Effects of substrate temperature and post-annealing on microstructure and properties of (AlCrNbSiTiV)N coatings

AlCrNbSiTiV nitride films were deposited by reactive radio-frequency magnetron sputtering from an AlCrNbSiTiV equimolar target. Effects of substrate temperatures from 100 °C to 500 °C and post-annealing on the chemical composition, microstructure and mechanical properties of the films were investigated. Experimental results indicate that all nitride films have a single face-centered cubic (NaCl-type) structure with the stoichiometric nitride ratio approximately as Al₈Cr₈Nb₇Si₉Ti₉V₈N₅₀. Increasing the substrate temperature increases the grain size and the compressive residual stress, but decreases the lattice constant. The highest hardness of (AlCrNbSiTiV)N nitride films is 41 GPa, corresponding to the super-hard grade. Even annealing in a vacuum at 900 °C for 5 h caused no notable change in the crystalline structure, lattice parameter, grain size or hardness. The super-hard level and thermal stability of these multi-component coatings are discussed.     

Properties of MoNxOy thin films as a function of the N/O ratio

The main purpose of this work is the preparation of single layer films of molybdenum oxynitride, MoN_xO_y. The films were deposited on steel substrates by dc reactive magnetron sputtering. The depositions were carried out from a pure Mo target and varying the flow rate of reactive gases. This allowed tuning of the crystallographic structure between insulating oxides and metallic nitrides and consequently changes in the electronic, mechanical and optical properties of the material. X-ray diffraction (XRD) results revealed the presence of molybdenum nitride for the films with low oxygen fraction: face-centered cubic phases (γ-Mo₂N) for low nitrogen flow rate or cubic MoN_x and hexagonal phase (δ-MoN) for high nitrogen flow rate. The increase of oxygen content induces an amorphization of the nitride phases and the appearance of MoO₃ phases. The increase of the oxygen fraction in the films induces also a high decrease in the film's hardness. Residual stresses were compressive, in the range of very few tenths of GPa to − 2 GPa. These results will be presented as a function of the deposition parameters, the chemical composition and the structure of the films.     

Carbon nitride films deposited by reactive sputtering and pulsed laser ablation

Carbon nitride films were deposited by reactive sputtering process and by pulsed laser ablation process with substrate bias. By applying the RF bias, it enables the ion irradiation on to the depositing film surface continuously. ECR plasma source was used for reactive sputtering. Nd:YAG laser (λ=532 nm, 210 mJ) was used to ablate a graphite target in the nitrogen atmosphere. The film properties were examined by XPS, Raman, nanoindentation measurement, and FE-SEM. It was shown that the films deposited by reactive sputtering had smooth surface and its hardness of approximately 30 GPa. However, the films deposited by pulsed laser ablation had uneven surface and low hardness. Both processes, the atomic composition ratio of N/C and sp³ bonding ratio increased with ion bombardment energy up to 100-150 eV, and level off above it. The maximum atomic composition ratio of N/C was 0.35 for reactive sputtering and 0.24 for laser ablation.     

Copper nitride films deposited by dc reactive magnetron sputtering

Copper nitride (Cu₃N) films were deposited on glass substrates by sputtering of copper target under various substrate temperatures in the range 303–523 K using dc reactive magnetron sputtering. The substrate temperature highly influenced the structural, mechanical, electrical and optical properties of the deposited films. The X-ray diffraction measurements showed that the films were of polycrystalline nature and exhibit preferred orientation of (111) phase of Cu₃N. The microhardness of the films increased from 2.7 to 4.4 GPa with the increase of substrate temperature from 303 to 473 K thereafter decreased to 4.1 GPa at higher temperature of 523 K. The electrical resistivity of the films decreased from 8.7 × 10⁻¹ to 1.1 × 10⁻³ Ωcm and the optical band gap decreased from 1.89 to 1.54 eV with the increase of substrate temperature from 303 to 523 K respectively.     

