Tribological and mechanical behaviors of TiN/CNx multilayer films deposited by magnetron sputtering

TiN/CN_x multilayer films with bilayer periods of 4.5-40.3 nm were deposited by direct-current magnetron sputtering. Layer morphology and structure of the multilayered films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The TiN/CN_x multilayers exhibited coherent epitaxial growth due to the mutual growth-promoting effect at small bilayer period and some crystalline regions going through the interface of TiN/CN_x. Nanoindentation tests showed that the hardness of the multilayers varied from 12.5 to 31 GPa, with the highest hardness being obtained with a bilayer period of 4.5 nm. The tribological properties of the films were investigated using a ball-on-disk tribometer in humid air, and the TiN/CN_x multilayer with a bilayer period of 4.5 nm also exhibited the lowest friction coefficient and the highest wear resistance.     

Tribological property and drilling application of Ti-C:H and Cr-C:H coatings on high-speed steel substrates

This study investigates the tribological properties and cutting performance of Ti-DLC and Cr-DLC doped metal coatings. The tribological properties of the coatings are evaluated by testing coated disks against an AISI 1045 steel counterbody under dry conditions using an oscillating friction wear tester, and then measuring the subsequent wear depth on the coated disk, the wear width on the steel counterbody, and the friction coefficient. The cutting performance of the coatings is evaluated by using coated high-speed drills to machine stainless steel workpieces, and then measuring the resulting flank wear and hole surface roughness. The results of the wear tests show that the Ti-C:H and Ti-C:H/TiC/TiCN/TiN coatings possess excellent tribological properties, including low coefficients of friction, low wear depths, and low wear widths. Regarding the machining tests, the Ti-C:H/TiC/TiCN/TiN coating has the lowest flank wear and yields the highest hole surface quality under both dry and cutting fluid drilling conditions. The single Ti-C:H coating has excellent tribological properties, but demonstrates a relatively poorer performance in the drilling of stainless steel. Finally, the Cr-DLC coatings all exhibit a poor cutting performance under dry cutting conditions.     

Preparation of various DLC films by T-shaped filtered arc deposition and the effect of heat treatment on film properties

Different types of diamond-like carbon (DLC) films (ta-C, a-C, ta-C:H and a-C:H) were prepared on super hard alloy (WC-Co) substrate using a T-shape filtered arc deposition (T-FAD) system. At first, the film properties, such as structure, hydrogen content, density, hardness, elastic modulus, were measured. Ta-C prepared with a DC bias of −100 V showed the highest density (3.1 g/cm³) and hardness (70-80 GPa), and the lowest hydrogen content (less than 0.1 at. %). It was found that the hardness of the DLC film is proportional to approximately the third power of film density. The DLC films were then heated for 60 min in an electric furnace at 550 °C in N₂. Only the ta-C film hardly change its structure, although other films were graphitized. The 200-nm thick ta-C film was then heated for 60 min through the temperature range from 400 to 800 °C in N₂ with 2 vol.% of O₂ and the film structure found to be stable up to 700 °C. The substrate was oxidized at 800 °C, indicating the ta-C film had a thermal barrier function up to that temperature.     

钛合金基类金刚石梯度薄膜的生物摩擦学性能评价

通过与钛合金／超高分子量聚乙烯摩擦副的对比，研究了DLC／UHMWPE摩擦副分别在干摩擦、生理盐水^L和Hank's溶液润滑下的摩擦磨损特性。用二次离子质谱和声波反射划痕仪分别测定了DLC梯度薄膜的组分分布和附着强度，并用扫描电子显微镜观察试样表面形貌，探讨其磨损机理。结果表明：用PSII-IBED法制备的DLC薄膜的组分由内向外呈梯度变化，膜的附着强度较高。DLC梯度薄膜是一种减摩耐磨材料，其摩擦系数随载荷的增大而减小。     

Structural design of Cr/GLC films for high tribological performance in artificial seawater: Cr/GLC ratio and multilayer structure

In this paper,graphite-like carbon(GLC)films with Cr buffer layer were fabricated by DC magnetron sputtering technique with the thickness ratio of Cr to GLC films varying from 1:2 to 1:20.The effect of Cr/GLC modulation ratio on microstructure,mechanical and tribological properties in artificial seawater was mainly investigated by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),nano-indenter and a reciprocating sliding tribo-meter.The propagation of defects plays an important role in the evolution of delamination,which is critical to wear failure of GLC films in artificial seawater.Designing the proper multilayer structure could inhibit the defects propagation and thus protect the basis material.The multilayer Cr/GLC film with optimized ratio of 1:3 demonstrates a low average friction coefficient of 0.08±0.006 and wear rate of(2.3±0.3)×10~(-8)mm~3/(N m)in artificial seawater,respectively.     

