Analysis of hardness of nanocrystalline coatings of aluminum-rich Ti1???x Al x N

Titanium aluminum nitride coatings were fabricated by a d.c. magnetron sputtering system from a Ti?CAl (60/40?wt%) target. Coatings were deposited on steel substrates, at a substrate temperature of 250?°C and a bias voltage of ?80?V. The nitrogen flow was varied from 1·5?C6?sccm and the Ar flow was kept constant at 20?sccm. The morphology and microstructure of the coatings were analysed by X-ray diffraction and scanning electron microscopy. The results of X-ray diffraction showed the presence of two cubic crystalline phases, TiN and AlN, which were confirmed by X-ray photoelectron spectroscopy. The Vicker hardness was obtained by the effective model of indentation. It was observed that the hardness of the coatings decreases from 22·8?C9·5?GPa with an increased nitrogen content from 1·5?C4·5?sccm. Subsequently, the hardness increased to 22·1?GPa by increasing nitrogen to 6?sccm. The behavior of hardness with grain size variation is consistent with the Hall-Peth relationship. The high value in the hardness of the coatings is mainly attributed to small grain sizes and the compressive stress present.     

An analysis of macroparticle-related defects on CrCN and CrN coatings in dependence of the substrate bias voltage

Chromium nitride coatings with and without a carbon content being assigned as CrCN and CrN were prepared by cathodic arc evaporation. The effect of negative substrate bias voltages (10-300 V) on the microstructure, phase composition and morphology of the coating surface was studied. X-ray diffraction data show that almost all coatings crystallized in the cubic structure with (111) and (200) diffraction lines appearing only for low negative bias voltage and a (220) diffraction line being present for the coatings deposited at higher negative bias voltages. For CrN coatings obtained at −300 V a hexagonal structure was also observed. In case of CrCN coatings the (220) diffraction line shows much higher intensity than in case of CrN coatings and was significantly broadened. On the surface of the coatings a large number of macroparticles of different size was observed. An increase of bias voltage causes a reduction of the areal density of macroparticles and a decrease of the mean surface roughness Ra.     

Deposition and characterization of smooth ultra-nanocrystalline diamond film in CH4/H2/Ar by microwave plasma chemical vapor deposition

The smooth ultra-nanocrystalline diamond (UNCD) films were prepared by microwave plasma chemical vapor deposition (MWCVD) using argon-rich CH₄/H₂/Ar plasmas with varying argon concentration from 96% to 98% and negative bias voltage from 0 to −150 V. The influences of argon concentration and negative bias voltage on the microstructure, morphology and phase composition of the deposited UNCD films are investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), atom force microscopy (AFM), and visible and UV Raman spectroscopy. It was found that the introduction of argon in the plasma caused the grain size and surface roughness decrease. The RMS surface roughness of 9.6 nm (10 micron square area) and grain size of about 5.7 nm of smooth UNCD films were achieved on Si(100) substrate. Detailed experimental results and mechanisms for UNCD film deposition in argon-based plasma are discussed. The deposited highly smooth UNCD film is also expected to be applicable in medical implants, surface acoustic wave (SAW) devices and micro-electromechanical systems (MEMS).     

Hardness and tribology measurements on ZrN coatings deposited by reactive sputtering technique

ZrN coatings have been grown in an rf sputtering deposition chamber, using different ratios of Ar/N₂ (5/1, 5/5, 1/5) in the reactive gas flow. After deposition, the coatings were thermally treated in a 500 °C oxygen atmosphere, in order to test the thermal stability of the layers or the oxynitride formation. The chemical composition, surface roughness and structural, mechanical and tribological properties of the as-deposited and annealed samples have been measured by energy dispersive spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffractometry, nanoindentation and pin-on-disk techniques, respectively. Deposition parameters determine the growth rate, crystalline structure and surface roughness, which affect the mechanical and tribological behaviour of the samples. The best mechanical and tribological performance and highest growth rate was found for the sample grown under 5 sccm Ar+1 sccm N₂ gas flow. The as-deposited layers have a low wear, showing an increase in hardness after annealing making them suitable as protective layers.     