Structural, morphological, and mechanical properties of amorphous carbon and carbon nitride thin films deposited by reactive and ion beam assisted laser ablation

Amorphous carbon nitride thin films have been prepared on Si (100) wafers by nitrogen ion beam assisted Nd:YAG laser ablation techniques. Amorphous carbon and carbon nitride films have also been prepared by the conventional laser ablation techniques for comparison. Raman spectroscopy and spectroscopic ellipsometry have been performed for the films to analyze structural properties, atomic force microscopy to observe surface morphologies, and scratch, acoustic emission, and Vicker hardness test to examine mechanical properties. The amorphous carbon nitride films deposited by the ion beam assisted laser ablation techniques had generally better mechanical properties compared to the amorphous carbon films and amorphous carbon nitride films deposited in N₂ atmosphere. The amorphous carbon nitride films deposited at optimum ion beam current of 10 mA and laser power density of 1.7 × 10⁹ W/cm² showed excellent mechanical properties: root mean square surface roughness of 0.33 nm, friction coefficient of 0.02–0.08, the first crack and critical load of 11.5 and 19.3 N respectively, and Vicker hardness of 2300 [Hv]. It is considered that the films have high potential for protective coatings for microelectronic devices such as magnetic data storage media and heads.     

Control of microstructures and properties of dc magnetron sputtering deposited chromium nitride films

Chromium nitride coatings have been prepared by a conventional DC magnetron reactive sputtering process in nitrogen-argon mixed atmospheres. The sputtering pressure and target voltage versus nitrogen flow rate curves were established in order to control the structures and properties of chromium nitride coatings. A good correspondence among the sputtering pressure, target voltage evolutions and the phase developments with respect to nitrogen flow rate has been found. The stoichiometric Cr₂N and CrN coatings were confirmed by EPMA and XRD analysis. Cryogenic fracture cross-section SEM images show columnar growth morphologies. Stoichiometric chromium nitrides present high hardness and elastic modulus as well as high H³/E² ratio in a nano-indenter test. Adhesion and tribological properties were evaluated by scratch and pin-on-disk tests, respectively. Chromium nitrides present normal adhesion failure critical load (Lc₂) between 10 and 20 N and friction coefficients ranging from 0.5 to 0.75.     

Effect of carbon content on the microstructure and properties of W–Si–C–N coatings fabricated by magnetron sputtering

A series of W–Si–C (4–5 at.%)–N nanocomposite coatings with different C contents have been deposited on Si wafer substrates by reactive magnetron sputtering of W–Si–C composite target in Ar + N₂ mixed atmosphere. Microstructure characteristics and mechanical properties of W–Si–C–N coatings were investigated in this paper. Results exhibited that W–Si–C–N coatings possess nanocomposite microstructure where nano-crystallites W₂(C, N) embedded in amorphous matrix of Si₃N₄/CNx/C. As the C content increased, the hardness and Youngs’ modulus of the W–Si–C–N coatings first increased and then decreased, reaching the maximum value of approximate 36 GPa and 382 GPa, respectively, for coatings containing 11.1 at.% C. All the coatings are in compressive stress state, ranging from 0.8 to 2.0 GPa. In addition, friction coefficient of the W–Si–C–N coatings considerably decreased with the increase of C content.     

Influence of N2 partial pressure on mechanical properties of (Ti,Al)N films deposited by reactive magnetron sputtering

The influence of the nitrogen partial pressure on the mechanical properties of (Ti,Al)N films deposited by DC reactive magnetron sputtering using a Ti-Al mosaic target at a substrate bias of −100 V is investigated. Nanoindentation tests reveal that with increasing N₂ partial pressure, the film hardness and elastic modulus increase initially and then decrease afterwards. The maximum hardness and elastic modulus are 43.4 GPa and 430.8 GPa, respectively. The trend is believed to stem from the variations in the grain size and preferential orientation of the crystals in the (Ti,Al)N films fabricated at varying N₂ partial pressure. The phenomenon is confirmed by results acquired using glancing angle X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS).     

Characterization of TiCr(C,N)/amorphous carbon coatings synthesized by a cathodic arc deposition process

Ternary TiCrN and nanocomposite TiCr(C,N)/amorphous carbon (a-C) coatings with different carbon contents (0-26.6 at.%) were synthesized by cathodic arc evaporation with plasma enhanced duct equipment. The structural, chemical, and mechanical properties of the deposited films were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), and nanoindentation measurement. The atomic content ratios of carbon/(Ti + Cr) and carbon/nitrogen increased with increasing C₂H₂ flow rate. A nanocomposite structure of coexisting metastable hard TiCr(C,N) crystallites and amorphous carbon phases was found in the TiCr(C,N)/a-C coatings, those possessed smaller crystallite sizes than the ternary TiCrN film. XPS analyses revealed the concentration of a-C increased with increasing carbon content from 8.9 at.% to 26.6 at.%. Exceeding the metastable solubility range of carbon within the TiCrN lattice, the carbon formed a-C phase in the deposited coatings. The nanocomposite TiCr(C,N)/a-C coatings exhibited higher hardness value of 29-31 GPa than the deposited TiCrN coating (26 ± 1 GPa). It has been found that the structural and mechanical properties of the films were correlated with the carbon content in the TiCr(C,N)/a-C coatings.     

