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二维谱分析在工程表面的研究中是有效和实用的,在介绍二维快速傅里叶变换基本概念的基础上,推导出了二维功率谱、角谱和半径谱在三维表面形貌中的应用计算方法,并对一些有代表性的精加工表面试件进行了实验研究。结论表明,二维谱分析技术可以表征表面纹理的方向性和不同波长对表面粗糙度高度均方根的影响。 相似文献
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以聚乙烯吡咯烷酮(PVP)为模板采用静电纺丝法并结合高温煅烧制备出二维CdO纳米棒,用SEM、TGA、DSC、FT-IR及XRD等手段对产物的形貌和结构进行了表征。结果表明,所得纳米棒为纯度较高的CdO,呈互相粘连的二维平面薄膜和多孔结构形貌。这种形貌的生成与聚合物的熔融分解有关。用这种材料修饰玻碳电极并检测了对葡萄糖的电氧化性能,结果表明:与普通CdO粉(末修饰的)玻碳电极相比,修饰过的电极表现出较强的响应性和抗干扰性。其原因是,CdO的二维纳米棒状形貌增大了比表面积,从而使其活性提高。将二维CdO纳米棒用于葡萄糖传感器,具有可行性。 相似文献
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基于计算机模拟的正常晶粒长大的三维特征和二维截面表征 总被引:8,自引:0,他引:8
用适当的三维MonteCarlo技术模拟了较完整的单相材料正常晶粒长大过程,获得了晶粒长大动力学和拓扑学的全面信息,对正常晶粒长大的三维特征和相应的二维截面有征进行对应分析表明:二维截面上测定的时间指数,具有三维系统一致随时间向稳态晶粒长的大理论值(n=0.5)趋近的特征,由二维截面单位面积上的晶粒人与时间的定量关系可以推断三维系统晶粒长大是否达到准确稳态,二维截面上的晶粒尺寸分布不能代表真实的三 相似文献
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根据二维转鼓的生产要求和提出的技术指标,对二维数控精密转台进行了精度计算和分析。介绍了对转台精度起主要影响作用的各项误差,得到二维数控精密转台的指向误差,并对指向误差进行分配,得出二维数控精密转台三类误差指标。 相似文献
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二维过渡金属磷化物(TMPs)有许多新奇的性质和应用.作为二维TMPs的一员,二维MoP有许多独特的物理化学性质.然而由于缺乏制备二维MoP的方法,目前还未成功制备二维MoP,因此限制了对二维MoP众多性质的探索.本文采用化学气相沉积法在液态金属镓(Ga)上制备了厚度为10 nm的二维MoP单晶.液态Ga具有原子级平整的表面,能作为制备二维材料的合适生长基底.在生长过程中, Mo源扩散到Ga表面与磷源反应,从而在Ga表面反应得到二维MoP单晶.此外,由于二维MoP具有本征的非中心对称结构,文中首次研究了二维MoP的二次谐波信号的产生.本文为其他二维TMPs的制备和性质探索提供了新思路. 相似文献
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压力容器接管角裂纹弹塑性断裂的工程分析方法研究 总被引:3,自引:0,他引:3
文中系统地研究了接管角裂纹二维平板模型的J积分全塑性解,新建立了以应力强度因子形状系数β为主导的全塑性解表达式;通过对式中塑性因子ω的特性分析,结合接管角二维模型与准三维模型的数学相似性对比,获得了依赖于二维模型解的准三维模型全塑性解。评定结果表明:使用准三维模型全塑性解可提高容器承压能力10%~20%,从而克服了二维平板模型解预测的保守性。 相似文献
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用热力学唯象埋论研究了二维应力对PbTiO3多晶铁电薄膜相转变的影响。理论分析表明,在二维应力的作用下,薄膜的相转变温度Tc将发生移动,该移动量△T的大小和正负不仅与应力的性质有关,而且与晶粒的取向有关。经推导给出了△T与晶粒取向之间的关系式。对晶粒呈随机取向的多晶薄膜,在二维张应力的作用下,平均Tc将向高温移动,并且相转变温区将展宽。 相似文献
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采用银基活性钎料钎焊碳/碳复合材料 总被引:2,自引:2,他引:0
采用银基活性钎料(Ag-Cu-Ti)对二维层间增强型和三维正交增强型C/C复合材料进行了真空钎焊工艺试验,采用扫描电镜(SEM)观察了钎焊接头和连接界面的微观组织形貌,测定了各元素的面分布,对钎焊接头进行了室温压缩剪切性能试验和三点弯曲强度试验。结果表明:钎料中的元素Ti向钎料和C/C界面区扩散并富集,生成了含元素C的Ti2Cu化合物相,形成了钎料对C/C基体的良好润湿,可获得组织致密的接头,接头室温三点弯曲强度为:39MPa,抗剪强度为22MPa。 相似文献
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Ti(OC4H9)4-MAPS体系溶胶-凝胶转变研究 总被引:1,自引:0,他引:1
研究了Ti(OC4H9)4-MAPS体系中Ti(OC4H9)4、MAPS、C2H5OH、H2O4个原料组分对聚钛硅氧烷产转变规律的影响。结果表明,增大水和Ti(OC4H9)4的用量或降低MAPS和C2H5OH的用量,菜成凝胶;反之,则易形成溶胶。 相似文献
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Nanostructures have attracted increasing interest in modern development of hard coatings for wear‐resistant applications. In plasma‐assisted vapor deposited thin films, nanostructures can evolve during growth or a post‐deposition annealing treatment. In this review we demonstrate, using TiB2.4, TiN–TiB2, Ti0.34Al0.66N, and Ti(N,B) as model‐coatings, the development of nanostructures and its influence on the mechanical properties of ceramic thin films. For TiB2.4 and TiN–TiB2 a two‐dimensional and three‐dimensional nanostructure, respectively, organizes itself during growth by segregation driven processes. Growth of Ti0.34Al0.66N and Ti(N,B) results in the formation of a supersaturated TiN based phase, which tends to decompose into its stable constituents during post‐deposition annealing via the formation of nm‐sized domains. As the hardness of a material is determined by resistance to bond distortion and dislocation formation and motion, which depend on the amount and constitution of obstacles provided, there is a direct relation between hardness and nanostructure. 相似文献
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Half‐Metallic Behavior in 2D Transition Metal Dichalcogenides Nanosheets by Dual‐Native‐Defects Engineering 下载免费PDF全文
