Structure and properties of Ti-B-N,Ti-Cr-B-(N), and Cr-B-(N) coatings deposited by magnetron sputtering of targets prepared by self-propagating high-temperature synthesis

Transmission and scanning electron microscopy, x-ray phase analysis, x-ray photoelectron spectroscopy, and atomic-force microscopy were used to study the structure and surface topography of Ti-B-N, Ti-Cr-B-(N), and Cr-B-(N) thin films. Physical, mechanical, and tribological characteristics of coatings were comparatively analyzed, including determination of the hardness, elastic modulus, elastic recovery, critical load, friction coefficient, and wear rate. It was shown that Ti-B-N and Ti-Cr-B-N coatings are superior to conventional TiN-and Ti-C-N-based coatings in terms of their physicomechanical and tribological properties. Ti-B-N and Ti-Cr-B-N coatings deposited under optimum conditions were characterized, accordingly, by a hardness of 31–34 and 40–47 GPa, an average elastic modulus of 378 and 506 GPa, a friction coefficient of 0.49–0.60 and 0.45–0.52, a dry-wear rate of (3.4–4.6) × 10^?7 and (6.0–6.8) × 10^?7 mm³ N^?1 m^?1, and a largest critical load of 50 and 22 N. Features in the determination of the physicomechanical properties of films during nanoindentation and their wear properties are discussed.     

Specific features of the determination of the mechanical characteristics of thin films by the nanoindentation technique

The hardness and the elastic modulus of Cu thin films on Si, Ti, Cu, and Al substrates are investigated. It is demonstrated that the use of the Oliver-Pharr method in combination with the technique for evaluating the true hardness makes it possible to determine uniquely the hardness of Cu thin films at different ratios between the hardnesses of the film and the substrate. The elastic modulus of thin films can be correctly measured by the Oliver-Pharr method only in the case where the film and the substrate exhibit identical elastic properties. In order to determine the elastic moduli of films with the use of the parameter P/S ², the film and the substrate should have close values of both the hardness and the elastic modulus.     

Correlation between structural and mechanical properties of PbTiO3 thin films grown by pulsed-laser deposition

Tetragonal lead titanate (PbTiO₃, PT) thin films are grown on (1 0 0) MgO substrate by pulsed-laser deposition (PLD) for expected applications in integrated optics. The realisation of outstanding and reliable devices into integrated circuits requires sufficient mechanical resistance despite that the obtained PT films display interesting waveguiding properties associated with low optical losses. Two mechanical properties characteristic of elasticity and hardness of PT films are studied. The elastic modulus (E or Young's modulus) and the hardness (H) are measured by the nanoindentation technique. These mechanical properties are correlated to the crystalline quality of PT/MgO thin films. The films show epitaxial relationship with the MgO substrate and the orientation of crystallites perpendicularly to the surface substrate may be the consequence of a growth process along c-axis, a-axis or both. Differences on curves plotting hardness and elastic modulus as a function of indentation depth are observed as the curves are less dispersed for the films mainly c-axis oriented.     

Analysis of the substrate effects of strain-hardening thin films on silicon under nanoindentation

Mechanical properties of thin films on substrates can be evaluated directly through nanoindentation. For a comprehensive study, thin films should be characterized via Young’s modulus, yield stress and strain-hardening exponent at constant temperature. In this paper, we evaluate these effects of thin films on silicon substrate through finite element analysis. Thin films, from soft to hard relative to the silicon substrate, are investigated in three categories: soft films on hard substrates, soft to hard films on no elastic mismatch substrates, and hard films on soft substrates. In addition to examining the load-displacement curve, the normalized hardness versus normalized indentation depth is checked as well to characterize its substrate effect. We found that the intrinsic film hardness can be acquired with indentation depths of less than 12% and 20% of their film thickness for soft films on hard substrates and for soft to hard films on no elastic mismatch substrates, respectively. Nevertheless, nanoindentation of hard films on soft substrates cannot determine the intrinsic film hardness due to the fact that a soft substrate cannot support a hard film. By examining the von Mises stresses, we discovered a significant bending phenomenon in the hard film on the soft substrate. PACS 61.43.Bn; 62.20.-x; 68.03.Hj; 68.05.Cf; 68.08.De     

