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    • Advances in the R&D of BSCCO HTS Tapes Worldwide

      1998(5):253-258.

      Abstract (1197) HTML (149) PDF 0.00 Byte (0) Comment (0) Favorites

      Abstract:评述了国外BSCCO高温超导(HTS)带材的最新进展。目前,工业轧制的Bi(Ph)-2223多芯带材短样的Jc(77K,0T)高达58000A·cm-2,千米以上长带的Jc(77K,自场)在1×104A·cm-2以上。用BSCCOHTS带村绕制的大线圈在20K产生了高达7T的磁场。在提高带材性能的同时,人们还研究成功许多制取BSCCO带材的改进工艺,其中,带材连续制取工艺可使BSCCO带的成本降低到一般产品的水平。

    • X-ray Study of Cube Textured Ni Substrate for YBCO Thick Films

      1998(5):259-262.

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      Abstract:High quality, sharp cube textured Ni substrates for YBCO thick films have been fabricated by a cold rolling and recrystallization annealing process. The prevalent quality evaluation of the cube textured Ni substrate are studied.. The results show that (001) spectrograms obtained from scanning and FWHM of (001) rocking curves by 6 scanning are relative to the f angles.Correspondent: Liu Chunfang, Professor, Superconducting Material Research Center, Northwest institute for Nonferrous Metal Research, Xi'an 710016, P. R. China, Tel:086-29-6231079

    • Magnetic Transition and the Intrinsic Magnetic Properties of Nd_3 (Fe, Mo)_ (29) Compound and Its Nitride

      1998(5):263-266.

      Abstract (1273) HTML (138) PDF 0.00 Byte (28) Comment (0) Favorites

      Abstract:The Nd3 (Fe,Mo)2, compound with the Nd, (Fe,Ti)29-type monoclinic structure and its nitride have been synthesized. The magnetic transition, lattice Parameters, and the intrinsic magnetic properties, including Curie temperature, Tc, saturation magnetization, and magnetocrystalline anisotropy, of the Nd3 (Fe,Mo)29compound have been studied. The results show that the nitride has a structure related to the parent, but the unit cell volume, Curie temperature, To, and saturation magnetization, are 5. 9%,70. 9% and 6. 6%, respectively, greater than those of parent compound. It is also found that the spin reorientation phenomenon occurs at about 230 K in the parent compound, and the magnetocrystalline anisotropy of the Nds (Fe,Mo)2, compound is an easy plane above 230 K and a cone from 4. 2 K to 230 K. After nitrogenation, this spin reorientation phenomenon disappears.

    • Calculation of the Maximum Hydrogen Capacity of the Amorphous Alloy Zr-Ni

      1998(5):275-277.

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      Abstract:In order to design an amorphous hydrogen storage alloy efficiently, the maximum hydrogen capacity of the amorphous alloy Zr-Ni has been calculated. Based on the Rhombic Unit Structure Model (RUSM) of the amorphous alloy, and the experimental result that hydrogen atoms exist in 3Zr1Ni and 4Zr tetrahedron interstices in the amorphous alloy Zr-Ni, the numbers of 3ZrlNi and 4Zr tetrahedron interstices in a RUSM, which correspond to the hydrogen capacity, have been calculated. Two extreme Zr distribution states (highly heterogeneous Zr distribution and homogeneous Zr distribution) have been calculated. The calculated curves of the hydrogen capacity with different Zr contents at two states indicate that the hydrogen capacity increases with the increase of Zr content and reaches the maximum at a Zr content of 75 at%, The theoretical maximum hydrogen capacity of the amorphous alloy Zr-Ni is 2.0 (H/M). The hydrogen capacity of heterogeneous Zr distribution alloy is higher than that of homogenous one for the same Zr content. The experimentally determined hydrogen capacity of the amorphous alloy Zr -- Ni lies between the two calculated curves, which proves that the calculated results reasonable. In this way the heterogeneous distribution of Zr atoms in amorphous alloy after a few hydrogen absorption-desorption cycles can be explained.Correspondent: Zhang Dongming, Associate Professor, State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, P. R. China, Tel: 086-27-87884448

    • Effect of Boron Content on the Microstructure and Properties of a Nanocrystalline Composite Ti-B-N Coating

      1998(5):278-281.

