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41.
42.
摩托车传动用滚子链磨损特性的研究 总被引:5,自引:1,他引:5
道路行驶磨损试验结果表明,摩托车传动用滚子链套筒和销轴零件的主要磨损形式是磨粒磨损,并伴随有疲劳磨损的特征.由微观分析和链条的磨损伸长量可知:套筒和销轴的初始表面硬度较高,有利于改善其磨损表面形貌状态和耐磨性;在磨粒磨损机制下,套筒和销轴零件的表面硬度较低,容易产生“犁切”,表面层的循环硬化现象比较明显,磨损严重;在油池润滑条件下,套筒和销轴零件的表面硬度较高,裂纹的扩展速率较快,循环软化现象也较明显,当表面硬度较低时发生循环硬化.循环软化与循环硬化是导致磨损严重的原因之一. 相似文献
43.
The primary interest of this study concerns the use of an inexpensive photographic digital camera as the detection system, using its own flash as the source of light to present a new analytical procedure to measure disposable multianalyte optical sensors for potassium, magnesium, hardness and conventional pH test strips. The camera arrangement was designed in a fixed position over an optical board with controllable ambient conditions. After acquiring the digital image, the analytical information contained in each test zone is analyzed using theRGB colour space. Reflectance measurements were developed to study the colourimetric and spectral characteristics of the test zones. We obtained the following application ranges and precision in terms of relative standard deviation (RSD %): for potassium from 3.2 × 10−7 to 0.1 M with a precision between 3.3 and 4.0%, for magnesium from 2.7 × 10−6 to 1.5 M showing a precision between 4.7 and 7.8% and finally for hardness from 4.3 × 10−2 to 200,000 mg L−1 CaCO3 and between 5.1 and 7.0%. Moreover, the analytical characteristics of several optical procedures were compared with the results presented here. The proposed method was statistically validated against a reference procedure using samples of water from different sources and beverages, indicating that there are no significant statistical differences at a 95% confidence level. 相似文献
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根据小皮Pin a,Pin b,GSP基㈥的保守序列,设计合成了3对特异性引物,对四倍体钩刺山羊草Aegilopstriumialis的基因组DNA和胚乳RNA进行Pin a,Pin b,CSP基因扩增、克降、序列测定和表达分析,发现了两个新型Pin a等位堆因、一个新刑Pin b等化基因和一个新型GSP等位基因,基因序列均与六倍体小麦的同源基因存在较大的差异,Southern Blot分析结果表明,该材料巾含有2个拷贝Pin a。基因,5个拷贝Pin b基因,2个拷贝GSP基因.RT-PCR和Western Blot都证实了Pin a,Pin b,GSP基因在籽粒胚乳中的表达.研究结果显示由羊草可以为小麦分子育种提供有用的遗传资源。 相似文献
47.
Calcite single crystals on neutron bombardment change their colour to pale red, red and deep red, as the duration of irradiation
increases. The irradiated surface becomes rugged and on etching, a large number of micropits are observed. Using Vicker’s
hardness indenter, it is observed that the hardress of the irradiated crystal increases with the increase in the total dosage.
From Laue x-ray diffraction studies of irradiated crystals, distortion of lattice is observed. Absorption spectra in the visible
region show an extra peak for irradiated samples which is absent for radiated ones. The radiation effects are annealed to
a considerable extent on heat treatment. The implications are discussed. 相似文献
48.
The hardness of NaCl and KCl crystals has been estimated from the lengths of dislocation rosette formed around indentation
at various temperatures up to 400°C. The hardness decreases with increasing temperature. This is due to the softening of the
crystals at elevated temperatures which results in the easy movement of dislocations. The results are discussed using a few
available relations which connect hardness to temperature. Arms of indentation dislocation rosette are well defined up to
300°C but around 400°C the rosette pattern is spread over a circular region. A possible mechanism is discussed. 相似文献
49.
Temporal evolution of local and global hardness during an ion-atom collision process has been studied within a quantum fluid
density functional framework. A dynamical variant of the maximum hardness principle has been found to be operative. Entropy
maximises in the encounter regime. Time dependence of density and its laplacian provides important insights into the collision
processvis-a-vis the hardness maximisation. 相似文献
50.
采用机械合金化法制备了W-Cu合金粉末。将制备出的W-Cu合金粉末置于爆炸压制成型的装置中进行爆炸压实,得到了最高致密度达98%的W-Cu合金。利用X射线衍射(XRD)分析了W-Cu混合粉末的合金化过程,研究了W-Cu合金粉末的还原温度对压实坯致密度的影响。通过电子探针微量分析仪(EPMA)观察了样品内部的成分与元素分布,利用扫描电子显微镜(SEM)对样品断口形貌进行了观察,并对样品的维氏硬度和电导率进行了测量。结果表明,W-Cu合金化粉末在爆炸冲击波作用下能够结合成高致密体,复合材料具有高硬度、组织均匀、晶粒细小的特点。 相似文献