Study on nanocrystalline Cr2O3 films deposited by arc ion plating: II. Mechanical and tribological properties

In this work, the influence of substrate bias voltage on the microhardness, adhesive strength, friction coefficient, and wear rate of AIP Cr₂O₃ films deposited on AISI 304 stainless steel substrates was investigated systematically. In the meantime, the wear failure mechanism of AIP Cr₂O₃ films in dry sliding contact was also analyzed and discussed. The results showed that the mechanical properties, adhesive behaviors, and tribological performance of AIP Cr₂O₃ films were greatly altered by applying a negative bias voltage. With increasing the bias voltage, the hardness, critical load, and tribological performance of AIP Cr₂O₃ films first were improved gradually, and then were impaired slightly again. When the bias voltage is − 100 V, the Cr₂O₃ film possessed the highest hardness, the strongest adhesion, and the best wear resistance. The essence of above phenomena was attributed to the variations of microstructure and defect density in the films induced by the substrate bias voltage increase. The main wear failure mechanism of AIP Cr₂O₃ films is crack initiation and propagation under the high contact stresses, inducing the local film with small area to flake off gradually, and eventually leading to the formation of a wear scar.     

Mechanical and tribological properties of multi-element (AlCrTaTiZr)N coatings

Multi-element (AlCrTaTiZr)N coatings are deposited onto Si and cemented carbide substrates by reactive RF magnetron sputtering in an Ar + N₂ mixture. The influence of substrate bias voltage, ranging from 0 to − 200 V, on the microstructural, mechanical and tribological properties of these nitride coatings is studied. A reduction in concentration of N and Al is observed with increasing substrate biases. The (AlCrTaTiZr)N coatings show the face-centered-cubic crystal structure (B1-NaCl type). The use of substrate bias changes the microstructure of the (AlCrTaTiZr)N coating from the columns with microvoids in boundaries to the dense and less identified columns. The compressive macrostress increases from − 0.9 GPa to − 3.6 GPa with an increase of substrate bias. The hardness and adhesion increase to peak values of 36.9 GPa and 60.7 N at the bias voltage of − 150 V, respectively. The tribological properties of the (AlCrTaTiZr)N coatings against 100Cr6 steel balls are evaluated by a ball-on-disc tribometer with a 10 N applied load. With an increase of substrate bias, the wear rate reduces while the friction coefficient almost keeps constant at 0.75. The lowest wear rate of 3.65 × 10^− 6 mm³/Nm is obtained for the (AlCrTaTiZr)N coating deposited at the bias voltage of − 150 V.     

Hydrogen quantification of magnetron sputtered hydrogenated amorphous carbon (a-C:H) coatings produced at various bias voltages and their tribological behavior under different humidity levels

Hydrogenated amorphous carbon (a-C:H) films have extraordinary tribological properties under dry conditions since the C-atoms at the surface are hydratized and not available for any bonding with the opposing material. Under wet conditions water molecules are weakly absorbed by the a-C:H-coatings so the interaction between the coating surface and the tribological counterpart changes to a dipole-like interaction which is disadvantageous for the tribological performance. According to this, the hydrogen-content plays an important role in the wear and friction behavior of diamond-like carbon (DLC) coatings under different humid conditions.This work focuses on the quantification of the hydrogen content of differently bias a-C:H top layered coating systems and their influence on the tribological behavior under different humidity conditions. By means of a magnetron sputter device DLC-coating systems with an a-C:H-top layer have been deposited at bias voltages between ? 75 and ? 200 V. In order to quantify the hydrogen content of the layers Nuclear Reaction Resonance Analysis (NRRA) was used. In combination with the results of the tribological tests under different humid conditions using a ball-on-disk-tester, correlations between the hydrogen content, the bias voltage and the wear and friction performance were made. A clear relationship between the bias voltage and the hydrogen content has been observed, since the values decrease consistently from 27.2 at.% at ? 75 V to a minimum of 19.9 at.% at ? 200 V bias voltage. Furthermore the different humidity levels show a strong influence on the tribological performance, while the bias voltage effects mainly the wear and friction results of the samples tested under wet conditions.     