Tribological behavior at elevated temperature of multilayer TiCN/TiC/TiN hard coatings produced by chemical vapor deposition

Multilayer hard coatings of TiCN/TiC/TiN on high speed steel substrates were deposited using a chemical vapor deposition system. Evaluations of microstructure, wear morphology of coatings were characterized by scanning electron microscopy, and optical microscopy. Friction coefficient and wear rates of coatings were investigated using ball-on-disk tester sliding against a WC ball at a constant load of 20 N. Tribological behavior of the coatings at room and elevated temperature were discussed. Different changing tendency of friction coefficient were observed from ball-on-disc experiments. Results showed that the friction coefficient of coatings increased gradually to a highest value, then to a relatively constant value at room temperature dry sliding wear. The friction coefficient exhibited a reverse variation tendency at temperature of 550 °C. It got a higher value at the first sliding friction cycles. Then the value of friction coefficient decreased, suffered irregular oscillations and kept a relatively lower value with increasing sliding time. Reasons of the variation of friction coefficient with sliding time and wear mechanism were analyzed and discussed at room and elevated temperatures, respectively.     

Si过渡层对梯度影响类金刚石薄膜结合力的影响研究

实验利用双放电腔微波-ECR等离子体源设备,采用复合PVD（physical vapor deposition）和PECVD（plasma enhanced chemical vapor deposition）的方法, 先后在NiTi基体上沉积Si和Si/α-C∶H过渡层,然后制备类金刚石薄膜.Raman光谱和透射电镜表明制备的梯度薄膜是典型的类金刚石薄膜,划痕的测试结果表明, Si过渡层沉积时间影响着梯度类金刚石薄膜与NiTi合金基体之间的结合强度,当沉积时间在60min左右时可获得具有最好结合强度的梯度薄膜,而超过或低于这个时间值会导致膜基结合强度降低.     

非平衡磁控溅射无氢DLC增透膜的研制

非平衡磁控溅射(UBMS)技术近年来得到了广泛地应用.采用该技术制备的类金刚石薄膜(DLC)具有许多独特的性质.本文利用正交实验方法,对非平衡磁控溅射技术制备无氢DLC膜增透膜进行了研究,得到了影响薄膜光学性能的主要因素和最佳的制备工艺.结果表明,非平衡磁控溅射制备的无氢DLC膜具有较宽的光谱透明区,锗基底单面沉积DLC膜,其峰值透射率达到61.4%,接近理论值.     

ZnO/Cu/ZnO multilayer films: Structure optimization and investigation on photoelectric properties

A series of ZnO/Cu/ZnO multilayer films has been fabricated from zinc and copper metallic targets by simultaneous RF and DC magnetron sputtering. Numerical simulation of the optical properties of the multilayer films has been carried out in order to guide the experimental work. The influences of the ZnO and Cu layer thicknesses, and of O₂/Ar ratio on the photoelectric and structural properties of the films were investigated. The optical and electrical properties of the multilayers were studied by optical spectrometry and four point probe measurements, respectively. The structural properties were investigated using X-ray diffraction. The performance of the multilayers as transparent conducting coatings was compared using a figure of merit. In experiments, the thickness of the ZnO layers was varied between 4 and 70 nm and those of Cu were between 8 and 37 nm. The O₂/Ar ratios range from 1:5 to 2:1. Low sheet resistance and high transmittance were obtained when the film was prepared using an O₂/Ar ratio of 1:4 and a thickness of ZnO (60 nm)/Cu (15 nm)/ZnO (60 nm).     

