Adherent amorphous hydrogenated carbon films on metals deposited by plasma enhanced chemical vapor deposition

This paper reports the findings of a study of the structural, mechanical, and tribological properties of amorphous hydrogenated carbon (a-C:H) coatings for industrial applications. These thin films have proven quite advantageous in many tribological applications, but for others, thicker films are required. In this study, in order to overcome the high residual stress and low adherence of a-C:H films on metal substrates, a thin amorphous silicon interlayer was deposited as an interface. Amorphous silicon and a-C:H films were grown by using a radio frequency plasma enhanced chemical vapor deposition system at 13.56 MHz in silane and methane atmospheres, respectively. The X-ray photoelectron spectroscopy technique was employed to analyze the chemical bonding within the interfaces. The chemical composition and atomic density of the a-C:H films were determined by ion beam analysis. The film microstructure was studied by means of Raman scattering spectroscopy. The total stress was determined through the measurement of the substrate curvature, using a profilometer, while micro-indentation experiments helped determine the films' hardness. The friction coefficient and critical load were evaluated by using a tribometer. The results showed that the use of the amorphous silicon interlayer improved the a-C:H film deposition onto metal substrates, producing good adhesion, low compressive stress, and a high degree of hardness. SiC was observed in the interface between the amorphous silicon and a-C:H films. The composition, the microstructure, the mechanical and tribological properties of the films were strongly dependent on the self-bias voltages. The tests confirmed the importance of the intensity of ion bombardment during film growth on the mechanical and tribological properties of the films.     

Influence of bias voltages on the structure and wear properties of TiSiN coating synthesized by cathodic arc plasma evaporation

Nanocomposite TiSiN films have been deposited on M2 tool steel substrates using TiSi alloy as target by a dual cathodic arc plasma deposition (CAPD) system. The influences of bias voltages on the microstructure, mechanical and tribological properties of the films were investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction techniques were employed to analyse the microstructure, grain size and residual stress. Nano-indentation and tribometer testers were used to measure the mechanical and tribological properties of nanocomposite TiSiN thin films. The results showed that the hardness of the films ranged from 25 to 37 GPa, which were higher than that of TiN (21 GPa). The coefficient of friction of the TiSiN thin films was more stable but was higher than that of TiN when wear against both Cr steel and WC-Co ball, respectively. When encountered with both Cr steel and WC-Co ball of the counter ball, the tribological mechanisms of TiSiN thin films are adhesive and abrasion wears, respectively. It has been found that the microstructure, mechanical and wear properties of the films were correlated to bias voltage, grain size, and amorphous Si₃N₄ nanocomposite formed in film structure, resulting in a superhard TiSiN coating.     

Nanoindentation and AFM studies of PECVD DLC and reactively sputtered Ti containing carbon films

Amorphous carbon film, bdalso known as DLC film, bdis a promising material for tribological application. It is noted that properties relevant to tribological application change significantly depending on the method of preparation of these films. These properties are also altered by the composition of the films. In view of this, bdthe objective of the present work is to compare the nanoindentation and atomic force microscopy (AFM) study of diamond like carbon (DLC) film obtained by plasma enhanced chemical vapour deposition (bdPECVD with the Ti containing amorphous carbon (Ti/a- C : H) film obtained by unbalanced magnetron sputter deposition (UMSD). Towards that purpose, DLC and Ti/a- C : H films are deposited on silicon substrate by PECVD and UMSD processes, respectively. The microstructural features and the mechanical properties of these films are evaluated by scanning electron microscopy (SEM), bdtransmission electron microscopy (TEM), nanoindentation and by AFM. The results show that the PECVD DLC film has a higher elastic modulus, hardness and roughness than the UMSD Ti/a- C : H film. It also has a lower pull off force than Ti containing amorphous carbon film.     

