马敬翙
,
刘光明
,
曾潮流
,
杜楠
,
赵晴
表面技术
doi:10.3969/j.issn.1001-3660.2006.04.005
采用电化学方法、扫描电镜、能谱分析等技术,研究了常温下镍基高温合金M17和M38G在NaCl溶液和含S2O2-3的NaCl溶液中的腐蚀行为.结果表明,在含质量分数为3.5% NaCl的溶液中,M17和M38G均会遭受严重的点腐蚀;向NaCl溶液(NaCl质量分数为3.5%)添加Na2S2O3(Na2S2O3质量分数为1.5%)后,由于溶液中的S2O2-3在试样表面活性点与Cl-竞争吸附并与H+结合,使两种合金的点蚀均受到抑制;M38G中存在微量的Nb、Ta、Mo等元素使得M38G合金在NaCl溶液中的耐腐蚀性能明显优于M17合金.
关键词:
镍基
,
高温合金
,
点蚀
,
电化学方法
,
腐蚀行为
林水东
,
丁马太
功能材料
用示差扫描量热法(DSC)考察了聚丙烯(PP)、聚丙烯/云母(PP/M)和聚丙烯/聚(丙烯-g-甲基丙烯酸甲酯)/云母复合材料(PP/PP-g-MMA/M)的非等温结晶过程.用Avrami方程和Ozawa方程对上述过程进行分析,n、t1/2、F(T)、Tp等参数表明,M和PP-g-MMA,特别是PP-g-MMA的掺入改变了PP的结晶成核和生长机理.用Dobreva方法分析填料的成核活性,ε数值表明,M有较强的成核活性,PP-g-MMA的掺入又进一步增强其成核活性,从而使结晶温度明显提高.Kissinger方法的计算结果表明,添加M可使PP的结晶活化能减小,再添加PP-g-MMA又使PP/M复合体系的结晶活化能进一步减小.
关键词:
聚丙烯
,
聚(丙烯-g-甲基丙烯酸甲酯)
,
云母
,
复合材料
,
非等温结晶动力学
Journal of Alloys and Compounds
Bulk metallic glasses (BMGs) Fe56Co7M2Zr10Mo5B20 (M = W or Ni) with diameters of 1.5 mm were fabricated by copper mould casting method. There is no significant difference in the glass properties such as glass transition temperature (T-g), onset temperature of crystallization (T-x), supercooled liquid region (Delta T-x), and offset temperature of melting (T-1) except that the onset melting temperature T-m, which are 1454 and 1464 K for the alloy containing W and Ni, respectively. The alloy containing W exhibits some paramagnetic properties while the Ni containing alloy shows fully ferromagnetic. The potentiodynamic polarization experiments show that these alloys have a high corrosion resistance in 3.5 % NaCl solution with strong passivation ability. The alloy containing W shows excellent pitting resistance with a wide passive range (Delta E = 852 mV) and low passive current density in the order of mu A m(-2). Electrochemical impedance spectroscopy (EIS) for either alloy consists only of single capacitive loop. (c) 2005 Elsevier B.V. All rights reserved.
关键词:
amorphous materials;casting;bulk metallic glasses;glass forming;ability;high saturation magnetization;p-c alloys;ferromagnetic glasses;amorphous-alloys;1.5 t;hcl;resistance;behavior;system
Intermetallics
The phase transformation of alumina formed during oxidation of beta-NiAl coating prepared on M38G alloy by pack cementation was investigated. Oxidation experiments were conducted at 950 degrees C for various times from 2 to 180 min. The phase composition and microstructure of the oxide scales were investigated by using glancing angle XRD, AFM and SEM. The results showed that at the initial oxidation stage needle-like theta-Al2O3 was formed and then it covered the sample surface rapidly. The formation of alpha-Al2O3 grains beneath the theta-Al2O3 layer was favored by depletion of Al in the beta-NiAl coating during oxidation. alpha-Al2O3 preferred growing on the top (ridge) of beta-NiAl grains, which resulted in the formation of net-like alpha-Al2O3 inner layer. With increasing time, theta-Al2O3 transformed to alpha-Al2O3 gradually. After 180 min oxidation, most of alpha-Al2O3 grains transformed into alpha-Al2O3. A mechanism of excessive voids' formation at the oxide/coating interface was also proposed in this paper. (c) 2007 Elsevier Ltd. All rights reserved.
关键词:
nickel aluminides, based on NiAl;oxidation;phase transformations;coatings, intermetallic and otherwise;high-temperature oxidation;theta-alpha-al2o3 transformation;behavior;coatings;superalloy;transition;layers
TIAN Baohong ZHENG Shi'an WU Lei Luoyang Institute of Technology
,
Luoyang
,
China ZHENG Shi'an
,
associate professor
,
Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471039
,
China
金属学报(英文版)
Determination was carried out of fatigue crack propagation rate of steel 65Cr5Mo3W2VSiTi (LM2)with various bainite contents and M/B duplex structure tempered at various tempera- tures.The threshold value of fatigue for each processing was estimated by experimental data. The mechanism for fatigue crack propagation of M/B duplex structure in steel LM2 seems to be non-continuous.The calculated fatigue crack micro-propagation rates are found to agree with the experimental data.
关键词:
duplex structure
,
null
,
null
,
null
蒋彦龙
,
陈国邦
,
甘智华
,
低温物理学报
doi:10.3969/j.issn.1000-3258.2004.02.006
本文开展了高性能G-M型单级脉管制冷机直流抑制和制冷特性实验研究.考察了直流流动对制冷机性能的影响,采用并联布置的双阀逆向型进气结构对直流进行抑制,成功地解决了脉管制冷机的直流问题;此外,深入研究了不同工作模式下,回热器填料布置方式对制冷特性的影响;估算了不同温度位下制冷循环的需气量,对不同压缩机输入功下的双向进气脉管制冷性能进行了研究,采用2kW(RW2)和4kW(CP4000)压缩机驱动时分别获得了18.4K和14.7K的最低制冷温度,在30K的相应制冷量分别为11.5W和29.5W.
关键词:
高性能
,
脉冲制冷机
,
直流
刘路
,
李世燕
,
樊荣
,
陈仙辉
低温物理学报
doi:10.3969/j.issn.1000-3258.2000.05.005
分别用固相反应和柠檬酸盐溶胶-凝胶法制备名义组成为Sr2(Gd1 5Ce0.5)Cu2Oz的前驱物,再用真空烧结的方法合成了(Hg,M)-1222相铜氧化合物(Hg0.75M0.25)Sr2(Gd1.5Ce0.5)Cu2Oz(M=W,Mo,V,Cr,Ti).溶胶-凝胶法同固相法相比混合更均匀,反应温度低,成相情况好.改进该方法后,用溶解度较高的Ce(NO3)3代替不溶于硝酸的CeO2,制得了纯1222相.研究了不同退火条件对样品电阻温度特性的影响,发现高氧压退火有助于超导转变.M=W,Mo时得到超导体,Tc(onset)在13～27K之间.
关键词:
