Mechanical and tribological properties evaluation of cathodic arc deposited CrN/ZrN multilayer coatings

Five nanostructured CrN/ZrN multilayer coatings were deposited periodically by cathodic arc evaporation. The bilayer periods of the CrN/ZrN multilayer coatings were controlled in the range of 5 to 30 nm. The structures and bilayer period of the multilayer coatings were characterized by an X-ray diffractometer. The microstructures of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Nanoindentation, scratch tests, Daimler–Benz Rockwell-C (HRC-DB) adhesion tests, microhardness and pin-on-disk wear tests were used to evaluate the hardness, adhesion, indentation toughness and tribological properties of thin films, respectively. It was found that the hardness and tribological properties were strongly influenced by the bilayer period of the CrN/ZrN multilayer coatings. An optimal combination of mechanical properties and excellent tribological behavior was found for a coating with a critical bilayer period of 30 nm.     

Tribological behavior of CrN/WN multilayer coatings grown by ion-beam assisted deposition

CrN monolayer coating and CrN/WN multilayer coatings were deposited on the silicon (100) substrate by ion-beam assisted deposition process. The bilayer period of these coatings was controlled at 8 nm and 30 nm. The cross-sectional morphology of nanoscaled multilayer coatings was characterized by scanning electron microscopy and transmission electron microscopy. The wear resistance of CrN/WN multilayer coatings and CrN monolayer coating was investigated using a pin-on-disc tribometer. The surface roughness (Ra) of the coatings was evaluated by atomic force microscopy, and that of CrN and WN monolayer coating was 6.7 and 5.9 nm, respectively. The employment of multilayer configuration in CrN/WN coating with bilayer period of 8 nm and 30 nm effectively reduced the surface roughness down to 1.9 and 2.2 nm, respectively. The friction coefficient of CrN monolayer coating and CrN/WN multilayer film with a bilayer period of 30 nm was 0.63 and 0.31, respectively. Owing to the high hardness/elastic modulus ratio, as well as the dense structure and the smooth surface roughness, the CrN/WN multilayer coatings exhibited better wear resistance in the consideration of friction coefficient and the worn surface morphology.     

磁控溅射制备的Cr/CrN和Cr/CrN/CrAlN涂层耐腐蚀性能对比研究

目的比较Cr/CrN/CrAlN涂层和Cr/CrN交替涂层的耐腐蚀性能。方法利用电化学极化曲线、阻抗谱和中性盐雾试验进行测量,结合扫描电子显微镜(SEM)和原子力显微镜(AFM)表征微观形貌,分析两种涂层耐腐蚀性能的差异。同时,为研究涂层在服役中的损伤工况,分析了预制划痕对Cr/CrN/CrAlN涂层耐腐蚀性能的影响。结果Cr/CrN/CrAlN涂层的自腐蚀电流密度较Cr/CrN交替涂层和TC4基体低2个数量级,腐蚀速率较小。无损伤的Cr/CrN/CrAlN涂层的极化电阻Rp为868.7 kΩ·cm^2,预制1条损伤划痕涂层的极化电阻为792.0 kΩ·cm^2,而带有5条损伤划痕涂层的极化电阻Rp仅为77.2 kΩ·cm^2,减小至原始涂层的8%。Cr/CrN/CrAlN涂层经288 h连续盐雾腐蚀后增重仅为0.1 mg/cm^2,远小于CrN涂层和TC4基体,且增重速率趋于平缓。CrN涂层在连续盐雾腐蚀24 h后,腐蚀增重速率明显增加。结论由于Cr/CrN/CrAlN涂层结构增加了微裂纹和位错运动的界面阻塞,避免孔隙的连通,阻碍了腐蚀介质进入基体,因此涂层的耐腐蚀性能提高。对于表面预制划痕的Cr/CrN/CrAlN涂层,首先发生涂层的局部腐蚀,通过阴极极化加速后,腐蚀凹坑延伸到涂层/基体界面,加剧涂层的局部剥离。     

