Hard nanocomposite Ti-Si-N films prepared by DC reactive magnetron sputtering using Ti-Si mosaic target

Hard nanocomposite Ti-Si-N films were deposited on 321 stainless steel substrates by direct current (DC) reactive magnetron sputtering using a Ti-Si mosaic target consisting of a Ti plate and Si chips. The composition, microstructure, and mechanical properties were investigated using EDX, XRD, XPS, nano-indentation, and scratch tests. The results indicate that the hardness of the Ti-Si-N film gradually rises with increasing Si contents in the layer until the peak value of 42 GPa appears corresponding to a Si content of 11.2 at.%. The hardness then decreases with further increase in the Si content. XRD and XPS reveal that the hardest Ti-Si-N film consists of fine TiN crystallites (approximately 8 nm in size) in an amorphous Si₃N₄ matrix. Preferential growth of TiN is indicated by the XRD patterns. All the Ti-Si-N films show high adhesive strength as indicated by the scratch tests. The strengthening mechanism of the nanocomposite films is also discussed.     

Study of the structural changes induced by air oxidation in Ti-Si-N hard coatings

3-μm thick Ti-Si-N coatings were deposited on polished X38CrMoV5 substrates by sputtering a composite Ti-Si target in Ar-N₂ reactive mixture. Oxidation tests were performed in air at 700 °C during 2 h. Whatever the silicon content in the range 0-4 at.%, no silicon containing compound was detected by XRD before air oxidation and only the TiN phase was evidenced. The mean grain size estimated from the full width at half maximum of the TiN (111) diffraction peak was close to 10 nm. As commonly reported for Ti-Si-N films, the hardness showed a maximum at 51 GPa versus the Si content. After oxidation of the TiN film, XRD and micro-Raman analyses revealed the occurrence of the TiO₂ rutile phase in the whole films thickness, indicating the total oxidation of the TiN film. On the other hand, the addition of silicon into the TiN-based coatings induced a strong improvement of the film oxidation resistance. Indeed, the oxide thickness was reduced to nearly 0.4 μm for films containing 1.2 at.% Si. Moreover, the silicon addition gave rise to a change in the structure of the oxide layer. In fact, weak diffraction peaks of the TiO₂ anatase phase were detected by XRD. The presence of the anatase phase was clearly shown by micro-Raman spectroscopy, which is a very sensitive method to detect this TiO₂ phase. The intensity of the anatase micro-Raman bands increased with the silicon concentration, whereas that of rutile decreased.     

TiSiN nanocomposite coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD)

TiSiN nanocomposite coatings were deposited on stainless steel by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD) by reaction of TiCl₄ and SiCl₄ with NH₃ at 850 °C. Coatings were characterized by means of GD-OES, XPS and XRD. TiSiN coatings with a Si content of 9 at.% showed a hardness of 28 GPa (the hardness of TiN and SiN_x coatings was around 21 GPa) and a lower oxidation rate under dry air at 600 °C. Our results show for the first time that AP/FBR-CVD can be tuned for the deposition of nanocomposite ceramic coatings.     

Syntheses and mechanical properties of Mo-Si-N coatings by a hybrid coating system

In this work, comparative studies on microstructure and mechanical properties between Mo₂N and Mo-Si-N coatings were conducted. Ternary Mo-Si-N coatings were deposited on steel substrates (AISI D2) and Si wafers by a hybrid method, where arc ion plating (AIP) technique was combined with a magnetron sputtering technique. Instrumental analyses of X-ray diffractometer (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) revealed that the Mo-Si-N coatings must be a composite consisting of fine Mo₂N crystallites and amorphous Si₃N₄. The hardness value of Mo-Si-N coatings significantly increased from 22 GPa of Mo₂N coatings to about 37 GPa with Si content of 10 at.% due to the refinement of Mo₂N crystallites and the composite microstructure characteristics. The average friction coefficient of the Mo-Si-N coatings gradually decreased from 0.65 to 0.4 with increasing Si content up to 15 at.%. The effects of Si content on microstructure and mechanical properties of Mo-N coatings were systematically investigated.     