The microstructure, mechanical and friction properties of protective diamond like carbon films on magnesium alloy

Protective hard coatings deposited on magnesium alloys are believed to be effective for overcoming their poor wear properties. In this work, diamond-like carbon (DLC) films as hard protective films were deposited on AZ91 magnesium alloy by arc ion plating under negative pulse bias voltages ranging from 0 to −200 V. The microstructure, composition and mechanical properties of the DLC films were analyzed by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and nanoindentation. The tribological behavior of uncoated and coated AZ91 magnesium alloy was investigated using a ball-on-disk tribotester. The results show that the negative pulse bias voltage used for film deposition has a significant effect on the sp³ carbon content and mechanical properties of the deposited DLC films. A maximum sp³ content of 33.3% was obtained at −100 V, resulting in a high hardness of 28.6 GPa and elastic modulus of 300.0 GPa. The DLC films showed very good adhesion to the AZ91 magnesium alloy with no observable cracks and delamination even during friction testing. Compared with the uncoated AZ91 magnesium alloy, the magnesium alloy coated with DLC films exhibits a low friction coefficient and a narrow, shallow wear track. The wear resistance and surface hardness of AZ91 magnesium alloy can be significantly improved by coating a layer of DLC protective film due to its high hardness and low friction coefficient.     

脉冲偏压电弧离子镀CNx薄膜研究

用脉冲偏压电弧离子镀通过控制不同的氮流量在(100)单晶Si基片上制备了不同成分的CN_x薄膜.用光学显微镜,XPS,XRD,激光Raman和Nanoindenter等方法研究了薄膜的形貌、成分、结构和性能.结果表明,薄膜表面平整致密、氮含量随着氮流量的降低而降低、结构为非晶且为类金刚石薄膜;随着氮含量从18.9%降低到5.3%(摩尔百分比,全文同),薄膜的硬度和弹性模量单调增加而且增幅较大,其中硬度从15.0 GPa成倍增加到30.0 GPa;通过氮流量的调整能够敏感地改变薄膜中的sp³键的含量,是CN_x薄膜的硬度和弹性模量获得大幅度调整的本质原因. 关键词： x薄膜')" href="#">CN_x薄膜 脉冲偏压 电弧离子镀 硬度     

Effect of air post contamination on mechanical properties of amorphous carbon nitride thin films

We report in this study the mechanical, structural and compositional characteristics of amorphous carbon nitride films (a-CN_x) deposited on Si(100) using RF magnetron sputtering of graphite targets in pure nitrogen and under different RF powers. The properties of the films were determined in their as deposited state using nuclear reaction analysis (NRA), elastic recoil detection (ERDA), infrared (IR) absorption and Raman spectroscopy. The mechanical properties were obtained combining nanoindentation and residual stress measurements. The presence of various types of C-N bonds, as well as the post-deposition contamination of the deposited films by oxygen and water (voids) is revealed. The measured hardness and Young modulus were 0.9-2.03 and 23-27 GPa, respectively. These results have been analysed in term of the matrix flexibility which results from the nitrogen content and the porous character of the films, which can affect deeply the estimation of the physical-mechanical properties of the films.     

Hydrogenated amorphous carbon thin films deposited by plasma-assisted chemical vapor deposition enhanced by electrostatic confinement: structure,properties, and modeling

Hydrogenated amorphous carbon (a-C:H) is a state-of-the-art material with established properties such as high mechanical resistance, low friction, and chemical inertness. In this work, a-C:H thin films were deposited by plasma-assisted chemical vapor deposition. The deposition process was enhanced by electrostatic confinement that leads to decrease the working pressure achieving relative high deposition rates. The a-C:H thin films were characterized by elastic recoil detection analysis, Rutherford backscattering spectroscopy, scanning electron microscopy, Raman spectroscopy, and nanoindentation measurements. The hydrogen content and hardness of a-C:H thin films vary from 30 to 45 at% and from 5 to 15 GPa, respectively. The hardness of a-C:H thin films shows a maximum as a function of the working pressure and is linearly increased with the shifting of the G-peak position and I _D/I _G ratio. The structure of a-C:H thin films suffers a clustering process at low working pressures. A physical model is proposed to estimate the mean ion energy of carbonaceous species arriving at the surface of a-C:H thin films as a function of processing parameters as pressure and voltage and by considering fundamentals scattering events between ion species and neutral molecules and atoms.     

