排序方式: 共有39条查询结果,搜索用时 15 毫秒
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Ni80Cr20超细丝经冷加工后呈规则的三维螺旋卷曲状态。实验研究了拉拔角度、变形量、拉拔速度和模具定径区长度对超细丝材曲率的影响,制定了NiCr合金丝单模冷拉拔工艺。结果表明:随拉拔角度的增加,丝材曲率逐渐增加;变形量增加,拉拔角度为17时,丝材曲率没有明显规律,基本在0.56 mm-1左右,但拉拔角度为0时,丝材曲率逐渐增加;拉拔速度小于10 mmin-1时,曲率逐渐增加,大于10 mmin-1时,曲率增加趋势变缓,大于30 mmin-1曲率又有所下降;定径区长度越长丝材曲率越小。分析认为,NiCr丝材表面产生的附加切变形及切变层的流动速度的不一致性是丝材产生卷曲的原因,且曲率越大残余应力越大。为减小不均匀变形,冷拉拔工艺采用0拉拔、拉拔速度10 mmin-1、模具定径区长度为模具定径区直径的60%。 相似文献
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采用脉冲激光沉积方法在不同衬底温度下制备了最高硬度与弹性模量分别达45 GPa和290 GPa,且表面十分光滑的类金刚石薄膜。在相对湿度为80%的条件下,薄膜最低的摩擦系数与磨损率分别为0.045与5.74×10-10 mm3·N-1·m-1。实验结果表明,硬度与弹性模量随衬底温度升高而降低,摩擦系数与磨损率随衬底温度升高而增大。拉曼光谱表明:在室温下制备的薄膜为典型类金刚石结构,sp3含量高达76.8%,而随温度升高,薄膜结构逐渐经无定形碳结构向纳米晶石墨结构方向发展,sp3含量也随之降低,力学性能变差。 相似文献
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The Cu2O and Au-doped Cu2O films are prepared on MgO(001) substrates by pulsed laser deposition. The X-ray photoelectron spectroscopy proves that the films are of Au-doped Cu2O. The optical absorption edge decreases by 1.6%after Au doping. The electronic and optical properties of pure and Au-doped cuprite Cu2O films are investigated by the first principles. The calculated results indicate that Cu2O is a direct band-gap semiconductor. The scissors operation of 1.64 eV has been carried out. After correcting, the band gaps for pure and Au doped Cu2O are about 2.17 eV and2.02 eV, respectively, decreasing by 6.9%. All of the optical spectra are closely related to the dielectric function. The optical spectrum red shift corresponding to the decreasing of the band gap, and the additional absorption, are observed in the visible region for Au doped Cu2O film. The experimental results are generally in agreement with the calculated results.These results indicate that Au doping could become one of the more important factors influencing the photovoltaic activity of Cu2O film. 相似文献
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以H2、反式-2-丁烯(T2B)和二茂铁混合气体为工作气体,用金属有机等离子体增强化学气相沉积法(PECVD)制备了Fe掺杂氢化非晶碳(a-C:H:Fe)薄膜。使用X射线光电子能谱(XPS)对a-C:H:Fe薄膜成分进行了分析。使用台阶仪、场发射扫描电镜(FESEM)、热重分析和紫外可见分光光度计(UV-VIS),对比分析了a-C:H薄膜和a-C:H:Fe薄膜的沉积速率、表面形貌、热稳定性和光学带隙变化。研究表明:相同制备条件下,相比a-C:H薄膜,a-C:H:Fe薄膜的沉积速率高,表面颗粒小,容易碳化,光学带隙变窄。 相似文献
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以H2、反式-2-丁烯(T2B)和二茂铁混合气体为工作气体,用金属有机等离子体增强化学气相沉积法(PECVD)制备了Fe掺杂氢化非晶碳(a-C:H:Fe)薄膜。使用X射线光电子能谱(XPS)对a-C:H:Fe薄膜成分进行了分析。使用台阶仪、场发射扫描电镜(FESEM)、热重分析和紫外可见分光光度计(UV-VIS),对比分析了a-C:H薄膜和a-C:H:Fe薄膜的沉积速率、表面形貌、热稳定性和光学带隙变化。研究表明:相同制备条件下,相比a-C:H薄膜,a-C:H:Fe薄膜的沉积速率高,表面颗粒小,容易碳化,光学带隙变窄。 相似文献
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用共沉淀法制备了钇铝石榴石(Y3Al5O12)纳米粉体,研究了正滴定、反滴定和一步注入工艺对钇铝石榴石纳米粉体合成过程及最终产物的影响。利用X射线衍射仪、傅立叶红外光谱仪、同步热分析仪、场发射电子显微镜对YAG前驱体及不同温度煅烧后的粉体进行表征。结果表明:通过正滴定、反滴定和一步注入工艺,分别制备出化学组成为10[8.9Al(OH)3+1·1NH4Al·(OH)2CO3]·3[Y2(CO3)3·3H2O]、10[7.3Al(OH)3+2.7NH4Al·(OH)2CO3]·3[Y2(CO3)3.3H2O]、10[Al(OH)3]·3[Y2(CO3)3·3H2O]的前驱体。前驱体经900℃煅烧2 h后,正、反滴定工艺得到的粉体主相为YAG(Y3Al5O12),但有少量的YAP(YAlO3),一步注入工艺则得到纯的YAG相。晶粒尺寸分别为85 nm、70 nm和65 nm,且一步注入工艺获得的粉体粒径分布较窄,分散性良好。 相似文献
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Zhangyang Zhou 《中国物理 B》2021,30(12):126803-126803
Manipulating metal-insulator transitions in strongly correlated materials is of great importance in condensed matter physics, with implications for both fundamental science and technology. Vanadium dioxide (VO2), as an ideal model system, is metallic at high temperatures and shown a typical metal-insulator structural phase transition at 341 K from rutile structure to monoclinic structure. This behavior has been absorbed tons of attention for years. However, how to control this phase transition is still challenging and little studied. Here we demonstrated that to control the Ag nanonet arrays (NAs) in monoclinic VO2(M) could be effective to adjust this metal-insulator transition. With the increase of Ag NAs volume fraction by reducing the template spheres size, the transition temperature (Tc) decreased from 68° to 51°. The mechanism of Tc decrease was revealed as:the carrier density increases through the increase of Ag NAs volume fraction, and more free electrons injected into the VO2 films induced greater absorption energy at the internal nanometal-semiconductor junction. These results supply a new strategy to control the metal-insulator transitions in VO2, which must be instructive for the other strongly correlated materials and important for applications. 相似文献