D.R.Huang
,
T.F.Ying
,
L.T.Kuo
,
S.J.Wang
,
H.C.Huang
,
C. Y.Huang
材料科学技术（英）
A single phase brushless spindle motor with innovative design has been developed for application in a DVD drive. The methods used to reduce the cogging torque and to improve the dynamic performance of this new design motor are proposed in this paper. The single phase brushless spindle motor is usually applied for cooling fan, pump and blower before the performance is improved by the reengineering process. The stator configuration and the drive circuit have been remodeled in order to meet the requirements of the spindle motor used in the DVD applications.
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Oxidation of Metals
The corrosion of Co-15 wt.% Y has been studied at 600-800 degrees C in H-2-H2S-CO2 mixtures providing a sulfur pressure of 10(-8) atm at 600-800 degrees C and of 10(-7)atm at 800 degrees C and an oxygen pressure of 10(-24)atm at 600 degrees C and of 10(-20)atm at 700-800 degrees C. The corrosion rates in such sulfidizing-oxidizing atmospheres were compared,,with those of pure cobalt and yttrium. The addition of yttrium to cobalt is only slightly beneficial, since Soi a yttrium content of 15 wt.% the corrosion rate is reduced quite significantly with respect to pure cobalt at 800 degrees C under 10(-7)atm S-2, only to a limited extent at 600 degrees C, and even slightly increased at 700 degrees C. Moreover, the alloy corrodes considerably more rapidly than pure yttrium at 800 degrees C, when the latter. behaves protectively.,At 600 and 700 degrees C, yttrium exhibited breakaway behavior, while the alloy corroded more rapidly than yttrium at short times, but more slowly at long times. Under all conditions, except at 800 degrees C under 10(-8) atm? Sr, the alloy forms ail external layer of cobalt sulfide overlying an intermediate region of very complex composition containing a mixture of the compounds of the two metals and ail innermost region of internal attack containing compounds of yttrium with both oxygen and sulfur. Thus, cobalt can still diffuse through the intermediate region to form the outer cobalt-sulfide layer at nonnegligible rates. The scaling behavior of rite Co-15% Y alloy is discussed by taking into account the limited solubility of yttrium in cobalt as well as the presence of an intermetallic Co-Y compound in the alloy.
关键词:
cobalt;yttrium;two-phase alloys;sulfidation;oxidation;high-temperature sulfidation;2-phase binary-alloys;most-reactive;component;ni-nb alloys;internal oxidation;oxidant pressures;h2-h2s;mixtures;co;behavior;600-degrees-c-800-degrees-c
Corrosion Science
The corrosion of pure yttrium and of a cobalt alloy containing approximately 15 wt% yttrium was studied at 600-800 degrees C in H-2-CO2 mixtures providing an equilibrium oxygen pressure of 10(-24) atm at 600 degrees C and 10(-20) atm at 700 and 800 degrees C. The corrosion of yttrium under these low oxygen pressures resulted in the growth of Y2O3 scales which was rather protective at 800 degrees C, presenting two approximately parabolic stages with a smaller rate Constant at longer times, but non-protective and faster at lower temperature. The oxidation of Co-15Y was rather irregular under all conditions, but generally slow: in particular, at 800 degrees C the rate decreased almost to zero after about 17 h oxidation. The oxidation of this alloy produced a thin external layer of pure cobalt metal overlying a region of internal oxidation, where the Y-rich phase was transformed into a mixture of cobalt metal and yttrium oxide. The microstructure of the internal oxidation region followed closely that of the original alloy, while no yttrium depletion was observed beneath the front of internal oxidation. These results are examined by taking into account the low solubility of Y in Co and the existence of an intermetallic compound in the alloy. (C) 1997 Elsevier Science Ltd.