Oxidation resistance improvement of arc-evaporated TiN hard coatings by silicon addition

Ti-Si-N coatings were deposited on M2 steel by arc evaporation using a Ti-Si composite target in an industrial reactor. The films structure before and after heat treatment at 700 °C was characterised by XRD. In addition, two types of quantitative experiments were performed in thermobalance: oxidation rate was deduced from isothermal thermogravimetric analyses at 800 °C, while the temperature of oxidation beginning (Tc) was measured in dynamic mode. Tc was then calculated by a mathematical approximation based on the non-linear least square. The results were compared to those obtained using TiN and SiN_x standards.Depending on the deposition conditions, ternary films have been deposited with an atomic ratio Si/Ti of 0.10 and 0.15. The hardness of the films was close to 40 GPa. Only the TiN phase was detected by XRD. The mean crystal size was estimated to be in the 6-8 nm range, which suggested the nanocomposite nature of the coatings. After air oxidation at 700 °C, it was found that this crystal size was not affected by the thermal treatment, indicating a good thermal stability of the structure. Moreover, incorporation of silicon into TiN-based coatings led to a drastic decrease of their oxidation rate, together with a shift of 200 °C of Tc. The high resistance of oxidation of Ti-Si-N films at elevated temperature is attributable to the network of refractory SiN_x, which acted as a diffusion barrier for oxygen and insulated TiN nanograins from the aggressive atmosphere.     

Deposition of nanocomposite thin films by a hybrid cathodic arc and chemical vapour technique

A hybrid technique is described for the synthesis of nanocomposite Ti-Si-N thin films based on the reactive deposition of Ti produced from a cathodic arc source and silicon from a liquid tetramethylsilane (TMS), precursor. The influence of the TMS flow rate on the structure and mechanical properties has been investigated. The film structure was found to comprise TiN crystallites and amorphous Si₃N₄. The X-ray diffraction data showed that with increasing TMS flow there is a decrease in the TiN crystalline size from 33 nm to 4 nm. The hardness of the films was found to be strongly dependent on the Si content and reached a maximum value of 41 GPa at ∼ 5% Si content at a total pressure of nitrogen and TMS of 0.8 Pa. Hardness enhancement was found to arise from the nanostructural change induced due to the addition of an amorphous Si₃N₄ phase into the film. Transmission electron microscopy (TEM) analysis confirmed the structure of the Ti-Si-N composites.     

Si添加对TiN涂层微结构、力学及抗氧化性能的影响

借助EDX、XRD、SEM及纳米压痕研究了采用磁控溅射技术制备的TiN和Ti-Si-N涂层的微观组织结构和力学性能。研究表明:TiN和Ti-Si-N涂层均呈面心立方结构,Si元素的加入使TiN涂层的组织形貌由柱状晶结构转变为Si3N4界面相包裹纳米晶TiN的纳米晶复合结构;由于界面强化效应,Si的加入使涂层的硬度显著增加;涂层的应力也随着Si元素的加入而增加;Si的加入使TiN涂层的抗氧性得到明显改善。     

Ti-Si-N纳米复合薄膜的制备及其力学性能

采用离子束溅射与磁过滤阴极弧共沉积技术在单晶硅片(400)表面制备Si含量(摩尔分数)为3.2%~15.5%范围内的TiSiN薄膜。采用X射线光电子能谱(XPS)、电子散射谱(EDS)、X射线衍射仪(XRD)研究TiSiN薄膜的显微结构和力学性能。结果表明:低Si含量的薄膜以面心立方晶型的Ti(Si)N固溶体形式存在,择优晶面为(200)面;当Si含量饱和后,出现Ti(Si)N和Si3N4非晶相,形成Ti(Si)N/Si3N4纳米复合结构。薄膜硬度范围在22~26GPa,采用Si3N4小球为对偶时薄膜的摩擦因数均维持在0.13~0.17之间。Si含量为10.9%时,硬度达最大值,结合较低的粗糙度,使其摩擦因数和磨损率达到最低值。     

Syntheses and mechanical properties of Ti-B-C-N coatings by a plasma-enhanced chemical vapor deposition

Quaternary Ti-B-C-N films were synthesized on AISI 304 and Si wafer by a PECVD technique using a gaseous mixture of TiCl₄, BCl₃, CH₄, Ar, N₂, and H₂. The microstructure of Ti-B-C-N films was characterized by instrumental analyses of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM) in this work. Our Ti-B(9 at.%)-C-N coatings had a fine composite microstructure consisting of nano-sized Ti(C,N) crystallites surrounded by amorphous BN phase. The micro-hardness of Ti-B-C-N coatings steeply increased from ∼ 21 GPa of Ti-C-N up to ∼ 42 GPa of Ti-B(9 at.%)-C-N films. In addition, Ti-B-C-N coatings showed the lowest average friction coefficient compared with other coatings of TiN, TiC, and Ti-C-N coatings prepared under the same PECVD condition. A systematic investigation of the microstructure and mechanical properties of Ti-B-C-N coatings with various boron contents is reported in this paper.     

