乏油环境下不同掺杂GLC膜的摩擦学行为

利用磁控溅射技术制备了类石墨碳膜(GLC)、掺杂金属Cr的类石墨碳膜(GLC/Cr)及掺杂WC的类石墨碳膜（GLC/WC）,考察了不同掺杂物对薄膜结构及其在乏油环境下摩擦学性能的影响。结果表明：掺杂Cr、WC使GLC薄膜中sp2键结构含量增加,促进了GLC膜的石墨化,降低了GLC薄膜的硬度及弹性模量;在乏油环境下,3种薄膜的摩擦因数相差不大,但表现出不同的抗磨损能力,其磨损寿命由高到低依次是GLC/Cr、GLC、GLC/WC。研究结果为提高航空发动机主轴轴承在超常工况下的寿命和可靠性提供了理论和试验依据。     

碳靶电流对磁控溅射GLC/Ti薄膜结构及摩擦学性能的影响*

为改善掺杂Ti的GLC/Ti薄膜的摩擦学性能,采用非平衡磁控溅射技术在不同C靶电流下制备了类石墨碳基薄膜。利用扫描电子显微镜(SEM)、拉曼光谱仪(Raman)对薄膜结构进行表征;采用纳米压痕仪测量薄膜的硬度及弹性模量;利用HSR-2M型高速往复试验机测试薄膜在干摩擦条件下的摩擦磨损性能,并用白光干涉仪观察磨痕表面形貌。结果表明:随着C靶电流的增大,薄膜的柱状生长趋势日趋明显,其致密性降低,sp~2键含量减小,石墨化程度和结合力降低,而硬度和弹性模量略增;随着C靶电流的增大,摩擦因数和磨损率均增大。因此,适当降低C靶电流可以提高磁控溅射GLC/Ti薄膜干摩擦条件下的减摩耐磨性能。     

Cr12MoV钢表面磁控溅射TiB2-TiN薄膜的摩擦磨损性能

采用磁控溅射技术在淬火态Cr12MoV表面制备SiC/TiN、SiC/TiB2-TiN薄膜(SiC为中间层),研究TiN、TiB2-TiN薄膜的组织结构和摩擦磨损性能。结果表明,SiC薄膜与基材和TiN、TiB2-TiN薄膜间都具有明显的且呈梯度的元素扩散,界面结合良好。在水润滑条件下与钢球对摩时(载荷0.5 N,时间0.5 h),TiN薄膜、TiB2-TiN薄膜具有良好摩擦磨损性能,其平均摩擦因数分别为0.33、0.31,低于淬火态Cr12MoV的0.45,磨损速率分别为2.0×10-8和1.5×10-8mm3/(N.m),低于淬火态Cr12MoV的8.66×10-7mm3/(N.m),其中在水润滑条件下TiB2-TiN薄膜比TiN薄膜具有更好的摩擦磨损性能。     

Hardness effect of stainless steel substrates on tribological properties of water-lubricated DLC films against AISI 440C ball

Diamond-like carbon (DLC) films were deposited on stainless steel substrates with different hardness by thermal electron excited plasma CVD method, and their tribological properties in water-lubricated conditions were investigated. EDS was used to estimate the wear of the films. The results show that the hardness of the substrates has little effect on the friction and, the wear loss of the films is much smaller than that measured by an optical interferometer. The deep wear track is mainly due to the plastic deformation of the substrates and the films but not due to wear. However, the failure of the films is closely related to the hardness of their substrates. The harder the substrate, the higher the failure-resistant capability. The film deposited on a soft substrate is easy to crack and fail due to the low deformation resistance of the substrate and rubbing at a high contact-pressure. On the other hand, the wear of the counter balls increases with the hardness of the substrates.     

Tribological properties of nickel-base nanocrystalline coatings sputter-deposited on austenitic stainless steel

500 nm-thick films are deposited on austenitic stainless steel by neutral (Ar⁺) or reactive (N⁺) ion beam sputtering of Ni or NiTi targets, with (or without) high energy 160 keV-Ar⁺ ion beam assistance. Most of the time the coatings are nanocrystalline and induce a large (excellent in some conditions) increase of the wear resistance. Only Ar⁺ ion beam sputtering of a NiTi target gives an amorphous deposit which does not improve the substrate tribological properties. The hardness and wear resistance of ion beam assisted films are larger than those obtained with non-ion beam assisted coatings. The presence of a hard TiN phase inside a ductile Ni phase, of grains with preferential orientation beneficial to slip, as well as film densification are the main factors which increase the wear resistance. The best results are obtained when the structure is composed of two phases, Ni and TiN. The TiN phase strengthens the already good tribological Ni properties and the Ni ductility induces mechanical accommodation during the friction process.     