Nanoindentation and nanoscratch behaviour of reactive sputtered deposited W–S–C film

Transition metal dichalcogenides having layered structure are promising self lubricating film and can be considered as substitute for carbon based films in several varieties of environmental conditions. The macrotribological properties of these films are studied extensively and are fairly well understood. However, mechanical and tribological behaviour of these films in millinewton load range have hardly been reported. Study of mechanical and tribological properties at applied load in the millinewton range is useful for possible application related to microelectro mechanical systems or micromechanical assemblies. In view of the above, the present work is undertaken to understand the indentation behaviour and scratch behaviour under constant and low applied load of reactive sputtered deposited W–S–C thin films. Towards that purpose, W–S films containing various amount of C are deposited on 100Cr6 steel using a radio frequency magnetron sputtering unit. The load vs. displacement curves of all these films are generated for four different loads to assess the load effect, substrate effect and size effect on the hardness and the load displacement curves of these films. Curves showing the variation of load as a function of the square of displacement are also evaluated in order to understand deformation and fracture mechanisms of these films and the interface between various microstructures of these films. The scratch behaviour of these films under constant load is determined to examine the friction and wear performance. The results show that the film containing 54 at.% carbon has the maximum hardness and the minimum scratch depth. In contrast, the minimum friction coefficient is exhibited by the film containing the maximum carbon.     

Tribological property enhancement of CrN films by metal vapor vacuum arc implantation of Vanadium and Carbon ions

CrN films have been extensively used in precision forming and molding applications because of their excellent tribological properties and oxidation-resisting characteristics. Vanadium and carbon ions are introduced into the near surface layer of deposited CrN films via metal vapor vacuum arc implantation to improve the wear performance of CrN films. Dense and smooth CrN film was deposited using a filtered arc deposition system, which provides fully ionized Cr plasma on the substrate surface. Subsequently, surface bombardment of the deposited CrN film with vanadium and carbon ions densifies the film and forms an alloy near the surface. These CrN-based films were characterized by X-ray photoelectron electron and Auger electron spectroscopies. Examinations of the tribological and mechanical film properties, including wear resistance, corrosion resistance and fracture toughness were performed and correlated with respect to the implantation parameters.     

CrAlSiN nanocomposite thin films for high-speed machining applications

CrAlSiN nanocomposite thin films with varying film chemistry were developed on tungsten carbide (WC) specimens using cylindrical cathodic arc physical vapor deposition (c-CAPVD) technique. The physical, mechanical, and tribological properties of all the films were comprehensively investigated for arriving at the film chemistry leading to the best properties with respect to mechanical applications. The best tribo-mechanical properties were obtained in films with Cr/(Al+Si) ratio of 1.2. This coating with best properties was translated on to WC drill bits for machining tests. The Al and Si content has shown major influence on the adhesion strength and phase constitution of the films, with a considerable change in residual stress too. The superior properties achieved could be attributed to the formation of a near-perfect nanocomposite structure, with the crystalline CrAlN phase surrounded by an amorphous Si₃N₄ phase. The tool life of the coated CrAlSiN tools was investigated during dry machining of EN 24 material. In comparison to the tool life of an uncoated tool and a TiAlSiN-coated tool, the best CrAlSiN coatings synthesized in this study performed exceedingly well. The present study clearly demonstrates the advantages of CrAlSiN over other existing similar coatings for high-speed machining.     

Structural, mechanical and tribological behavior of fullerene-like carbon film

Hydrogenated carbon films containing fullerene-like structures (FL-C:H) were synthesized using magnetron sputtering of a graphite target in methane and argon atmospheres. The results indicate clearly that a substantial part of the film is made up of fragments of such fullerene-like structures mixed in a hydrogenated amorphous carbon matrix. The film exhibits excellent mechanical properties with a hardness of 27.4 GPa and almost complete elastic recovery (as high as 95%). The tribological properties of the FL-C:H film were tested and compared with a-C:H and a-C films. The results show that the lowest friction coefficient of the FL-C:H film, about 0.02, is recorded in oxygen environment. The ranges of dispersion of the friction coefficient for the FL-C:H film are merely 0.02 in different testing environments, much lower than that of a-C:H and a-C films, which indicates the friction-coefficient-insensitivity of the FL-C:H film to different atmospheres.     