Mechanical Behaviors of Ti-Si-N Coatings Deposited by Bias Sputtering

Ti-Si-N hard coatings were deposited on steel substrates by reactive unbalanced magnetron sputtering from Ti and Si elemental targets in a mixture of Ar and N2 gases.The influences of negative bias voltage(in the range of-30 to-80 V)on the mechanical properties of the coatings were investigated.In particular,the critical cycle during dynamic impact tests was employed to indicate the bonding strength of the coatings.It was found that the Ti-Si-N coatings prepared at lower constant bias voltages could effectively improve the adhesion and the cyclic impact performance,but their hardness was dropped significantly to 13 GPa at a bias of-30 V.Higher bias voltage values induced greater hardness.A maximum hardness of 47 GPa was obtained at a bias of-60 V.However,the coating adhesion was worse in this case,and the number of impact cycles(～8×10 3)that the coatings could endure was much shorter than that of TiN binary coatings(～2×104).On the other hand,the bias voltage was varied linearly from-40 to-60 V during Ti-Si-N deposition.Under this circumstance,the hardness of the coatings deposited with the bias-graded configuration remained very high(42 GPa),and the adhesion strength was improved substantially.Also,the critical impact cycle could reach as high as 1.8×104.Therefore,bias-graded deposition can provide an effective processing route to prepare Ti-Si-N superhard coatings with high adhesion strength and impact resistance.     

Ti-Si-N films prepared by magnetron sputtering

A film growth mechanism, expressed in terms of depositing hard films onto the soft substrate, was proposed. Multicomponent thin films of Ti-Si-N were deposited onto Al substrate with a double-target magnetron sputtering system in an Ar-N2 gas mixture. The Ti-Si-N films were investigated by characterization techniques such as X-ray diffraction (XRD), atomic force microscope (AFM), electron probe microanalyzer (EPMA), scratch test and nanoindentation. The as-deposited films have a good adhesion to Al substrate and appear with smooth and lustrous surface. The films show nanocomposite structure with nano TiN grains embedded in an amorphous SiNx matrix. The maximum hardness of the films was achieved as high as 27 Gpa. The influences of the N2 flow rate and substrate temperature on the growth rate and quality of the films were also discussed. For all samples, the Ar flow rate was maintained constant at 10 ml. min-1, while the flow rate of N2 was varied to analyze the structural changes related to chemical composition and friction coefficient. The low temperature in the deposited Ti-Si-N films favors the formation of crystalline TiN, and it leads to a lower hardness at low N2 flow rate. At the same time, the thin films deposited are all crystallized well and bonded firmly to Al substrate, with smooth and lustrous appearance and high hardness provided. The results indicate that magnetron sputtering is a promising method to deposit hard films onto soft substrate.     

Effect of C2H2 gas flow rate on synthesis and characteristics of Ti–Si–C–N coating by cathodic arc plasma evaporation

The influences of C₂H₂ gas flow rate on the synthesis, microstructure, and mechanical properties of the Ti–Si–C–N films were investigated. Quaternary Ti–Si–C–N coatings were deposited on WC-Co substrates using Ti and TiSi (80:20 at.%) alloy target on a dual cathodic arc plasma evaporation system. The Ti–Si–C–N coatings were designed with Ti/TiN/TiSiN as an interlayer to enhance the adhesion strength between the top coating and substrate. The Ti–Si–C–N coatings were deposited under the mixture flow of N₂ and C₂H₂. Composition analysis showed that as the C₂H₂ gas flow increased, the Ti, Si and N contents decreased and the carbon content increased in the coatings. The results showed the maximum nanohardness of approximately 40 GPa with a friction coefficient of 0.7 was obtained at the carbon content of 28 at.% (C₂H₂ = 15 sccm). However, as the C₂H₂ gas flow rate increased from 15 to 40 sccm (carbon content from 25.2 to 56.3 at.%), both the hardness and friction coefficient reduced to 20 GPa and 0.3, respectively. Raman analysis indicated the microstructure of the deposited coating transformed from Ti–Si–C–N film to TiSi-containing diamond-like carbon films structure, which was strongly influenced by the C₂H₂ flow rate and is demarcated at a C₂H₂ flow of 20 sccm. The TiSi-containing diamond-like carbon films reveal low-friction and wear-resistant nature with an average friction coefficient between 0.3 and 0.4, lower than both TiSiN and Ti–Si–C–N films.     