      Abstract (1441) HTML (145) PDF 0.00 Byte (13) Comment (0) Favorites

      Abstract:By adding of boron to the Ti-N coating, Ti-B-N coatings with boron contents from 5% to 16 % have been deposited on steels using activated ion plating. The effect of boron content on the microstructure and the properties of the Ti-B-N coating have been studied. A diffusion zone exists at the coating/substrate interface. TEM analysis indicates that the coating has a dense nanocrystalline composite structure and a crystal size smaller than 50 urn. The phase composition of the coating is fee TiN, simple orthorhombic TiB, cubic BN and simple hexagonal Ti-B-N. The mechanical properties, such as microhardness, toughness adhesion and sliding friction coefficient of the Ti-B-N coating are much better than those of the Ti-N coating, and the deposition temperature is much lOwer than that for the Ti-N coating.Correspondent: Yang Qiaoqin, Ph. D, Associate Professor, Material Test & Research Centre, Hunan University, Changsha 410083,P. R. China, Tel: 086-731-8822663

    • Crystallization of the Amorphous Alloy Fe-Mo-W-B Obtained by Electroless Plating

      1998(5):282-285.

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      Abstract:Amorphous Fe-Mo po W-B alloy deposits have been made by electroless plating. The structure and the crystallization of the alloy have been studied by X-ray diffraction (XRD). It is found that the structure is amorphous if the boron content is within the range of 9. 8 at % to 27. 3 at %, which is wider than that of the binary Fe -- B, but narrower than that of ternary Fe-Mo-B amorphous film. A two-step crystallization process is observed for the deposits. At first, the crystalline phases a-Fe, Fe3B and (Mo,W)2B precipitates, followed by amorphous Fe3B, (Mo,W)B and Fe2(Mo,W) films form at high temperature Correspondent: Wang Lingling, Associate Professor, Department of Applied Physics, Hunan University, Changsha 410082, P. R.China, Tel: 086-731-8822351

    • Study of the Permeability of a Metal Fiber Medium with Graded Pore Size

      1998(5):286-289.

      Abstract (1217) HTML (139) PDF 0.00 Byte (0) Comment (0) Favorites

      Abstract:The influence of the porosity of a filter medium and the metal fiber diameter of additional layers of filter medium with graded pore size on air permeability has been investigated. The relationships of the air permeability of the metal fiber filter media to the porosity and the pore size, and an empirical equation for the permeability, the porosity and the pore size are obtained using a statical method. The results show that the air permeability of the filter medium which consists of a control layer and additional layers of thick fiber with gradient pore size is much higher than that of the medium with uniform pore size under the same conditions. The air permeability coefficient of the filter medium increases with the increasl of the fiber diameter of additional layers. The obtained empirical equation can be used for evaluating the air permeability coefficient of the metal fiber filter medium with gradient pore size.Correspondent: Liao Jichang, Professor, Northwest institute for Nonferrous Metal Resesearch, Xi' an 710016, P. R. China, Tel: 08629 626749

    • Ultrapressure Forming and Low-Temperature Sintering of Tungsten

      1998(5):290-293.

      Abstract (1584) HTML (150) PDF 0.00 Byte (1) Comment (0) Favorites

      Abstract:选用FSSS粒度3μm-4μm的FW-1型工业钨粉,在湿氢中经1200℃11h的高温处理,粉末的粒度,粒形都产生了相应的变化,并具有良好的成型性能。该粉末在超高压条件下,生坯的相对质量密度可达90%以上。烧结实验证实,这种高密度铁生坯,具有优良的烧结性能。经1800℃h或2100℃1h烧结,其相对质量密度分别达到9.65%和94.76%。

    • Preparation of Nanocrystalline Tungsten Powder and Study of Its Sinterability

      1998(5):294-297.

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      Abstract:Nano-crystalline tungsten powder prepared by high - energy ball milling was consolidated without pressure and with pressure, respectively. The change of the particle size and morphology, and the relative density of the sintering compact as a function of consolidation temperature has been studied by SEM, TEM and X - ray diffraction. The sinterability of nanocrystalline tungsten powder is compared with that of coarse - grained tungsten powder. It is found that the usual layered structure does not develop during the high - energy ball milling of brittle materials. This work demonstrates that the sinterability of nanocrystalline powder is far superior to that of a coarse - grained one.Correspondent: Chen Xianfeng, Candidate for Master Degree, State Key Laboratory for Mechanical Behavior of Materials, Xi'arl Jlao'tong University, Xi'an 710049, P. R. China, Tel: 086 - 29 - 3268912

    • Study of Titanium Brazing with Al-Ti-Al Clad Metal Sheet

      1998(5):298-301.

