血管支架用镁合金微细管制备工艺与性能研究

镁合金作为新型可降解医用金属材料,在血管支架领域具有广阔的应用前景。由于镁合金晶体结构为密排六方结构,塑性变形能力差,导致镁合金微细管制备困难。本文针对作者开发的新型可降解Mg-4Zn-0.2Mn-0.2Ca镁合金,采用热挤压-拉拔复合工艺成功制备出外径3.1～3.6 mm、壁厚0.25～0.4 mm的微细管。针对外径3.6 mm,壁厚0.4 mm微细管组织演变及机械性能开展的研究结果表明：微细管材的塑性变形经过了滑移、孪生及再结晶等过程,并产生了显著的加工硬化现象；管材的抗拉强度为427.3 MPa,屈服强度为383.4 MPa,伸长率为5.2%；经300 ℃,30 min的退火处理,管材组织变得相对均匀,强度有所降低,但伸长率增加到18.0%,有利于后期支架的精密加工。     

电爆喷射沉积法制备镁合金微细管

镁合金作为新型可降解生物材料,在第四代血管支架植入产品领域具有重要的应用价值,但微细管材较大的加工难度制约了其应用推广.提出电爆喷射沉积镁合金微细管的新方法,并对其工艺过程进行了试验研究.结果表明,丝径0.5 mm、初始电压14 kV、沉积距离25 mm时获得的沉积层的均匀性、致密性以及整体性较好且具备纳米晶组织结构,并制备出外径3.5 mm、壁厚0.12 mm的镁合金微细管,符合镁合金血管支架的尺寸要求.     

大口径AZ31镁合金管材宽展分流挤压工艺仿真研究

宽展分流挤压工艺(SDEP)是宽展挤压和分流挤压有机结合的新挤压工艺。它可以利用小吨位设备挤压大口径管材。使用DEFORM-3D有限元软件对大口径AZ31镁合金圆管宽展分流挤压(宽展比率α=2.54)过程中的挤压力、挤压温度以及焊合压力变化规律进行了仿真。结果表明:宽展分流挤压AZ31镁合金圆管(外径360 mm,壁厚10 mm)的挤压力为22.7 MN,比普通分流挤压的挤压力降低28%;AZ31镁合金管材(外径360 mm,壁厚10 mm)宽展分流挤压过程中焊合压力达到了225 MPa,宽展分流挤压的金属材料焊合质量良好。     

材料表面微纳形貌对血管细胞行为影响的研究综述

镁合金具有良好的生物相容性、优良的力学性能以及可完全降解的特点,是制备血管支架的理想材料。然而在支架植入初期,支架表面平滑肌细胞增殖速率超过内皮细胞增殖速率,导致支架内再狭窄的发生。近年来,在材料表面构筑微纳尺度形貌,通过调控血管内皮细胞和平滑肌细胞行为,实现支架表面快速内皮化成为一种新的研究思路。从基底材料、形貌特征、制备工艺、细胞种类以及实验结果等方面,系统地总结了近年来关于材料表面微纳形貌对血管细胞行为的影响。因为目前镁合金表面微纳形貌对血管细胞行为影响的报道尚少,从镁合金种类、形貌制备工艺、形貌特征以及形貌功能等方面详细整理了不同研究领域,在镁合金表面制备微纳形貌的相关研究。与此同时,分析了在镁基血管支架表面制备微纳尺度形貌用于实现支架表面快速内皮化研究所面临的挑战,并介绍了本课题组相关研究工作进展。     

挤压铸造AZ91D镁合金流动性研究

以不同壁厚的矩形试样为研究对象,运用正交试验设计,研究了壁厚、浇注温度、模具温度、挤压速度对挤压铸造AZ91D镁合金流动性影响规律。试验结果表明:对壁厚为1 mm、2 mm、3 mm试样的流动性影响最大的因素是浇注温度,对4 mm试样则是模具温度。当浇注温度在700℃到750℃变化时,增加浇注温度对提高AZ91D镁合金的流动性是有利的;对厚壁铸件(3 mm和4 mm)通过提高模具温度而增加镁合金的充型能力是非常有效的;增加挤压速度对薄壁试样的流动性影响不是很明显,但是随着试样壁厚的增加,影响逐渐增大。试验结果也表明,挤压铸造工艺不适合于生产壁厚小于3 mm的镁合金铸件,否则难以得到轮廓清晰的完整铸件。     

ZM6镁合金焊丝热挤压-热拉拔工艺研究

采用热挤压-热拉拔的方法制备了(φ)3 mm的ZM6镁合金焊丝,并对组织演变进行了观察.结果表明,通过对挤压比、挤压温度、挤压速度的合理选择可以制备出(φ)4mm的焊丝坯料,再选用适当的拉拔道次和拉拔温度等参数能够生产出表面质量良好的(φ)3 mm的ZM6镁合金焊丝.ZM6镁合金热挤压后晶粒明显细化,经过4个道次热拉拔后晶粒尺寸进一步减小.     