Nitrogen-incorporation induced changes in the microstructure of nanocrystalline WO3 thin films

Nitrogen incorporated tungsten oxide (WO₃) films were grown by reactive magnetron sputter-deposition by varying the nitrogen content in the reactive gas mixture keeping the deposition temperature fixed at 400 °C. The crystal structure, surface morphology, chemical composition, and electrical resistivity of nitrogen doped WO₃ films were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrical conductivity measurements. The results indicate that the nitrogen-incorporation induced changes in the microstructure and electrical properties of WO₃ films are significant. XRD measurements coupled with SEM analysis indicate that the increasing nitrogen content decreases the grain size and crystal quality. The nitrogen concentration increases from 0 at.% to 1.35 at.% with increasing nitrogen flow rate from 0 to 20 sccm. The corresponding dc electrical conductivity of the films had shown a decreasing trend with increasing nitrogen content.     

Mechanical and tribological properties of V–C–N coatings as a function of applied bias voltage

The aim of this work is to determine the mechanical and tribological behavior of V–C–N coatings deposited on industrial steel substrates (AISI 8620) by using carbon–nitride coatings as a protective materials. The coatings were deposited on silicon (100) and steel substrates via magnetron sputtering and by varying the applied bias voltage. The V–C–N coatings were characterized by X-ray diffraction (XRD), exhibiting the crystallography orientations (111) fcc for V–C–N conjugated by VC (111) and VN (111) phases and (200) fcc for VCN conjugated by VC (200) and VN (200) phases. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition of metallic carbon–nitride materials. Atomic force microcopy (AFM) was used for determination of the change in grain size and roughness with deposition parameters. By using nanoindentation, pin-on-disk, and scratch test curves, it was possible to estimate the hardness, friction and critical load of V–C–N surface material. Scanning electron microscopy (SEM) was performed to analyze morphological surfaces changes. Mechanical and tribological behavior in VCN/steel_[8620] system, as a function of a bias voltage deposition, showed an increase of 58% in the hardness, and reduction of 39% in the friction coefficient, indicating thus that the V–C–N coatings may be a promising material for industrial applications.     

Reactive magnetron sputtering of indium tin oxide films on acrylics – morphology and bonding state

Indium tin oxide (ITO) films were deposited on acrylics by low temperature reactive magnetron sputtering. The effects of oxygen flow and bias voltage on the microstructure, surface morphology and bonding state of films were evaluated. In this investigation, X-ray photoelectron spectroscopy, X-ray diffraction, Atomic force microscope were used. It was found that the grain size of ITO films increased and surface roughness decreased with the increase of oxygen flow rate. The XPS spectra of In 3d and Sn 3d indicated that the oxygen flow had little effect on the binding energy of ITO films. The relative strength of O²⁻_II increased, while that of O²⁻_I decreased with increasing oxygen flow rate. The grain size increased with the bias voltage. However, at a maximum voltage of −90 V fine grains were detected due to the formation of numerous nuclei resulting from bombardment of high energy particles. The bias voltage had little effect on the bonding state of In, Sn and O ions.     

Deposition of nano-scaled CrTiAlN multilayer coatings with different negative bias voltage on Mg alloy by unbalanced magnetron sputtering

In a magnetron sputtering system, the negative substrate bias voltage has been used as a basic process parameter to modify the deposition structure and properties of coatings. In this paper we report the effect of bias voltage ranging from −40 V to −90 V on nano-scaled CrN/TiN/CrN/AlN (CrTiAlN) multilayer coatings synthesized on a Mg alloy by a closed-field unbalanced magnetron sputtering ion plating system in a gas mixture of Ar + N₂. The technological temperature and atomic concentration in the multilayer coatings were controlled by adjusting the current density of different metal magnetron targets and the plasma optical emission monitor. The composition, crystallographic structure, deposition model and friction coefficient of multilayer coatings were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ball-on-disc testing. The experimental results show that the deposition model and friction coefficient of nano-scaled CrTiAlN multilayer coatings were significantly affected by the negative bias voltage (V_b). The nitride species in multilayer coatings mainly involve CrN, AlN and TiN, and XRD analysis shows that the crystallographic structure was face-centered cubic. Under different bias voltage conditions, the multilayer coating composition shows a fluctuation, and the Al and Cr concentrations respond in the opposite sense to the bias voltage, attaining their greatest values at V_b = −70 V. The surface and cross-sectional morphology shows deposition model change from a columnar model into non-columnar model with the increase in negative bias voltage. The friction coefficient of the nano-scaled multilayer coatings at V_b = −55 V stabilize after 10 000 cycles.     

