电磁屏蔽膜设备的开发及应用

介绍了国内外对电磁屏蔽膜(EMI)研究的现状,比较了制备EMI膜的各种方法,指出采用磁控溅射法制备的EMI膜质量较好,并给出制备EMI膜的工艺流程。     

Magnetron sputtered NbN films with electroplated Cr interlayer

NbN films were deposited on SS substrates by reactive DC magnetron sputtering at various N₂ flow rates and substrate biasing. Coatings were studied for their thickness, structure, hardness and adhesion aspects. Process parameters were optimized for deposition of NbN coatings. NbN coatings were then extended on to MS substrates with Cr interlayer in three different thicknesses of 2, 4 and 10 μm. Cr was deposited by electroplating. The duplex coatings have been studied for the improvement with respect to surface hardness by Knoop micro indentation, adhesion by scratch testing and corrosion performance by potentiodynamic polarization technique. Open circuit potentials were also measured.     

磁控溅射微纳米梯度镀层对45钢及40Cr钢弹性变形性能的影响

利用磁控溅射离子镀技术在屈强比不同的45钢及40Cr钢基体上制备Cr、类石墨碳(Graphite-like-carbon,GLC)及CrTiAlN微纳米梯度镀层,通过考察镀层/金属复合体系弹性模量和屈服强度的变化来研究镀层对基体弹性变形行为的影响。研究结果表明:磁控溅射离子镀层可以改善金属基体的弹性变形性能,但镀层对不同金属基体力学参量的影响不同;屈强比低的45钢,镀层可同时提高弹性模量和屈服强度,在v=0.1mm/min的低速拉伸时,45钢试样的屈服强度可提高20%左右;屈强比高的40Cr钢,镀层对其屈服强度基本无影响,但对弹性模量提高的程度更显著,当拉伸速度为0.7mm/min时,40Cr钢试样的弹性模量可提高60%,而45钢仅为22%;镀层/基体复合体系的弹性模量随拉伸速度的增加表现为先增大后减小的特点,其变化规律不同于金属基体;镀层的高硬度和良好的膜基匹配能力有助于阻碍工件表面及亚表面微塑性形变区的扩展,从而提高试样的力学性能。     

Cr涂层锆合金包壳高温蒸汽氧化动力学及微观机理研究

Cr涂层锆合金包壳具备抗高温蒸汽氧化性能优异、耐腐蚀和耐磨蚀性能良好、工程应用难度较小等特点,成为最具前景的近期型事故容错燃料候选材料之一。本工作以Zr-1Nb合金管为基体材料,采用磁控溅射工艺制备均匀致密Cr涂层,涂层厚度范围12～15μm。通过同步综合热分析仪开展双面高温蒸汽氧化试验,氧化温度为1000、1100和1200℃,氧化时间为300～5000s,系统研究反应堆事故工况下Cr涂层锆合金包壳高温蒸汽氧化行为。采用扫描电子显微镜、能谱仪和X射线衍射仪表征高温氧化产物膜微观形貌特征、氧化层厚度、元素分布以及物相组成等,建立Cr涂层氧化动力学模型,探讨高温氧化机理。研究表明,高温蒸汽环境中,Cr涂层锆合金包壳外壁形成致密Cr2O3层,有效阻止O元素扩散至Zr合金基体,从而提升复合包壳的耐高温性能。其次,Cr涂层高温蒸汽氧化动力学曲线遵循抛物线规律,氧化速率常数比锆合金低大约2个数量级,显著提升锆合金包壳抗高温蒸汽氧化性能。     

Experimental verification of model for prediction of coating composition deposited by sputtering using mosaic target in nitrogen

Sputtering, a physical vapor deposition technique, is widely used for preparation of compound coatings. Binary, ternary or multi component compound coatings deposited by sputtering find a variety of applications. The properties of these coatings depend strongly on the composition of the films. A mathematical model has been developed to predict the composition of the metallic constituents of the coatings deposited by reactive sputtering using two metals mosaic target in the presence of a reactive gas atmosphere. The model has been worked out utilizing first order approximation and taking into consideration that there is no resputtering effect at the substrate. The model developed can also calculate the percentage of covered areas of the target surfaces (target poisoning) with reactive gas flow. The model has been verified experimentally for Ti-Al mosaic target in a nitrogen gas environment utilizing experimental data of sticking coefficient values.     

Morphologic investigation and growth of the alumina scale on magnetron-sputtered CoCrAl NCs with and without yttrium

Nanostructured coatings exhibit superior oxidation resistance due to preferable formation of pure α-Al₂O₃ scale. In this work, the morphology and growth of the scale formed on magnetron-sputtered CoCrAl nanocoatings (NCs) with and without yttrium at 1000, 1100 and 1200 °C have been investigated in detail, by scanning electron microscopy observations of the time-dependent evolution of the scale surface and cross-sectional features. There were several observations: (1) intrinsic oxide ridges appeared on the surface scale on both NCs but their appearance was delayed on CoCrAlY, (2) CoCrAl coating tended to form a scale which was composed of multi-layered equiaxed crystals, especially at 1100 and 1200 °C, while the scale on CoCrAlY appeared double-layered and with inner columnar-like grains, (3) large interface cavities appeared after oxidation of CoCrAl at 1100 and 1200 °C but it was not be observed for oxidation of CoCrAlY. The results strongly suggest that the contribution of outward aluminum diffusion to the growth of the α-Al₂O₃ scale on both NCs is increased with an increase of time and temperature, and that it was reduced in the presence of yttrium. Additionally, compared to the scale on the normal commercial MCrAl (M=Fe, Ni, Co) alloys, the scale formed on the NCs is finer-grained and wrinkle-resistant. Based on the morphological investigation, a growth mechanism of the alumina scale on both NCs was proposed.     

Enhancing piezoelectric response in (002)-Oriented TaxAl(1−x)N films by magnetron-sputtering composition-tunable AlTa alloys

Aluminum nitride (AlN) films suffer from poor piezoelectric response due to the local hexagonal symmetry of wurtzite crystal structure. The fundamental mechanism of improving piezoelectric response in Ta-doped AlN thin films has not been fully understood. Here, we report that composition-tunable AlTa alloys, instead of Al and Ta individual sputtering targets, can be employed to deposit (002)-oriented Ta_xAl_(1−x)N films by magnetron-sputtering, where Ta-doping ratio is tunable by changing Al:Ta composition ratio of the AlTa alloys. Importantly, Ta-doping enhances spontaneous polarization to improve piezoelectricity significantly, as suggested by a threefold increase of the effective piezoelectric coefficients (d_33,eff) upon doping 7 at.% Ta. A better alignment of spontaneous polarization for stronger piezoelectric response originates from the reduction in point defects and crystalline disorder in the reduced-symmetrical wurtzite structure by doping Ta in the Ta_xAl_(1−x)N. This study provides significant insights in improving piezoelectric response in AlN for the development of high-performance film-bulk-acoustic-resonators.