关键词:
cobalt;yttrium;alloys;internal oxidation;2-phase binary-alloys;high-temperature oxidation;most-reactive;component;possible scaling modes;low oxidant pressures;internal;oxidation;a/o al;corrosion;1173-k
Oxidation of Metals
The corrosion of pure yttrium and of two Fe-base alloys containing approximately 15 and 30 wt.% Y was studied at 600-800 degrees C in H-2-CO2 mixtures providing an equilibrium oxygen pressure of 10(-24) atm 600 degrees C and 10(-20) atm at 700 and 800 degrees C. The corrosion of yttrium under these low oxygen pressures resulted in the growth of Y2O3 scales and presented two approximately parabolic stages at 800 degrees C, while at 600-700 degrees C it was faster and nonprotective. The corrosion of the two alloys followed approximately the parabolic rare law, except for Fe-15Y at 600 degrees C which oxidized nearly linearly. At 600 and 700 degrees C, when the gas-phase oxygen pressure was in the field of stability of iron oxide, the alloys formed also a thin external Fe3O4 layer, while at 800 degrees C, when the oxygen pressure was below the stability of FeO, a thin outermost layer of pure iron was observed to form. Under all conditions a region of internal oxidation formed in the alloy, in which the yttrium-rich phases were transformed into a mixture of iron metal and oxides, which included double Fe-Y oxides as well as Y2O3. The microstructure of the internal-oxidation region followed closely that of the original alloys, which moreover did not undergo any yttrium depletion. These results are examined by taking into account the low solubility of yttrium ib iron and the presence of intermetallic compounds in the alloys.
关键词:
iron;yttrium;alloys;internal oxidation;2-phase binary-alloys;high-temperature oxidation;most-reactive;component;possible scaling modes;low oxidant pressures;internal;oxidation;al alloys;a/o al;corrosion;1173-k
Corrosion Science
The corrosion of two iron-based alloys containing 15 and 30 wt% yttrium and of pure yttrium has been studied at 600-800 degrees C in H-2-H2S-CO2 mixtures under a sulfur pressure of 10(-8) atm and an oxygen pressure of 10(-24) atm at 600 degrees C and of 10(-20) atm at 700-800 degrees C to establish the effect of yttrium additions on the resistance of pure iron to mixed sulfidizing-oxidizing atmospheres of high sulfur potential. The presence of yttrium is only slightly beneficial, since even a yttrium content of 30 wt% can only reduce the corrosion rate of iron to a limited extent at 600 and 800 degrees C, but not at 700 degrees C. More precisely, at 600 and 700 degrees C, when yttrium shows breakaway, the alloys corrode more rapidly than pure yttrium at short times, but presumably more slowly at long times. On the contrary, at 800 degrees C, when yttrium behaves protectively, the two alloys corrode considerably more rapidly than pure yttrium. Under all conditions the two alloys form an external FeS layer overlying a very complex intermediate region containing a mixture of the compounds of the two metals and an innermost zone of internal attack containing compounds of yttrium with both oxygen and sulfur, Thus, iron can still diffuse through the intermediate region at nonnegligible rates to form the outer FeS layer. The scaling behavior of these alloys is discussed by taking into account the limited solubility of yttrium in iron as well as the presence of intermetallic Fe-Y compounds. (C) 1999 Elsevier Science Ltd. All rights reserved.
