采用磁过滤电弧离子镀技术在高速钢基体上沉积TiAlN涂层。研究了N2分压对TiAlN涂层的相结构、化学成分、力学性能、沉积速率、表面粗糙度、结合强度以及摩擦磨损性能的影响。结果表明,N2分压的变化对涂层的结构与性能影响显著。随着N2分压的增加,TiAlN涂层呈现 (111) 择优取向,其硬度最高可达34 GPa。涂层的沉积速率和表面粗糙度随着N2分压的增大而逐渐降低。此外,由于大颗粒的去除使得涂层表面质量得到提升,所制备的TiAlN涂层均具有较低的摩擦系数 (0.15~0.33),并且呈现良好的抗磨损性能,其最低磨损率为8.8×10-7 mm3/(Nm)。
TiAlN coatings were deposited on high-speed steel substrate by filtered arc ion plating technic. Effect of nitrogen partial pressure on phase structure, chemical composition, mechanical properties, deposition rate, surface roughness, adhesion and tribological properties of TiAlN coatings is studied. The results reveal that there is a strong influence of nitrogen partial pressure on coating structure and properties. By varying the nitrogen partial pressure, the maximum hardness of 34 GPa is achieved for the TiAlN coating with a strong (111) preferred orientation. The deposition rate and surface roughness of the coatings decrease gradually with increasing the nitrogen partial pressure. Due to the improved surface quality by eliminating the most of macro-particles, all the TiAlN coatings show relatively low coefficient of friction, which varies in the range of 0.15~0.33. The coatings also possess good wear resistance, showing the lowest wear rate of 8.8×10-7 mm3/(Nm).
选用TiAl (70% (原子分数) Ti,30%Al) 合金靶作为阴极靶材,其直径为60 mm。沉积涂层的基体材料选用硬度为HRC 63的高速钢,样品尺寸为20 mm×20 mm×3 mm。实验前对基体样品进行机械研磨 (使用SiC砂纸逐级磨至2000#),抛光 (先后使用2.5和1 μm粒径金刚石研磨膏),最后在丙酮及酒精中超声清洗各10 min。采用DY-DH-4A型磁过滤电弧离子镀设备沉积TiAlN涂层,涂层沉积前将设备真空室本底真空抽至4×10-3 Pa,然后将Ar气引入真空室,使其工作压强保持在0.3 Pa。实验中弧源电流设置为90 A,在-800 V脉冲基体偏压下对基体表面进行高能粒子轰击5 min,以去除基体表面的氧化物和污染物,随后将基体偏压调至-500和-200 V,分别进行3 min的金属过渡层沉积。此后基体偏压保持在-200 V,将Ar气压强调至0.15 Pa,同时引入N2并在不同的N2分压下沉积TiAlN涂层,时长90 min。沉积过程在室温下进行,没有应用额外的加热源;基体样品安装在挂架上,转速为26 r/min。
采用D/Max 2400 X射线衍射仪 (XRD) 分析涂层的相结构,入射X射线为Cu靶的
2.1.1 TiAlN涂层的晶体结构 如
2.1.3 TiAlN涂层相结构与化学成分的相互关系 TiAlN涂层中Ti/Al原子比的变化趋势在
2.2.1 TiAlN涂层的硬度和弹性模量 如
2.2.2 TiAlN涂层的表面粗糙度和沉积速率 由
(2) N2分压为0.4 Pa下所制备的具有最高硬度 (34 GPa) 的TiAlN涂层表现出了最低的结合强度和抗摩擦磨损性能,而在N2分压为0.6 Pa下硬度为33.4 GPa的TiAlN涂层表现出最佳的综合性能。
The authors have declared that no competing interests exist.
61Texturing was performed on rake face of the tool in preferred orientation by wire-EDM process.61TiN and TiAlN coatings with 4μm thickness were made on the cutting tool using Physical Vapor Deposition (PVD) technique.61Machining forces and surface roughness were found to be less in TiAlN coated textured tools.61Machinability of Ti-6Al-4V alloy can be increased by textured tools especially PE.T with TiAlN coated tool.
