等离子喷涂纳米ZrO_2涂层均匀性及熔炼试验研究

作为石墨坩埚模具熔铸隔离涂层,火焰喷涂CaZrO3涂层在应用上存在缺陷,采用等离子喷涂方法在石墨坩埚模具表面制备均匀纳米ZrO2隔离涂层,涂层抗热震性能良好。熔炼考核后涂层光洁,未受浸蚀,涂层与基体结合良好,无龟裂、剥离。     

C／C复合材料抗烧蚀TaC涂层的制备

报道1种制备C／C复合材料抗烧蚀TaC涂层的新技术。用红外光谱、XRD及SEM分析和表征醇基钽膜，用XRD和SEM分析和表征TaC涂层。制备出的醇基钽是非晶态结构，在C／C复合材料上将这种凝胶铺展形成致密的多层膜。在石墨化炉中多层膜被转化为TaC涂层。在1200℃时，形成的涂层中含有TaC和Ta2O5。高于1400℃时涂层中只有TaC存在。1600℃时所形成的涂层是1种连续致密的层状结构，1400℃时所形成的涂层是1种多微孔的网状结构。     

热处理对钽强化激光熔覆NiCrBSi涂层的影响

通过在激光熔覆NiCrBSi涂层(Ni60)中添加钽(Ta)元素来提高900℃热处理后涂层的耐磨性。研究了900℃热处理对激光熔覆NiCrBSi和钽强化NiCrBSi复合涂层显微组织、硬度以及耐磨性能的影响。利用带能谱仪的扫描电镜和衍射仪分析涂层的显微组织和物相。通过盘-销实验评价涂层的耐磨性。结果表明:经过900℃热处理后涂层中的M7C3和M23C6发生了分解,钽强化复合涂层和纯NiCrBSi涂层中的硬度都有所下降,但由于复合涂层中原位生成的TaC未发生分解,使得其硬度和耐磨性都高于纯NiCrBSi涂层。     

热处理对钽强化激光熔覆NiCrBSi涂层的影响

通过在激光熔覆NiCrBSi涂层(Ni60)中添加钽(Ta)元素来提高900℃热处理后涂层的耐磨性.研究了900℃热处理对激光熔覆NiCrBSi和钽强化NiCrBSi复合涂层显微组织、硬度以及耐磨性能的影响.利用带能谱仪的扫描电镜和衍射仪分析涂层的显微组织和物相.通过盘-销实验评价涂层的耐磨性.结果表明:经过900℃热处理后涂层中的M7C3和M23C6发生了分解,钽强化复合涂层和纯NiCrBSi涂层中的硬度都有所下降,但由于复合涂层中原位生成的TaC未发生分解,使得其硬度和耐磨性都高于纯NiCrBSi涂层.     

原位反应渗透法制备石墨／AlN涂层材料

采用喷射法在石墨基体表面形成BN薄层，利用Al与BN原位渗透反应并渗入石墨基体，在基体获得AlN涂层来增强石墨的抗腐蚀能力。采用DTA、XRD分析方法，对原位反应过程进行分析，并探索了热处理工艺条件对反应物相结构的影响，确定了的最佳热处理工艺条件。采用SEM分析方法，对喷射工艺参数以及AlN涂层／石墨微观结构进行分析；采用EPMA对合成AlN涂层／石墨进行元素分布分析。结果表明：采用原位合成工艺可获得致密结构的AlN涂层，同时在石墨基体与涂层之间形成致密的结合界面。     

石墨炉原子吸收法测定合金钢、铜合金及铝合金中微量钛

拟定了利用石墨炉原子吸收测定铜合金、铝合金及碳素钢中微量钛的分析方法，操作简便，快速，灵敏度高，精密度好，从机理上探讨和用实验证明了用热解石墨涂层管比碳化锆涂层处理石墨管，碳化钽涂层处理石墨管，平台石墨管及标准石墨管测定钛时的灵敏度要高，比较了4种有机试剂对测定钛的效应，提高灰化温度可以消除Fe,Al,Cu的基体干扰，且不影响钛的测定。     