不锈钢基体预处理对合成类金刚石碳膜的影响

本文研究了在射频等离子体增强化学气相沉积工艺中不同的预处理方法对不锈钢基底上类金刚石碳膜生长的影响。所沉积的碳膜的结构和形貌分别用激光Raman光谱和扫描电子显微镜进行了分析，薄膜与基底的结合力通过划痕实验进行了表征。实验结果表明，通过采用合适的过渡层能显著提高类金刚石碳膜与基底的结合力，而通过化学腐蚀的方法对提高结合力的帮助不大。     

Wear behaviour and rolling contact fatigue life of Ti/TiN/DLC multilayer films fabricated on bearing steel by PIIID

In order to improve the friction and wear behaviours and rolling contact fatigue (RCF) life of bearing steel materials, Ti/TiN/DLC (diamond-like carbon) multilayer hard films were fabricated onto AISI52100 bearing steel surface by plasma immersion ion implantation and deposition (PIIID) technique. The micro-Raman spectroscopy analysis confirms that the surface film layer possess the characteristic of diamond-like carbon, and it is composed of a mixture of amorphous and crystalline phases, with a variable ratio of sp²/sp³ carbon bonds. Atomic force microscope (AFM) reveals that the multilayer films have extremely smooth area, excellent adhesion, high uniformity and efficiency of space filling over large areas. The nanohardness (H) and elastic modulus (E) measurement indicates that the H and E of DLC multilayer films is about 32 GPa and 410 GPa, increases by 190.9% and 86.4%. The friction and wear behaviours and RCF life of DLC multilayer films specimen have also been investigated by ball-on-disc and three-ball-rod fatigue testers. Results show that the friction coefficient against AISI52100 steel ball decreases from 0.92 to 0.25, the longest wear life increases nearly by 22 times. In addition, wear tracks of the PIIID samples as well as wear tracks of the sliding steel ball were analyzed with the help of optical microscopy and scanning electron microscopy (SEM). The L₁₀, L₅₀, L_a and mean RCF life L of treated bearing samples, in 90% confidence level, increases by 10.1, 4.2, 3.5 and 3.4 times, respectively. Compared with the bearing steel substrate, the RCF life scatter extent of Ti/TiN/DLC multilayer films sample is improved obviously.     

Tribological properties of Ti2N-Wx% coatings deposited by magnetron sputtering

Ti₂N-W_x% coatings with different tungsten contents were deposited using unbalanced magnetron sputtering technology. The microstructures and mechanical properties of Ti₂N-W_x% coatings have been characterized by SEM, X-ray diffraction (XRD), nanoindentation and adhesion techniques. The tribological performance of the coatings was investigated using an oscillating friction and wear tester under dry conditions. Indexable inserts with Ti₂N-W_x% coatings were applied to turning AISI 1045 steel material by a lathe. Micron-drills with Ti₂N-W_x% coatings were adopted in the ultra-high speed (10⁵ rpm) Printed Circuit Board (PCB) through-hole drilling test. Experimental results indicate that the coating microstructure, mechanical properties and wear resistance vary according to the tungsten content. Ti₂N-W_14% coated inserts showed the best wear resistance in 1045 steel turning and PCB through-hole drilling tests. The service life of a Ti₂N-W_14% coated tool is five times greater than that of an uncoated tool in PCB through-hole drilling test.     

Emission properties of DLC films on Si substrates

DLC films were deposited on polished both n-type and p-type silicon substrates. The silicon resistivity was ～0.02 Θ cm. Some of the DLC films 20 nm thick were deposited on the n-type Si surface with the submicron cones. SEM and Raman spectroscopy were used for structural investigations. Field electron emission occurs after dielectric breakdown, except for the samples with Si cones for which the emission seems to originate from SiC formed during the first stage of electron emission. It seems that too much sp² graphite phase may give rise to the observed increase in the turn-on field from 50 V/μm up to 150 V/μm.     

Raman spectroscopy and mechanical properties of multilayer tetrahedral amorphous carbon films

In order to take the tetrahedral amorphous carbon (ta-C) films as the high acoustic impedence layer in a Bragg reflector isolating acoustic wave from the substrate in solidly mounted resonator, the multilayer films consisting of sp2-rich layers and sp3-rich layers were deposited from a filtered cathodic vacuum arc by adjusting the substrate bias. The microstructure of the films was evaluated using a visible Raman spectroscopy. The stress was calculated according to the changed curvature of the coated and bare substrate. The hardness, modulus and scratching were measured using a nanoindenter. It has been shown that the multilayer structure maintaining high tetrahedral content, high hardness and high elastic modulus is still characterized with lower intrinsic stress and better adhesion.     

