CrSiN纳米复合薄膜的摩擦学性能

采用中频非平衡反应磁控溅射技术在单晶硅P(111)基材上制备了CrSiN纳米复合薄膜。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、Kevex能谱仪(EDX)、高分辨率透射电子显微镜(HRTEM)和纳米压痕仪对薄膜的相结构、化学成分组成和力学性能进行了测试分析。利用球-盘式摩擦磨损试验机(UMT-2)考察了薄膜和GCr15钢球对磨的摩擦学性能并采用扫描电镜(SEM)观察磨痕形貌。结果表明:CrN薄膜中Si元素的掺杂改变了薄膜晶体结构,所制备的CrSiN复合薄膜为多相复合结构,即nc-CrN/aSi3N4所组成的纳米晶/非晶复合结构。CrSiN纳米复合薄膜的力学性能均优于CrN薄膜,其硬度均高于CrN薄膜的硬度,其中Si原子数分数为12.6%时薄膜的硬度达到最大,对应纳米晶/非晶复合强化。CrSiN纳米复合薄膜的摩擦因数低于CrN薄膜,具有很好的抗磨损性能,并具有一定的润滑作用。     

CrN、CrSiN薄膜在不同介质下的摩擦学性能对比研究

采用中频非平衡反应磁控溅射法在单晶硅〖BF〗P(111)〖BFQ〗和不锈钢（304SS）基材上制备CrN和CrSiN薄膜;利用球-盘式摩擦磨损试验机（CSM）考察2种薄膜在不同介质（空气、去离子水、质量分数35%NaCl 溶液）中和WC/Co球对摩的摩擦学性能。结果表明：大气环境下,CrN与CrSiN薄膜的磨损机制主要是磨粒磨损;水润滑下,CrN薄膜主要因机械抛光作用,CrSiN薄膜主要因摩擦化学反应,使得摩擦因数减小;在35%NaCl 溶液中CrN薄膜易被腐蚀,由于NaCl颗粒析出以及涂层接触区域的腐蚀和磨损产物,作为第三体的润滑作用,导致摩擦磨损发生明显变化,而CrSiN薄膜不易被腐蚀,主要因摩擦化学反应,使得摩擦磨损性能发生显著变化。     

Effect of Si addition to CrN coatings on the corrosion resistance of CrN/stainless steel coating/substrate system in a deaerated 3.5 wt.% NaCl solution

CrSiN coatings with different Si concentration (Si/(Cr + Si) ratio: 0, 3.7, 11.7, 20%) were deposited on stainless steel substrates using a closed field unbalanced magnetron sputtering (CFUBM) system. The variation in the microstructure of the films with the Si concentration was measured by XRD. The corrosion behavior of the CrSiN coatings in a deaerated 3.5% NaCl solution was investigated by potentiodynamic tests, electrochemical impedance spectroscopy (EIS) and surface analyses. The microstructure of the CrSiN film was found to depend on the Si concentration. The results of the potentiodynamic polarization tests showed that the corrosion current density and porosity decreased with increasing Si/(Cr + Si) ratio. The EIS measurements showed that the corrosion resistance of the Si-bearing CrN was improved by the phase transformation of the film, which led to an increase in the pore resistance and charge transfer resistance. The Si-bearing CrN possesses the best corrosion resistance at a Si/(Cr + Si) ratio of 20%, measured by the maximization of the pore resistance and charge transfer resistance.     

Mechanical and tribological properties of CrN/Ag and CrSiN/Ag nanoscale multilayers

This paper presents a concept of combining hard CrN (or CrSiN) and soft Ag lubricating materials in a nanoscale multilayer structure. The CrN/Ag and CrSiN/Ag multilayers are synthesized by reactive direct current (DC) magnetron sputtering techniques. The thickness of the Ag nanolayer in the multilayers is fixed to 4 nm while that of CrN and CrSiN nanolayers vary from 4 to 20 nm. The nitride layer effects on the mechanical and tribological properties of the multilayers have been investigated. Different mechanisms of the adhesion failure have been observed on the multilayer surfaces, depending on the nitride nanolayer types and their thicknesses. The CrSiN/Ag films exhibit poor adhesion whereas CrN/Ag multilayers demonstrate very good adhesion to AISI M2 steel substrates. The study of friction behaviors of the CrN/Ag multilayers against 100Cr6 steel balls reveals that the multilayers have low friction coefficients in comparison with that of a CrN single layer. The decrease of friction coefficients is related to the presence of the solid lubricant (Ag) nanolayer in the coatings.     