Structural and mechanical properties of multi-element (AlCrMoTaTiZr)Nx coatings by reactive magnetron sputtering

(AlCrMoTaTiZr)N_x high-entropy films were deposited on silicon wafer and cemented carbide substrates from a single alloy target by reactive RF magnetron sputtering under a mixed atmosphere of Ar and N₂. The effect of nitrogen flow ratio R_N on chemical composition, morphology, microstructure, and mechanical properties of the (AlCrMoTaTiZr)N_x films was investigated. Nitrogen-free alloy film had an amorphous structure, while nitride films with at least 37 at.% N exhibited a simple NaCl-type FCC (face-centered cubic) structure. Mixed structures occurred in films with lower nitrogen contents. Films with the FCC structure were thermally stable without phase decomposition at 1000 °C after 10 h. The (AlCrMoTaTiZr)N film deposited at R_N = 40% exhibited the highest hardness of 40.2 GPa which attains the superhard grade. The main strengthening mechanisms for this film were grain-size and solid-solution strengthening. A residual compressive stress of 1.04 GPa was small to account for the observed hardness. The nitride film was wear resistant, with a wear rate of 2.8 × 10^− 6 mm³/N m against a loaded 100Cr6 steel ball in the sliding wear test. These high-entropy films have potential in hard coating applications.     

Characterisation of nano-structured titanium and aluminium nitride coatings by indentation, transmission electron microscopy and electron energy loss spectroscopy

Titanium and aluminium nitride Ti_1 − xAl_xN films deposited by radiofrequency magnetron reactive sputtering onto steel substrate are examined by transmission electron microscopy over all the range of composition (x = 0, 0.5, 0.68, 0.86, 1). The deposition parameters are optimised in order to grow nitride films with low stress over all the composition range. Transmission electron microscopy cross-section images of Vickers indentation prints performed on that set of coatings show the evolution of their damage behaviour as increasing x Al content. Cubic Ti-rich nitrides consist of small grains clustered in rather large columns sliding along each other during indentation. Hexagonal Al-rich films grow in thinner columns which can be bent under the Vickers tip. Indentation tests carried out on TiN and AlN films are simulated using finite element modelling. Particular aspects of shear stresses and displacements in the coating/substrate are investigated. The growth mode and the nanostructure of two typical films, TiN and Ti_0.14Al_0.86N, are studied in detail by combining transmission electron microscopy cross-sections and plan views. Electron energy loss spectrum taken across Ti_0.14Al_0.86N film suggests that a part of nitrogen atoms is in cubic-like local environment though the lattice symmetry of Al-rich coatings is hexagonal. The poorly crystallised domains containing Ti and N atoms in cubic-like environment are obviously located in grain boundaries and afford protection of the coating against cracking.     

Study on adhesion and wear resistance of multi-element (AlCrTaTiZr)N coatings

Multi-element (AlCrTaTiZr)N films were deposited on cemented carbide and M2 steel substrates by reactive RF magnetron sputtering. Prior to nitride film deposition, an interlayer between the film and the substrate was introduced to improve adhesion property. The influence of interlayer materials (Ti, Cr, and AlCrTaTiZr alloy) and interlayer thickness (0–400 nm) on the adhesion and tribological properties of films was investigated. In this study, the nitride film deposited at R_N = 20% exhibited the highest hardness (35.2 GPa) and the lowest residual compressive stress (? 1.52 GPa), and was prepared as the top layer for further testing. The interlayer materials can effectively improved the film adhesion onto the cemented carbide substrates, and the adhesive failure was not observed even under the normal load of 100 N. For M2 steel substrates, only the Cr interlayer can slightly improve the film adhesion, and the cohesive and adhesive failure can be found at relatively lower applied load. The optimal interlayer thickness was 100–200 nm for the 1 µm-thick (AlCrTaTiZr)N film and can be related to the stress evolution. The friction coefficient and wear rate for the (AlCrTaTiZr)N film were 0.82 and 4.9 × 10^? 6 mm³/Nm, respectively, and almost kept constant under different interlayer materials and thickness. The worn-through event of the nitride film during tribological test occurred easily owing to its poor adhesion behavior, and can be improved by interlayer additions.     