Adhesion improvement of hydrogenated diamond-like carbon thin films by pre-deposition plasma treatment of rubber substrate

For reduction of friction and enhancement of wear resistance of dynamic rubber seals, thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) via magnetron-enhanced plasma chemical vapor deposition (ME-PCVD). Pre-deposition plasma treatment of HNBR substrate is proved to be crucial for the improvement of film performance due to enhanced interfacial adhesion. The columnar structure and the crack network formed during deposition enhance the flexibility of DLC thin films and exhibit strain tolerance up to 5%. Below 50% stretch strain and after unloading, thin DLC films of ∼ 300 nm thickness still adhere on the rubber substrates and no spallation or delamination is observed. The thin DLC film deposited on Ar-plasma pre-treated rubber at − 400 V substrate bias potential exhibits a very low coefficient of friction of 0.175 (compared to > 1 of uncoated HNBR rubber). After tribotests even under high normal load of 3 N, almost no wear can be seen on the films. Such tribological property is even better than that of 1 µm thick DLC or Me-DLC coated rubbers.     

Deposition of nanolayered CrN/AlBN thin films by cathodic arc deposition: Influence of cathode arc current and bias voltage on the mechanical properties

Thin films of CrAlBN were deposited on SKD 11 tool steel substrate using Cr and AlB cathodes in a cathodic arc plasma deposition system. The influence of AlB cathode arc current and substrate bias voltage on the mechanical and the structural properties of the films was investigated. The CrAlBN thin films had a multilayered structure in which the nano-crystalline CrN layer alternated with the amorphous AlBN layer. The hardness of the films increased as the AlB cathode arc current was raised from 35 to 45 A, and then decreased with further increase of the current. The hardness of the films increased rapidly with the increase of the bias voltage from − 50 to − 150 V. Further increase in the bias voltage decreased the hardness. The maximum hardness of 48 GPa was obtained at the bias voltage of − 150 V. With the increase of bias voltage, a good correlation between the residual stress and the hardness of the films was observed.     

The effect of applied substrate negative bias voltage on the structure and properties of Al-containing a-C:H thin films

Al-containing hydrogenated amorphous carbon (Al-C:H) films were prepared using a magnetron sputtering Al target in the CH₄ and Ar mixture atmosphere with various applied substrate pulse negative bias voltages. The hydrogen content and internal stress of the film decrease dramatically with the substrate pulse bias voltage increase. However, the hardness values of the films keep at high level (∼ 20 GPa) without any obvious changes with the increase of the applied substrate pulse bias voltages. The Al-C:H film prepared at applied substrate high bias voltage shows a long wear life and low friction coefficient.     

Structure and properties of selected (Cr–Al–N,TiC–C,Cr–B–N) nanostructured tribological coatings

The paper will present the state-of-art in the process, structure and properties of nanostructured multifunctional tribological coatings used in different industrial applications that require high hardness, toughness, wear resistance and thermal stability. The optimization of these coating systems by means of tailoring the structure (graded, superlattice and nanocomposite systems), composition optimization, and energetic ion bombardment from substrate bias voltage control to provide improved mechanical and tribological properties will be assessed for a range of coating systems, including nanocrystalline graded Cr_1−xAl_xN coatings, superlattice CrN/AlN coatings and nanocomposite Cr–B–N and TiC/a-C coatings. The results showed that the superlattice CrN/AlN coating exhibited a super hardness of 45 GPa when the bilayer period Λ was about 3.0 nm. Improved toughness and wear resistance have been achieved in the CrN/AlN multilayer and graded CrAlN coatings as compared to the homogeneous CrAlN coating. For the TiC/a-C coatings, increasing the substrate bias increased the hardness of TiC/a-C coatings up to 34 GPa (at −150 V) but also led to a decrease in the coating toughness and wear resistance. The TiC/a-C coating deposited at a −50 V bias voltage exhibited an optimized high hardness of 28 GPa, a low coefficient of friction of 0.19 and a wear rate of 2.37 × 10⁻⁷ mm³ N⁻¹ m⁻¹. The Cr–B–N coating system consists of nanocrystalline CrB₂ embedded in an amorphous BN phase when the N content is low. With an increase in the N content, a decrease in the CrB₂ phase and an increase in the amorphous BN phase were identified. The resulting structure changes led to both decreases in the hardness and wear resistance of Cr–B–N coatings.     

