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.     

Cathodic arc plasma deposition of nano-multilayered Zr-O/Al-O thin films

Thin films of Zr-O/Al-O were deposited on SKD 11 tool steel substrate using Zr and Al cathodes in a cathodic arc plasma deposition system. The substrates were mounted on a rotating holder which alternatively exposed them to plasma from the two cathodes. The influence of the Zr and Al cathode arc currents and the substrate bias on the mechanical and the structural properties of the films were investigated. Films with a nano-layered structure of alternating Al-rich and Zr-rich layers were obtained. The Zr layers contained nano-crystallites of (101) oriented t-ZrO structure. Crystallites with α-Al₂O₃ structure were observed only when the substrate was negatively biased in the 100-150 V range. The hardness of the film decreased with the increase of Zr cathode current from 60 to 80 A, increased when the Al cathode current increased from 25 to 30 A, and decreased when the Al cathode current increased from 30 to 35 A. The hardness of the film increased with the increase of bias voltage up to − 150 V and then decreased with further increase of the negative bias. The film structure was elucidated by HRTEM microscopy. Good correlation between the residual stress and the hardness enhancement of the films was observed.     

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.     

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.     

Effect of bias voltage on microstructure and properties of Ti-doped graphite-like carbon films synthesized by magnetron sputtering

Ti-doped graphite-like carbon (GLC) films with different microstructures and compositions were fabricated using magnetron sputtering technique. The influence of bias voltages on microstructure, hardness, internal stress, adhesion strength and tribological properties of the as-deposited GLC films were systemically investigated. The results showed that with increasing bias voltage, the graphite-like structure component (sp² bond) in the GLC films increased, and the films gradually became much smoother and denser. The nanohardness and compressive internal stress increased significantly with the increase of bias voltage up to −300 V and were constant after −400 V. GLC films deposited with bias voltages in the range of -300--400 V exhibited optimum adhesion strength with the substrates. Both the friction coefficients and the wear rates of GLC films in ambient air and water decreased with increasing voltages in the lower bias range (0--300 V), however, they were constant for higher bias values (beyond −300 V) . In addition, the wear rate of GLC films under water-lubricated condition was significantly higher for voltages below −300 V but lower at high voltage than that under dry friction condition. The excellent tribological performance of Ti-doped GLC films prepared at higher bias voltages of −300--400 V are attributed to their high hardness, tribo-induced lubricating top-layers and planar (2D) graphite-like structure.     

Study on nanocrystalline Cr2O3 films deposited by arc ion plating: I. composition, morphology, and microstructure analysis

Nanocrystalline Cr₂O₃ thin films were deposited on silicon wafers with (100) orientation by arc ion plating (AIP) technique at various negative bias voltages. By virtue of X-ray diffraction analysis, scanning electron microscope, and high-resolution transmission electron microscope, the influence of substrate bias voltage on the film growth process, microstructure, and characteristics was investigated systematically, including the phase constituents, grain size, lattice constant, chemical compositions, as well as surface and cross-section morphologies. With increasing the bias voltage, the grain size and lattice constant of AIP Cr₂O₃ films first decreased slightly, and then increased gradually again. Both reached the minimum (35 nm and 13.57 Å) when the bias voltage was − 100 V. However, the bias voltage had little effect on the phase constituents and chemical compositions of AIP Cr₂O₃ films. During the film growth process, the surfaces of Cr₂O₃ films were getting smoother with the negative bias voltage increase, in the meantime, their microstructures evolved from coarse columnar grains to fine columnar grains, short columnar recrystallized grains, and fine columnar grains again.     

基片偏压对电弧离子镀ZrN薄膜微结构和表面形貌的影响(英文)

在不同的基片偏压下利用电弧离子镀技术制备氮化锆薄膜,以考察基片偏压对氮化锆薄膜微结构和表面形貌的影响。利用XRD、EPMA和FE-SEM等技术对不同偏压时得到ZrN薄膜的相结构、成分和表面形貌进行表征。结果表明,薄膜中存在立方氮化锆和六方纯锆相;随着基片偏压的增大,薄膜的择优取向由(111)变为(200),最后变为(111),晶粒尺寸由30nm减小至15nm。同时发现,随着基片偏压的增大,薄膜微结构由明显的柱状特征变为致密的等轴晶特征,表明由偏压增强的离子轰击能有效抑制柱状晶生长;薄膜沉积速率和锆氮摩尔比随着基片偏压的增大先增大后减小,在-50V时达到最大。     

