磷化时间与温度对镁合金磷化膜的影响

目的研究钙系磷化液的磷化温度及时间对磷化膜结构与性能的影响。方法通过控制单因素变量,在不同磷化温度和时间条件下在镁合金表面制备磷化膜。通过扫描电镜(SEM)、X射线衍射仪(XRD)以及极化曲线测试等方法对AZ31镁合金表面磷化膜的形貌、结构与性能进行分析。结果镁合金表面钙系磷化膜呈花瓣状结晶生长,其主要成分为CaHPO_4·2H_2O。随着磷化时间的增加,磷化膜的厚度不断增加,但磷化时间过长使得磷化膜的平整度有所下降。极化曲线测试分析表明,磷化时间为30 min时,腐蚀电位与极化电阻最大,腐蚀电流密度最小,此时磷化膜耐蚀性最佳。当磷化温度为30℃时,磷化膜致密性最好,磷化膜的结晶度及覆盖能力在磷化温度为30℃时达到最佳。极化曲线测试结果显示,磷化温度为30℃时的磷化膜极化电阻最大,腐蚀电流密度最小,耐蚀性最优。结论磷化时间为30 min、温度为30℃时所得磷化膜的质量最好,耐蚀性最佳。     

AZ31镁合金表面磷化工艺研究

研究了AZ31镁合金表面的磷化处理工艺,分析了磷化时间和封孔处理对镁合金表面磷化膜耐腐蚀性能的影响,并利用金相显微表面分析、腐蚀电位及极化曲线测量、腐蚀失重试验等方法评价了磷化膜的耐腐蚀性能.研究结果表明,磷化处理可以显著改善AZ31镁合金的耐腐蚀性能,并且随着磷化时间的增加,镁合金表面磷化膜的耐腐蚀性能不断得到提高;封孔处理可以有效地封闭镁合金表面磷化膜中残留的腐蚀活性通道,进一步提高镁合金表面磷化膜的耐腐蚀性能.     

AZ31B镁合金表面硅烷处理研究

采用硅烷溶液浸湿处理在AZ31B镁合金表面生成一层保护膜,采用扫描电镜、金相显微镜及体式显微镜观察试样表面形貌,并通过傅立叶红外光谱(FTIR)对硅烷膜与基体的键合进行测试分析;采用盐水浸泡、动电位极化曲线研究硅烷膜层的耐腐蚀性能,并与磷化膜层进行对比.结果表明:AZ31B镁合金经硅烷化处理,可以在其表面生成一层极薄的透明硅烷膜层,该膜层平整致密,对镁合金的自腐蚀电位影响不大,但大幅度降低了镁合金的自腐蚀电流密度,很好地抑制了镁合金的腐蚀.     

工艺参数对AZ31镁合金磷化膜耐蚀性能及表面形貌的影响

以磷酸二氢锰和无氟添加剂为主要成分,通过化学沉积的方法在AZ31镁合金表面获得了均匀且无氟、无镍和无铬的磷化膜。采用硫酸铜点蚀测试、扫描电镜及电化学极化曲线表征手段,详细地研究了成膜温度、游离酸及酸比工艺对AZ31镁合金磷化膜耐蚀性能及表面形貌的影响。结果表明：在成膜温度95℃,游离酸FA 4-5, 酸比TA/FA 15~20的条件下,可获得晶粒<20 μm的致密磷化膜,耐CuSO₄点蚀时间>5 min。磷化AZ31镁合金的自腐蚀电位比未处理基体正移110 mV,自腐蚀电流密度降低3个数量级。成膜温度<75℃时,不能得到完整的磷化膜;成膜温度≥75℃时,随着成膜温度的升高,磷化膜颗粒得到细化,膜层更加致密,进而有效地抑制AZ31镁合金的阳极溶解和阴极析氢,提高了耐蚀性能。但升高成膜温度,加速磷酸盐的水解,容易产生大量的磷化渣,而游离酸的控制,能够有效减少磷化渣的产生,降低生产成本,提高膜层质量。     

AZ31B镁合金表面火焰喷涂Al-Mg_2Si涂层的耐腐蚀性能

为提高AZ31B镁合金表面的耐腐蚀性能,用火焰喷涂方法在镁合金表面制备Al-Mg_2Si复合涂层。采用XRD、SEM和EDS分析涂层的物相组成、微观组织及元素分布;通过电化学试验测试样品在3.5%NaCl溶液中的腐蚀电位、腐蚀电流密度;通过3.5%NaCl溶液浸泡试验测试样品的腐蚀速率;并测试涂层的显微硬度。结果表明:涂层中的主要物相有Mg_2Si、Al,组织比较致密,元素分布均匀。Tafel极化曲线测试表明,Al-Mg_2Si涂层样品与AZ31B镁合金样品相比腐蚀电位从-1.489 V正移到-1.366 V,腐蚀电流密度从2.817×10~(-3) A/cm~2降低到1.198×10~(-3) A/cm~2。浸泡试验结果表明,喷涂Al-Mg_2Si的镁合金的腐蚀速率明显低于没有喷涂的镁合金。显微硬度测试表明,涂层的显微硬度集中分布在259~308 HV0.05之间,镁合金为50~60 HV0.05。因此在AZ31B镁合金表面火焰喷涂Al-Mg_2Si涂层可以提高其耐腐蚀性能,表面硬度显著提高。     