Influence of bilayer period and thickness ratio on the mechanical and tribological properties of CrSiN/TiAlN multilayer coatings

Nanostructured CrSiN/TiAlN multilayer coatings were deposited by a bipolar asymmetric reactive pulsed DC magnetron sputtering system. The thickness ratio of CrSiN to TiAlN layers was fixed at 1:1. The bilayer periods of the coatings were controlled to be from 6 to 40 nm. Furthermore, two CrSiN/TiAlN multilayer coatings with the same bilayer period (20 nm) but different CrSiN/TiAlN thickness ratios (2:8 and 8:2) were also deposited to explore the influence of thickness ratio on the mechanical properties of the multilayer coatings. The crystalline structures of the coatings were determined by a glancing angle X-ray diffractometer. The microstructures of thin films were examined by a scanning electron microscopy and a transmission electron microscopy, respectively. A nanoindenter, a micro Vickers hardness tester, and a pin-on-disk wear tester were used to evaluate the hardness, the toughness and the tribological properties of the thin films, respectively. The maximum hardness of the multilayers was obtained when the bilayer period was at 10 nm for the coating with the same thickness ratio of CrSiN to TiAlN layers (1:1). Meanwhile, the thickness ratio of CrSiN to TiAlN layer had great influence on the hardness and the toughness properties of the multilayer coatings. The hardness and the toughness of the CrSiN/TiAlN multilayer coatings increased as the individual TiAlN layer thickness increased.     

Microstructure and defect characterization at interfaces in TiN/CrN multilayer coatings

Microstructures of TiN/CrN multilayer coatings deposited on austenite steel (Cr Ni 18 8) by pulsed laser deposition (PLD) are characterized using transmission electron microscopy while their mechanical properties were assessed in a ball-on-disk test. All coatings have the same total thickness of about 1 μm. The individual layers show a highly defective columnar structure, which is characterized by conventional electron microscopy (TEM) as well as by high resolution TEM. These techniques, combined with measurements of the local chemical composition through EDS prove that PLD allows to produce fully separated CrN and TiN layers. The friction, and consequently the wear, are lowered by increasing the total number of layers in the coating.     

Microstructure, mechanical and tribological properties of CrN/W2N multilayer films deposited by DC magnetron sputtering

CrN/W₂N multilayer films with various bilayer periods of 15-85 nm were deposited on high speed steel (W18Cr4V) substrates by means of DC closed field unbalanced magnetron sputtering. The morphology and microstructure of the multilayer films were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The mechanical and tribological properties were evaluated using a nanoindentor, Rockwell and scratch tests and a conventional ball-on-disk tribometer, respectively. There were some transverse grains at the layer interface and the interface between the CrN and W₂N layers was not so sharp owing to atom diffusion through the interface. In the bilayer period range, the microhardness, elastic modulus and adhesive strength of the CrN/W₂N multilayer films increased with the decrease of bilayer period. The CrN/W₂N multilayer film with a bilayer period of 15 nm showed the highest hardness (29.2 GPa), elastic modulus (376 GPa) and best adhesion strength, it also had the highest wear resistance and lowest friction coefficient.     

Thermal stability behaviors of Cr(N,O)/CrN double-layered coatings by TGA/DTA analysis

In this study, Cr(N,O)/CrN double-layered coatings were synthesized using the cathodic arc deposition (CAD) process. CrN film was first deposited onto a substrate as an interlayer to ensure better adhesion, and Cr(N,O) film was subsequently deposited on top of the CrN layer as the surface layer. Variation in the Cr(N,O) coating composition was achieved through changing the O₂/N₂ flow ratio during the last stage of processing. Phase structure, chemical composition, and morphology of the resulting coatings were analyzed and observed using the X-ray diffractometer, Auger electron spectrometer and SEM. In addition, oxidation behavior of the coatings was investigated using TGA/DTA methods. The tests were carried out by increasing temperature up to 1000 °C in ambient air. With the introduction of oxygen gas during the CAD process, a superficial layer was produced in the Cr(N,O) constituent containing CrN and Cr₂O₃ phases. The formation of the oxide phase attributed to the reaction of chromium and oxygen was more favorable than that of chromium and nitrogen. The results also showed that Cr(N,O)/CrN double-layered coatings exhibited superior oxidation resistance at elevated temperature than that of CrN single-layer coated specimen (870 °C vs. 750 °C).     