Yun Tong Yuqiao Guo Kejun Mu Huan Shan Jun Dai Yi Liu Zhe Sun Aidi Zhao Xiao Cheng Zeng Changzheng Wu Yi Xie 《Advanced materials (Deerfield Beach, Fla.)》2017,29(40)
Two‐dimensional transition metal dichalcogenides (TMDs) have been regarded as one of the best nonartificial low‐dimensional building blocks for developing spintronic nanodevices. However, the lack of spin polarization in the vicinity of the Fermi surface and local magnetic moment in pristine TMDs has greatly hampered the exploitation of magnetotransport properties. Herein, a half‐metallic structure of TMDs is successfully developed by a simple chemical defect‐engineering strategy. Dual native defects decorate titanium diselenides with the coexistence of metal‐Ti‐atom incorporation and Se‐anion defects, resulting in a high‐spin‐polarized current and local magnetic moment of 2D Ti‐based TMDs toward half‐metallic room‐temperature ferromagnetism character. Arising from spin‐polarization transport, the as‐obtained T‐TiSe1.8 nanosheets exhibit a large negative magnetoresistance phenomenon with a value of ?40% (5T, 10 K), representing one of the highest negative magnetoresistance effects among TMDs. It is anticipated that this dual regulation strategy will be a powerful tool for optimizing the intrinsic physical properties of TMD systems. 相似文献
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By first‐principles calculations we investigate the structural, electronic, and magnetic properties of the (LaMnO3)2/(SrTiO3)2 superlattice. We find that a monoclinic C2h symmetry is energetically favorable and that the spins order ferromagnetically. Under both compressive and tensile uniaxial strain the electronic structure of the superlattice shows a half‐metallic character. In particular, a fully spin‐polarized two‐dimensional electron gas, which traces back to the Ti 3dxy orbitals, is achieved under compressive uniaxial strain. 相似文献
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鲁燕萍 《真空科学与技术学报》2002,22(4):293-295
在AlN陶瓷的Ti Ag Cu活性封接工艺中 ,研究Ti的引入方式对其与金属封接抗拉强度的影响。其中Ti以四种不同方式引入 :涂Ti粉、夹Ti箔、直接使用Ti Ag Cu合金焊料以及溅射Ti膜 相似文献
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Effect of pore size on the tensile behavior of open-cell Ti foams: Experimental results 总被引:1,自引:0,他引:1
Mohamed Shehata Aly 《Materials Letters》2010,64(8):935-2075
Open-cell Ti foams having an average pore size of 50 and 150 µm, respectively have been subjected to room temperature tensile tests to explore their tensile properties. Since extensometry is difficult in foams due to problems such as localized surface deformation and attachment of clip gauges, the foams' mechanical properties have been measured in this work accurately by the help of a camera which records the resulting dimensional changes during the loading. The camera acts as a non-contact extensometer and thus it helps in avoiding any small amounts of pre-deformation that might be caused by the attachment of conventional extensometer to the sample's surface prior to testing. Ti foam samples of smaller pores were found to experience higher strength and elongation than those with larger ones. The cell walls in both foam samples failed suddenly in the 45° maximum shear plane direction. 相似文献
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未来的航空航天运载火箭需要使用绿色的燃料,使运动件有好的摩擦学性能,当前对其研究的公开报道较少.利用环-块式摩擦磨损试验机对1Cr18Ni9Ti不锈钢与ZrO2陶瓷摩擦副在质量分数25%,50%和75%的H2O2介质中,于3种滑动速度和3种载荷条件下的摩擦磨损行为进行了研究.通过三维白光共焦显微镜分析了试样磨损表面的形貌和粗糙度.结果表明:在H2O2质中,1Cr18Ni9Ti/ZrO2摩擦的总的趋势是H2O2浓度越高、载荷越大,摩擦系数越小;1Cr18Ni9Ti的磨损随着H2O2浓度的提高、载荷的增大而增大;在高浓度H2O2中1Cr18Ni9Ti与ZrO2摩擦副之间的主要磨损机制是较严重的犁沟型磨损和黏着磨损. 相似文献