Oxidation of Fe-7Cr-12Ni-(0-6)Al-(0-7)Si alloys

A series of Fe-7Cr-12Ni-(0-6)Al-(0-7)Si alloys was oxidized at test temperatures between 800° and 1000 °C. The master alloy, Fe-7Cr-12Ni, had no oxidation resistance at temperatures above 800 °C. Aluminum additions to the master alloy produced a protective A1₂O₃ layer over the substrate metal which prevented rapid oxidation and allowed time for a Cr₂O₃ layer to develop underneath. Silicon addition to the master alloy produced an SiO₂ oxide sublayer at the metal-oxide interface which, when formed, provided an effective barrier to oxidation. A combination of 1.5-pct-Al and 2.0-pct-Si additions provided the best oxidation protection.     

铝-钢双金属管材的生产与应用

论述了铝-钢双金属管的生产的方式与应用领域，根据潜在市场需求和现有生产技术条件，分析了开发铝-钢双金属管的生产技术和应用市场的可行性。从而为铝合金管和钢管的深加工技术发展开辟了新途径。     

原位溶胶-凝胶法制备CoFe_2O_4/Bi_(0.5)(Na_(0.8)K_(0.2))_(0.5)TiO_3复合材料的磁电性能

采用原位溶胶–凝胶法制备xCoFe_2O_4/(1-x)Bi_(0.5)(Na_(0.8)K_(0.2))_(0.5)TiO_3(x为Co Fe_2O_4的摩尔分数,x=0.2,0.3,0.4)复合材料,研究磁性相CoFe_2O_4的含量对Co Fe_2O_4/Bi_(0.5)(Na_(0.8)K_(0.2))_(0.5)TiO_3复合材料结构、形貌及铁电性、铁磁性和磁电耦合性能的影响。结果表明,该复合材料中只存在CoFe_2O_4和Bi_(0.5)(Na_(0.8)K_(0.2))_(0.5)TiO_3两相;材料的饱和磁化强度和剩余磁化强度随Co Fe_2O_4含量增加而增大,而饱和极化强度和剩余极化强度随CoFe_2O_4含量增加而减小;当偏置磁场强度为72 k A/m时,0.3Co Fe_2O_4/0.7Bi_(0.5)(Na_(0.8)K_(0.2))_(0.5)TiO_3复合材料的磁电电压系数达11.8 m V/A。     

Comparison of 10-0 polypropylene and 10-0 nylon sutures in rat arterial anastomosis

The selection of suture materials is an important factor in further improving the results of microsurgical operations. In this study, two kinds of nonabsorbable suture materials, 10-0 polypropylene and 10-0 nylon monofilament, were compared in end-to-end anastomosis of 66 femoral arteries of adult rats. Both suture types were of identical size (70 microns needle/28 microns suture) and each artery received eight sutures. The vessels were harvested at various intervals from 2 hr to 180 days postoperatively and were evaluated by pathology, radiology, and tensile strength test. The results show that both sutures are capable of achieving excellent long-term patency (100%) of anastomosed sites. Polypropylene suture was equivalent to nylon in mechanical integrity of the anastomosis sites but was superior in handling, knotting, and biocompatibility. These physical and biological properties of polypropylene sutures may offer the benefits of diminished early and late complications at anastomosis sites and reduced operation time. Enhancement of contrast against surrounding tissue may make polypropylene a superior alternative to nylon sutures for microsurgical use.     

Hybridized valence electrons of 4f~(0-14)5d~(0-1)6s~2: the chemical bonding nature of rare earth elements

The chemical bonding nature of rare earth(RE) elements can be studied by a quantitative analysis of electron domain of an atom. The outer electrons of RE elements are within the valence shell 4f~(0-14)5d~(0-1)6s~2, which are involved in all chemical bonding features. We in this work found that the chemical bonding characteristics of 4f electrons are a kind of hybridizations, and classified them into three types of chemical bonding of 4f~(0-14)5d~(0-1)6s~2, furthermore, the coordination number ranging from 2 to 16 could thus be determined. We selected Y(NO_3)_3, La(NO_3)_3, Ce(NO_3)_3, YCl_3, LaCl_3, and CeCl_3 as examples to in-situ observe their IR spectra of chemical bonding behaviors of Y~(3+), La~(3+) and Ce~(3+) cations, which could show different chemical bonding modes of 4f and 5d electrons. In the present study, we obtained the direct criterion to confirm whether 4f electrons can participate in chemical bonding, that is, only when the coordination number of RE cations is larger than 9.     

Thermodynamic Properties of the Quasibinary System Bi2Se3 - Bi2Te3 over a Broad Temperature Range

We have studied the heat capacity and enthalpies of solid solutions in the quasibinary system Bi₂Se₃ - Bi₂Te₃ at low and high temperatures. Based on low-temperature measurements of the heat capacity, we have calculated the values of the enthalpy, entropy, and reduced Gibbs energy of the compounds under standard conditions. We have determined the temperature dependences of the thermodynamic functions for the solid solutions Bi₂Se₃ - Bi₂Te₃ (50, 70, and 80 mole% Bi₂Te₃) in the temperature range 298.15 K - T_mp. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 80–85, July–August, 2005.     

替代HPb59-1的铋黄铜开发及性能

为顺应形势，我公司开发了可用于替代传统铅黄铜HPb59-1的无铅易切削铋黄铜，其w（Pb）〈0．01％，铅浸出量〈0．004mg/L，机械性能及切削性能不低于HPh59-1。加锰后，不但进一步强化了合金的机械性能，而且提高了耐脱锌性。在此基础上，开发了铋黄铜的加工工艺，试制出了热轧材、挤压材及拉拔线材。