CrN Layers Research Articles

Synthesis of monolayer MoNx and nanomultilayer CrN/Mo2N coatings using arc ion plating

Monolayer MoNx and nano-multilayer CrN/Mo2N coatings were prepared by arc ion plating and characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), friction tester and hardness tester. The results from TEM and XRD analysis showed that the crystal structure of MoNx and CrN/Mo2N coatings has a cubic lattice structure. The microhardness of MoNx coatings deposited at lower N2 pressure is about 2100 HV which is higher than 1950 HV of the coatings deposited at higher N2 pressure. The variation of friction coefficient of MoNx coatings influenced by N2 pressure is obvious at higher N2 pressure. The modulation period of CrN/Mo2N coatings is from 58.5 nm to 11.17 nm with increasing substrate rotation speed (Srs) in the range of 1–5 rpm. The maximum hardness of CrN/Mo2N nanomultilayer coatings, when the Srs is 7 rpm, is approximately 2950 HV. The value is 1.5 times higher than those of the MoNx monolayer coating (2000 HV). These enhancement effects in superlattice films could be attributed to the resistance to dislocation glide across interface between the MoN and CrN layers. The value of average friction coefficient of CrN/Mo2N nanomultilayer coatings is about 0.33 which is higher than 0.3 of MoNx coatings and lower than 0.6 of CrN. The wear rate of CrN/Mo2N nanomultilayer coatings is about 7 × 10−7 mm3/N·m which is obviously lower than 3.3 × 10−6 mm3/N·m of CrN coatings and higher than 1.2 × 10−7 mm3/N·m of MoNx coatings.

Microstructure, adhesion and tribological properties of CrN/CrTiAlSiN/WCrTiAlN multilayer coatings deposited on nitrocarburized AISI 4140 steel

In this study, the CrN/CrTiAlSiN/WCrAlTiN multilayer coatings have been deposited on polished AISI 4140 steel substrates (named only-coating specimens) and plasma nitrocarburized specimens (named duplex specimens) by cathodic multi-arc evaporation. The microstructure and composition of the specimens were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) with Energy dispersive X-ray analysis (EDX), and transmission electron microscope (TEM) techniques. The micro-hardness and nano-hardness were measured by Vickers hardness tester and nanoindentation, respectively. The adhesion and tribological behavior were evaluated using the Rockwell-C indentation and micro-tribometer, respectively. The results showed that plasma nitrocarburizing gives rise to a modified layer due to diffusion of nitrogen/carbon, leading to surface hardness, H, of 13.0 GPa, compared to H = 6.8 GPa for the untreated steel. Notably, it shows that the super-hardness (H = 47.9 GPa) multilayer coating consists of a bottom CrN layer, a middle CrTiAlSiN layer, and an outmost superlattice WCrTiAlN layer. The nitrocarburizing pretreatment considerably improves adhesion strength of the duplex specimen compared with the only-coating one. The improved mechanical and tribological properties of the duplex specimen are mainly related to the gradient in the hardness profile of the diffusion nitrocarburized layer.

Mechanical and anti-wear properties of multi-module Cr/CrN coatings

The objects of investigations were Cr/CrN multi-module coatings deposited using a cathodic arc evaporation method (CAPVD) on HS6-5-2C steel used as a substrates. Analysed coatings possesses seven Cr/CrN modules of fixed thickness each, with various thicknesses of Cr and CrN layers. Aiming for the evaluation of mechanical properties of tested multi-module Cr/CrN coatings, its hardness and Young's modulus were measured, on the basis of which were determined values of H/E and H3/E2 ratios. Coatings wear and friction coefficients were measured in so called ball-on-disc test. The adhesion of the coatings was evaluated using scratch tester and was shown that main mechanism of adhesive damage of all tested coatings at higher loads are buckle spallations. All tested coatings are also characterised by good adhesion to the substrate, which is evidenced by the fact that cracked coating remains inside the scratch track. Basing on the analysis of obtained experimental results it was confirmed and explicitly shown that the thickness of the individual layers of Cr and CrN in the multi-module coating significantly affects its critical loads (in scratch test), fracture toughness and wear rate.

Study of Advanced Nanoscale ZrN/CrN Multilayer Coatings

The scientific interest in the investigation of nitride composites as protecting materials in tool and machining industries intensively increases. The good oxidation resistance of CrN single-layer films and high melting point, good chemical and thermal resistance of ZrN compound are motive factors for designing of multilayer composites composed of these metal nitrides. The suggested advantages of ZrN/CrN multilayer coatings as structural materials are the high-temperature resistance, high density and extreme hardness compared to the metal-nitride systems. Experimental ZrN/CrN multilayer coatings were deposited on AISI 321 steel substrates by using a cathodic arc evaporation device equipped with two high-purity metal Cr and Zr targets. Structural, chemical and morphological characteristics together with mechanical properties of multilayer composites were analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and Vickers hardness tester. SEM analysis revealed an increase of roughness and concentration of the droplets on the surface of the coatings when negative bias potential decreased to -70 V. The results of data obtained from the X-ray analysis showed (200) and (111) plane for ZrN and Cr2N phases as the most intense. The peak positions of ZrN were shifted towards lower diffraction angles comparing with bulk values and indicated a decrease of the inter-planar distance and formation of compressive stresses. The calculated lattice strain values in the ZrN were higher than those of the CrN, indicated a greater presence of dislocations and defects in the lattice of ZrN. The averaged crystallite sizes in ZrN and CrN layers were 11-14 and 7-12 nm, respectively. The maximum value of the Vickers microhardness was found to be 6600HV0.01 that is 2.1 and 1.8 times greater than the corresponding values of binary CrN and ZrN coatings.