Characterization and tribological application of diamond-like carbon (DLC) films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique

Diamond-like carbon (DLC) films were successfully prepared on glass substrates and surfaces of selenium drums via radio frequency plasma enhanced chemical vapor deposition method. The microstructure, surface morphology, hardness, film adhesion, and tribological properties of the films were characterized and evaluated by X-ray photoelectron spectroscopy, atomic force microscopy, and micro-sclerometer and friction-wear spectrometer. The results showed that DLC films have smooth surfaces, homogeneous particle sizes, and excellent tribological properties, which can be used to improve the surface quality of the selenium drums and prolong their service life.     

Microstructure and Tribological Behavior of Stripe Patterned TiN Film Prepared with Filtered Cathodic Vacuum Arc Deposition (FCVAD)

This paper describes an experimental investigation into the influence of the stripe interspace and applied load on the tribological behavior of stripe patterned TiN films. The stripe patterned TiN films are deposited on an H13 steel surface by masked deposition with the filtered cathodic vacuum arc discharge (FCVAD) technique. The surface micro morphology, chemical composition, crystal structure, and mechanical properties of the films is characterized using 3D white light interferometry, scanning electron microscopy (SEM), X‐ray diffractometry (XRD), and a nano‐indentation tester, respectively. The tribological performance of patterned TiN is measured using a UMT‐5 tribometer, and the friction and wear mechanisms are analyzed, compared with that of the full TiN film and H13 steel substrate. The results show that the stripe patterned TiN films has better tribological properties than the full TiN film. These results are attributed to the synergistic effect between the surface pattern and the TiN film. The stripe interspace and the applied load has a more significant effect on the wear rate of the stripe patterned TiN films than the coefficient of friction of their friction pairs. A further study, however, is needed to analyze the relationship between the applied load and the wear rates of the stripe patterned TiN films.

     

Characterization and tribological application of diamond-like carbon (DLC) films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique

Diamond-like carbon (DLC) films were successfully prepared on glass substrates and surfaces of selenium drums via radio frequency plasma enhanced chemical vapor deposition method. The microstructure, surface morphology, hardness, film adhesion, and tribological properties of the films were characterized and evaluated by X-ray photoelectron spectroscopy, atomic force microscopy, and micro-sclerometer and friction-wear spectrometer. The results showed that DLC films have smooth surfaces, homogeneous particle sizes, and excellent tribological properties, which can be used to improve the surface quality of the selenium drums and prolong their service life.     

Optimization of chemical vapor deposition diamond films growth on steel: correlation between mechanical properties, structure, and composition

In the present work we perform optimization of mechanical and crystalline properties of CVD microcrystalline diamond films grown on steel substrates. A chromium-nitride (Cr-N) interlayer had been previously proposed to serve as a buffer for carbon and iron inter-diffusion and as a matching layer for the widely differing expansion coefficients of diamond and steel. However, adhesion and wear as well as crystalline perfection of diamond films are strongly affected by conditions of both Cr-N interlayer preparation and CVD diamond deposition. In this work we assess the effects of two parameters. The first one is the temperature of the Cr-N interlayer preparation: temperatures in the range of 500 degrees C-800 degrees C were used. The second one is diamond film thickness in the 0.5 microm-2 microm range monitored through variation of the deposition time from approximately 30 min to 2 hours. The mechanical properties of so deposited diamond films were investigated. For this purpose, scratch tests were performed at different indentation loads. The friction coefficient and wear loss were assessed. The mechanical and tribological properties were related to structure, composition, and crystalline perfection of diamond films which were extensively analyzed using different microscopic and spectroscopic techniques. It was found that relatively thick diamond film deposited on the Cr-N interlayer prepared at the temperature similar to that of the CVD process has the best mechanical and adhesion strength. This film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. In other cases, cracking and delamination of the films took place at low to moderate indentation loads.     

Structural, mechanical, and tribological properties of fluorinated mesoporous silica films: Effect of functional moiety and surfactant template concentrations

Thin organo-functional coatings are inherently weak and can be easily damaged and their functional properties degraded by wear. Encapsulating organo-functional moieties into surfactant-templated ceramic coatings has the possibility of extending the functional lifetime of such materials. This study examines the effects of functional silane and surfactant template concentrations on the structural, mechanical, and tribological properties of hydrophobic silica films. Fluorinated silica films were synthesized via sol-gel co-condensation of tetraethoxysilane and a perfluoropolyether silane, templated with PEO₁₀₆PPO₇₀PEO₁₀₆ surfactant (Pluronic F127), and coated on glass substrates. The results show that the increasing concentrations of fluorinated silane and surfactant template generally improve hydrophobicity of films worn by abrasion. However, surfactant templating creates void spaces which are detrimental to the mechanical properties of the material, as was determined by nitrogen adsorption porosimetry and nanoindentation. Tribological results from atomic force microscopy suggest that the low-friction surface generated by encapsulation of fluorosilane moieties grafted to internal surfaces mitigates to some extent the detrimental effect of film porosity on hardness and wear resistance.     

