Application of optical transmission interferometry for in-situ structural investigations of titanium dioxide sputter-deposited coatings

Titanium dioxide coatings (from 0.1 to 1.5 μm thick) have been dc sputter-deposited on glass slides from titanium targets in various Ar-O₂ reactive gas mixtures. Deposition rate and optical properties were controlled in-situ by optical transmission interferometry (OTI) with an optical fibre located behind the glass substrate in order to perform a real-time control of transmittance of the growing film. Thus, it is possible to determine in-situ the optical indices (n, k) and the thickness of the as-deposited film by using a simple simulation, developed on Matlab software. The optical properties of the films were investigated in relation to their structure, which depends on the sputtering conditions adopted. In particular, the effects of the sputtering pressure (working pressure and oxygen partial pressure), the discharge power and the substrate location into the reactor are investigated in detail. Films structure is assessed by standard grazing incidence X-ray diffraction (XRD).     

K17F高温合金溅射微晶层的抗高温氧化行为

研究了铸态高温合金Ｋｌ７Ｆ及其溅射微晶（小于０．ｌμｍ）层的高温氧化行为．结果表明，微晶层为均匀的γ相组织，它大幅度提高铸态合金的９００至１０００℃的抗氧化性能，甚至比渗Ａｌ涂层还好在高温下，Ｋ１７Ｆ生成以Ａｌ２Ｏ３为主，含有Ｎｉ，Ｃｒ，Ｔｉ氧化物的氧化膜，它在氧化过程中易剥落，而溅射微晶层表面只生成单一的α－Ａｌ２Ｏ３膜，具有优异的防护性和粘附性，在５００ｈ的氧化过程中未见剥落．     

Preparation and characterization of GaN films grown on Ga-diffused Si （111） substrates

Hexagonal GaN films were prepared by nitriding Ga2O3 films with flowing ammonia. Ga2O3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.) magnetron sputtering. This paper have investigated the change of structural properties of GaN films nitrided in NH3 atmosphere at the temperatures of 850, 900, and 950℃ for 15 min and nitrided at the temperature of 900℃ for 10, 15, and 20 rain, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the structure, surface morphology and composition of synthesized samples. The results reveal that the as-grown films are polycrystalline GaN with hexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained when nitrided at 900℃ for 15 min.     

反应溅射制备AlN薄膜中沉积速率的研究

通过对浅射过程中辉光放电现象及薄膜沉积速率的研究，发现随着氮浓度的增大，靶面上形成一层不稳定的AlN层，由于AlN的溅射速率远小于Al，从而使薄膜的沉积速率显著下降。同时还研究了其它溅射参数对薄膜沉积速率的影响。结果表明：随靶基距的增大靶功率的减小，不同程度引起沉积速率的下降；随着溅射气压的增大，最初沉积速率不断增大，当溅射气压增大到一定程度时，沉积速率达到最大值，之后随溅射气 压的增大，又不断减小。     

Ti/TiB2多层镀层的组织和性能研究

为了进一步提高超硬TiB2镀层与基体的结合力,采用磁空溅射法在高速钢表面上制备了多层相间的Ti/TiB2超硬镀层.利用多种实验方法测试和研究了镀层的组织结构,形貌,表面粗糙度,硬度和与基体的结合力.结果表明,镀层的Ti/TiB2相间层数对这些性能有很大的影响.当层数从二逐渐增加到十二,TiB2镀层的（001）织构逐渐消失而变成无择优取向,镀层表面粗糙度增加,但镀层硬度基本不变.只有当层数为十二时,镀层硬度才明显降低.结果也表明,多层镀层可有效地提高镀层与基体的结合力,并存在着一最佳的多层结合.本文也对多层结构对其它组织和性能特征的影响进行了分析.     

Characteristics of ZnO thin film deposited on various metal bottom electrodes

ZnO films for electronic applications were deposited by radio-frequency (rf) sputtering onto various metal bottom electrodes (Pt/Ti, W, Ni) to investigate such structural properties as crystallinity and surface morphology. The crystallinity, surface morphology and composition of the as-deposited films were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Rutherford back-scattering spectrometry (RBS), respectively. The preferred orientation and surface morphologies were strongly influenced by the type of bottom electrodes. The ZnO films with (200) texturing deposited on Pt/Ti/SiO₂/Si showed a smoother and smaller grain size than those deposited on W and Ni. The ZnO films on Pt and W electrodes exhibited compressive residual stress. This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials”, organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei University, Seoul, Korea on October 25–26, 2002.     