过滤电弧沉积的TiN/TiCrN/CrN/CrTiN多层膜

用过滤电弧技术在高速钢表面沉积了TiN／TiCrN／CrN／CrTiN多层膜，用扫描电镜(SEM)观察了截面和断口形貌及划痕后的形貌。使用俄歇电子谱仪进行剥层成分分析，用纳米压痕仪测试了多层膜和单层膜的显微硬度和弹性模量。结果表明，在调制周期大于l00nm时，多层膜的显微硬度符合Ha11—Petch关系，在80nm时，则脱离线性关系。划痕法测试多层膜的结合力达到80N。     

基体材料对Cr/CrN多层涂层在海水环境中磨蚀性能的影响

目的 讨论海水环境下不同基体材料对Cr/CrN交替的多层复合涂层磨蚀性能的影响,为海水环境下耐磨蚀材料基体的选择和应用提供参考。方法 采用多弧离子镀技术在316L不锈钢和TC4钛合金基体上沉积Cr/CrN多层复合涂层,通过XRD、SEM等技术对涂层材料的微观结构进行表征,通过硬度测试、结合力测试、电化学分析、摩擦磨损试验等技术对涂层材料的力学性能、电化学性能以及摩擦学性能进行分析,比较不同基体对Cr/CrN多层涂层在海水环境中磨蚀性能的影响。结果 以TC4钛合金为基体的Cr/CrN多层涂层的硬度为1727.2HV0.3,虽略小于以316L不锈钢为基体的涂层硬度（2241.5HV0.3）,但其在膜-基结合力、海水环境下电化学性能和摩擦学性能等方面均优于以316L不锈钢为基体的涂层。结合力测试中,以TC4为基体的多层涂层初始裂纹出现在31 N,扩展裂纹出现在42 N,大于316L基体涂层的22 N和35 N。电化学测试中TC4基体涂层的腐蚀电位为?0.20 V,大于316L基体涂层的腐蚀电位（?0.21 V）。海水环境下TC4基体涂层的平均摩擦系数和磨损率分别为0.35和2.9950×10?5 mm3/(N?m),均小于316 L基体涂层的平均摩擦系数（0.36）和磨损率（4.9895×10?5 mm3/(N?m)）。结论 TC4钛合金更适合作为海水环境用Cr/CrN多层涂层耐磨蚀材料的基体材料。     

调制比对Cr/CrN/Cr/CrAlN多层膜结构及性能的影响

目的 探究Cr/CrN/Cr/CrAlN多层膜的最佳调制比.方法 利用电弧离子镀技术,在TC4钛合金上制备了不同调制比的Cr/CrN/Cr/CrAlN多层膜.利用扫描电子显微镜观察膜层表面和截面形貌;用Image-Pro分析软件对表面的大颗粒进行定量分析;利用X射线衍射法表征膜层的晶体结构;采用维氏硬度计测量膜层的显微硬度;采用划痕试验仪测量膜层与基体之间的结合力(临界载荷);通过基片弯曲法测量并计算得到膜层的残余应力;利用根据ASTM G76-05标准特制的AS600-喷砂试验机进行了抗冲蚀性能测试;采用三维表面轮廓仪测量冲蚀坑深度.结果 膜层表面质量和生长取向与LCr/CrN:LCr/CrAlN调制比密切相关,随着Cr/CrN比例的增加,膜层表面质量越来越好,择优取向由(111)晶面转为(200)晶面.多层膜的硬度随Cr/CrN比例的增加,呈下降趋势,结合力、残余应力和韧性则随之呈先升后降的趋势,并在LCr/CrN:LCr/CrAlN为1:2时,达到最佳.多层膜的抗砂粒冲蚀性能变化与力学性能变化一致,在LCr/CrN:LCr/CrAlN为1:2时达到最佳,其抗冲蚀能力是TC4基材的3倍以上,多层膜呈典型的脆性断裂失效形式.结论 在调制比LCr/CrN:LCr/CrAlN=1:2时,膜层获得最佳的抗冲蚀性能.     