Flächeneinfluss bei der PACVD‐Beschichtung

Impact of the active surface on properties of DLC films in the PACVD coating chamber. In the automotive industry, economic and stable industrial processes to apply hard coatings for tribological applications are required. Hence detailed knowledge about the influence of coating parameters on the film characteristics is essential. the following paper deals with the process of plasma activated chemical vapor deposition with focus on the effect of the parameter “active area in the coating chamber“ on the properties of diamond‐like‐carbons (DLC). the coatings are deposited in an industrial coating chamber using reactive magnetron sputtering with a pulsed bias voltage (40 kHz) and at constant pressure. During the investigation of the influence of active area and current density on the mechanical and tribological properties of the DLC films, the expected correlation between active area and current density could be confirmed. By regulating the current density, consistent film properties could be achieved, independently of the active area in the chamber. Furthermore improved wear characteristics of the film – crucial for the endurance of heavily loaded automotive components – were achieved by adapting the load pattern of the chamber.     

The X-ray photoelectron spectroscopy depth profiling and tribological characterization of ion- plated gold on various metals

An investigation was conducted to examine, by X-ray photoelectron spectroscopy analysis and depth profiling, the atomic nature of such tribological properties as friction and microhardness of ion-plated gold. Friction properties were measured with (1) a gold film, (2) the graded interface between gold and nickel substrate and (3) the nickel substrate. All sliding was conducted against hard silicon carbide pins in two processes. The first is the adhesive process in which friction arises primarily from adhesion between sliding surfaces, and the second is a non-adhesive process, namely abrasion, in which friction occurs as a result of the hard pin sliding against the film, indenting into it and plowing a series of grooves. The other substrates used in this study included copper and 440C stainless steel. Reference experiments were also conducted with vapor-deposited gold on the substrates. A vacuum environment is used in order to maximize the adhesion effect, while oil is used to minimize the adhesion effect. The results of the investigation indicate that the friction related to adhesion as well as the friction related to abrasion are influenced by the coating depth. The trends in friction behavior as a function of film depth are, however, just the opposite. The graded interface exhibited the highest adhesion and friction, while the graded interface resulted in the lowest abrasion and friction. The coefficient of friction due to abrasion is inversely related to the hardness. The greter the hardness of the surface, the lower are the abrasion and friction. The microhardness in the graded interface exhibited the highest hardness due to an alloy hardening effect. Almost no graded interface between the vapor- deposited gold film and the substrates was detected.     

纳米食品保鲜膜研究进展

目的 综述纳米材料及其制备纳米保鲜膜,以及其在食品保鲜中研究和应用现状。方法 介绍常用纳米包装保鲜膜中常用的纳米材料,包括ZnO纳米粒子、TiO₂纳米粒子、SiO₂纳米粒子、介孔SiO₂纳米粒子、Ag纳米粒子,以及纳米保鲜膜制备方法。结果 在传统膜或保鲜膜中添加纳米粒子,可以有效改善膜的力学性能、阻隔性能及抑菌性能,可有效延长食品货架期和贮藏保鲜期。结论 与传统膜相比,纳米膜在食品包装保鲜具有优异特性,具有巨大应用潜力。然而,如何改善光催化等纳米薄膜应用的局限性需要进一步研究。     

Structure, mechanical and tribological properties of diamond-like carbon films on aluminum alloy by arc ion plating

