳离子均不干扰。此法用于测定试样中的钯，结果相当满意。     

容量法测定铝酸钠溶液中氧化镓的方法研究

主要讨论了铝酸钠溶液中的氧化镓，在过量EDTA存在下，用氟化铵掩蔽铝，使镓完全络合，过量EDTA标准溶液以PAN为指示剂，用硫酸铜标准溶液回滴，求得氧化镓的含量。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.