Effects of nitrogen content on structure and mechanical properties of multi-element (AlCrNbSiTiV)N coating

AlCrNbSiTiV metallic and nitride films were deposited by reactive radio-frequency unbalanced magnetron sputtering. The composition, microstructure and mechanical properties of the coatings deposited at different nitrogen flow rates were evaluated. The deposited AlCrNbSiTiV metallic film has an amorphous structure. The nitride films, regardless of the nitrogen flow ratio, were found to have only an FCC structure register on the XRD profiles. A Stoichiometric nitride ratio, i.e. (Al,Cr,Nb,Si,Ti,V)₅₀ N₅₀ is attained for a nitrogen flow ratio (R_N) of 10% and higher. At the lowest nitrogen flow ratio there is a preferred (200) orientation; however the films become less textured at higher nitrogen flow ratios. Nano-grained structures are obtained for all flow ratios, with grain sizes ranging from 8.7 to 12.3 nm. At the highest nitrogen flow rates the coatings have a compressive stress of around 4.5 GPa. The (Al,Cr,Nb,Si,Ti,V)₅₀ N₅₀ nitride coatings have both a high hardness and elastic modulus of 41 and 360 GPa, respectively. The maximum H/E ratio occurs at a nitrogen flow ratio of 20%.     

Ti-Si-N复合膜的微结构及性能研究

为研究Si的加入及含量对薄膜结构和性能的影响,采用磁控反应溅射法制备了一系列不同Si含量的Ti-Si-N复合膜,采用XRD、微力学探针和SEM研究了薄膜的微结构、力学性能和抗氧化性.结果表明:随着Si含量的增加,薄膜晶粒尺寸减小,硬度升高,抗氧化性能提高.Si含量为4%～12%(原子数分数)时,晶粒尺寸随含量增加而急剧下降;当Si含量超过9%时,薄膜硬度处于峰值区;Si含量在7%以上时,薄膜具有较高的抗氧化能力.探讨了Ti-Si-N复合膜硬度升高和抗氧化能力提高的机理.     

多弧离子镀制备TiSiN涂层的结构及其摩擦学行为

为了研究Si含量对TiSiN涂层性能的影响,采用多弧离子镀技术在Ti6Al4V表面制备了不同Si含量(质量分数)的TiSiN涂层。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、电子能谱仪(EDS)、X射线光电子能谱仪(XPS)纳米压痕仪、摩擦磨损试验机表征其表面形貌、成分,力学性能及摩擦学性能。结果表明:随着靶材中Si含量的增加,涂层硬度从35GPa增加到42GPa。在TiSiN涂层中Si元素主要以Si3N4非晶态存在,形成了非晶Si3N4包裹TiN纳米晶结构。当靶材中Si含量为8%时,涂层在海水中的磨损率约为2.1×10-6 mm3/(N·m),此时涂层的摩擦性能最好。     

Microstructure and mechanical properties of pulsed DC magnetron sputtered nanocomposite Cr-Cu-N thin films

The nanocomposite Cr-Cu-N thin films have been deposited at a substrate temperature of 250 °C by a bipolar asymmetric pulsed DC reactive magnetron sputtering process. Different Cu contents ranging from 0.4 to 14.9 at.% were achieved. The structures of Cr-Cu-N thin films were analyzed by XRD. The surface and cross sectional morphologies of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanoindentation and scratch tests were adopted to evaluate the mechanical and tribological properties of Cr-Cu-N coatings. The influences of Cu content on the structure, mechanical and tribological properties of Cr-Cu-N coatings were explored. It is observed that the columnar structure no longer exists when the Cu content exceeds 10.9 at.%. The stability of CrN phase in the coating is influenced by the Cu content. The scratching coefficient of thin films decreases with increasing Cu content. Sufficient adhesion and tribological properties of Cr-Cu-N coatings are achieved. The maximum average hardness around 20 GPa and scratching coefficient around 0.1 are found in the coatings with around 2.1 to 2.6 at.% Cu in this work.     

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.     