不同Ti靶电流对Ti掺杂类石墨碳膜的结构和性能的影响(英文)

利用磁控溅射的方法成功制备Ti掺杂类石墨碳(Ti-GLC)膜。采用拉曼光谱、X射线光电子谱(XPS)、扫描电子显微镜(SEM)、原子力显微镜(AFM)、纳米压痕仪和球盘式摩擦机分别表征不同Ti靶电流下制备的Ti-GLC膜的成分、结构和性能。随着Ti靶电流的增加,薄膜中sp2键的比率和Ti含量增加,同时薄膜的硬度和内应力也增大,但较高的Ti靶电流将会促使薄膜产生鳞片状结构从而使其变疏松。较少的Ti掺入量可以降低GLC膜的干摩擦因数,纯GLC膜在水润滑条件下的摩擦因数最低。在较低Ti靶电流下制备的Ti-GLC膜在干摩擦及水润滑条件下均具有较高的抗磨性能。     

Mechanical properties of high-density diamond like carbon (HD-DLC) films prepared using filtered arc deposition

Because high density DLC (HD-DLC) films prepared using filtered arc deposition (FAD) systems possess high hardness, low friction coefficients, and a smooth surface, they have been good candidates for use in tribological applications. The aim of present work is the investigation of the mechanical and structural properties of HD-DLC films.The experimental conditions were the following: arc current, 50 A; base pressure, less than 3 × 10^− 3 Pa; substrate bias, DC-100 V; substrate temperature, less than 100 °C. The HD-DLC films were formed on silicon wafers and tungsten carbide (WC) substrates. The film properties of hardness, composition, structure, and friction were analyzed.The film hardness is high, 80-90 GPa, with a low friction coefficient of less than 0.1.     

Magnetron reactively sputtered Ti-DLC coatings on HNBR rubber: The influence of substrate bias

In this study, Ti-containing diamond-like carbon (Ti-DLC) coatings have been deposited on HNBR (hydrogenated nitrile butadiene) rubber and also on Si wafer as reference via unbalanced magnetron reactive sputtering from a Ti target in C₂H₂/Ar plasma. The deposition rates of coatings on rubber and Si wafer were about the same. Columnar structures resulting from a rough interface were often observed in the coatings deposited on rubbers. Only at a high bias voltage of − 300 V the coating on HNBR rubber became column-free whereas a bias voltage of − 100 V could already restrain the columnar structure and thus produced dense and smooth coatings on Si wafer. A segmented morphology of the coatings on HNBR rubber is formed as a result of the large difference in thermal expansion between the coating and HNBR rubber. The crack network that separates the patches plays an important role in maintaining the coating flexibility. The size of the patches reduces with increasing bias voltage and thus the variation of deposition temperature. A high bias voltage enhances the hardness of Ti-coating and the rubber-coating adhesion, and guarantees a good tribological performance. When sliding against ø6 mm 100Cr6 steel ball counterpart, very low coefficients of friction were achieved (< 0.25 for the coated rubber versus > 1.3 for the uncoated). The Ti-DLC coating can be considered as a promising material for the enhancement of tribological performance of rubbers.     

Cathodic arc plasma deposition of nano-multilayered ZrN/AlSiN thin films

Thin films of ZrN/AlSiN were deposited on SKD 11 tool steel substrate using Zr and AlSi cathodes in an Ar/N₂ gas mixture in a cathodic arc plasma deposition system. The influence of the AlSi cathode arc current and the substrate bias voltage on the mechanical and structural properties of the films was investigated. X-ray diffraction, electron probe micro-analysis, high resolution transmission electron microscopy, nanoindentation and profilometry were used to characterize the films. The ZrN/AlSiN thin films had a multilayered structure by rotating the substrate in which nano-crystalline ZrN layers alternated with amorphous AlSiN layers. The hardness of the films increased as the AlSi cathode arc current was raised from 35 to 40 A, and then decreased with a further increase of the current. The hardness of the films increased with the increase of the bias voltage from − 50 to − 100 V. Further increase in the bias voltage decreased the hardness. The films exhibited a maximum hardness of 38 GPa. With the increase of bias voltage, the residual stress of the films correlated well with the hardness.     

