液中脉冲放电在45钢表面沉积TiC陶瓷涂层的工艺优化

将高熔点金属Ti电极置人含碳的液相介质中,利用脉冲放电所产生的低温高能等离子体在45钢基体上沉积TiC硬质金属陶瓷涂层,并对液中放电沉积TiC的工艺进行了正交优化设计.结果表明,峰值电流对TiC的形成与性能的影响最为显著,其次是脉冲宽度,再次是脉冲间隔和极间距.最佳制备工艺为:峰值电流5A,脉冲宽度12μs,脉冲间隔120μs,极间距离30μm.     

液相脉冲放电沉积TiC陶瓷涂层的滑动磨损性能研究

将高熔点金属Ti电极置入含碳的液相介质中,利用脉冲放电所产生的低温高能等离子体在45钢基体上沉积了TiC硬质金属陶瓷涂层,对TiC陶瓷涂层进行了滑动磨损试验。结果表明:在本试验条件下,TiC涂层的滑动摩擦系数较小,且较稳定;在相同的磨损实验条件下,TiC涂层的磨损质量损失是未处理表面的1/10左右,是化学复合镀N i-P-SiC(纳米)镀层的1/6左右,说明涂层的耐磨性相对较好。涂层磨损形貌观察发现:涂层磨痕均为浅显的平行犁沟,表明涂层的磨损机理为轻微磨粒磨损。     

液相脉冲放电沉积TiC陶瓷涂层的滑动磨损性能研究

将高熔点金属Ti电极置入含碳的液相介质中，利用脉冲放电所产生的低温高能等离子体在45钢基体上沉积了TiC硬质金属陶瓷涂层，对TiC陶瓷涂层进行了滑动磨损试验。结果表明：在本试验条件下，TiC涂层的滑动摩擦系数较小，且较稳定；在相同的磨损实验条件下，TiC涂层的磨损质量损失是未处理表面的1／10左右，是化学复合镀Ni-P-SiC（纳米）镀层的1／6左右，说明涂层的耐磨性相对较好。涂层磨损形貌观察发现：涂层磨痕均为浅显的平行犁沟，表明涂层的磨损机理为轻微磨粒磨损。     

放电镀膜时等离子体通道内粒子状态的计算机模拟

目的 分析液相脉冲放电微观机理,解释放电过程中放电通道对电极的影响。 方法 以 45 钢表面液相脉冲放电沉积 TiC 陶瓷涂层放电沉积瞬间极板间形成的单脉冲等离子体为研究对象,用粒子模拟的方法描述了放电通道中电子、钛离子的运动及分布状态。 结果 放电通道中电子的运动较为活跃,在放电形成的开始阶段,电子由工件电极负极激发,迅速向工具电极移动,期间通过与液相介质中的中性粒子碰撞,迅速往工具电极积累,运动过程中遵循等离子体的集体运动特性,过程贯穿于整个等离子体的形成过程;在相同的时间步长内,放电通道中 Ti 离子的运动比电子要缓慢得多,在脉冲放电期间需要较多的时间才能迁移到极板。 结论 放电镀膜时,所用极间距应大于电火花成形加工时的极间距。     

金属喷涂、堆焊与修复 金属喷涂工艺与设备

高强度涂层结合性能的试验研究及有限元分析，脉冲放电工艺参数对TiC涂层形成的影响，高速电弧喷涂枪结构优化的试验，曲轴表面改性用金属陶瓷电弧喷涂药芯丝材的研制，电弧喷涂铝青铜复合涂层的抗高温氧化作用与机理，灰口铸铁件内油污对电弧喷涂涂层结合强度的影响，多功能微弧等离子喷涂技术。[编者按]     

等离子喷涂制备Co基TiC金属陶瓷涂层的微观形貌及耐高温腐蚀性能

采用等离子喷涂技术在GH586合金表面制备了一层Co基TiC金属陶瓷涂层。研究了TiC含量对Co基TiC金属陶瓷涂层显微组织及耐高温腐蚀性能的影响。结果表明:TiC陶瓷颗粒与Co基粉体有良好的润湿性,呈现相互包裹的结构,涂层结合紧密无缺陷;TiC的加入,提高了Co基TiC金属陶瓷涂层的耐磨性,但当TiC含量过高时,团聚现象严重,导致涂层的耐高温腐蚀性能降低;TiC质量分数为10%时,TiC颗粒在涂层中分布较为均匀,此时涂层的耐高温腐蚀性能和耐磨性都较优。     

液相介质中脉冲放电制备(Ti,Al)C涂层及其高温磨损性能研究

将Ti、Al按一定比例混合压制烧结成电极,置于含碳的液相介质中,利用脉冲放电所产生的低温高能等离子体在45钢基体上沉积(Ti,Al)C硬质金属陶瓷涂层;并对涂层进行高温磨损试验。结果表明:试验温度高于200℃时,涂层的摩擦系数随温度的升高而降低;观察涂层磨损形貌发现,低温时,磨痕为平行犁沟,表明涂层的磨损机理为磨粒磨损;高温时,犁沟比室温时浅且表面有氧化物,其磨损机理为轻微磨粒磨损和氧化磨损。     

TiC/Ni金属陶瓷电火花加工温度场仿真研究

为深入研究TiC/Ni金属陶瓷电火花加工过程,进行了TiC/Ni金属陶瓷电火花加工单脉冲放电温度场仿真。建立了TiC/Ni金属陶瓷颗粒随机分布模型,运用ANSYS软件采用生死单元法对TiC/Ni金属陶瓷进行单脉冲温度场仿真研究,并对结果进行了实验验证。结果表明:TiC/Ni金属陶瓷颗粒随机分布模型适于TiC/Ni金属陶瓷电火花加工温度场仿真,且随着峰值电流及脉宽的增大,TiC/Ni金属陶瓷蚀除体积增加,表现为试验时材料蚀除率增加。     

反应火焰喷涂的TiC/Fe金属陶瓷复合涂层

以TiFe粉和碳的前驱体(石油沥青)为原料,通过碳化制备Ti-Fe-C系反应喷涂复合粉末,并通过普通火焰喷涂技术成功制备了TiC/Fe金属陶瓷复合涂层;采用XRD、SEM和EDS对喷涂粉末和涂层的成分、组织结构进行了分析,同时对涂层耐磨性能进行了对比研究.结果表明:采用前驱体碳化复合技术制备的Ti-Fe-C系复合喷涂粉末粒度均匀、无有害相生成;喷涂所得到的TiC/Fe金属陶瓷复合涂层由片状的铁基体和弥散分布的TiC颗粒组成;TiC颗粒大致呈球形,粒度一般在0.5 μm以下;相同条件下所获涂层的磨损体积大约是常规火焰喷涂Ni60涂层的1/5.     

液相脉冲放电沉积涂层的温度场模拟及研究

通过有限元数值模拟的方法,选取合适的热源模型、热边界条件,建立了液体介质中在45钢表面进行脉冲放电沉积TiC陶瓷涂层的热传导模型。采用有限元分析软件ANSYS对液相脉冲电火花放电表面温度场进行数值模拟,研究了脉冲电流参数对温度场和涂层表面形貌的影响。结果表明:工具电极的最高温度远高于工件的最高温度;温度均在轴向上降低较快,而在径向上分布较均匀;最高温度随加工电流的增加呈缓慢下降趋势;随脉冲电流的增大,沉积到工件上的火山口状涂层颗粒明显增大。     

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.