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941.
Ivasashin O. M. Markovskii P. E. Dneprenko V. N. Boguslaev V. A. Nalimov Yu. S. Gerasimchuk O. N. 《Strength of Materials》1992,24(6):391-397
The influence of the structure and crystallographic texture of VT3-1 alloy formed by thermomechanical processing of a forging and also of the production factors of subsequent production of a gas turbine engine blade from the forging on the fatigue resistance characteristics was investigated. It was established that the reason for the reduction in fatigue limit and the significant spread in test data is nonuniformity of the structure and texture, both in different forgings and within the same forging, caused by variations in such parameters of thermomechanical processing as the temperature and degree of deformation. The nonuniformity plays a determining role in the reduction in fatigue limit as the result of hydrogen absorption during chemical etching. It was shown that such an effect may be eliminated by degassing vacuum annealing and the general level of fatigue resistance characteristics may be increased as the result of thermomechanical processing of forgings with strict observance of the specified forging temperature.Translated from Problemy Prochnosti, No. 6, pp. 12–19, June, 1992. 相似文献
942.
L. A. Borzenkov A. T. Kalashnikov O. I. Kiselev A. N. Ryapolov M. B. Semun'kin Yu. L. Uvarovskii 《Journal of Mining Science》1992,27(5):434-438
Research Institute of Kursk Magnetic Anomaly and Polytechnical Institute, Lebedin Mining and Concentration Plant, Gubkin. Mining Institute, Moscow. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 67-71, September-October, 1991. 相似文献
943.
944.
羊皮服装革的压缩性能及其与丰满性的关系的研究 总被引:6,自引:0,他引:6
本文研究了羊皮服装革的压缩性能。对压缩系数(Kc)与羊皮服装革手感丰满性的关系进行了讨论。结果表明:压缩系数Kc反映出革的手感丰满程度。 相似文献
945.
Forcibly reeled silkworm (Bombyx mori) silk was used to study how exposure to a degumming treatment (boiling in distilled water for 30 min) affects tensile properties. Because forcibly reeled and naturally spun fibers exhibit comparable mechanical behavior, the results can be generalized to material obtained conventionally from cocoons. The effects of degumming include: a decrease in the initial elastic modulus, a decrease in the stress at the proportional limit (yield strength), a change in the qualitative shape of force‐displacement curves, and significant qualitative and quantitative variability in force‐displacement data from samples subjected to nominally identical degumming histories. Immersion in water at room temperature or heating in air at 100°C for 30 min are both qualitatively equivalent to a 30‐min degumming treatment in boiling water, in terms of the effect on silk tensile properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1431–1437, 2002; DOI 10.1002/app.10366 相似文献
946.
By using the technology of the sequential interpenetrating polymer network, a series of novel damping materials based on a polydimethylsiloxane (PDMS)/polyacrylate (PAC) matrix with polymethacrylate (PMAC) were synthesized. They have a controllable broad transition peak spanning the temperature range of 150–220°C and the medial value of loss factor with maximum of 0.35–0.60. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and atomic force microscopy (AFM) were applied to analyze and characterize the transition behavior and the microphase structure of the materials. It was found that the size and height of a transition peak at both the low‐ and the high‐temperature zones change as a function not only of the concentration of PMAC and PDMS but also of the kind of PMAC; simultaneously, the low‐ temperature behavior was also governed by the crystallization of PDMS. The content of the crosslinking agent exerts a significant influence on the configuration of the curves of the transition peaks. AFM shows a characteristic phase morphology of double‐phase continuity containing a transition layer and domain less than 1 μm, indicating that the interwoven multilayer networks are the key to incorporation of the immiscible components and form a broad damping functional region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 545–551, 2002 相似文献
947.
N‐(4‐Acetoxyphenyl) maleimide (APMI) and three kinds of comonomers bearing a trimethylsilyl group were copolymerized at 60°C in the presence of azobisisobutyronitrile (AIBN) as an initiator in 1,4‐dioxane to obtain the three IP, IIP, and IIIP copolymers. These copolymers were removed from the acetoxy group in a transesterification process into new IVP, VP, and VIP copolymers with a pendant hydroxyl group. Two modified processes were adopted to prepare photoresists using these copolymers. The first process involved mixing the dissolution inhibitor, o‐nitrobenzyl cholate, with the new copolymers. Second, o‐nitrobenzyl cholate was introduced into the copolymers using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in dimethylformamide (DMF). The cyclic maleimide structure is responsible for the high thermal stability of these copolymers. After irradiation using deep–UV light and development with aqueous Na2CO3 (0.01 wt %), the developed patterns showed positive images and exhibited good adhesion to the silicon wafer without using any adhesion promoter. The resolution of these resists was at least 0.8 μm and an oxygen‐plasma etching rate was 1/5.3 to that of hard‐baked HPR‐204. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2791–2798, 2002; DOI 10.1002/app.10255 相似文献
948.
949.
介绍了火工品检验过程中常见的几个质量问题,如零部件报废、工艺控制、外观质量、绝缘电阻等,对常见问题的原因进行了分析,并提出了质量控制的措施。 相似文献
950.