Y. T. Xing
,
Y.Z. Wang
,
G.W. Qiao
金属学报(英文版)
The paramagnetic Meissner effect (PME) was observed on the field-cooled M-T curvesof melt-textured Y0.99Nd0.01Ba2Cu3O7-y in applied magnetic fields from 1kOe toJ0kOe. In the magnetic field below 1kOe, the sample undergoes the typical transi-tion from the normal state to the superconducting state when it was cooled down. Theapplied magnetic fields in which the PME occurs, are very high compared with thefields reported in literatures. We propose that the occurrence of the PME may be dueto a phase transition of flux vortices in the superconductors.
关键词:
YBCO superconductor
,
null
冯辉君
,
陈林根
,
谢志辉
,
孙丰瑞
工程热物理学报
基于构形理论,以导热和对流换热总(火积)耗散率最小为优化目标,对T-Y形肋片进行构形优化,得到同时考虑导热和对流换热(火积)耗散性能的T-Y形肋片最优构形.结果表明:存在最佳单元级直肋和中部空腔高度和长度比使得T-Y形肋片无量纲当量热阻取得二次最小值.增大肋片高度和长度比和肋片占比有助于提高T-Y形肋片整体传热性能.T-Y形肋片与T形肋片相比,T-Y形肋片二次最小无量纲当量热阻降低32.33％,此时T-Y形肋片温度梯度场更均匀,整体传热性能得到明显提高.
关键词:
构形理论
,
(火积)耗散率最小
,
T-Y形肋片
,
对流换热
,
广义热力学优化
张明明
,
李文超
,
张圣麟
腐蚀与防护
采用动电位极化曲线，电化学阻抗谱（EIS）和中性盐雾试验（NSS）研究了溶液中加入不同含量纳米Y2 O3对铝合金AA6061-T6表面硅烷膜耐蚀性的影响，采用扫描电镜（SEM）对其形貌进行了观察。结果表明，在1，2-双-三乙氧基硅烷（BTSE）溶液中加入少量纳米Y2 O3可提高硅烷膜在3．5％ NaCl溶液中的耐蚀性。硅烷膜对铝合金的保护只起到物理屏障作用。纳米Y2 O3抑制了电化学腐蚀过程中阴极还原反应的发生，但不影响电极反应的动力特征。SEM表明在BTSE硅烷溶液中添加10～20 mg/L的纳米Y2 O3后，硅烷膜表面变得平滑致密。
关键词:
硅烷膜
,
纳米Y2 O3
,
耐蚀性能
,
铝合金
刘光明
,
张都清
,
任善平
表面技术
doi:10.16490/j.cnki.issn.1001-3660.2015.12.017
目的 研究纳米Y2 O3 预处理对T91钢抗水蒸汽氧化性能的影响,分析稀土元素作用的机理及长期氧化后的失效机制. 方法 采用将Y2 O3、铝粉、粘结剂制备成料浆涂覆于T91钢表面,并在720 ℃水蒸汽中预处理48 h. 预处理样品和空白样品同时置于在700 ℃高温水蒸汽中氧化,获取循环氧化动力学曲线并进行对比,检验预处理对提高材料抗高温水蒸汽腐蚀的效果. 对氧化的样品采用XRD、SEM/EDS对氧化物结构、形貌、成分进行分析. 结果 预处理后在样品表面形成了含Y2 O3 的富铬氧化物薄膜. 在高温水蒸汽环境的氧化过程中,试样处理600 h时,质量增加轻微,仅为0. 152 g/cm2. 但在600 h后质量增加明显,预处理膜层逐渐退化,表面出现Fe2 O3 突出物. 空白样在腐蚀初期即明显增加,氧化70 h后,质量增加达12. 17 mg/cm2 ,氧化过程中可见氧化产物的剥落,氧化膜附着力差. 结论 纳米Y2 O3预处理可提高T91钢抗水蒸汽氧化性能,但随着氧化时间延长,富铬氧化膜将逐渐退化.
关键词:
纳米Y2O3
,
T91钢
,
预处理
,
水蒸汽
,
高温氧化
,
富铬氧化膜
肖阳
,
张新明
,
陈健美
,
蒋浩
中国有色金属学报
研究了Mg-9Gd-4Y-0.6Zr合金挤压T5态在250～400℃之间的高温组织与力学性能. 结果表明:该合金具有非常优异的高温力学性能,其力学性能明显优于WE54;该合金在250、300、350和400℃时的抗拉伸强度分别为348、262、150和62MPa;该合金在400℃拉伸时还具有粗晶超塑性,晶界上有再结晶的细晶,晶内有大量孪晶同时共存.
关键词:
Mg-Gd-Y-Zr合金
,
耐热镁合金
,
高温力学性能
,
T5态
,
粗晶超塑性
马宏
,
彭晓东
,
谢卫东
腐蚀学报（英文）
利用对掺法熔铸镁合金AJ61+xY, 研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为. 结果表明, 添加稀土Y使AJ61镁合金的晶粒明显细化,Mg17Al12 相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al2Y、Al3Y, AJ61镁合金的耐腐蚀性得到明显改善. 耐腐蚀性顺序为:AJ61+1.5%Y>AJ61+2.0%Y>AJ61+1.0%Y>AJ61+0.5%Y.
关键词:
Mg-6Al-1Sr 镁合金
,
yttrium
,
microstructure
,
corrosion resistance
马宏
,
彭晓东
,
谢卫东
腐蚀学报（英文）
利用对掺法熔铸镁合金AJ61++xY,研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为.结果表明,添加稀土Y使AJ61镁合金的晶粒明显细化,Mg17Al12相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al2Y、Al3Y,AJ61镁合金的耐腐蚀性得到明显改善.耐腐蚀性顺序为:AJ61+1.5%Y＞AJ61+2.0%Y＞AJ61+1.0%Y＞AJ61+0.5%Y.
关键词:
Mg-6Al-1Sr镁合金
,
钇
,
显微组织
,
耐腐蚀
Yan NIU
,
Weitao WU and Chaoliu ZENG (State Key Lab. for Corrosion and Protection
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)F. Gesmundo and F. Viani (Instituto di Chimica
,
Facolta di Ingegneria
,
Un
材料科学技术（英文）
The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe
关键词:
International Journal of Hydrogen Energy
Hydrogen absorption/desorption properties of La(0.2)Y(0.8)Ni(5-x)Mn(x) (x = 0.2, 0.3, 0.4) alloys for high-pressure hydrogen compression application were investigated systematically. The Pressure Composition isotherms and absorption kinetics were measured at 293, 303 and 313 K by the volumetric method. XRD analyses showed that all the investigated alloys presented CaCu(5) type hexagonal structure and the unit cell volume increased in both a and c lattice axes with Mn substitution. Hydrogen absorption/desorption measurements revealed that Mn could lower the plateau pressure effectively, improve the hydrogen storage capacity and absorption kinetics but slightly increase the slope of the pressure plateau and hysteresis. The study results suggest that La(0.2)Y(0.8)Ni(4.8)Mn(0.2) is suitable for the high-pressure stage compression of the hydrogen compressor and the other two alloys, La(0.2)Y(0.8)Ni(4.7)Mn(0.3) and La(0.2)Y(0.8)Ni(4.6)Mn(0.4), for the preliminary stage. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
关键词:
Hydrogen storage;Metal hydride;Hydrogen compressor;Pulverization;hysteresis;absorption;kinetics;hydrides;systems