深振荡磁控溅射复合沉积CrN/TiN超晶格涂层的摩擦学性能

研究了IN718高温合金、WC-6%Co硬质合金和Si(100)基体上深振荡磁控溅射复合沉积CrN/TiN超晶格涂层的摩擦学性能。研究表明,涂层的生长对基体的类型没有选择性。随着基体硬度的升高,划痕结合力失效临界载荷增大,涂层结合力失效机制由翘曲失效转变为基体/涂层协同变形,未发现涂层的剥落失效。载荷为2N时,磨损机制由磨粒磨损和氧化磨损转变为轻微磨粒磨损。载荷为4 N时,IN 718基体上涂层的磨损机制为严重的氧化磨损,WC-6%Co基体上的涂层的磨损机制为磨粒磨损和氧化磨损,氧化物的产生、堆积和转移导致摩擦系数的波动。     

Multilayered gradient CrN/ZrN coatings synthesized by magnetron sputtering

The multilayer gradient CrN/ZrN coatings were synthesized by a dual cathode DC magnetron sputtering.The influence of different species of reaction gases and partial pressures on structure and mechanical properties was investigated using XRD, AES, XPS, and nanoindentation. The results show that N2-NH3 mixture process gas is of benefit to the synthesis of superhard multilayered gradient CrN/ZrN coatings. The presence of the preferred orientations of CrN(111), (200) and ZrN (111), (220) in the structure is a main reason for superhardness of multilayered gradient coatings.     

Growth and characterization of Cr2N/CrN multilayer coatings

A series of monolithic and multilayer coatings of chromium nitride with various compositions and architectures were deposited at low temperatures (<200°C) on silicon substrates using ion-assisted reactive magnetron sputtering. All coatings had a total thickness in the 1.5±0.3 μm range. The multilayer coatings were designed such that their period and CrN fraction varied in the range 30–150 nm and 0.50–0.93, respectively. Real-time in situ ellipsometry was used to monitor and control the deposition process. The deposited coatings were characterized post-deposition using X-ray diffraction (XRD), Rutherford backscattering (RBS), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). The primary chromium nitride phases (Cr₂N and CrN) in the films were identified using XRD. The chemical composition of selected samples was determined from RBS and XPS measurements. The phase composition of the deposited layers was deduced from the analysis of the SE data. The mechanical properties of the coatings were evaluated using a nanoindenter. The measured hardness values were in excess of 20 GPa. The results of the different characterization and testing techniques were correlated and follow-up work on this project suggested.     

调制周期对Cr/CrN纳米多层膜的结构与性能的影响

采用多弧离子镀技术在65Mn钢表面制备了不同调制周期的Cr/CrN纳米多层膜.采用俄歇能谱仪(AES)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、纳米硬度仪、轮廓仪和划痕仪,分析了不同调制周期Cr/CrN纳米多层膜的成分分布、微观结构、力学性能、残余应力和结合强度.结果表明,Cr/CrN纳米多层膜的表面平整致密,截面层状调制结构清晰,其调制结构为Cr层-过渡层-CrN层的"三明治"结构,调制比约为1∶ 1.多层膜由CrN、Cr2N和Cr相组成,在CrN(200)方向上出现择优取向.当调制周期为80 nm时,多层膜的硬度值相对较高.随调制周期的增大,Cr/CrN多层膜的残余应力值减小,结合强度值先增大后减小.当调制周期为120 nm时,涂层的划痕临界载荷值相对较高,为69 N.     