61Comparison of monolithically grown and multilayered CAE coatings61Ti0.45Al0.36Ta0.19N and TiAlN/TaAlN coatings exhibit enhanced thermal stability.61Pronounced age-hardening of 37±2 and 35±2GPa between 1000 and 1100°C61Only monolithic Ti0.45Al0.36Ta0.19N withstands 20h oxidation tests at 850°C.
61Multicomponent TiAlSiN hard coating is deposited on 316L SS as bipolar plates for PEMFC.61Electrochemical results indicate that the TiAlSiN coating has excellent corrosion resistance in PEMFC's environment.61The TiAlSiN coating satisfies the quality requirement for BPs (<0.0102Ω02cm2).61The TiAlSiN coating should be more conducting in cathode side of a PEMFC.
Chromium and titanium–aluminium nitrides were deposited, by physical vapour deposition techniques, on stainless steel substrates and their corrosion behaviour was studied in two different environments: a gaseous environment containing HCl at a temperature of 350°C and a 1 M HCl aqueous solution environment, at room temperature. X-ray photoelectron spectroscopy was used to study the mechanism of the reactions that occurred in the gaseous environment. This analysis shows an oxidation of the surface caused by the substitution of nitrogen by oxygen. Open circuit potential and potentiodynamic polarisation measurements were performed in the aqueous solution environment. The aqueous corrosion behaviour of the nitride coatings is strongly dependent on the microdefect density of the coating.
Hydrothermal corrosion of thin TiAlN and CrN PVD films (of 3μm thickness) in 100 MPa water over a temperature range of 20–950 °C is compared to the behavior of TiN films over the same T– P conditions. Corrosion resistance increases in the sequence TiN → TiAlN → CrN. A FeTiO 3 (ilmenite) layer on the surface of the TiAlN film is almost chromium-free and provides protective properties up to 700 °C, whilst ülvospinel formation leads to spallation of oxide scale due to high level growth stresses. Formation of a very stable spinel scale on the surface of the CrN films provides long-term corrosion protection in 100 MPa water up to 800 °C. Nitride films on low-alloyed steel can substitute for expensive super alloy in wet air oxidation systems, with working temperatures up to 700 °C in the case of TiAlN, or 800 °C in the case of CrN coatings.
In this study, thin films of titanium nitride were prepared by the arc ion plating process and deposited onto polished WC-Co substrates to investigate macroparticles (MPs), morphology and surface roughness. The deposition variables explored were arc current, deposition time, substrate distance, nitrogen pressure, substrate bias, target thickness and electromagnetic coil current of the target. The results show that the number of MPs and their area ration vary directly with arc current, deposition time and target thickness, inversely with substrate distance, substrate bias and nitrogen pressure. Positive relationships exist between the deposition rate and the number of MPs, and between the deposition rate and the surface roughness.
Abstract The cathode spot of a vacuum arc generates a spray of liquid droplets directed almost parallel to the cathode surface as well as a highly ionized plasma jet directed normal to the cathode surface. Theories include droplet ejection by the reaction force of back-streaming ions on the underlying microscopic liquid pool and formation from explosive debris. The droplets have an exponentially decreasing size distribution and velocities ranging from 10 to 800 m s-1. During their motion in the arc, the macroparticles can be further accelerated and deflected, obtain a negative charge, be heated to temperatures of around 2000 掳C and evaporate. The macroparticle mass emission rate from the cathode increases with increasing arc current and average cathode surface temperature and decreases with increasing cathode material melting temperature. Cathodes with gaseous surface layers have less macroparticle erosion than clean cathodes. Droplet production can be reduced by maintaining as low a temperature as possible on the cathode surface near the cathode spots by providing effective cooling, by operating at low cathode current densities, by using magnetic fields to provide for directed rapid cathode spot movement and, in reactive deposition, by operating a poisoned cathode. Macroparticle inclusions can be reduced by substrate biasing and by concentrating the plasma flow with magnetic fields and can be eliminated completely by using a curved magnetic plasma duct.