Influence of CH4 Flow Rate on Microstructure and Properties of Ti-C:H Films Deposited by DC Reactive Magnetron Sputtering

Nanocomposite Ti-containing hydrogenated carbon films (Ti-C:H) were prepared using a DC reactive magnetron sputtering system. The relationship between CH₄ flow rate and the film characterization and tribological behaviors in both ambient air and deionized water conditions were investigated. Results showed that the Ti content in the as-deposited Ti-C:H films decreased and the sp³ content increased with an increase in CH₄ flow rate. TiC nanocrystallites can be formed at a relatively low CH₄ flow rate, whereas there was almost no formation of TiC in the amorphous carbon matrix at the highest CH₄ flow rate. The hardness, elastic modulus, and internal stress of the films were decreased firstly and then increased as the CH₄ flow rate increased, whereas their adhesion presented an inversely changing trend. The friction coefficients and wear rates of Ti-C:H films in both ambient air and deionized water conditions decreased with increasing CH₄ flow rate from 8 to 12 sccm and then increased as the CH₄ flow rate continually increased. In particular, the nanocomposite Ti-C:H film deposited with a CH₄ flow rate of 12 sccm could achieve superior combining mechanical properties and low friction and high antiwear behaviors in both ambient air and deionized water conditions, indicating potential applications as a protective and lubricating film for mechanical components.     

A comparative study on the microstructure and tribological properties of Si3N4 and TiN films produced by the IBED method

The tribological properties of Si₃N₄ and TiN thin films produced by ion beam enhanced deposition (IBED) were compared on a SRV friction and wear testing machine. The friction coefficient of all thin films shows a descending tendency with increase in load, and is lower than that of 52100 steel. All the IBED films show a much better wear resistance than 52100 steel, especially in the higher load and frequency ranges; it can reach six times that of the latter. In order to understand the reasons for their excellent properties, the microstructure, microhardness and bonding strength with the substrate were analysed by SEM, X-ray diffraction, Knoop hardness and scratching test methods separately. The results show that the TiN(1) film exhibits the best tribological properties, which are closely related with its greater hardness and bonding strength.     

Evaluation of wear and tribological properties of coatings rubbing against copper

A new crossed-cylinders tribo-tester is proposed. This tribo-tester can decrease the tendency of the chatter vibration. The tribological properties of coatings against copper is evaluated with this tribo-tester. The wear rate of TiN, TiC and TiCN rubbing against copper is higher than the substrate high speed tool steel: SKH51 (JIS). The catalytic action of copper for oxidation of Ti-based coatings is a main reason of this high wear rate of TiN, TiC and TiCN rubbing against copper. The wear rate of CrN rubbing against copper is in a very low level because CrN shows the excellent oxidation resistance and Cr₂O₃ film formation decreases the wear loss of CrN coating.     

MoSx/MoSx-Mo纳米多层膜的制备及其环境摩擦学特性

用直流磁控溅射在钢基体上交替溅射制备了MoSx/MoSx-Mo纳米多层膜。采用划痕仪测试薄膜与基体的结合力;采用SEM和XRD分析了纳米多层膜的形貌和显微结构;在球-盘式微摩擦试验机上测试了纳米多层膜在真空和潮湿空气中的摩擦学性能。结果表明,纳米多层膜的结合力优于纯MoS2膜。随着溅射沉积气压的升高,MoSx(002)面择优取向减弱,纳米多层膜的结合力下降。溅射气压0.24 Pa沉积的纳米多层膜在真空和潮湿空气中都呈现出最低的摩擦因数和磨损率,具有优异的环境摩擦磨损特性。     

不同介质下CrN_X薄膜的摩擦学特性研究

采用电弧离子镀技术在45#钢衬底表面沉积了CrNX薄膜.用显微硬度计测试了薄膜的硬度,用X射线衍射仪分析了薄膜的相结构,用球-盘式摩擦磨损试验机评价了在不同介质条件下(干摩擦、水润滑、油润滑)CrNX薄膜的摩擦学性能,用表面轮廓仪测试了磨痕处的磨痕轮廓,用扫描电镜(SEM)观察了薄膜磨痕形貌.结果表明,相对于干摩擦,水润滑和油润滑条件下,CrNX薄膜的摩擦因数和磨痕深度都有明显降低的趋势.干摩擦条件下薄膜主要表现为磨粒磨损;水润滑条件下,主要表现为腐蚀磨损;油润滑条件下由于油膜在两摩擦表面的吸附,薄膜几乎无磨损.     