Structure and physicomechanical properties of nanocrystalline boride-nitride films

Results are presented from an electron-microscopy study and x-ray structural analysis of nanocrystalline films based on titanium boride, obtained by rf and dc magnetron sputtering. The composition and formulas of the films are determined by Auger analysis. The hardness and elastic and electrical properties of the films are investigated. The role of size effects and deviations from stoichiometry (structural vacancies) is discussed. Fiz. Tverd. Tela (St. Petersburg) 39, 1859–1864 (October 1997)     

多组分复合薄膜的光学、电学、机械性能及其应用

复合薄膜因其可具有比单组份薄膜更加优异的性能而得到广泛的应用。通过以膜层的防护、催化、电学、光学以及力学性能等复合思想为切入点，阐述了通过膜层的复合掺杂旨在增强合金的抗腐蚀性，提高润滑摩擦性能，改善膜层的导电性能以及进行光学薄膜折射率和光谱吸收的调控，增强膜层的硬度及拉伸强度等机械性能的方法。对国内外的相关前沿成果进行简要介绍，并对复合薄膜的未来发展进行展望，为相关领域的研究提供参考。     

Mechanical properties of thin Ag films on a silicon substrate studied using the nanoindentation technique

The mechanical properties of thin Ag films of equal thickness containing grains of various sizes were studied. The film hardness was measured using the Oliver-Pharr techniques based on indentation work calculations or on direct measurements of the area of pyramid imprints in AFM images. In order to avoid the influence of a substrate on the measured hardness, a technique was developed to determine the true values of the film hardness. It was established that the hardness of Ag films decreases with an increase in mean grain size, whereas the elastic modulus remains almost unchanged. It was shown that the dependence of the yield stress of Ag films on grain size does not obey the classical Hall-Petch law.     

Effects of helium implantation on mechanical properties of (Al_(0.31)Cr_(0.20)Fe_(0.14)Ni_(0.35)) O high entropy oxide films

It is widely accepted that helium(He) bubbles can prevent dislocations from moving and causing hardening and embrittlement of the material. However, He can affect the mechanical properties of materials in various ways. In this work,ultrafine nanocrystal high entropy oxide(HEO) films with He implantation are prepared by using a radio frequency(RF)reactive magnetron sputtering system to investigate the effects of He bubbles located at grain boundary on the mechanical properties of the films. The mechanical properties of the HEO films are investigated systematically via nanoindentation measurements. The results indicate that the grain boundary cavities induced by He implantation can degrade the hardness,the elastic modulus, and the creep resistance of the HEO films. The mechanical properties of the HEO films are sensitive to the interaction between the He bubbles and the dominating defects.     

脉冲偏压电弧离子镀C-N-V薄膜的成分、结构与性能

用脉冲偏压电弧离子镀方法在硬质合金基体上制备了一系列不同成分的C-N-V薄膜.用X射线光电子能谱、激光Raman光谱、 X射线衍射(XRD)、透射电子显微镜(TEM)和纳米压痕等方法分别研究了薄膜的成分、结构与性能.Raman光谱,XRD和TEM结果表明,所制备的薄膜为在类金刚石(DLC)非晶基体上匹配有VN晶体的碳基复合薄膜.随V和N含量的增加,薄膜硬度与弹性模量先增加后下降,在N含量为204%,V含量为218%时薄膜硬度与弹性模量具有最大值,分别为368和5697 GPa,高于相同条件下制备的 关键词： C-N-V薄膜 类金刚石薄膜 纳米复合薄膜 电弧离子镀     

Growth kinetics and properties of nanostructured hafnium diboride films

The composition, structure, substructure, and physicomechanical properties of hafnium diboride films deposited by nonreactive rf magnetron sputtering are studied by X-ray diffraction (including photographic recording) and electron microscopy. The results obtained are analyzed, and the film growth kinetics is revealed.     