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.     

氮离子注入浓度对弹条钢基体Cr/CrSiN复合涂层的摩擦学性能影响研究

在轨道用扣件弹条钢(60Si2Cr)上注入不同浓度的氮离子,用电弧离子镀技术沉积了Cr过渡层,并在其上制备了CrSiN/Cr复合涂层。在UMT-3多功能摩擦磨损机上对复合层进行了法向载荷为20N的摩擦磨损实验,探讨了经不同氮离子注入浓度后Cr/CrSiN复合涂层摩擦磨损行为和损伤机理,研究发现,经氮离子注入后,复合涂层表面硬度明显的增加,随着离子注入浓度的升高涂层的耐磨性逐渐提高,其磨损机制主要为剥落和磨粒磨损。     

等离子体增强磁控溅射CrSiN涂层摩擦磨损行为

目的基于细晶强化理论,借助新型涂层制备技术获得综合性能优良的CrSiN涂层,研究Si含量对涂层微观结构、力学性能及耐磨性能的影响规律。方法采用等离子体增强磁控溅射技术,制备四种含有不同Si含量的Cr Si N涂层。使用X射线能谱仪(EDS)、X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)和原子力显微镜(AFM),分析涂层的化学成分、晶体结构、微观形貌和表面粗糙度。使用纳米压痕/划痕仪测试涂层的显微硬度、杨氏模量和结合力。使用摩擦磨损试验仪考察涂层的摩擦磨损行为。结果 Cr Si N涂层中Si含量随着Si靶功率的增加而增加。所有涂层中均未检测到含Si物相,主要由Cr N相组成。随着Si含量的增加,CrN(111)衍射峰逐渐减弱直至消失,涂层由疏松的三角锥结构逐渐变为致密平整的CrN纳米晶和Si3N4非晶共存的复合结构,涂层表面粗糙度显著降低,涂层的显微硬度、杨氏模量、结合力及耐磨性能均呈现先增后降的趋势。结论 Si含量为18.5%的Cr Si N涂层具有最佳的耐磨性能,此时涂层的硬度、杨氏模量、结合力和平均摩擦系数分别约为27 GPa、327 GPa、30 N和0.289。     

Microstructures and mechanical properties evaluation of TiAlN/CrSiN multilayered thin films with different bilayer periods

The Ti_0.45Al_0.55N/Cr_0.75Si_0.25N nanoscale multilayered coatings were deposited periodically by a bipolar asymmetric pulsed DC reactive magnetron sputtering technique. The structures and bilayer period of multilayer coatings were characterized by an X-ray diffractometer. The surface and cross-sectional morphologies of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The surface roughness of thin films was explored by atomic force microscopy (AFM). A nanoindenter, a micro Vickers hardness tester and pin-on-disk wear tests were used to evaluate the hardness, fracture toughness and tribological properties of the thin films, respectively. Six coatings with bilayer period ranges from 6 nm to 40 nm were produced in this work. It was observed that the hardness increased with increasing bilayer period and reached the maximum at 12 nm and then leveled off at periods larger than 12 nm. An optimal hardness, and plastic deformation resistance, as well as adequate tribological behaviors were found on the coating with a critical bilayer period of 12 nm.     

A comparative study of Cr−X−N (X=Zr, Si) coatings for the improvement of the low-speed torque efficiency of a hydraulic piston pump

The internal parts of hydraulic pumps operating at variable speed should be protected from insufficient lubrication. The axial piston type pumps employ a steel-base cylinder barrel rotating on a soft bronze valves plate with a slide contact, where the insufficient lubrication of these components can cause rapid wear of the valve plate and increase the friction loss. In this study, the cylinder barrel surface was deposited with CrZrN coatings, which were expected to improve the tribological contact with a valve plate under low-speed mixed lubrication conditions. Its effect on the improvement of the low-speed torque efficiency of a hydraulic piston pump was investigated and compared with that from the CrSiN coating. The coated cylinder barrels showed much lower friction coefficients and wear rates of the valve plates than the uncoated plasma-nitride one. In particular, the CrZrN coatings revealed better performance than the CrSiN coatings. By representing the improvement in the torque efficiency of the whole pump based upon the degree of the friction coefficient reduction, the CrZrN coatings exhibited approximately a 0.35% higher improvement at 300 bar and 100 rpm than CrSiN coatings. The possible failure modes of the coatings coated on the barrel were sugested and the microstructures of the coatings seemed to have a strong effect on the film failure mode.