The low hardness and poor tribological performance of aluminum alloys restrict their engineering applications. However, protective hard films deposited on aluminum alloys are believed to be effective for overcoming their poor wear properties. In this paper, diamond-like carbon (DLC) films as hard protective film were deposited on 2024 aluminum alloy by arc ion plating. The dependence of the chemical state and microstructure of the films on substrate bias voltage was analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy. The mechanical and tribological properties of the DLC films deposited on aluminum alloy were investigated by nanoindentation and ball-on-disk tribotester, respectively. The results show that the deposited DLC films were very well-adhered to the aluminum alloy substrate, with no cracks or delamination being observed. A maximum sp³ content of about 37% was obtained at −100 V substrate bias, resulting in a hardness of 30 GPa and elastic modulus of 280 GPa. Thus, the surface hardness and wear resistance of 2024 aluminum alloy can be significantly improved by applying a protective DLC film coating. The DLC-coated aluminum alloy showed a stable and relatively low friction coefficient, as well as narrower and shallower wear tracks in comparison with the uncoated aluminum alloy.     

Analysis of electron spectroscopy for chemical analysis of the transferred film formed during sliding wear for carbon fibre reinforced polyetheretherketone and its composites

The transferred film formed during sliding of carbon fibre reinforced polyetheretherketone (PEEK) influences greatly its tribological properties. In this paper a study on electron spectroscopy for chemical analysis (ESCA) for the films was carried out. It is indicated in this study that the transferred films formed of the carbon fibre reinforced PEEK composite are thinner, continuous and uniform, and have better tribological properties as compared with neat PEEK and PEEK-PTFE (polytetrafluoroethylene). The compositions of the transferred films are variable along the direction of thickness of the films, this reveals that there is a preferential transform in graphite and PTFE among the films. Based on this study, an adhesive transfer mechanism is proposed for the formation of transferred films during sliding wear.     

Metal-doped diamond-like carbon films synthesized by filter-arc deposition

Diamond-like carbon (DLC) thin films are extensively utilized in the semiconductor, electric and cutting machine industries owing to their high hardness, high elastic modulus, low friction coefficients and high chemical stability. DLC films are prepared by ion beam-assisted deposition (BAD), sputter deposition, plasma-enhanced chemical vapor deposition (PECVD), cathodic arc evaporation (CAE), and filter arc deposition (FAD). The major drawbacks of these methods are the degraded hardness associated with the low sp³/sp² bonding ratio, the rough surface and poor adhesion caused by the presence of particles. In this study, a self-developed filter arc deposition (FAD) system was employed to prepare metal-containing DLC films with a low particle density. The relationships between the DLC film properties, such as film structure, surface morphology and mechanical behavior, with variation of substrate bias and target current, are examined. Experimental results demonstrate that FAD-DLC films have a lower ratio, suggesting that FAD-DLC films have a greater sp³ bonding than the CAE-DLC films. FAD-DLC films also exhibit a low friction coefficient of 0.14 and half of the number of surface particles as in the CAE-DLC films. Introducing a CrN interfacial layer between the substrate and the DLC films enables the magnetic field strength of the filter to be controlled to improve the adhesion and effectively eliminate the contaminating particles. Accordingly, the FAD system improves the tribological properties of the DLC films.     

端羟基含苯基聚二甲基硅氧烷薄膜的制备和摩擦学性能研究

采用旋涂法在功能化基底上制备交联聚硅氧烷薄膜,用DF-PM型静-动摩擦试验机评价薄膜的摩擦学性能.在表面羟基化基上制备的聚硅氧烷薄膜同钢球对摩时,摩擦系数较低,耐磨寿命更长,适合作为低载荷下的减摩抗磨防护层.     

碳纤维增强聚醚醚酮复合材料滑动摩擦转移膜的ESCA研究

碳纤维增强聚醚醚酮在滑动时形成的转移膜对其摩擦学性能有重要影响,本文对此转移膜进行了Ｘ射线光电子能谱化学分析（ＥＳＣＡ）。表明,与纯聚醚醚酮和聚醚醚酮＋聚四氟乙烯相比,碳纤维增强聚醚醚酮形成的转移膜最薄,连续性与均匀性最好,因此其摩擦学性能最好。转移膜的成份沿着其深度方向发生变化,表明此膜中石墨和聚四氟乙烯存在着优先转移。在这一研究的基础上,本文对滑动摩擦转移膜的形成提出粘着转移机制。