Influence of substrate bias on microstructure and morphology of ZrN thin films deposited by arc ion plating

Zirconium nitride thin films were fabricated using arc ion plating under negative substrate biases to investigate the influence of substrate bias on the ZrN films. The phase, composition, and surface morphology of the ZrN ?lms, with respect to substrate bias, were studied by XRD, EPMA, and FE-SEM, respectively. The results show that cubic ZrN and hexagonal Zr phases form in the ZrN films. The competition between surface energy and strain energy makes the preferred orientation change from (111) to (200) and then back to highly (111) preferred orientation as a function of substrate bias. With the increase of bias voltage, the crystallite size of ZrN films reduces from 30 to 15 nm. Meanwhile, the film microstructure evolves from an apparent columnar structure to a highly dense equiaxed structure, indicating that the ion bombardment enhanced by substrate bias can suppress the columnar growth in the ZrN films. Deposition rate and mole ratio of Zr to N increase with the increase of bias voltage and reach the maximum at –50 V, and then show a decline trend when bias voltage further increases.     

Layer formation by resputtering in Ti-Si-C hard coatings during large scale cathodic arc deposition

This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound Ti-Si-C cathodes and rotating substrate fixture. For the as-deposited films, electron microscopy and energy dispersive X-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles, when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with sizes up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.     

Density, stress, hardness and reduced Young's modulus of W-C:H coatings

Density, hardness and compressive stress of tungsten contained in an amorphous-hydrogenated-carbon matrix (W-C:H) have been studied as a function of composition and bias voltage. W-C:H coatings were deposited by reactive sputter deposition from a tungsten-carbide (WC) target on silicon substrate in an argon-acetylene plasma. W-C:H coatings obtained at different acetylene flow rates and substrate bias voltages, were characterized by scanning electron microscopy, X-ray diffraction, nanoindentation and substrate curvature method. It has been observed that compressive stress, hardness and reduced Young's modulus decrease when the acetylene flow is increased from 0 to 10 sccm. Also, compressive stress and hardness increases with the substrate bias voltage. In particular, for W-C:H coatings obtained at 5 sccm of acetylene flow, the compressive stress and hardness increase from − 1.6 GPa to − 3.2 GPa and from 19 GPa to 24 GPa, respectively, when increasing the substrate bias from 0 to 200 V. The variation of the internal stress, hardness and density of the coatings is discussed in terms of composition and structure of the W-C:H coatings.     

Deposition of dense and smooth Ti films using ECR plasma-assisted magnetron sputtering

We report high quality Ti films grown in a novel electron cyclotron resonance (ECR) plasma-assisted magnetron sputtering (PMS) deposition system. The films are compared with films deposited by conventional direct current (DC) magnetron sputtering. Using ECR-PMS, the argon plasma bombardment energy and Ti film deposition rate can be controlled separately, with the substrate bias voltage under feedback control. Results from SEM, AFM, XRD and PAS (scanning electron microscopy, atomic force microscopy, X-ray diffraction and positron annihilation spectroscopy) show that the properties of Ti films prepared by ECR-PMS are greatly improved compared with conventional sputtering. SEM and AFM confirmed that ECR-PMS Ti films have a dense, smooth, mirror-like surface. Increasing the substrate bias of the ECR plasma from − 23 V to − 120 V while keeping a fixed sputtering bias voltage of − 40 V, the intensity of the (100) reflection of Ti film was a little strengthened, but (002) remained strongly preferred orientation. The XRD peak broadening of ECR-PMS Ti films is more than for conventional magnetron sputtering, due to grain refinement induced by Ar ion bombardment. Doppler broadening of PAS analysis reveals that the Ti films have fewer vacancy defects compared with films prepared by the conventional magnetron.     

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 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.     