基体负偏压对类金刚石涂层结构和性能的影响

采用直流等离子体增强化学气相沉积技术(DC-PECVD),通过控制基体负偏压的变化在YG8硬质合金基体上制备一系列类金刚石涂层。选用扫描电子显微镜、原子力显微镜、拉曼光谱、X射线光电子能谱、粗糙度仪对涂层形貌和结构进行表征测试。同时,利用显微硬度计、划痕测试仪系统地分析涂层的显微硬度和界面结合性能。结果表明:随着负偏压增大,涂层表面形貌逐渐平整光滑、致密,颗粒尺寸减小及数量降低。拉曼光谱表明,涂层具有典型的类金刚石结构,涂层中sp3键含量呈先增大后减小趋势,最大值约67.9%出现在负偏压为1000V左右,负偏压过大导致sp3键含量降低。显微硬度随负偏压变化规律与sp3键基本相符,sp3键含量决定显微硬度值大小。负偏压过大对吸附离子产生反溅射作用导致涂层厚度减小。当负偏压为1100V时,涂层与基体间的界面结合性能最优。     

Effect of nitrogen flow rate on properties of nanostructured TiZrN thin films produced by radio frequency magnetron sputtering

The effect of nitrogen flow rate on structure and properties of (Ti,Zr)N thin films was investigated in the study. Two types of (Ti,Zr)N thin films were found with different nitrogen flow rates, one is the single-phase solid solution of (Ti,Zr)N that appeared for nitrogen flow rates of 2-7 sccm, the other one is the phase of both (Ti,Zr)N and TiZr mixture for the lower nitrogen flow rates of 1 sccm. The grain size of the films was also determined by X-ray diffraction, and the size was less than 20 nm. The (Ti,Zr)N films show excellent hardness ranging from 35.5 to 37.5 GPa with exhibiting (111) preferred orientation.     

Influence of nitrogen flow rates on materials properties of CrN x films grown by reactive magnetron sputtering

Chromium nitride (CrN) hard thin films were deposited on different substrates by reactive direct current (d.c.) magnetron sputtering with different nitrogen flow rates. The X-ray diffraction patterns showed mixed Cr₂N and CrN phases. The variations in structural parameters are discussed. The grain size increased with increasing nitrogen flow rates. Scanning electron microscopy image showed columnar and dense microstructure with varying nitrogen flow rates. An elemental analysis of the samples was realized by means of energy dispersive spectroscopy. The electrical studies indicated the semiconducting behaviour of the films at the nitrogen flow rate of 15?sccm.     

Deposition,structure and hardness of Ti–Cu–N hard films prepared by pulse biased arc ion plating

In this work, Ti–Cu–N hard nanocomposite films were deposited on 304 stainless steel (SS) substrate by using pulse biased arc ion plating system with Ti–Cu alloy target. The effects of negative substrate pulse bias voltages on chemical composition, structure, morphology and mechanical properties were investigated. The composition and structure of these films was found to be dependent on the pulse bias, whereas the pulse biases put little influence on hardness of these films. The XPS spectra of Cu 2p showed that obtained peak values correspond to pure metallic Cu. Cu content in Ti–Cu–N nanocomposite films changed with pulse bias voltage. In addition, X-ray diffraction analysis showed that a pronounced TiN (111) texture is observed under low pulse bias voltage while it changed to TiN (220) orientation under high pulse bias voltage. Surface roughness of the Ti–Cu–N nanocomposite films achieved to the minimum value of 0.11 μm with the negative pulse bias voltage of −600 V. The average grain size of TiN was less than 17 nm. The mechanical properties of Ti–Cu–N hard films investigated by nanoindentation revealed that the hardness was about 22–24 GPa and the hardness enhancement was not obtained.     