Synthesis and characterization of multilayer CrN/ZrN coatings

In this study, multilayer CrN/ZrN coatings with various bi-layer periods (δ) were deposited by closed-field unbalanced magnetron sputtering and their compositions, crystalline structures and morphologies were characterized by auger electron spectroscopy (AES), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Additionally, the mechanical properties of the coatings were characterized by nano-indentation and wear tests. The XRD results showed that the diffraction peak of multilayer CrN/ZrN coatings is observable between the CrN (111) and the ZrN (111). This peak has a strong tendency to increase the intensity and sharpen the width as the substrate rotation speed increases, indicating that the grain size of the multilayer CrN/ZrN coatings gradually increases. The hardness of films was dependent on the bi-layer period (δ), and the maximum hardness and elastic modulus were approximately 31.8 GPa and 321.5GPa, respectively. Moreover, the results of the wear tests showed that the multilayer CrN/ZrN coatings exhibited greatly improved wear resistance compared to the monolithic CrN coatings.     

Effect of tribological media on tribological properties of multilayer Cr(N)/C(DLC) coatings

In this research, Cr(N)/C(DLC) multilayered coatings were deposited on M2 steel substrates by an unbalanced magnetron sputtering technique. By varying the substrate rotation speed, four multilayered coatings with different bilayer thickness were produced. The bilayer thickness and structure of multilayered coatings were characterized by low-angle XRD, XPS depth profile, and cross-section TEM observation. The tribological investigation focused on the effect of layer thickness and tribological media on tribological property of the multilayer coatings against Al counterface. A pin-on-disc tribometer with a tribological medium container was used to investigate the wear behaviours of the four multilayered coatings under dry and wet (distilled water and S500 coolant) sliding. A stylus surface profilometer was used to measure wear rate. The investigation of wear tracks and wear mechanism was performed using Scanning Electron Microscopy (SEM). The research results showed that coatings with different bilayer period performed different tribological behaviour. The proper tribological media applied in the wear tests could improve the wear properties of multilayer coatings.     

Interface-directed spinodal decomposition in TiAlN/CrN multilayer hard coatings studied by atom probe tomography

Microstructural and compositional changes in TiAlN/CrN multilayered films occurring at temperatures up to 1000 °C were studied at different length scales by a combination of atom probe tomography, transmission electron microscopy and X-ray diffraction. We observe the onset of decomposition of the multilayer structure at 700 °C via the mechanism of interface-directed spinodal decomposition of TiAlN layers, where Al atoms preferentially move toward the nearest interface and segregate there. The interface-directed mechanism later transforms into isotropic spinodal decomposition and is accompanied by intense interdiffusion between the constituting layers. Distinct compositional gradients across columnar grain boundaries (extending perpendicular to the multilayers) are detected at this stage of decomposition. Drastic differences in decomposition behavior across the film depth were observed at elevated temperatures (800–1000 °C): the layered structure completely dissolves in the near-surface part but persists in the regions distant from the surface. The influence of residual stresses caused by the sputter deposition process on the thermally induced evolution of the multilayer thin films is discussed.     

Structural and mechanical properties of AlTiN/CrN coatings synthesized by a cathodic-arc deposition process

Monolayered AlTiN and Multilayered AlTiN/CrN coatings were synthesized by a cathodic-arc deposition process, using TiAl (with 50/50 and 33/67 at.%) and Cr elemental cathodes. The atomic ratio of Al/(Ti + Al) in the AlTiN coatings was reduced to 0.44 and 0.61, respectively, compared with the corresponding Ti₅₀Al₅₀ and Ti₃₃Al₆₇ cathode materials. The multilayered AlTiN/CrN films showed smaller crystallite size, larger lattice strain, higher hardness, higher residual stress, and better adhesion strength as well than the monolayered AlTi films. The multilayered Al_0.35Ti_0.22N_0.43/CrN coating exhibited the highest hardness of about 38 GPa and the highest H³/E*² ratio value of 0.188 GPa, indicating the best resistance to plastic deformation, among all the coatings studied.     