偏压对DLC薄膜结构及摩擦学性能的影响

目的通过调节偏压,改善无氢DLC薄膜的微观结构,提高其力学性能和减摩抗磨性能。方法采用离子束辅助增强磁控溅射系统,沉积不同偏压工艺的DLC薄膜。采用原子力显微镜(AFM)观察薄膜表面形貌,采用拉曼光谱仪对薄膜的微观结构进行分析,采用纳米压痕仪测试薄膜硬度及弹性模量,采用表面轮廓仪测定薄膜沉积前/后基体曲率变化,并计算薄膜的残余应力,采用大载荷划痕仪分析薄膜与不锈钢基体的结合力,采用TRB球-盘摩擦磨损试验机评价薄膜的摩擦学性能,采用白光共聚焦显微镜测量薄膜磨痕轮廓,并计算薄膜的磨损率。结果偏压对DLC薄膜表面形貌、微观结构、力学性能、摩擦学性能都有不同程度的影响。偏压升高导致碳离子能量升高,表面粗糙度呈现先减小后增加的趋势,-400V的薄膜表面具有最小的表面粗糙度且C─C sp^3键含量最多,这也导致了此偏压下薄膜的硬度最大。薄膜的结合性能与碳离子能量大小呈正相关,-800 V时具有3.98 N的最优结合性能。不同偏压工艺制备的薄膜摩擦系数随湿度的增加,均呈现减小的趋势,偏压为-400V时,薄膜在不同湿度环境中均显示出最优的摩擦学性能。结论偏压为-400 V时,DLC薄膜综合性能最优,其表面粗糙度、硬度、结合力和摩擦系数分别为2.5 nm、17.1 GPa、2.81 N和0.11。     

Hexagonal diamond formation on steel substrates by negative bias microwave plasma enhanced chemical vapor deposition

This paper reports for the first time the synthesis of hexagonal diamond thin films on high-speed steel substrates by multi-mode microwave plasma enhanced chemical vapor deposition. Before deposition of the films, the substrate surface was treated by scratching with diamond powder. The deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy. The XRD patterns of (100) and (101) planes and the Raman peaks at ~ 1317-1322 cm^− 1 were observed, confirming the formation of hexagonal diamond phase in the prepared films. The effects of voltage bias on the phase formation, microstructure and hardness of the films were also studied by setting the voltage to 0, − 70, − 150 and − 190 V. The highest hardness of 23.8 GPa was found in the film having clusters of size about 550 nm deposited under a bias voltage of − 150 V. These clusters were built up of grains of size about 14 nm.     

15-5PH不锈钢表面类石墨碳基多层膜结构设计及摩擦学行为

针对马氏体沉淀硬化不锈钢15-5PH(0Cr15Ni5Cu4Nb)在海水环境中易腐蚀磨损的问题,采用直流磁控溅射的方法在15-5PH钢样片上制备调制周期分别为940、375和234nm的掺杂Cr的类石墨碳基多层膜（分别标记为Cr/GLC-S1、Cr/GLC-S2和Cr/GLC-S3）,采用扫描电子显微镜（SEM）、拉曼光谱仪（Raman）、MFT-5000多功能摩擦磨损试验机等仪器设备系统考察三种类石墨碳基多层薄膜的结构及摩擦学性能。研究结果表明：不同调制周期的类石墨多层膜表面均呈现“菜花状”形貌,随着调制周期的减小,“菜花状”颗粒逐渐减小,膜层变得致密;sp2键含量逐渐增大,石墨化程度加剧,机械性能更加优异。在干摩擦条件下,调制周期适中的Cr/GLC-S2薄膜具有良好的减摩耐磨性能,磨损形式以磨粒磨损为主,而调制周期较大的Cr/GLC-S1和调制周期较小的Cr/GLC-S3薄膜,在高载荷下均发生不同程度的脆性剥落,导致其摩擦学性能劣化。在人工海水环境中,Cr/GLC-S1和Cr/GLC-S2薄膜在中低载荷下的摩擦学性能较好,磨损形式仍以磨粒磨损为主,在高载荷下三种多层膜均发生不同程度...     