Deposition,structure and hardness of Ti–Cu–N hard films prepared by pulse biased arc ion plating

In this work, Ti–Cu–N hard nanocomposite films were deposited on 304 stainless steel (SS) substrate by using pulse biased arc ion plating system with Ti–Cu alloy target. The effects of negative substrate pulse bias voltages on chemical composition, structure, morphology and mechanical properties were investigated. The composition and structure of these films was found to be dependent on the pulse bias, whereas the pulse biases put little influence on hardness of these films. The XPS spectra of Cu 2p showed that obtained peak values correspond to pure metallic Cu. Cu content in Ti–Cu–N nanocomposite films changed with pulse bias voltage. In addition, X-ray diffraction analysis showed that a pronounced TiN (111) texture is observed under low pulse bias voltage while it changed to TiN (220) orientation under high pulse bias voltage. Surface roughness of the Ti–Cu–N nanocomposite films achieved to the minimum value of 0.11 μm with the negative pulse bias voltage of ?600 V. The average grain size of TiN was less than 17 nm. The mechanical properties of Ti–Cu–N hard films investigated by nanoindentation revealed that the hardness was about 22–24 GPa and the hardness enhancement was not obtained.     

Effect of bias voltage on microstructure and mechanical properties of arc evaporated (Ti, Al)N hard coatings

In the present study, authors report on the effect that substrate bias voltage has on the microstructure and mechanical properties of (Ti, Al)N hard coatings deposited with cathodic arc evaporation (CAE) technique. The coatings were deposited from a Ti _{0· 5}Al _{0· 5} powder metallurgical target in a reactive nitrogen atmosphere at three different bias voltages: U _B ?=??? 25, ?50 and ?100 V. The coatings were characterized in terms of compositional, microstructural and mechanical properties. Microstructure of the coatings was investigated with the aid of X-ray diffraction in glancing angle mode, which revealed information on phase composition, crystallite size, stress-free lattice parameter and residual stress. Mechanical properties were deduced from nano-indentation measurements. The residual stress in all the coatings was compressive and increased with increasing bias voltage in a manner similar to that reported in literature for Ti–Al–N coatings deposited with CAE. The bias voltage was also found to significantly influence the phase composition and crystallite size. At ?25 V bias voltage the coating was found in single phase fcc-(Ti, Al)N and with relatively large crystallites of ~ 9 nm. At higher bias voltages (?50 and ?100 V), the coatings were found in dual phase fcc-(Ti, Al)N and fcc-AlN and the size of crystallites reduced to approximately 5 nm. The reduction of crystallite size and the increase of compressive residual stress with increasing bias voltage both contributed to an increase in hardness of the coatings.     

Influence of the aluminum incorporation on the structure of sputtered ZrNx films deposited at low temperatures

We have studied the influence of the Al incorporation in the crystalline structure of ZrN thin films deposited by dc magnetron sputtering processes at low temperature. The incorporation of the aluminum in the films depends directly on the Ar/N₂ ratio in the gas mixture and the power applied to the aluminum cathode during the deposition. The chemical composition and the crystalline structure of the films were analyzed by Energy Dispersive X-ray (EDX) spectroscopy and X-ray Diffraction (XRD), respectively. When Al atoms are incorporated into the ZrN coatings, the strong ZrN (200) preferred orientation is modified to a combination of phases related to (111) ZrN with a contribution of cubic (111) AlN and possibly (211) Zr₃N_4, which are detected by XRD for high aluminum concentrations. Fourier Transform Infrared (FTIR)spectroscopy allowed us to complete the identification of the nitrides and oxides incorporated into the deposited films. The effect of a bias voltage applied to the substrate has also been investigated and related to the changes in the microstructure and in the nanohardness values of the ZrAlN films.     

Effect of substrate bias voltage on structural and mechanical properties of pulsed DC magnetron sputtered TiN-MoSx composite coatings

TiN-MoS_x composite coatings were deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) using separate Ti and MoS₂ targets in an Ar and N₂ gas environment. The effect of substrate bias voltage on the structure and mechanical properties of TiN-MoS_x composite coating has been studied. The structure and composition of the coating were evaluated using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) by X-ray and grazing incidence X-ray diffraction (GIXRD). Scratch adhesion tests, Vickers microhardness tests and ball-on-disc tests with a cemented carbide (WC-6%Co) ball were carried out to investigate mechanical properties of the coating. Application of substrate bias was found to transform the structure of TiN-MoS_x composite coating from open columnar to a dense columnar structure. The changes in grain size and texture coefficient appear to be associated with variation in substrate bias voltage. The mechanical properties of the coating such as adhesion and composite microhardness were also observed to be related to the change in bias voltage. A maximum hardness of 22 GPa was obtained for a coating deposited at substrate bias voltage of −40 V. The improved structural and mechanical properties of the coating deposited at −40 V were also reflected in its excellent wear resistance property.     