Nanoindentation measurements on modified diamond-like carbon thin films

In the present study, we explored the effect of metallic interlayers (Cu and Ti) and indentation loads (5-20 mN) on the mechanical properties of plasma produced diamond-like carbon (DLC) thin films. Also a comparison has been made for mechanical properties of these films with pure DLC and nitrogen incorporated DLC films. Introduction of N in DLC led to a drastic decrease in residual stress (S) from 1.8 to 0.7 GPa, but with expenses of hardness (H) and other mechanical properties. In contrast, addition of Cu and Ti interlayers between substrate Si and DLC, results in significant decrease in S with little enhancement of hardness and other mechanical properties. Among various DLC films, maximum hardness 30.8 GPa is observed in Ti-DLC film. Besides hardness and elastic modulus, various other mechanical parameters have also been estimated using load versus displacement curves.     

Surface characteristics and nanoindentation study of Ni-Mn-Ga ferromagnetic shape memory sputtered thin films

In present paper, the off-stoichiometric Ni-Mn-Ga ferromagnetic shape memory alloy thin films are fabricated using radio frequency magnetron sputtering method. The compositions, microstructures and mechanical properties of the thin films are characterized by energy dispersive X-ray spectrum (EDAX), X-ray photoelectron spectroscopy (XPS), scanning electronic microscope (SEM), atomic force microscope (AFM) and nanoindentation test, respectively. The results show that there is a thinner layer of oxides consisting of NiO, Ga₂O₃ and an unspecified manganese oxidation (Mn_xO_y) at the surface, whereas a small amount of MnO precipitates exist in internal layers of post-annealed Ni-Mn-Ga thin films. The hardness and elastic modulus decrease with increasing film thickness. Nanoindentation tests reveal that the hardness and elastic modulus of the films can be up to 5.5 and 155 GPa, respectively. The Ni-Mn-Ga thin films have remarkably improved the ductility of Ni-Mn-Ga ferromagnetic shape memory alloys bulk materials.     

衬底温度对类金刚石薄膜力学性能的影响

 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。     

Structural, electrical and mechanical properties of NiO thin films grown by pulsed laser deposition

Nickel oxide (NiO) thin films were prepared by reactive pulsed laser deposition on thermally oxidized Si substrates in 10 Pa oxygen pressure. The substrate temperature during deposition was varied and its influence on the structural, electrical and nanomechanical properties was studied. It was proved that the structural properties were affected by the increase of substrate temperature improving the crystalline structure. Furthermore, a higher substrate temperature resulted in a thicker NiO film, which was attributed to an increased grain size. This effect influenced the electrical properties, too. Resistivity measurements showed that it increased with the increase of substrate temperature. For the first time, the nanomechanical properties of NiO films were studied. The formation and improvement of crystalline structure affected the nanomechanical properties. Nanoindentation testing of NiO thin films revealed an increase of hardness (H) and elastic modulus (E) and a decrease of surface roughness when increasing the substrate temperature.     

Variation of the mechanical properties of pulsed laser deposited PMMA films during annealing

The structural and mechanical properties of polymethyl methacrylate (PMMA) thin films produced by pulsed laser deposition in ultra-high vacuum were investigated by infrared spectroscopy, electron microscopy, size-exclusion chromatography and microhardness measurements. After preparation, the film hardness and elastic modulus are found to be increased. This is caused by a reduced chain length of the polymer film to values of 5800 g/mol and by cross links of an amount of about 20% of the polymer, while the chemical structure of the deposited films is comparable to the target material. During annealing, relaxation processes lead to a reduction of the film hardness, without changing the cross-linked part in the samples. PACS 81.05.Lg; 81.15.Fg; 68.55.Jk; 68.60.Bs; 68.60.Dv     

沉积温度对钛硅共掺杂类金刚石薄膜生长、结构和力学性能的影响

采用中频磁控溅射Ti80Si20复合靶在单晶硅表面制备了共掺杂的类金刚石薄膜.研究了沉积温度对薄膜生长速率、化学成分、结构、表面性质和力学性能的影响.结果表明:随沉积温度升高,薄膜生长速率降低,薄膜Ti和Si原子浓度增加,C原子浓度降低;在高温下沉积的薄膜具有低sp3C含量、低表面接触角、低内应力和高的硬度与弹性模量.基于亚表层注入生长模型分析了沉积温度对薄膜生长和键合结构的影响,从薄膜生长机制和微观结构解释了表面性质和力学性能的变化.