CrN/NbN coatings deposited by HIPIMS: A preliminary study of erosion-corrosion performance

Nanoscale CrN/NbN multilayer PVD coatings have exhibited resistance to erosion-corrosion. However growth defects (under dense structures and droplets) in the coating produced by some deposition technologies reduce the ability to offer combined erosion-corrosion resistance. In this work a novel High Power Impulse Magnetron Sputtering (HIPIMS) technique has been utilised to pretreat substrates and deposit dense nanoscale CrN/NbN PVD coatings (HIPIMS-HIPIMS technique). This new technique, rich with metal ion plasma, deposits very dense structures and offers virtually defect free coatings (free of droplets as observed in cathodic arc technique and under-dense structures observed in standard dc sputtering). Plasma diagnostic studies revealed a high metal ion-to-gas ion ratio (Cr:Ar) of 3:1 for HIPIMS pretreatment conditions with the detection of 14% Cr²⁺ and 1% Cr³⁺ ions and J_s of 155 mAcm^− 2. For deposition conditions the metal ion-to-gas ratio was approximately 1:4 which is significantly higher compared to DC at 1:30. Characterisation results revealed a high adhesion of L_C 80 N, high hardness of 34 GPa and Young's modulus of 381 GPa. Low friction coefficient (0.46) and dry sliding wear coefficient, K_C (1.22 × 10^− 15 m³Nm^− 1) were recorded. The effect of deposition technique (droplet defect and intergranular void free coatings) on erosion-corrosion resistance of CrN/NbN coatings has been evaluated by subjecting the coatings to a slurry impingement (Na₂CO₃ + NaHCO₃ buffer solution with Al₂O₃ particles of size 500-700 µm) at 90° impact angle with a velocity of 4 ms^− 1. Experiments have been carried at − 1000 mV, + 300 mV and + 700 mV representing 3 different corrosion conditions.     

Mechanical and tribological properties of multilayered TiSiN/CrN coatings synthesized by a cathodic arc deposition process

The monolayered TiSiN and multilayered TiSiN/CrN were synthesized by cathodic arc evaporation. The Ti/Si (80/20 at.%) and chromium targets were used as the cathodic materials. With the different I_[TiSi]/I_[Cr] cathode current ratios of 1.8, 1.0, and 0.55, the multilayered TiSiN/CrN coatings possessed different multilayer periods (Λ) of 8.3 nm, 6.2 nm, and 4.2 nm. From XRD and TEM analyses, both the monolayered TiSiN and multilayered TiSiN/CrN revealed a typical columnar structure and B1-NaCl crystalline, no peaks of crystalline Si₃N₄ were detected. Among the multilayered TiSiN/CrN coatings, the multilayered coating with Λ = 8.3 nm possessed higher hardness of 37 ± 2 GPa, higher elastic modulus of 396 ± 20 GPa and the lower residual stress of − 1.60 GPa than the monolayered (Ti_0.39Si_0.07)N_0.54 coating(− 7.25 GPa). Due to the higher Cr/(Ti +Cr + Si) atomic ratio, the multilayered TiSiN/CrN with Λ = 5.5 nm possessed the lowest friction coefficient. But the lowest of wear rate was obtained by the multilayered TiSiN/CrN with Λ = 8.3 nm, because of higher H³/E^?2 ratio of 0.323 GPa. The monolayered TiSiN possessed the highest wear rate of 2.87 μm²/min. Therefore, the mechanical and tribological property can be improved by the design of multilayered coating.