TiN/Ti涂层在波箔轴承中的摩擦磨损性能

采用真空离子镀的方法在304不锈钢基体上喷涂厚度为3μm的TiN/Ti薄层,利用硬度计、三维形貌仪、划痕试验仪对涂层基本力学性能进行分析,通过球盘试验机分析涂层试样的摩擦磨损性能,根据波箔轴承性能测试实验台的测试结果:研究TiN/Ti涂层对基体表面耐磨减摩性能的影响。研究结果表明:TiN涂层硬度可达HV1 500,是基材硬度的5.5倍;TiN/Ti涂层平均摩擦因数为0.23,相对不锈钢304基材的平均摩擦因数0.71,降低了68%,磨损量也仅为基材的18.75%;GCr15与PTFE对磨的最大摩擦力矩可达2.4 N·mm,而TiN/Ti与PTFE对磨的最大摩擦力矩仅为1 N·mm,仅为GCr15的41.7%。TiN/Ti涂层表现出了优异的承载能力和耐磨减摩性能。     

两步压入法--薄膜力学性能的可靠测量方法

提出了采用力学探针测量薄膜力学性能的两步压入法.该方法通过大载荷压入展示基体变形对薄膜硬度的影响,从而选择不影响基体变形的小载荷测出薄膜的硬度和弹性模量.对高速钢基片上的TiN硬质薄膜,单晶硅片上的金属Ni薄膜和(Ti,Al)N/VN纳米多层膜的测量表明,两步压入法能够测出各种性质薄膜的力学性能,并且具有准确可靠的特点.此外,两步法对(Ti,Al)N/VN纳米多层膜的力学性能的测量表明,该体系的纳米多层膜存在硬度和弹性模量异常升高的超硬、超模量效应.     

大气环境下Au/TiN复合薄膜的滑动摩擦磨损性能

以30CrMnSi钢为基体,用磁控溅射法制备出Au/TiN复合薄膜材料,研究了薄膜在大气环境中的滑动摩擦磨损性能。结果表明:该复合薄膜材料与9Cr18钢球构成的滑动摩擦副,在接触压力不大于1.0GPa条件下,摩擦系数小于0.15,摩擦次数超过3×105;在较宽的温度、湿度和磁场范围内,薄膜的摩擦磨损性能保持稳定。当接触压力增大至3.0GPa时,薄膜的摩擦系数增大,耐磨寿命减小。该薄膜可用于大气环境下长寿命低载荷精密摩擦副的润滑。     

Investigation of antiwear coatings deposited by the pvd process

The tribological properties of various PVD‐deposited coatings (vacuum arc method) have been tested, both single‐layer coatings (TiN, CrN, Ti(C,N), and Cr(C,N)) and multilayer coatings (Cr(C,N)/CrN/Cr and CR(C,N)/(CrN+Cr₂N)/CrN/Cr). An unlubricated ball‐on‐disc tribosystem was used in which an Al₂O₃ ball is pressed against a coated steel disc rotating in the horizontal plane. A novelty of the method is the removal of wear debris from the contact zone using a draught of dry argon. This improves the repeatability of the test results and the stability of the tribological characteristics. It is shown that CrN coatings exhibit the best antiwear properties and Ti(C,N) the worst. Multilayer coatings have better antiwear properties than single‐layer ones. The friction coefficients for CrN and Cr(C,N) coatings are much smaller than for the commonly used TiN. A correlation has also been found between the physical properties of the coatings tested (adhesion of the coating to the substrate assessed in scratch tests, and coating hardness) and their antiwear properties. An improvement in coating‐substrate adhesion results in wear reduction, while greater hardness (causing a coating embrittlement increase and a change in the wear mechanism) brings about greater wear. There is no correlation between the physical properties and the friction coefficients of the coatings tested.     

Micro/Nanotexture Design for Improving Tribological Properties of Cr/GLC Films in Seawater

Microdimples with different diameters and Cr/graphite-like carbon (GLC) films were fabricated on silicon by laser surface texturing and magnetron sputtering technology, respectively. The texturing effects on the microstructures and tribological performance in seawater were comparatively investigated. The results showed that both the friction coefficients and wear rates in seawater decreased with an increase in dimple diameter in the lower range and then increased with a further increase in diameter. The Cr/GLC film with an appropriate diameter of dimples (1.5 µm) is effective in enhancing the tribological properties due to entrapment of wear particles and seawater in the dimples. In addition, the roughness and graphitization contact area have obvious effects on the wear resistance. If the surface roughness is too high, the graphitization contact area will decrease, and the ratio of minimum aqueous film thickness to the surface roughness is so small that the load is almost totally borne by the boundary film.     

