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991.
利用有限元分析的方法,依据拉应力和比应力最小原则对PSZ/Mo功能梯度材料进行了优化设计,确定了FGM的最佳形状分布因子、层数和每一层的厚度。并对最优成分分布FGM在稳态隔热状态下所产生的温度场和热应力进行了计算,得出进行PSZ/Mo功能梯度材料优化设计所需考虑的主要因素。 相似文献
992.
993.
The effect of an NiAl microcrystalline coating prepared by magnetron sputtering on the high-temperature oxidation behavior of NiAl–28Cr–5Mo–1Hf was investigated in static air at 1000–1150°C. The additions of Cr, Mo, and Hf changed the single -phase structure into a multiphase structure [-NiAl, -Cr(Mo), and Heusler phase]. The NiAl–28Cr–5Mo–1Hf alloy formed a nonprotective mixed scale of Al2O3+Cr2O3+HfO2 and exhibited relatively large weight gains. The large weight gains were attributed to extensive internal oxidation. The sputtered NiAl microcrystalline coating remarkably improved the oxidation resistance of NiAl–28Cr–5Mo–1Hf due to the formation of a compact and adherent Al2O3 scale at all test temperatures. It was found that the --Al2O3 transformation caused the anomalous behavior of the oxidation–kinetics curves of the NiAl microcrystalline coating in the temperature range 1000–1150°C. A change in the morphology of scales occurred with the transformation. 相似文献
994.
不同基体炭C/C复合材料的摩擦磨损性能 总被引:7,自引:4,他引:7
以炭纤维针刺毡为预制体,采用化学气相沉积法(CVI)和结合液相浸渍树脂或沥青法制备了热解炭为粗糙层与光滑层结构的准三维C/C复合材料,并研究了这些材料在0.6 MPa的模拟刹车压力下的摩擦磨损性能与磨损机理.研究表明:基体炭为粗糙层热解炭与树脂炭的C/C复合材料摩擦表面能形成较厚且连续的自润滑摩擦膜,摩擦稳定性最好,摩擦因数适中,氧化磨损小,磨损机理主要为膜的部分脱落、氧化磨损与相对较小的磨粒磨损;基体炭为光滑层热解炭与树脂炭或沥青炭的C/C复合材料摩擦表面形成的摩擦膜较薄且不连续,摩擦稳定性差,摩擦磨损较大,磨损机制主要为膜的部分脱落、磨粒磨损与更严重的氧化磨损;随着密度的升高,C/C复合材料摩擦稳定性增加,摩擦因数增加,磨损降低;基体炭为单一沥青炭的C/C复合材料,由于没有热解炭对纤维的保护,纤维断裂多,线性磨损尤其大,磨损机理主要为大量的磨粒磨损与氧化磨损. 相似文献
995.
The influence of externally located platinum on the isothermal stability of -Al2O3 scales formed at high temperatures has been examined. It has been observed that a nickel-base alloy forms an external scale of -Al2O3 during oxidation at 1200°C, but this scale breaks down isothermally, enabling a faster-growing Cr2O3-rich scale to develop. However, in the presence of platinum metal alongside the specimen in the furnace hot zone, the breakdown of the -Al2O3 scale is postponed for a substantial period of time. It appears that platinum, as the volatile species PtO2, is incorporated into the growing -Al2O3 scale where it either influences the stress relief mechanism at temperature or reduces oxidation growth stress generation and thus significantly enhances the isothermal stability of the scale. 相似文献
996.
997.
H. -Y. Nie M. J. Walzak N. S. McIntyre 《Journal of Materials Engineering and Performance》2004,13(4):451-460
Atomic force microscopy (AFM) uses a very sharp pointed mechanical probe to collect real-space morphological information of
solid surfaces. AFM was used in this study to image the surface morphology of a biaxially oriented polypropylene film. The
polymer film is characterized by a nanometer-scale, fiberlike network structure, which reflects the drawing process used during
the fabrication of the film. AFM was used to study polymer-surface treatment to improve wettability by exposing the polymer
to ozone with or without ultraviolet (UV) irradiation. Surface-morphology changes observed by AFM are the result of the surface
oxidation induced by the treatment. Due to the topographic features of the polymer film, the fiberlike structure has been
used to check the performance of the AFM tip. An AFM image is a mixture of the surface morphology and the shape of the AFM
tip. Therefore, it is important to check the performance of a tip to ensure that the AFM image collected reflects the true
surface features of the sample, rather than contamination on the AFM tip. 相似文献
998.
针对齿轮结构复杂、造型困难、使用频繁的特点,研究基于Pro/E平台的渐开线齿轮三维参数化造型技术;运用Pro/TOOLKIT、VC 对Pro/E软件进行二次开发,可根据用户输入的齿轮设计参数,自动生成齿轮的三维实体. 相似文献
999.
1000.
Segmentation of volumetric data is an important part of many analysis pipelines, but frequently requires manual inspection and correction. While plenty of volume editing techniques exist, it remains cumbersome and errorprone for the user to find and select appropriate regions for editing. We propose an approach to improve volume editing by detecting potential segmentation defects while considering the underlying structure of the object of interest. Our method is based on a novel histogram dissimilarity measure between individual regions, derived from structural information extracted from the initial segmentation. Based on this information, our interactive system guides the user towards potential defects, provides integrated tools for their inspection, and automatically generates suggestions for their resolution. We demonstrate that our approach can reduce interaction effort and supports the user in a comprehensive investigation for high‐quality segmentations. 相似文献