多弧离子镀负偏压对氮化钛薄膜的影响

目的确定适当的负偏压,提高多弧离子镀氮化钛薄膜的综合性能。方法采用不同的负偏压,在4Cr13不锈钢表面制备Ti N薄膜,探讨偏压对薄膜表面质量、结构、硬度、结合力和摩擦系数的影响。结果负偏压对薄膜表面质量的影响较大:负偏压为0 V时,Ti N薄膜表面凹凸不平,液滴较多;随着负偏压升高,薄膜表面变得光滑,液滴减少并变小,薄膜致密性也得到提高。在不同负偏压下,Ti N薄膜均呈现出在(111)晶面的择优取向,但随着负偏压的增大,这种择优取向逐渐减弱,当负偏压达到400 V时,薄膜在(220)晶面的峰值逐渐增强。随着负偏压从0增至400 V,薄膜的硬度、结合力和耐磨性均先提高,后降低。当负偏压为300 V时,薄膜的硬度和结合力达到最大,分别为2650HV和58 N;摩擦系数和磨损量最小,分别为0.48和0.1065 mm3。结论施加适当的负偏压可以提高薄膜的硬度、结合力、耐磨性等性能,当负偏压为300 V时,薄膜的各项性能达到最佳。     

High Temperature Tribological Properties of Ti-GLC Films Deposited on Different Bearing Steel SubstratesEI北大核心CSCD

针对航空发动机主轴轴承服役工况恶劣和类石墨碳基薄膜在高温环境下的性能研究不足等问题,采用磁控溅射技术在不同轴承钢基体(M50 钢、M50NiL 钢和 W9Cr4V2Mo 钢)上沉积 Ti-GLC 薄膜,探究在不同温度下的摩擦学性能。采用 SEM、 Raman 分析薄膜的微观结构,采用纳米压痕仪、划痕仪等测试其力学性能,利用 MFT-5000 型多功能摩擦磨损试验机测试所镀薄膜在不同温度下(室温、200 ℃、250 ℃和 300 ℃)的摩擦学性能。结果表明：在三种不同轴承钢基体沉积的 Ti-GLC 薄膜,其硬度和弹性模量变化不大,结合力从大到小依次为 M50＞M50NiL＞W9Cr4V2Mo。随着温度的升高,三种钢基体沉积 Ti-GLC 薄膜的摩擦因数均逐渐增大,而磨损率则先减小后增大,且表现出不同的磨损形式。三种轴承钢基体沉积 Ti-GLC 薄膜的最佳工作温度区间为室温~200 ℃,M50 钢基体所镀薄膜具有更好的力学性能和摩擦学性能,其结合力达到 80 N 以上, 300 ℃时的平均摩擦因数为 0.125,磨损率仅为 3.05×10^?17 m³ /(N·m)。研究成果为类石墨碳基薄膜在高温环境下的实际应用奠定了理论基础。     

载荷、摩擦副及介质环境对多层Ti掺杂类石墨薄膜的摩擦学行为影响EI北大核心CSCD

针对非晶碳基薄膜高内应力和低膜基结合强度的问题,采用闭合场非平衡磁控溅射系统在316L不锈钢基体上制备多层结构掺杂类石墨薄膜(GLC),探究载荷、摩擦副和介质环境对薄膜摩擦学行为的影响。结果表明,制备得到的多层结构GLC薄膜结构致密均匀,膜基之间没有明显缺陷,且力学性能良好。薄膜在干摩擦条件下的摩擦因数曲线呈明显的三阶段特征,分别对应于轻微的磨粒磨损、薄膜的剥离以及对磨球上碳质转移膜的形成。薄膜的平均摩擦因数随载荷的增加而显著提高,磨损率呈先减小后增大的趋势。相对于ZrO_(2)陶瓷球,Si_(3)N_(4)陶瓷球因其较高的黏着倾向和较大的赫兹接触半径导致其较高的摩擦因数和磨损率。GCr15金属球因其较低的硬度,导致碳质转移膜随金属磨削的剥离而脱落,造成相对较高的摩擦因数和磨损率。相对于室温空气环境下,GLC薄膜在NaCl溶液中由于受到水溶液的冲洗和腐蚀介质Cl^(-)的侵蚀,导致薄膜从基体的快速剥离,造成更高的摩擦因数和磨损率。研究成果可为提高非晶碳基薄膜在不同工作环境下的服役寿命和使用效率提供理论指导。     