Microstructure and mechanical properties of CrAlN coatings deposited by modified ion beam enhanced magnetron sputtering on AISI H13 steel

CrAlN coatings were deposited on silicon and AISI H13 steel substrates using a modified ion beam enhanced magnetron sputtering system. At the modified ion beam bombardment, the effects of bias voltage and Al/(Cr + Al) ratio on microstructure and mechanical properties of the coatings were studied. The X-ray diffraction data showed that all CrAlN coatings were crystallized in the cubic NaCl B1 structure, showing the (111), (200), and (220) preferential orientation. It is noted that the (111) diffraction peak intensity decreased and the peaks broadened as the bias voltage increased at the same ratio of Al/Cr targets power, which is attributed to the variation in the grain size and microstrain. The microstructure observation of the coatings by field emission scanning electron microscopy cross-section morphology shows that the columnar grain became more compact and dense with increasing substrate bias voltage and Al concentration. At a substrate bias voltage of −120 V and a Al/(Cr + Al) ratio of 40%, the coating had the highest hardness (33.8 GPa) and excellent adhesion to the substrate.     

氧气流量对MPCVD法制备超纳米金刚石膜的影响

采用微波等离子化学气相沉积技术,以CH_4/H_2/Ar为气源,通过调节O_2流量,增强等离子体对非金刚石相的刻蚀能力,提高超纳米金刚石膜中金刚石相的含量。并利用扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱及X射线光电子能谱(XPS)分别对超纳米金刚石膜的形貌、生长速率、晶型、晶粒尺寸及金刚石含量进行了表征分析,重点研究了O_2流量对晶粒尺寸及金刚石含量的影响。实验结果表明,随O_2流量的增加,平均晶粒尺寸从8.4nm增大至16.1nm,随后减小至9.6nm;当O_2流量为0.7sccm时,金刚石相含量由71.58%提升至85.46%,平均晶粒尺寸约为9.6nm。     

Effect of composition on mechanical behaviour of diamond-like carbon coatings modified with titanium

In this study, diamond-like carbon (DLC) films modified with titanium were deposited by plasma decomposition of metallorganic precursor, titanium isopropoxide in CH₄/H₂/Ar gas atmosphere. The obtained films were composed of amorphous titanium oxide and nanocrystalline titanium carbide, embedded in an amorphous hydrogenated (a-C:H) matrix. The TiC/TiO₂ ratio in the DLC matrix was found to be dependent on the deposition parameters. The dependence of the films chemical composition on gas mixture and substrate temperature was investigated by X-ray photoelectron spectroscopy, whereas the crystallinity of TiC nanoparticles and their dimension were evaluated by X-ray diffraction. The size of TiC crystallites varied from 10 to 35 nm, depending on the process parameters. The intrinsic hardness of 10-13 GPa, elastic modulus of 170-200 GPa and hardness-to-modulus ratio of obtained coatings were measured by the nanoindentation technique. Obtained results demonstrated a correlation of mechanical properties with the chemical composition and the ratio of amorphous/crystalline phases in the films. In particular, the formation of nanocrystalline TiC with atomic concentration not exceeding 10% and with grain size between 10 nm and 15 nm resulted in significantly enhanced mechanical properties of composite material in comparison with ordinary DLC films.     

基体偏压对AlCrSiN涂层结构及力学性能的影响

AlCrSiN涂层因具有高硬度、优异的耐磨损性及抗高温氧化性而备受关注。为提高AlCrSiN涂层的性能,采用电弧离子镀技术制备了AlCrSiN涂层,研究了基体偏压对AlCrSiN涂层微观组织及力学性能的影响。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度计、划痕仪及球-盘式摩擦磨损试验机对AlCrSiN涂层的表面形貌、物相组成和力学性能进行表征。研究结果表明:不同基体偏压的AlCrSiN涂层具有B1-NaCl晶体结构和无柱状晶结构;适当提高基体偏压,可细化AlCrSiN涂层的晶粒,提高涂层的表面质量及致密性,从而提高涂层的性能;基体偏压为150V的涂层致密性最好,具有更高的硬度(3 430HV)、结合力(76N)及更好的耐磨损性能。