Reactive deposition of Al-N coatings in Ar/N2 atmospheres using pulsed-DC or high power impulse magnetron sputtering discharges

In this paper, the metal to ceramic transition of the Al-N₂ system was investigated using classical reactive pulsed-DC magnetron sputtering and HIgh Power Impulse Magnetron Sputtering (HIPIMS) at a constant average current of 3 A. Optical emission spectroscopy measurements revealed more ionised aluminium species in the HIPIMS discharge compared to pulsed-DC sputtering. It also showed excited N⁰ and ionised N⁺ species in reactive Ar/N₂ HIPIMS discharges. The corresponding evolution of the consumed nitrogen flow as a function of the N₂ partial pressure revealed that a higher amount of reactive gas is needed to achieve stoichiometric AlN with HIPIMS. Electron probe micro-analysis and X-ray diffraction measurements confirmed that a partially poisoned aluminium target is enough to allow the deposition of stoichiometric hcp-AlN thin films via HIPIMS. To go further in the comparison of both processes, two stoichiometric hexagonal aluminium nitride thin films have been deposited. High power impulse magnetron sputtered hcp-AlN exhibits a higher nano-hardness (18 GPa) than that of the coating realised with conventional pulsed-DC sputtering (8 GPa).     

Investigation of structural,optical and micro-mechanical properties of (NdyTi1 − y)Ox thin films deposited by magnetron sputtering

TiO₂ and (Nd_yTi_1 − y)O_x thin films were deposited by reactive magnetron sputtering process from mosaic Ti–Nd targets and characterised by X-ray diffraction (XRD), Raman optical spectroscopy and nanoindentation technique. XRD measurements revealed that as-prepared titanium dioxide and TiO₂ thin films with 4 and 7 at.% of Nd had nanocrystalline rutile structure, while coatings with larger amount of Nd were amorphous. Raman spectroscopy investigations showed that the increase of the neodymium concentration caused amorphisation of the coatings and hindered their crystal growth. All as-prepared coatings were transparent in the visible wavelength range with a transmittance of approximately 80%. The refractive index and extinction coefficient of the thin films gradually decreased with the increase of the neodymium concentration. Micro-mechanical properties, i.e. hardness and elastic modulus, were determined using traditional load-controlled nanoindentation testing and continuous stiffness measurements. The highest hardness and elastic modulus values were obtained for thin films with 7 at.% of Nd and were approximately 14.8 GPa and 166.3 GPa, respectively.     

Tungsten/tungsten nitride performance at elevated temperature

Abstract

Multilayer physical vapour deposition (PVD) coating of W/W₂N (tungsten/tungsten nitride) on Orvar Supreme steel was tested under the different conditions to investigate their friction and wear behaviour with their mechanical properties. Coatings were sputtered by reactive magnetron sputtering in a N₂/Ar atmosphere. Pin on disc test was performed on Orvar Supreme steel at room temperature to elevated temperature (800°C). Steel ball (100Cr6) and alumina ball are used to evaluate the frictional and wear properties. Scanning electron microscopy (SEM) and energy dispersive X-ray analyses were performed to obtain the microstructure and chemical composition of the material. Mechanical properties of coating were evaluated using nanoindentation and scratch test.     

Influence of RF power on the electrical and mechanical properties of nano-structured carbon nitride thin films deposited by RF magnetron sputtering

Nano structured carbon nitride thin films were deposited at different RF powers in the range of 50 W to 225 W and constant gas ratio of (argon: nitrogen) Ar:N₂ by RF magnetron sputtering. The atomic percentage of Nitrogen: Carbon (N/C) content and impedance of the films increased from 14.36% to 22.31% and 9 × 10⁻¹ Ω to 7 × 10⁵ Ω respectively with increase in RF power. The hardness of the deposited films increased from 3.12 GPa to 13.12 GPa. The increase in sp³ hybridized C-N sites and decrease of grain size with increase in RF power is responsible for such variation of observed mechanical and electrical properties.     

