温度、pH和Cl-浓度对NiTi形状记忆合金电化学行为的影响

通过正交试验法,采用动电位扫描技术研究了温度、pH和Cl-浓度对NiTi形状记忆合金在模拟口腔溶液中电化学行为的影响.结果表明温度、pH和Cl-浓度对NiTi的点蚀行为都有较大影响.溶液温度为25℃时点蚀电位最负,随着温度的升高,点蚀电位逐渐升高.溶液中的Cl-浓度很低时(不超过0.1 mol/L)点蚀电位较高,随着Cl-浓度的增加,点蚀电位急剧下降.当溶液的pH为6.0时,点蚀电位最高.     

316L不锈钢耐蚀性能的回归正交试验研究

在吸收式热泵工况条件下,采用二次回归正交设计研究了热泵用管材316L不锈钢在热网水中的点蚀电位Eb关于温度、Cl-浓度和p H值的关系,建立了三元二次回归模型。结果表明,各因素对316L不锈钢点蚀电位影响的显著程度为p H值温度Cl-浓度,且温度与p H值、Cl-浓度与p H值的交互作用较为明显。温度与Cl-浓度对点蚀电位影响负相关,而p H值则正相关。随温度的升高,其显著性在减弱,当高于75℃时,温度对点蚀电位影响则正相关但作用微弱。p H值的显著性明显且随p H值增大而增大。热网水中Cl-浓度较小,其对316L不锈钢的腐蚀无显著性影响。在热泵运行过程中应注意热网水p H值与温度的变化,把p H值控制在10.5及其以上为宜。     

X70钢在模拟土壤溶液中点蚀敏感性影响因素交互作用研究

通过正交试验法,采用动电位扫描技术研究了Cl-浓度、pH值和温度对X70钢在HCO3-+Cl-介质中电化学行为的交互影响.结果表明:Cl-浓度、pH值、温度三因素对X70管线钢在模拟土壤溶液中腐蚀及钝化行为影响较大,三因素对其点蚀敏感性影响依次为:pH值Cl-浓度温度;在Cl-浓度为0.010 mol/L、温度35℃、pH值为8.2的模拟土壤溶液中X70钢的点蚀敏感性最大,钝化区间较窄(-0.257~0.204 V),当电位超过0.204 V时已处于过钝化状态.     

敏化对不锈钢孔蚀性能的影响

用电化学测试技术研究了不同敏化处理的304不锈钢的耐孔蚀性能,探讨了Cl-浓度、温度和pH值对孔蚀电位Eb的影响。结果表明,敏化热处理导致Eb值下降;随Cl-浓度增加,介质温度升高,pH下降,使Eb值变负;不锈钢的晶间腐蚀使耐孔蚀性能变劣     

316L不锈钢在吸收式热泵中耐蚀性能的研究

通过电化学动电位扫描技术,采用正交试验法,研究了溴化锂(LiBr)吸收式热泵用管材316L不锈钢在热网水中的耐蚀性,建立了316L点蚀电位关于热网水温度、Cl-浓度和p H值三因素数学模型。通过腐蚀失重和电化学极化法进行了316L不锈钢在吸收器LiBr溶液中的点蚀性能研究。结果表明:温度与Cl-浓度对316L点蚀电位影响负相关,而p H值对其影响正相关,且各因素影响的显著程度为p H值温度Cl-浓度。吸收器条件下316L不锈钢的腐蚀速率仅为0.78μm/a,其表面点蚀坑多但较浅,且分布较均匀;但是316L点蚀电位Eb低于其氧平衡电位φ较多,点蚀仍可能发生。     

碳钢在碱性溶液中的孔蚀电位与HCO_3~-/Cl~-比值关系的研究

研究了Na HCO3+Na Cl碱性溶液中,较宽Cl-浓度(0.001~0.3 mol/L)范围内Cl-浓度及HCO_3~-和Cl-的浓度比值([HCO_3~-]/[Cl-])对Q235碳钢小孔腐蚀电位的影响。结果表明,Cl-浓度较大(0.02 mol/L)时,碳钢的稳定孔蚀电位Eb和亚稳态孔蚀电位Em都与[HCO_3~-]/[Cl-]符合很好的线性关系,[HCO_3~-]/[Cl-]升高Eb和Em线性增大;当Cl-浓度较小(0.02 mol/L)时,Eb和Em与[HCO_3~-]/[Cl-]之间不存在良好的线性关系,该条件下碳钢表面在发生稳定孔蚀前观察不到微米级的亚稳态小孔。     

光亮退火处理304不锈钢在NaCl溶液中的耐蚀性

采用稳态阳极极化曲线、恒电位开路衰减响应曲线和电化学噪声等多种电化学测试技术研究了光亮退火处理的304不锈钢在0.01-0.6mol/L NaCl溶液中的耐蚀性能.研究结果表明,不锈钢的点蚀击穿电位Eb值与Cl-浓度的对数呈线性关系,在同一浓度下,光亮不锈钢的Eb值比普通不锈钢大约正400-600mV;在0.6mol/L NaCl溶液中不锈钢恒电位开路衰减及电流噪声的测量结果也表明,光亮退火处理使不锈钢在NaCl溶液中钝化膜的稳定性明显改善,耐点蚀能力显著提高.     

应变作用下Q235碳钢在NaHCO_3+NaCl溶液中的孔蚀行为

用动电位极化、EIS和XPS等方法研究了应变作用下Q235碳钢在Na HCO3+Na Cl溶液中的孔蚀行为。结果表明:在0.2 mol·L-1Na HCO3+0.01 mol·L-1Na Cl溶液中,与无应变试样相比,8%的应变导致Q235碳钢的孔蚀电位Eb升高;随溶液Cl-浓度升高,应变试样的Eb逐渐降低,当Cl-浓度增大到0.1 mol·L-1时,应变试样的Eb值降低到与无应变试样相同的水平。另一方面,应变导致Q235钢钝化膜中Fe3+/Fe2+比值减小,膜阻抗降低,电荷转移电阻变小,钝化膜的稳定性有所降低。在实验条件下应变导致Eb升高的现象归因于溶液中HCO3-的存在,应变促进钢表面的阳极溶解,进而促进了HCO3-在表面的优先吸附,一定程度上抑制了Cl-促进孔蚀的作用。随溶液中HCO3-/Cl-的比值降低,应变导致的Eb值变化逐渐减小直至消失。     

316L不锈钢在有机胺脱硫溶液中的耐蚀性

采用浸泡方法研究了316L不锈钢在烧结烟气有机胺脱硫溶液中的腐蚀行为,主要对pH、温度、Cl-浓度和SO42-浓度变化引起的影响进行了分析。结果表明,316L不锈钢在脱硫溶液中存在点蚀行为,随着溶液pH、温度、SO42-浓度(60~140g/L)、Cl-浓度(1~10g/L)因素的变化,均有不同程度的腐蚀;但当pH4、温度80℃、ρ(Cl-)10g/L时,对316L的腐蚀影响较为明显。     

SO_4~(2-)对X80管线钢在含Cl~-的NaHCO_3溶液中点蚀行为影响

通过动电位极化方法研究了SO42-对X80管线钢在含0.01 mol/L NaCl的0.5 mol/L NaHCO3溶液中点蚀行为的影响,并通过电容测量方法对其机理进行了研究。结果表明:当溶液中SO24-和Cl-共存时,随着SO42-浓度的增大,点蚀电位降低,点蚀数量增加,X80钢发生点蚀的倾向性增大。这主要是因为吸附在试样表面的SO42-增加了X80钢表面钝化膜内的缺陷数量,从而增加了点蚀萌生的位置和几率。     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.