水玻璃自硬砂复合溃散剂的研究

研究了硬化剂炉渣粉、溃散剂滑石粉单独及复合使用对水玻璃砂初始强度、残留强度、可使用时间及抗吸湿性的影响。结果表明：该复合剂能大幅度降低水玻璃砂的残留强度，溃散性优良，成本低廉，具有一定的推广价值。     

新型易溃散改性水玻璃砂的研究

介绍了水玻璃工艺研究取得的最新进展，研制的新型改性水玻璃是一种无机和有机相复合的铸造粘剂，具有常温强度高，残留强度低，抗吸湿性好等优点，生产实际表明，采用新型改性水玻璃粘结剂的酯硬化工艺，可使水玻璃的加入量降为2．5％－3．0％，水玻璃砂的溃散性显著改善。     

微波硬化水玻璃砂的性能

采用微波硬化水玻璃砂,具有强度高、硬化速度快、水玻璃加入量少、残留强度低等许多优点,应是未来水玻璃砂工艺发展的重要方向。研究了微波硬化水玻璃砂的性能特征,测试了影响微波硬化水玻璃砂强度、残留强度、表面稳定性、吸湿性等性能的因素。试验结果表明：微波硬化水玻璃砂的硬化强度,主要受水玻璃加入量的影响,随微波加热时间、微波加热功率的增加而增加;微波硬化水玻璃砂的残留强度,随水玻璃加入量的增加而增大,受微波加热时间、微波加热功率的影响不大;微波硬化水玻璃砂的表面稳定性和吸湿性,主要取决于水玻璃加入量,水玻璃加入量越大、砂样的表面稳定性越好、但吸湿性越大。     

超声波对铸造水玻璃砂性能的影响

水玻璃砂在混制后会出现老化现象,从而降低其强度、溃散性、抗吸湿性等。把模数为2.6左右的水玻璃放在频率为20kHz、功率为480W的超声波处理器中进行改性处理后测试其相关性能。结果发现,水玻璃的粘度随超声处理时间的延长不断降低,在30min时水玻璃粘度降低11%,水玻璃的润湿性较改性前提高13%~37%;水玻璃砂的干强度增幅达到48%;同时,水玻璃砂的高温残留强度下降41%;水玻璃在超声改性前后混制得到的水玻璃砂的抗吸湿性提高8%。结果表明,超声波处理可以提高水玻璃砂的强度和抗吸湿能力,同时能够提高型砂的溃散性。     

甘油对铸造水玻璃砂保质期及其性能的影响

水玻璃砂在混制后等待造型时因表面水分散失而导致粘结强度降低,严重时不能使用。用甘油对水玻璃进行改性,测试了改性水玻璃和未改性水玻璃配制砂样的保质期,同时探讨了改性剂对型砂强度、吸湿性及800℃时残留强度的影响。结果表明,用3%的甘油改性的水玻璃作为粘结剂的型砂保质期是未改性水玻璃砂的2倍;在加入0～3%甘油范围内,水玻璃中每加入1%的甘油可提高水玻璃砂干抗拉强度约7%,相应地可以减少水玻璃砂的粘结剂用量,但型砂残留强度并没有因粘结剂含量的减少而明显变化;用甘油改性水玻璃,没有明显改善或恶化水玻璃砂的吸湿性。因此,用甘油对水玻璃砂改性可有效延长其保质期。     

复合硬化剂─—钠水玻璃自硬砂试验研究

在分析了钠水玻璃砂各种硬化方法的基础上，认为尽可能抑制化学硬化，加强物理硬化，则有利于自硬砂强度的提高．为此研究出了由有机酯ＭＤＴ－９０１与ＢＳ干燥剂组成的新型复合硬化剂．在钠水玻璃用量为３％时，加入复合硬化剂０．３％可以提高固化速度获得较高强度通过研究还指出了不同模数及比重的钠水玻璃可以有效地调节固化速度及强度，应用此复合硬化剂还可降低成本，降低砂芯吸湿性，改善溃散性。应用于生产集装箱箱角件效果良好．     

复合硬化剂——钠水玻璃自硬砂试验研究

在分析了钠水强度砂各种硬化方法的基础上，认为尽可能抑制化学硬化，加强物理硬化，则有利于自硬砂强度的提高。为此研究出了由有机酯ＭＤＴ－９０１与ＢＳ干燥剂组成的新型复合硬化剂。在钠水玻璃用量为３％时，加入复合硬化剂０．３％可以提高固化速度获得较高强度通过研究还指出了不同模数及比重的钠水玻璃可以有效地调节固化速度及强度，应用此复合硬化剂还可降低成本，降低砂芯吸湿性，改善溃散性，应用于生产集装箱箱角件效果     

水玻璃复合改性剂的研究

采用正交试验法研究了几种附加物对水玻璃砂常温强度和残留强度的影响。结果表明，复合改性剂可使水玻璃用量降低20％～30％，常温强度提高1．5～2倍，残留强度降低2～3倍．     

调高水玻璃模数的研究

使用较高模数的水玻璃混制的型砂具有残留强度低、吹CO2时间短等优点，并有好的抗吸湿性和表面稳定性。一般低模数的水玻璃可以通过在其中加入一定量的无定形二氧化硅来提高模数，但研究表明，用这种方法调得的高模数水玻璃质量并不十分理想，在使用上存在很大问题。     

酯硬化水玻璃再生砂的性能特征

通过试验对酯硬化水玻璃干法再生砂和湿法再生砂的性能进行了比较分析，认为与干法再生砂比，湿法再生砂具有残留Ｎａ２Ｏ含量低，抗压强度高、可使用时间长，吸湿性低等优点，文中讨论了如何提高酯硬化水玻璃砂干法再生效率，质量的方法，提出了提高湿法再生砂质量的几项措施。     

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.     

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。