AZ31镁合金小直径薄壁管拉拔工艺及性能研究

实验研究了多道次拉拔过程中拉拔速度、拉拔变形量对AZ31镁合金小直径薄壁管材组织和性能的影响。研究结果表明,温度为300℃、拉拔速度为0.30 mm·s-1时,管材壁厚减薄均匀,可以保证镁合金管材的拉拔顺利进行。多道次拉拔可以成功制备Φ4 mm×0.2 mm的AZ31镁合金小直径薄壁管材。且随着累计变形程度的增加,镁合金的晶粒显著细化,当累积变形量达到95.4%时,平均晶粒尺寸从开始的22μm减小到8μm左右。最终小直径薄壁镁合金管材的抗拉强度达到了247.3 MPa,相应的伸长率为16.8%。     

Zr基块体非晶合金超塑性微挤压成形数值模拟

利用压缩实验数据建立了Zr55Cu30Ni5Al10大块非晶合金在过冷温度区域内的流动应力模型,并选用DE-FORM-3D软件对杯形非晶合金零件超塑性微挤压成形过程进行了模拟,得到了挤压过程中坯料的速度场、应变速率场和应力场的分布规律。分析发现在挤压过程中材料的应变速率极不均匀,因此,对材料的流动变形过程进行了合理分区,分析各区域的形状、大小及变化历程。在此基础上,利用反挤压工艺成功挤出了外径为2.2 mm、壁厚为0.05 mm的杯形零件。SEM显示,该成形件壁厚均匀,尺寸和几何形状满足设计要求。     

微张力减径的钢管质量及其控制

介绍了衡阳钢管厂φ108mm三辊轧管机组配置12架微张力减径机生产中厚壁钢管的外径精度、壁厚精度及内外表面质量情况。实践证明采用合理的减径工艺制度,用一组微张力减径机代替二辊减径机+回转定径机生产中厚壁钢管是极为成功的。     

超大规格6061铝合金薄壁管生产工艺技术研究

超大规格铝合金薄壁管生产难度大。试验研究了外径270 mm、壁厚6 mm的6061铝合金管材生产工艺技术。在45 MN挤压机上采用无润滑半穿孔反向挤压出尺寸精度高的管坯;在拉拔工序,采用专用夹钳、辅助垫,避免了夹头拉断,并采用硬质合金模具使管材表面光洁;整径过程控制减径量;辊式矫直过程采用预矫直、精心逐渐调整矫直辊压力及角度。生产出了尺寸精度高、弯曲度小、表面质量好、力学性能符合要求的6061铝合金薄壁管材。     

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.     

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。     

Acta Metallurgica Sinica(English Letters)

<正>Copyright Information For Authors As soon as an article is accepted for publication,authors will be requested to assign copyright of the article(or to grant exclusive publication and dissemination rights)to the publisher(respective the owner if other than Springer).This will ensure the widest possible protection and dissemination of information under copyright laws.More information about copyright regulations for this journal is available at www.springer.com/40195.     

Acta Metallurgica Sinica(English Letters)

<正>Copyright Information For Authors As soon as an article is accepted for publication,authors will be requested to assign copyright of the article(or to grant exclusive publication and dissemination rights)to the publisher(respective the owner if other than Springer).This will ensure the widest possible protection and dissemination of information under copyright laws.More information about copyright regulations for this journal is available at     

Yilin Hydraulic Group Harbin General Hydraulic Machinery Works Co.,Ltd.

正Harbin General Hydraulic Machinery Works Co.,Ltd.of Yilin Hydraulic Group is the most professional production base of large-scale metallurgy oil cylinder and oil machinery cylinder in the Northeast of China.The main products include metallurgy cylinder,swell-shrink cylinder,rotating injection device,lifting cylinder,main lifting jack,front lifting jack,engineering oil cyl-     

Weihai HHH Mach. & Elec. Group

正Weihai HHH Mach.Elec.Group is the most technical company focusing on Power transmission and Hydra-controlling.HHH has the ability of developing and testing of complete sets of transmission system with relevant technical training.HHH provide efficient,excellent cost-effective power transmission system and intelligent electric fluid transmission and control system to OEM customers,who are     

Letter of Congatutulation

正I take great pleasure in congratulating CHINA FOUNDRY journal on its 10th anniversary.The CHINA FOUNDRY journal started ten years ago.Since its inaugural,China has seen exceptional growth in the Castings Sector and rapid development in Machinery Industry.The journal is becoming an important communication platform for experts     

The 9th China International Diecasting Congress& The 1st International Symposium on Nonferrous Alloys and Special Casting Technologies held in Shanghai

The 9th China International Diecasting Congress and the 1st International Symposium on Nonferrous Alloys and Special Casting Technologies （ISNASCT） were successfully held in Shanghai on July 19-22, 2014. Both events were jointly sponsored by Chinese Mechanical Engineering Society, Die Casting Commission of World Foundry Organization and Non-Ferrous Materials Commission of World Foundry Organization, and organized by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） and China Productivity Promotion Center of Foundry Industry.     

Dangyang Iron Tower——Corrosion-resistant cast iron casting

<正>Made in 1061 A.D.(North Song Dynasty)Height:17.9m,weight:53.3tThe Dangyang Tower,located outside of the Yuanquan temple in Dangyang county of Hubei province,is the tallest ancient iron tower in China.On the base,there are sculptures of eight Herculean men supporting the