PVD method is used to deposit (Ti,Al)N coatings on the surface of W6Mo5Cr4V2 steels. The value of bias voltage changes from -100V to -400V. X-ray diffraction (XRD), Scanning electron microscope(SEM) and UNMT-1 were employed to analysis the microstructure and mechanical properties of (Ti,Al)N coatings. The research results showed that the microstructure and mechanical properties of coatings became better when the value of bias voltage was -400V. The size and quantity of particles on coatings both decreased obviously. The adhesion between coatings and substrates increase to 54.6N. The hardness of (Ti,Al)N coatings rise to 39.7N.
采用弯曲磁过滤真空阴极放电弧 离子镀法制备高质量TiN薄膜。用场致发射电子扫描显微镜观察薄膜表面与截面形貌。分析弯曲磁过滤对膜表面质量与晶粒尺寸、膜基结合形态的影响。磁过滤能 有效减少大颗粒数量,减小大颗粒尺寸,形成光滑的TiN薄膜表面,细化TiN晶粒,形成结合紧密的膜基结构。
Nanocrystalline titanium nitride thin films have been deposited by high pressure reactive magnetron sputtering from an elemental titanium target using a mixture of an inert gas and nitrogen. The mean crystallite or grain size in these films is in the range 8鈥12 nm as measured from X-ray line broadening. Interestingly, the type of inert gas used in the sputtering gas mixture significantly influences the microstructure and preferred orientation in these films. Thus, using a 70% He+30% N 2 gas mixture results in a strongly (002) oriented film whereas using a 70% Ar+30% N 2 gas mixture results in a strongly (111) oriented film with a similar grain size. In addition, films have also been deposited using pure nitrogen as the sputtering gas. These films exhibited a strong (002) orientation and had a significantly larger grain size as compared with those deposited using a mixture of an inert gas and nitrogen. Details of the microstructure in these films have been investigated by transmission electron microscopy. The ability to tailor the size and preferred orientation of grains in the TiN thin films (by proper choice of sputtering gas) is expected to have a significant impact on the properties of these films in a variety of technological applications.
ABSTRACT Thin TiN films were deposited at ambient temperature on silicon substrates using the filtered cathodic vacuum-arc technique. The nitrogen flow rate, deposition rate and substrate bias were varied systematically to investigate their effect on the mechanical and structural properties of the films. It was found that an increase in the nitrogen flow rate results in an increased hardness, surface roughness and grain size. The increased ion bombardment due to the higher amount of nitrogen ions makes film nucleation favourable on the denser (111) orientation. An increase in deposition rate results in an increase of stress, hardness and surface roughness. This is due to the increase in the momentum transfer resulting in film densification. Increasing the negative substrate bias decreases both the film stress and the hardness, which can be attributed to ion-induced stress-relief behaviour at higher momentum-energy transfer. The results demonstrate the dominant influence of ion-energy flux on the properties of the films.
(Ti, Al)N films were deposited by a new off-plane double bend filtered cathodic vacuum arc technique under a nitrogen atmosphere. The substrates were held at ambient temperatures during the deposition of (Ti, Al)N films. Atomic force microscopy and X-ray diffraction were used to characterize the structure of the films. The internal stress, micro-hardness and Young's modulus were also studied. All (Ti, Al)N films deposited were atomic smooth. The surface roughness increases with increasing nitrogen pressure. The crystal structure, internal stress and mechanical properties of (Ti, Al)N films are strongly dependent on the nitrogen partial pressure. At lower nitrogen pressure, the structure of (Ti, Al)N films is composed of (Ti, Al)N phase, metal-rich nitride phase and metallic phase. The deposited films show (111) preferred orientation growth. With increasing nitrogen pressure, the structure change to single fcc type (Ti, Al)N phase, and a mixed (111) and (220) orientation was observed. Further increase of nitrogen pressure causes the disappearance of (Ti, Al)N phase and the formation of porous films. The hardness and Young's modulus of (Ti, Al)N films increase to a maximum at the pressure of 1.98脳10 鈭1 Pa, then decrease with increasing nitrogen pressure. The variation trend of internal stress in the films with nitrogen pressure is the same as that of hardness.