      Abstract (1339) HTML (137) PDF 0.00 Byte (8) Comment (0) Favorites

      Abstract:The results of a study of commercial pure (C P) titanium brazing with Al - Ti - Al clad metal sheet are presented. The clad metal sheet has been produced by a proprietary roll bonding process. Both surfaces of the clad metal sheet are coated with an Al alloy brazing layer to a thickness of 0. 1 mm; the central sheet is C P titanium with thickness of 0. 4 mm. The clad metal sheet has been used as a substitute for monometallic Al alloy brazing foil in the braze bonding of titanium honeycomb structures; its use makes the brazing process simply and homogenizes the brazing bonding. The shear strength, macro - and microstructure of the brazed bond are investigated. The shear strength values of the joint welds with different brazing sheets are compared. The results show that the clad metal sheet braze bonded structure has a sufficiently high shear strength, more than 76 MPa.Correspondent: Luo Guozhen, Professor, Northwest institute for Nonferrous Metal Research, Xi'an 710016, P. R, China, Tel:086-29-6231078

    • Effect of Quenching on the Corrosion Resistance of the Zr-1Nb Alloy

      1998(5):302-305.

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      Abstract:研究了两种不同制度淬火以及淬火后的冷加工对Zr-1Nb合金抗360℃,18.6MPa高温水和500℃,10.3MPa高温蒸汽腐蚀性能的影响,并对影响机理进行了分析。研究表明,无论是(α+β)双相区淬火还是严单相区淬火,都使合金的抗高温水和高温蒸汽腐蚀性能严重恶化,淬火后的450℃,16h时效没有改变这种现象;在淬火与时效间加一道冷加工能有效改善淬火态合金的抗腐蚀性能。

    • Influence of Annealing Process on the Mechanical Properties of the Zr-4 Sheets

      1998(5):306-308.

      Abstract (1119) HTML (141) PDF 0.00 Byte (1) Comment (0) Favorites

      Abstract:研究并测定了两种退火方式的Zr-4合金板室温和高温的力学性能。结果表明:消应力退火的板材与再结晶退火的相比,其室温抗拉攻屈服强度分别提高16.705和18.74%,400℃温度下分别提高42.41%和64.04%。在400℃温度一消应力退火板材第二阶段蠕变速率与再结晶退火的相比降低一个数量级;其疲劳强度极限提高43%。

    • Effect of Calcination Temperature and Time on Size and Structure of Nanostructured ZrO_2 Powders Prepared by Precipition

      1998(5):309-312.

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      Abstract:Zirconium oxychloride, urea and ammonia have been used to produce the precursor by the precipition method. The precur' sor was heat-treated to obtain the zirconia powders. Differential thermal analysis shows that the precursor changes into amorphous zirconia at 300C, and then transforms to tetragonel zirconia at 450C. The processes are endoergic and exoergic, respectively. XRD analysis shows that the monoclinic zirconia not can be obtained below 700C. The content of monoclinic zirconia increases as the calcination time increases. The zirconia powders so obtained are nanostructured. The size of the powders increases quadratically with the calcination temperature. The particle size increases linearly with calcination time.Correspondent: Liao Shuzhi, Doctor, Associate Professor, Department of Physics, Hunan Educational institute, Changsha 410012,P. R. China, Tel: 086 - 731 - 8826401

    • Application of Rhodamine 6G in Photometric Analysis of Noble Metal and Rare Metal

      1998(5):313-316.

      Abstract (1343) HTML (140) PDF 0.00 Byte (10) Comment (0) Favorites

      Abstract:A recent advance in the application of rhodamine 6G to the photometric analysis of noble metals and rare metals is reviewed. This paper centers on extraction photometric analysis, floatation photometric analysis, fluorimetric analysis, water phase photometric analysis. Also considered are their systems of determination and the conditions of coloring reactions, maximum absorption, molar absorptivity, limit of detection, interference and the range of determination. The main characteristics of extraction photometric analysis, floatation photometric analysis and fluorimetric analysis are also introduced.Correspondent: Duan Qunzhang, Professer, Central South University of Technology, Changsha 410083, P. R. China, Tel: 086 731-8826911

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