Characterization of TiBN films grown by ion beam assisted deposition

This paper presents one of the first attempts to measure and model the ellipsometric data for ternary nitride coatings in general and TiBN coatings in particular. TiBN coatings with a functionally graded underlayer of Ti/TiN have been deposited at low temperatures (<200 °C) on a silicon substrate using ion beam assisted deposition (IBAD). The coating selected for detailed analysis had a total thickness of 1.5±0.2 μm. The deposited structure was characterized post-deposition using X-ray diffraction (XRD), atomic force microscopy (AFM), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), infrared spectroscopic ellipsometry (IR-SE), and visible-light spectroscopic ellipsometry (VIS-SE). The primary phases (TiB₂, TiN, and BN) in the film were identified using XRD. The surface morphology and nanocrystalline nature of the coating (grain size of 5–7 nm) were deduced using AFM. The chemical composition and phase composition of the sample was determined from RBS and XPS measurements and was subsequently deduced from the analysis of the VIS-SE data. The refractive indices for the constituent phases were deduced from the investigation of TiB_2, TiN and BN single layers with SE. Good correlation was observed between RBS, XPS and VIS-SE for the data on the TiBN sample. XPS and IR-SE suggested that BN formed in the amorphous form. The chemical composition study using these various techniques shows that in-situ SE is a potential technique to control the growth of ternary nitride coatings. Finally, the mechanical properties of the coating were evaluated using a nanoindenter. The hardness and elastic modulus were measured to be 42 GPa and 325 GPa, respectively.     

Influence of deposition conditions on mechanical and tribological properties of nanostructured TiN/CNx multilayer films

Nanostructured TiN/CN_x multilayer films were deposited onto Si (100) wafers and M42 high-speed-steel substrates using closed-filed unbalanced magnetron sputtering in which the deposition process was controlled by a closed loop optical emission monitor (OEM) to regulate the flow of N₂ gas. Multilayers with different carbon nitride (CN_x) layer thickness could be attained by varying the C target current (0.5 A to 2.0 A) during the deposition. It was found that the different bilayer thickness periods (i.e. the TiN layer thickness Λ_TiN was fixed at 3.0 nm while the CN_x layer thickness Λ_CNx was varied from 0.3 to 1.2 nm) significantly affected the mechanical and tribological properties of TiN/CN_x multilayer films. These multilayer films were characterized and analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), Rockwell-C adhesion test, scratch test, pin-on-disc tribometer, and nanoindentation measurements. XPS analyses revealed that the chemical states, such as TiN, TiC, TiN_xO_y and TiO_2, existed in a TiN layer. Nanoindentation results showed that the hardness was highly dependent on the bilayer thickness. A maximum hardness of ~ 41.0 GPa was observed in a multilayer film at bilayer thickness Λ_TiN = 3.0 nm and Λ_CNx = 0.9 nm. All multilayer films exhibited extreme elasticity with elastic recoveries as high as 80% at 5 mN maximum load. The compressive stresses in the films (in a range of 1.5-3.0 GPa) were strongly related to their microstructure, which depended mainly on the incorporation of nitrogen in the films. By scratch and Rockwell-C adhesion tests, the multilayer films with smaller bilayer thicknesses (Λ_TiN = 3.0 nm, Λ_CNx = 0.3 and 0.6 nm) exhibited the best adhesion and cohesive strength. The critical load value obtained was as high as ~ 78 N for the films with Λ_TiN = 3.0 nm, Λ_CNx = 0.9 nm. The friction coefficient value for a multilayer at Λ_TiN = 3.0 nm and Λ_CNx = 0.9 nm was found to be low 0.11. These adhesive properties and wear performance are also discussed on the basis of microstructure, mechanical properties and tribochemical wear mechanisms.     

基体脉冲偏压对TiN/Cu纳米复合薄膜组织结构、力学及耐磨性能的影响

本文采用轴向磁场增强电弧离子镀在高速钢基体上沉积了TiN/Cu纳米复合薄膜,研究了基体脉冲偏压幅值对薄膜成分、结构、力学性能及耐磨性能的影响。结果表明,薄膜中铜含量随着脉冲偏压幅值的增加先增加而后降低,在一个较低的范围内(1.3-2.1at.%)。X射线衍射结果表明所有的薄膜均出现TiN相,并未观察到Cu相。薄膜的择优取向随着脉冲偏压幅值的增加而改变。薄膜的最高硬度为36GPa,是在脉冲偏压幅值为-200V时得到的,对应了1.6at.%的Cu含量。与纯的TiN薄膜相比,Cu的添加明显增强了薄膜的耐磨性能。