Effect of substrate bias in amorphous carbon films having embedded nanocrystallites

The effect of substrate bias on the structural, morphological, electrical and mechanical properties of amorphous carbon (a―C) films having embedded nanocrystallites deposited by filtered cathodic jet carbon arc technique has been investigated. X-ray diffraction exhibits predominantly an amorphous nature of the film. High resolution transmission electron microscope investigations reveal largely an amorphous structure. However, an ultra-fine nanograined microstructure with the average grain size between 20 and 50 nm was observed throughout the entire film and the majority of the individual grains were single crystallites with the preferred interplanar spacing of about 0.2 nm. All the parameters evaluated were seen to depend strongly on the negative substrate bias and exhibit maxima or minima in the properties of the films deposited at − 150 V substrate bias. These a-C films having embedded nanocrystallites act as hard coating materials.     

Nanomechanical and electrochemical properties of ZrN coated NiTi shape memory alloy

Zirconium nitride (ZrN) thin films were deposited on NiTi and Si substrates in the 23–570 °C temperature range by direct current reactive magnetron sputtering using N₂/Ar gas mixture. The film hardness, corrosion behavior, phase composition, and texture were determined. The deposited films were composed mainly by the cubic ZrN phase, whose texture varies with substrate temperature, changing progressively from (111) to (200) texture as the temperature increases. The hardness of the films is influenced by the texture and has a linear relationship with the ratio of the texture coefficients P(111)/P(200). The higher hardness is obtained for ZrN thin films with (200) texture. Electrochemical tests show that NiTi coated with (200)-oriented ZrN films has higher tendency to passivation and greater stability of the passive film as compared to (111)-oriented ZrN films, despite no abrupt changes was observed when the texture changes from (111) to (200).     

Study on the role of PVD TiN coating in improving the performance of electroplated monolayer superabrasive wheel

The monolayer grinding wheels, coated with a physical vapour deposited (PVD) coating (viz. TiN, HfN, TiN + ZrN etc.), have been reported to outperform their uncoated counterparts as claimed in some patented literatures. The present work aims at exploring the mechanism how PVD TiN augments the performance of nickel electroplated monolayer superabrasive wheels. This study also includes the effect of negative substrate bias voltage on performance of TiN coated electroplated cBN wheels during grinding of hardened bearing steel. TiN was deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) technique in an in-house PVD coating system. The structure of the TiN coating and post-grinding condition of the wheels were observed using scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) line scan, Electron probe micro analysis (EPMA) and secondary ion mass spectrometry (SIMS) depth profiling at the junction of TiN and nickel layer indicated the occurrence of inter-diffusion between them and grazing incidence X-ray diffraction (GIXRD) confirmed the formation of Ni-Ti intermetallic phases at their interface. The scratch test revealed a significant increase in cohesive and adhesive strengths of nickel layer when TiN was deposited at a bias voltage of −60 V or beyond that. The uncoated cBN wheel exhibited large number of grit fracture at the bond level and some grit pull-out. Such failures of grit were significantly arrested with TiN coating deposited at the bias voltages of −60 V and −90 V.     

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.     

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.     

The nanostructured phase transition and thermal stability of superhard f-TiN/h-AlSiN films

The superhard Ti–Al–Si–N films were synthesized by multi-arc ion plating technology and the influence of vacuum annealing on the structures and properties of the films was investigated. Transmission electron microscopy observation confirmed that the as-deposited Ti–Al–Si–N films were consisted of fcc-TiN/hcp-AlSiN multilayers with a period of 8 nm. The result also showed that a minute layer of cubic structure was observed in hcp-AlSiN layer at the interface between TiN layers and AlSiN layers, which resulted in an epitaxial growth between TiN layers and AlSiN layers. The annealing experiment of the Ti–Al–Si–N films was performed in vacuum furnace for 2 h at temperatures ranging from 700 to 1100 °C. With increasing annealing temperatures, no novel phases were observed indicating that the film retained the sharp interfaces. The grains of the film coarsened and showed mixed orientations at 1100 °C. The transformation of h-AlSiN into h-AlN and Al-depleted AlSiN_x and partial crystalline SiN_x was speculated during the annealing process by the XPS and DSC results. The film retained super hardness of above 47 GPa even at 1100 °C due to the formation of crystalline SiN_x and the minute c-(Al, Si)N layer between c-TiN layers and h-AlSiN layers which delayed the transformation of (Al, Si)N from cubic phase to hexagonal phase. The adhesion strength of the film was also discussed and that vacuum annealing could improve the adhesion strength.     

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.