Effect of the aluminium content and the bias voltage on the microstructure formation in Ti1 − xAlxN protective coatings grown by cathodic arc evaporation

The effect of aluminium contents and bias voltage on the microstructure of cathodic arc evaporated Ti_1 − xAl_xN coatings was investigated with the aid of X-ray diffraction experiments and transmission electron microscopy. The coatings were deposited from mixed Ti-Al targets with different Ti:Al ratios (60:40, 50:50, 40:60 and 33:67) at bias voltages ranging between − 20 V and − 120 V. The microstructure of the coatings was described in terms of the phase composition, crystallite size and residual stress and related to the indentation hardness. The microstructure features were found to be related to the uniformity of the local distribution of Ti and Al in (Ti,Al)N, which was controlled, for a certain overall chemical composition of the coatings, by the bias voltage. The consequences of large local fluctuations of the Ti and Al concentrations in Ti_1 − xAl_xN that occurred at higher bias voltages were the phase segregation, which was indicated through the formation of the fcc-(Ti,Al)N/fcc-AlN nanocomposites and the increase of the compressive residual stress in the face-centred cubic (Ti,Al)N. Concurrently, the increasing bias voltage contributed significantly to the reduction of the crystallite size. Higher residual stress and smaller crystallite size increased the hardness of the coatings. The overall chemical composition of the coatings influenced mainly their phase composition. The high concentration of Al in (Ti,Al)N led to the formation of wurtzitic AlN in the coatings.     

Mechanical properties of silicon-doped diamond-like carbon films prepared by pulse-plasma chemical vapor deposition

Silicon-doped diamond-like carbon (Si-DLC) films were prepared by dc pulse-plasma chemical vapor deposition (CVD), using a mixture of acetylene (C₂H₂) and tetramethylsilane (TMS) as the material gas. The pulse voltage was varied from − 2 to − 5 kV, and the TMS flow ratio (TMS/(C₂H₂ + TMS)) was varied from 0 to 40%. At a pulse voltage of − 2 kV, an increase in TMS flow ratio leads to a decrease in hardness. In contrast, at a pulse voltage of − 5 kV, an increase in TMS flow ratio leads to a slight increase in hardness. The high hydrogen concentration in the films due to an increase in TMS flow ratio promotes the formation of polymeric sp³ C―H bonds, resulting in the fabrication of soft films at a low pulse voltage of − 2 kV. However, an increase in the effect of ion peening on the growth face results in the formation of hard films at a high pulse voltage of − 5 kV. Then, at a pulse voltage of − 5 kV fabricating hard Si-DLC films, an increase in TMS flow ratio leads to an increase in the silicon content in the films, resulting in a decrease in the friction coefficient. Therefore, it is clarified that Si-DLC films fabricated by dc pulse-plasma CVD under a high pulse voltage and high TMS flow ratio exhibit high hardness and a low friction coefficient. Moreover, to investigate the friction coefficient of Si-DLC films fabricated by dc pulse-plasma CVD, films deposited by dc plasma CVD were also evaluated. To obtain the same low friction coefficient, dc pulse-plasma CVD requires less TMS than dc plasma CVD. Hence, it is also clarified that Si-DLC films can be fabricated at a low cost by dc pulse-plasma CVD.     

脉冲磁控溅射MoS2涂层的组织结构及摩擦学性能

采用单极性脉冲磁控溅射技术在A286基体表面制备MoS₂低摩擦系数涂层(LFC)。利用XRD、SEM等手段表征涂层的成分与微观组织;采用原位纳米力学测试系统、球-盘式摩擦磨损试验机分析涂层的力学和摩擦学性能,并探讨了脉冲偏压对涂层结构、力学和摩擦学性能的影响。结果表明,脉冲偏压由300V增加到600V,MoS₂涂层择优取向发生了(002)向(100)转变,当脉冲偏压增至800V时又恢复(002)择优取向,;随着脉冲偏压的增加,涂层的硬度及弹性模量出现先减少后增大趋势,摩擦系数在0.065~0.076范围内波动,呈现出先增加后减小趋势;偏压为800V的涂层摩擦学性能最佳,其磨损率仅为基体的13.5%。