硅、铈、锑和锡对块状石墨形成的影响

用电解铁,高纯硅,石墨,纯铈,锑和锡制成含有不同硅、铈、锑和锡含量,且C%+1/3Si%=4.45%的13种母合金。每种合金用高纯度氧化铝坩埚在1 450℃,氩气保护下的电炉中重熔,然后在30 K/min速率下冷却,获得冷却曲线。用光学显微镜和扫描电镜观察它们的石墨形貌。为了讨论硅和铈含量对块状石墨形成的影响,进行了试验。在第一个试验中,变化了0.15%硅铈合金中的硅含量从0到4%;在第二个试验中,使用了含有0.1%和0.2%不同铈量的3.5%和4%硅的试样。在第三个试验中,使用了含铈0.1%,含硅4%的试样,研究了锑和锡对块状石墨形成的影响。试验结果表明,硅含量大于3.0%,块状石墨的体积分数会增加。随后讨论了不同含量的硅和铈对块状石墨形成的影响。不能确定3.5%和4.0%的硅量差对块状石墨形成的差别,证实了含有0.2%铈的样品中块状石墨的体积分数大于0.1%铈的试样。由于高硅含量,还不能确定锑和锡的加入对防止块状石墨形成的作用,还需要做进一步的研究。     

原位反应渗透法制备石墨/AlN涂层材料

采用喷射法在石墨基体表面形成BN薄层,利用Al与BN原位渗透反应并渗入石墨基体,在基体获得AlN涂层来增强石墨的抗腐蚀能力.采用DTA、XRD分析方法,对原位反应过程进行分析,并探索了热处理工艺条件对反应物相结构的影响,确定了的最佳热处理工艺条件.采用SEM分析方法,对喷射工艺参数以及AlN涂层/石墨微观结构进行分析;采用EPMA对合成AlN涂层/石墨进行元素分布分析.结果表明:采用原位合成工艺可获得致密结构的AlN涂层,同时在石墨基体与涂层之间形成致密的结合界面.     

V元素对TiAlN涂层高温氧化行为的影响

为了考察V元素对Ti—Al-N涂层高温氧化行为的影响,用多弧离子镀法在W18Cr4V1Co5高速钢试样表面涂镀了Ti—Al-N和Ti—Al-V—N涂层。对两种涂层试样在不同温度和不同时间下进行氧化处理。用SEM观测两种涂层的组织结构,用XRD分析其相组成,用CTA分析其升温氧化和恒温氧化动力学行为。实验结果表明,V的加入使涂层晶粒细化,组织更加致密;两种涂层均在750℃以后才测量到氧化增重;Ti-Al-N涂层的氧化转折点为920℃,超过920℃,涂层迅速氧化,逐渐失效;Ti—Al-V—N涂层在超过1000℃增重仍非常缓慢,并具有抗氧化保护的作用。V元素的加入大大降低了氧化速率,从而有效地提高了涂层的抗氧化性能。     

混合电容器多孔氧化钌阴极涂层的制备与表征

采用电沉积方法制备了混合电容器钽基多孔氧化钌阴极涂层材料,探讨了电沉积过程中电沉积液的pH值随电沉积时间的变化关系,研究了电沉积时间对氧化钌沉积质量的影响.用X射线衍射和扫描电镜分别表征了热处理前后的涂层结构及涂层的多孔形貌,用循环伏安法测量了涂层的电容,并研究了热处理温度对电容量大小及其稳定性的影响.结果表明:电沉积的氧化钌为非晶态,涂层为纳米多孔结构;热处理有利于涂层孔隙结构及大小的均匀性,不同温度的热处理使涂层具有不同的电容,经热处理后涂层的电容稳定;经100℃热处理1 h后的多孔氧化钌涂层具有最大的比电容.     

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.     

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。     

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.     

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.     

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).     

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.