关键词:
iron;yttrium;alloys;sulfidation;oxidation;high-temperature sulfidation;2-phase binary-alloys;fe-nb alloys;most-reactive component;internal oxidation;oxidant pressures;h2-h2s;mixtures;behavior;ni;600-degrees-c-800-degrees-c
Physics Letters A
The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A(a)B(b)C(c))(y)D, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c-a, b-c and a-b planes. The phase diagrams of the transition temperature T-c and compensation temperature T-comp are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet ((NiaMnbFecII)-Mn-II-Fe-II)(1.5) [Cr-III (CN)6] - zH(2)O. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
mixed ferro-ferrimagnet;Ising model;four sublattices;phase diagram;transition temperature;compensation temperature;magnetic-properties;prussian blue;alloy
Corrosion Science
The oxidation of pure Co and two Co-Y alloys containing 2 at.% and 5 at.% Y has been studied at 600-800 degrees C in air. The oxidation of pure cobalt at all temperatures followed the parabolic rate law. The oxidation of the two alloys approximately followed the parabolic rate law at 800 degrees C, but was closer to cubic behavior at 600 and 700 degrees C except Co-5Y at 600 degrees C, which deviated from the cubic and parabolic rate law. The corrosion of both alloys at the three temperatures produced an external scale containing Co oxides (Co3O4, CoO) and Y2O3 and an internal oxidation region where Co17Y2 was converted into Co and Y2O3. The distribution of Y2O3 closely followed that of the intermetallic compound (Co17Y2) in the original alloy. The corrosion mechanism of the alloys is examined. (C) 1999 Elsevier Science Ltd. All rights reserved.
关键词:
Co;Y;oxidation;high-temperature oxidation;possible scaling modes;internal oxidation;oxidant pressures;h-2-h2s mixtures;sulfidation;oxygen
Oxidation of Metals
The oxidation of Fe- Y alloys containing 2 and 5 at.% Y and pure iron has been studied at 600-800 degrees C in air. The oxidation of pure iron follows the parabolic rate law at all temperatures. The oxidation of Fe-Y alloys at 600 degrees C approximately follows the parabolic rate law, but not at 700 and 800 degrees C, where the oxidation goes through several stages with quite different rates. The oxide scales on Fe-2Y and Fe-5 Y at 700 and 800 degrees C are composed of external pure Fe oxides containing Fe2O3, Fe3O4, and FeO, with FeO being the main oxide and an inner mixture of FeO and YFeO3. The scales on Fe-2Y and Fe-5Y at 600 degrees C consist of Fe2O3, Fe3O4, and Y2O3, with a minor amount of FeO. Significant internal oxidation in both Fe-Y alloys occurred at all temperatures. The Y-containing oxides follow the distribution of the original intermetallic compound phase in the alloys. The effects of Y on the oxidation of pure Fe are discussed.
关键词:
pure Fe;Fe-Y alloys;oxidation;high-temperature oxidation;possible scaling modes;2-phase;binary-alloys;low-oxygen pressures;oxidant pressures
李鹏
,
胡耀波
,
熊惟皓
,
林真
硬质合金
doi:10.3969/j.issn.1003-7292.2000.02.001
研究了稀土元素Y对Ti(C,N)基金属陶瓷微观组织和性能的影响.Y在Ti(C,N)基金属陶瓷中可以起到净化粘结相/硬质相界面的作用,并使其包覆层的厚度略有增加,从而使硬质相颗粒得到细化.当Y含量为0.8wt%时细化效果最明显,此时Ti(C,N)基金属陶瓷的抗弯强度和硬度值最大.
关键词:
稀土元素
,
Y
,
金属陶瓷
,
组织与性能
Journal of Applied Physics
The magnetic properties of R2Co14B1-xCx (x=0, 0.5 and R=Y, Sm) compounds have been studied by measuring the temperature dependence of the easy- and hard-magnetization curves on magnetically aligned samples between 1.5 and 300 K for Y2Co14(B,C) and at 4.2 K for Sm2Co14(B,C). The magnetic anisotropy of Y2Co14B increases due to the substitution of C for B, whereas the saturation magnetization decreases. Between 1.5 and 300 K, the anisotropy field of Y2Co14B0.5C0.5 increases about 2 T and the Co moment decreases about 0.05mu(B). The anisotropy field Of Sm2Co14B also increases upon C substitution and the saturation magnetization decreases slightly. The ac susceptibilities of both SM2Co14B and Sm2Co14B0.5C0.5 exhibit anomalies that may arise from a spin reorientation within the basal plane.
关键词:
nd2fe14b;exchange;nd2co14b;r2fe14b;field