多层膜界面粗糙度的低角X射线衍射研究

对磁控溅射方法制备的Ｗ／Ｓｉ周期多层膜在Ｘ射线衍时仪上进行了低角Ｘ射线衍射实验，并用动力学理论分析了膜层的周期结构和界面粗糙度，在对实验谱线的拟合过程中，考虑了界面的不对称性、周期的随机涨落及系统偏差等因素对衍射强度的影响，并讨论了各个参量对衍射强度影响的程度．     

近等原子比TiNi合金薄膜的组织及相变动态观察

采用磁控溅射法制备TiNi非晶薄膜。通过X射线衍射（XRD）、透射电子显微镜（TEn）等方法研究了TiNi合．金薄膜的组织形貌、电子衍射花样，并对其相变过程进行了动态观察。结果表明：态薄膜为非晶态，对其在515℃进行1h的晶化处理后，薄膜中析出了TiNi3相；晶化处理后的TiNi合金薄膜加热到100℃时，薄膜中R相和马氏体相以切变方式完全转变为奥氏体；当冷却至室温时，是以R相、马氏体相以及少量的奥氏体相存在。其加热过程中的相劐顶序为：马氏体相→R相→奥氏体相。冷却过程中的相变顺序为：奥氏体相→R相→马氏体相。     

Deformation and failure mechanism of nano-composite coatings under nano-indentation

Two nano-composite coatings based on nc-TiC particles in an a-C:H matrix are deposited via closed-field unbalanced reactive magnetron sputtering. The compositions of the coatings are varied by changing the acetylene gas flow during the depositions. A Cr/Cr–Ti/Ti–TiC graded interlayer is introduced between substrate and coating. Electron probe micro-analyses (EPMA) show that the Ti content of the coatings varies between 31.7 and 11.5 at.%. The coatings exhibit a hardness (H) of 20.0 and 15.7 GPa, and a Young's modulus (E) of 229.4 and 136.6 GPa, respectively, as measured through nano-indentations. Cube corner indentations are performed to probe the fracture toughness of the coatings through the determination of critical indentation loads (L_r) at which radial cracks start to propagate. Transmission electron microscopy (TEM) observations and energy-filtered TEM are employed to characterize the coatings nanostructures. The variation in Ti content is accompanied by a variation in TiC particle size and volumetric fraction, as well as a change in the columnar structure of the coatings. A focus ion beam (FIB) slicing technique is employed to prepare samples from nano-indented locations of coated Silicon and stainless steel (SS) substrates. TEM inspection of the FIB sliced samples determines that the most brittle phase in the coating is the C-enriched columnar boundary, and identifies the location of failure within the interlayer. As a consequence of the different nanostructure, the coatings exhibit different elastic recovery properties and toughness.     

A comparative study of reactive direct current magnetron sputtered CrAlN and CrN coatings

Approximately 1.5 μm thick CrN and CrAlN coatings were deposited on silicon and mild steel substrates by reactive direct current (DC) magnetron sputtering. The structural and mechanical properties of the coatings were characterized using X-ray diffraction (XRD) and nanoindentation techniques, respectively. The bonding structure of the coatings was characterized by X-ray photoelectron spectroscopy (XPS). The surface morphology of the coatings was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The XRD data showed that the CrN and CrAlN coatings exhibited B1 NaCl structure. Nanoindentation measurements showed that as-deposited CrN and CrAlN coatings exhibited a hardness of 18 and 33 GPa, respectively. Results of the surface analysis of the as-deposited coatings using SEM and AFM showed a more compact and dense microstructure for CrAlN coatings. The thermal stability of the coatings was studied by heating the coatings in air from 400 to 900 °C. The structural changes as a result of heating were studied using micro-Raman spectroscopy. The Raman data revealed that CrN coatings got oxidized at 600 °C, whereas in the case of CrAlN coatings, no detectable oxides were formed even at 800 °C. After annealing up to 700 °C, the CrN coatings displayed a hardness of only about 7.5 GPa as compared to CrAlN coatings, which exhibited hardness as high as 22.5 GPa. The potentiodynamic polarization measurements in 3.5% NaCl solution indicated that the CrAlN coatings exhibited superior corrosion resistance as compared to CrN coatings.