Nanoindentation and atomic force microscopy measurements on reactively sputtered TiN coatings

Titanium nitride (TiN) coatings were deposited by d.c. reactive magnetron sputtering process. The films were deposited on silicon (111) substrates at various process conditions, e.g. substrate bias voltage (V_B) and nitrogen partial pressure. Mechanical properties of the coatings were investigated by a nanoindentation technique. Force vs displacement curves generated during loading and unloading of a Berkovich diamond indenter were used to determine the hardness (H) and Young’s modulus (Y) of the films. Detailed investigations on the role of substrate bias and nitrogen partial pressure on the mechanical properties of the coatings are presented in this paper. Considerable improvement in the hardness was observed when negative bias voltage was increased from 100–250 V. Films deposited at |V _B| = 250 V exhibited hardness as high as 3300 kg/mm². This increase in hardness has been attributed to ion bombardment during the deposition. The ion bombardment considerably affects the microstructure of the coatings. Atomic force microscopy (AFM) of the coatings revealed fine-grained morphology for the films prepared at higher substrate bias voltage. The hardness of the coatings was found to increase with a decrease in nitrogen partial pressure.     

Influence of sputtering parameters and nitrogen on the microstructure of chromium nitride thin films deposited on steel substrate by direct-current reactive magnetron sputtering

Chromium nitride thin films were deposited on SA-304 stainless steel substrates by using direct-current reactive magnetron sputtering. The influence of process conditions such as nitrogen content in the fed gas, substrate temperature, and different sputtering gases on microstructural characteristics of the films was investigated. The films showed (200) preferred orientation at low nitrogen content (< 30%) in the fed gas. The formation of Cr₂N and CrN phases was observed when 30% and 40% N₂ were used, with a balance of Ar, respectively. Field emission scanning electron microscopy and atomic force microscopy were used to characterize the morphology and surface topography of the thin films, respectively. Microhardness tests showed a maximum hardness of 16.95 GPa for the 30% nitrogen content.     

Friction and wear properties of Cr:(Wx,N0.1) coatings deposited by magnetron sputtering

This paper discusses the friction and wear properties of Cr:(W_x,N_0.1) coatings with different tungsten contents. The Cr:(W_x,N_0.1) coatings with x being in the range of 0-0.16 were deposited using unbalanced magnetron sputtering technology. The microstructures and mechanical properties of Cr:(W_x,N_0.1) coatings have been characterized by SEM, TEM, X-ray diffraction (XRD), nanoindentation and adhesion techniques. The tribological properties of the coatings were investigated using an oscillating friction and wear tester under dry conditions. Indexable inserts with Cr:(W_x,N_0.1) coatings were applied to turning AISI 1045 steel material by a lathe. Micron-drills with Cr:(W_x,N_0.1) coatings were adopted in the ultra high speed (10⁵ rpm) PCB through-hole drilling test. Experimental results indicate that the coating microstructure, mechanical properties and wear resistance vary according to the tungsten content. All the coatings crystallize in the BCC phase. Cr:(W_0.06,N_0.1)-coated tools showed the best wear resistance in 1045 steel turning and PCB through-hole drilling tests. The service life of Cr:(W_0.06,N_0.1)-coated tool is three times greater than that of an uncoated tool in PCB through-hole drilling test.     

PECVDTM Coatings in Industrial Applications

The adoption of GPI's Linear PECVD^TM process has accelerated over the last year. Several R&D and production reactor modules were installed at major companies and a turnkey in‐line system was completed. Through these installations, customers are confirming the superior deposition rate, uniformity and stability of Linear PECVD^TM compared to reactive sputtering. Today Linear PECVD^TM is being used to deposit oxide and nitride films on a variety of substrates. The films include SiO₂, TiO₂, Al2₂O₃, SiN, ZnO, and SnO and the applications include multi‐layer AR coatings, single layer oxides and nitrides in combination with sputtered films, thin‐film solar coatings, barrier films, anti‐smudge coatings and TCO's. This progress demonstrates that GPI's Linear PECVD^TM technology may soon displace reactive sputtering of oxides and nitrides for large area substrates in architectural glass, flat panel display and flexible web applications.