Tribological performance evaluation of (1 1 1) preferred oriented TiN duplex coatings

The duplex surface coating of hot work tool steel, which comprises nitriding of a substrate and coating of a TiN layer, has been the subject of a series of studies as a potential surface modification for tools and machine parts. Through sliding experiment against an aluminum alloy without lubrication, it was shown on a wear map that there are two domains depending on sliding conditions: the wear domain and the transfer domain. In this study, focusing on the improvement in the tribological properties of the duplex coating in terms of the wear domain, the effects of film characteristics on film resistance to erosion wear and film life were investigated. Two kinds of duplex coatings with different film characteristics were prepared by hollow cathode discharge ion plating: a newly developed TiN film with a strong (1 1 1) orientation and an ordinary TiN film with (1 1 1) and (2 0 0) orientations. The erosion wear rate of duplex coating was evaluated by a micro slurry jet erosion test. Film life was evaluated by a sliding test against an aluminum alloy as in previous experiments. It was revealed that the duplex coating with the newly developed TiN film (N-coating) shows higher erosion resistance than previously reported duplex coating (C-coating). From the sliding test, it was also revealed that the N-coating whose XRD intensity ratio of (1 1 1) to (2 0 0) is over 100 shows a wear mode with only chipping, with no scratching, which shortens film life. The film life of N-coating increases about twice as long as C-coating, which has shown higher performance than a conventional duplex coating. Possible mechanisms of the improvement in the tribological properties with N-coating are discussed.     

Microstructure, Morphology and Properties of Titanium Containing Graphite-Like Carbon Films Deposited by Unbalanced Magnetron Sputtering

A series of graphite-like carbon films with a titanium concentration of about 3.0 at.% were successfully deposited on silicon wafer substrates using an unbalanced magnetron sputtering system with different bias voltages. The microstructure, surface morphology, and properties of the titanium-containing graphite-like carbon films were subsequently studied using different characterization techniques. The results show that the resulting titanium-containing graphite-like carbon films are completely dominated by sp² sites and that these films have moderate hardness, low internal stress, and superior tribological properties with low friction and a high load-bearing capacity. The hardness (H), elastic modulus (E), H/E, H ³/E ², and internal stress of the titanium-containing graphite-like carbon films initially increase with increasing bias voltage, only to be followed by a decrease with further increases in the bias voltage. Tribologically, the studied carbon film shows a slight increase in friction with increasing bias voltage, while the wear rate initially decreases, followed by an obvious increase. The tribological properties of the studied titanium-containing graphite-like carbon films are greatly improved under the liquid paraffin-lubricated condition, achieving extremely low friction (~0.045) and wear (~10^?9 mm³/Nm). The effect of bias voltage on the microstructure and properties of the titanium-containing graphite-like carbon films is discussed in detail.     

Substrate Effects on the Micro/Nanomechanical Properties of TiN Coatings

Nanoindentation and nanoscratch tests were performed for titanium nitride (TiN) coatings on different tool steel substrates to investigate the indentation/scratch induced deformation behavior of the coatings and the adhesion of the coating–substrate interfaces and their tribological property. In this work, TiN coatings with a thickness of about 500 nm were grown on GT35, 9Cr18 and 40CrNiMo steels using vacuum magnetic-filtering arc plasma deposition. In the nanoindentation tests, the hardness and modulus curves for TiN/GT35 reduced the slowest around the film thickness 500 nm with the increase of indentation depth, followed by TiN/9Cr18 and TiN/40CrNiMo. Improving adhesion properties of coating and substrate can decrease the differences of internal stress field. The scratch tests showed that the scratch response was controlled by plastic deformation in the substrate. The substrate plays an important role in determining the mechanical properties and wear resistance of such coatings. TiN/GT35 exhibited the best load-carrying capacity and scratch/wear resistance. As a consequence, GT35 is the best substrate for TiN coatings of the substrate materials tested.     

Tribological Thermostability of Carbon Film with Vertically Aligned Graphene Sheets

Tribological thermostability of carbon film with vertically aligned graphene sheets was studied with annealing temperatures up to 1,750 °C. The carbon film was deposited on silicon carbide substrate by electron cyclotron resonance plasma sputtering. Tribological thermostabilities of the carbon film in terms of friction coefficient, wear life, and nanoscratch depth were investigated by Pin-on-Disk tribometer and atomic force microscopy. The evolution of nanostructure of vertically aligned graphene sheets in the carbon film as a function of annealing temperature was examined by Raman spectroscopy and transmission electron microscopy. The results showed that the friction coefficient, wear life, and nanoscratch depth of the carbon film were thermally stable up to 1,250 °C. When the annealing temperature was 1,500 °C, the friction coefficient and the nanoscratch depth increased, the wear life decreased, but still all were of considerable values. These variations were attributed to the initiation of tubular-like structure originated from graphene sheets stacks. After annealing at 1,750 °C, tribological performances degraded catastrophically due to the abundant formation of tubular-like structures and the appearance of a graphitic interlayer between the film and the substrate.     

MECHANICAL PROPERTIES AND ANTI-WEARABILITY STUDIES OF MULTILAYER THIN COATINGS ON CUTTING TOOLSS

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