聚苯胺含量对镁合金上聚苯胺环氧涂层防腐性能的影响

在AZ31B镁合金表面制备了含本征态聚苯胺O%,1%,2%,4%,6%的聚苯胺/环氧防腐涂层,通过Tafel极化曲线、电化学阻抗谱测试及中性盐雾实验对比了其在3.5%NaCl溶液中的防腐性能.结果表明:聚苯胺的含量时聚苯胺环氧涂层的防腐性能有较大影响,聚苯胺的质量分数为2%时,涂层具有最佳的防腐性能.     

AZ31镁合金表面亲水薄膜的制备与腐蚀性能研究

在AZ31镁合金表面制备了具有亲水性功能的薄膜.室温下以不同外加电位、时间为条件对镁合金表面进行恒电位法有机镀膜,采用循环伏安法研究了镁合金表面有机膜的生长机理,并结合电化学特性曲线和盐雾腐蚀试验,通过分析镀膜时间和镀膜电位对有机薄膜耐腐蚀性能的影响,确定最佳有机镀膜时间为10min,镀膜电位为1.0 V.     

AZ91D镁合金微弧氧化膜的腐蚀行为研究

利用双向全波脉冲电源对AZ91D镁合金在硅酸盐体系中进行了微弧氧化处理,通过电化学阻抗谱(EIS)测试、极化曲线分析并结合XRD和SEM等分析方法对微弧氧化处理的镁合金腐蚀行为进行了研究.结果表明,微弧氧化膜表面分布着几微米的微孔,微弧氧化膜中主要含有MgF2,Mg2SiO4和Al2O3.AZ91D镁合金经过微弧氧化处理之后,耐蚀性能明显提高,自腐蚀电流密度降低3个数量级,自腐蚀电位高出约300 mV,阻抗值高出3个数量级,研制的微弧氧化膜对镁合金具有很好的防腐保护性能.     

葡萄糖对镁合金阳极氧化膜性能的影响

研究由NaOH、Na2SiO3、Na2B4O7组成的电解液体系中不同葡萄糖浓度对AZ31B镁合金阳极氧化膜性能的影响。通过电压—时间曲线、Cass盐雾试验、SEM、EDS、XRD、EIS和动电位极化曲线等考察阳极氧化膜的性能和表面形貌。结果表明:葡萄糖可以有效地抑制火花放电,使氧化膜致密,微孔分布均匀及孔径变小;与未添加葡萄糖所形成的氧化膜相比,添加葡萄糖所形成的氧化膜的自腐蚀电位正移,自腐蚀电流密度降低;当葡萄糖浓度为10 g/L时所制备氧化膜的耐蚀性能最优,其自腐蚀电位和自腐蚀电流密度分别为-1.265 V和1.55×10-8 A/cm2。     

AZ31B镁合金表面喷熔Al涂层的组织和性能

目的提高AZ31B镁合金的耐蚀性。方法采用氧乙炔在AZ31B镁合金表面喷熔Al涂层,对喷熔的Al涂层进行扫描电镜(SEM)分析,采用能谱仪(EDS)对涂层进行面扫描检测涂层元素的分布情况。利用电化学分析法、浸泡试验检测喷熔涂层的耐蚀性,用维氏硬度计测试喷熔涂层的硬度。结果喷熔的Al涂层与AZ31B镁合金基体结合良好,呈现冶金结合。喷涂过程中,喷熔的Al涂层呈等轴晶生长。通过面扫描结果可知,喷熔涂层中发现Mg元素,说明基体中的Mg元素发生了扩散。通过电化学测试可知,喷熔Al涂层的自腐蚀电压为-1.45 V,比AZ31B镁合金的自腐蚀电压(-1.5 V)降低了0.05 V;喷熔Al涂层的自腐蚀电流密度为1.58×10~(-4) A/cm~2,约为AZ31B镁合金自腐蚀电流密度(8.66×10-4 A/cm2)的1/5。由浸泡实验可知,喷熔Al涂层的平均腐蚀速率约为AZ31B镁合金的1/5倍。喷熔Al涂层的显微硬度是AZ31B镁合金基体硬度的2.9倍。结论喷熔Al涂层的组织较好,性能比镁合金基体有所提高。     

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.     

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.     

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.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.