High quality transparent conductive ZnO/Ag/ZnO multilayer films deposited at room temperature

We have fabricated, by simultaneous DC and RF magnetron sputtering, multilayer transparent electrodes having much lower electrical resistance than the widely used transparent conductive oxide electrodes. The multilayer structure consists of three layers (ZnO/Ag/ZnO). Ag films with different film thickness were used as metallic layers. Optimum thicknesses of Ag and ZnO films were determined for high optical transmittance and good electrical conductivity. Several analytical tools such as spectrophotometer, atomic force microscopy, scanning electron microscopy and four-point probe were used to explore the possible changes in electrical and optical properties. A high quality transparent electrode, having resistance as low as 3 Ω/sq and high optical transmittance of 90% was obtained at room temperature and could be reproduced by controlling the preparation process parameters. The electrical and optical properties of ZnO/Ag/ZnO multilayers were determined mainly by the Ag film properties. The performance of the multilayers as transparent conducting materials was also compared using a figure of merit.     

不锈钢衬底上沉积类金刚石薄膜的硬度

利用射频辉光放电法在不锈钢衬底上制备了类金刚石薄膜，用显微硬度计测试了薄膜与衬底复合膜度和衬底硬度。并用Ｂ．Ｊｏｎｓｏｎ和Ｂ．Ｈｏｇｍａｒｋ方法将薄硬度分离出来，得到了硬度值与制与制备参数间的关系，确定了在不锈钢衬底上沉积高度和强附丰度类金刚石薄膜的最佳工艺条件范围，并对实验结果进行了理论解释。     

Research of optical and structural properties in Cu/Ti multilayer films

The Cu/Ti multilayer (ML) films were deposited on Si(1 0 0) and Si(1 1 1) substrate with a series of pair layers with Vanguard sputtering system. The influences of periodic number and substrate structure on UV-reflectivity of Cu/Ti superlattice films were investigated carefully. The result shows that the Cu/Ti ML films have clear layer-structure. The ML films deposited on Si(1 0 0) and Si(1 1 1) have UV-reflectivity of about 90% and 67% at 200 nm, respectively, but they have lower soft X-ray reflectivity of about 1.9% at 13.04 nm in terms of wavelength, with near normal incidence of 5°. The transmission microscope image indicates that the fabricated Cu/Ti ML films have superlattice structure.     

DLC膜厚度对镁基表面DLC/MAO复合膜层性能的影响

采用线性离子束沉积技术于AZ80镁合金微弧氧化(MAO)陶瓷层表面沉积不同厚度的类金刚石碳(DLC)膜,形成DLC/MAO复合膜层.对比研究4种膜基系统的表面结构特征、力学性能以及摩擦学性能差异.结果表明:随DLC膜厚度增加,复合膜层表面微孔数量减少,孔径减小,但凹凸不平趋势增加,且DLC膜表面颗粒特征更加明显,表现为DLC-80min/MAO/AZ80膜基系统具有最小的表面粗糙度,最大的硬度H、弹性模量E及H/E值;不同厚度DLC/MAO/AZ80膜基系统平均摩擦因数较MAO/AZ80显著降低;DLC膜厚度增加导致3种复合膜基系统的表面微观结构改变,使得摩擦因数与磨痕形貌存在差异;各膜基系统     

极板负偏压对类金刚石薄膜性质的影响

用射频－直流辉光放电系统制备类金刚石薄膜，研究了极板负偏压（Ｖ）对类金刚薄膜性质的影响。结果表明，类金刚石薄膜的性质明显依赖于极板负偏压，在所研究的范围（－３００－９００Ｖ）内，随Ｖ绝对值的增加，薄膜的折射率，消光系数，生长速率，及硬度增加，电阻率下降，Ｖ的变化使膜中Ｈ一及ｓｐ＾３／ｓｐ＾２的比例发生变化，从而使膜的性质发生变化。     

TiNi合金表面沉积类金刚石薄膜的性能评价

类金刚石膜作为新型的生物材料得到了广泛的关注。本实验制备的薄膜为典型的类金刚石膜,膜层比较致密、均匀和光滑。膜层硬度随离子束能量变化,在束电源为750V附近出现峰值,硬度达到了15GPa,该膜的摩擦系数为0.124。在Troyde’s模拟体液中的电化学分析表明,类金刚石膜显著提高了TiNi合金表面抗点蚀能力。