Mechanical and anti-wear properties of multi-module Cr/CrN coatings

The objects of investigations were Cr/CrN multi-module coatings deposited using a cathodic arc evaporation method (CAPVD) on HS6-5-2C steel used as a substrates. Analysed coatings possesses seven Cr/CrN modules of fixed thickness each, with various thicknesses of Cr and CrN layers. Aiming for the evaluation of mechanical properties of tested multi-module Cr/CrN coatings, its hardness and Young's modulus were measured, on the basis of which were determined values of H/E and H3/E2 ratios. Coatings wear and friction coefficients were measured in so called ball-on-disc test. The adhesion of the coatings was evaluated using scratch tester and was shown that main mechanism of adhesive damage of all tested coatings at higher loads are buckle spallations. All tested coatings are also characterised by good adhesion to the substrate, which is evidenced by the fact that cracked coating remains inside the scratch track. Basing on the analysis of obtained experimental results it was confirmed and explicitly shown that the thickness of the individual layers of Cr and CrN in the multi-module coating significantly affects its critical loads (in scratch test), fracture toughness and wear rate.

Multilayered ZrN/CrN coatings with enhanced thermal and mechanical properties

Multilayered ZrN/CrN coatings were produced by the cathodic arc physical vapor deposition (CA-PVD). Morphology, element distribution, structural and thermal properties were investigated. Microhardness and nanoindentation tests were conducted to study the mechanical properties of the coatings. The experimental results of scanning electron microscopy (SEM) revealed the cellular microrelief of the surface and well-defined multilayered architecture of the coatings. Energy dispersive spectroscopy (EDS) provided the chemical characterization of the coatings and revealed the formation of stoichiometric composition in coatings. X-ray diffraction (XRD) studies showed that (200) and (111) plane reflections of ZrN and Cr2N phases, correspondingly, were with maximum intensity. Transmission electron microscopy (TEM) analysis revealed that the films comprise of nanometric equiaxed grains with average sizes from 12.8 to 15.1 nm for ZrN layers and from 14.5 to 28.1 nm for CrN layers. The high-temperature heat treatment caused exothermic and endothermic reactions, which were mainly attributed to the improvements or disordering of the coatings' structure, consequently. The highest values of microhardness (4966HV0.025) and nanohardness (24.58 GPa) were obtained for the sample with a bilayer thickness of 732 nm, the average crystallite size of 13.3 nm and nitrogen content of 49 at%. Experimental results indicated that deposited composites can be effectively used in the production of industrial tools, implements for cutting etc.

Study of corrosion and tribocorrosion of Fe3Al-based duplex PVD/HVOF coatings against alumina in NaCl solution

In this study, we assess the corrosion and tribocorrosion of the duplex (thin-on-thick) coating systems formed by thin CrN or DLC layers sputter deposited on top of thick Fe3Al layers thermal sprayed using high velocity oxy-fuel (HVOF) technique on 304-type stainless steel (SS304) substrates. The corrosion behavior of the duplex coatings was evaluated using a three-electrode cell, and the tribocorrosion assessment was carried out using a reciprocating ball-on-flat tribometer in which the tribological contact was immersed in the electrolyte. The microstructure and surface morphology of the coatings were analyzed using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Results show that the corrosion resistance of the Fe3Al coatings increased by approximately 1 and 3 orders of magnitude with the addition of CrN and DLC top layers, respectively. The electrochemical impedance spectroscopy analysis reveals that the poor corrosion behavior of the Fe3Al coating can be attributed to the presence of defects (porosity, cracks and inter-splat boundaries) in the HVOF layer that favor the infiltration of electrolyte and the formation of corrosion products. The tribocorrosion experiments confirm that addition of DLC and CrN layers is particularly beneficial when the duplex system is subjected to wear tests during cathodic polarization. However, in the anodic regime, defects formed at the surface by the wear process are detrimental since the electrolyte infiltrates the top layer and causes the dissolution of the Fe3Al interlayer. We demonstrate that under this situation, material losses are due to synergistic effects of wear and corrosion.

Effect of Pulsed Laser Ablation on the Increase of Adhesion of CRN Coating-Substrate

Abstract The contribution deals with analysis of the influence of the substrate surface laser ablation before deposition process to improve the adhesion of coating-substrate system. The coatings were applied to the high-speed steel 6-5-2-5 (STN 19 852) and WC-Co cemented carbide with cobalt content of 10 wt%. LAteral Rotating Cathodes (LARC®) process was chosen for evaporation of individual CrN layers. Influence of laser ablation on the substrate morphology, structure, roughness, presence of residual stresses inside the substrates and layers and their adhesion behavior between the layers and the base material was studied. Scanning electron microscopy fitted with energy dispersive spectroscopy was utilized to investigate morphology and fracture areas of substrates with CrN layers. X-ray diffraction analysis was employed to detect the residual stresses measurements. Adhesion between the coatings and substrate was analyzed using “Mercedes” testing.

Removal of CrN Contamination from EUV Mask Backside Using Dry Cleaning

For EUV lithography, a reflective mask is essential because of use of the strong energy, wavelength of 13.5 nm. The EUV mask consists of multi-layered, multi-material structure and is susceptible to various contaminants. Since EUV lithography process should be used in a high vacuum environment, an electrostatic chuck (ESC) is used to fix or hold the EUV mask using electrostatic force. In general, in order to use ESC chuck, it needs a thin conductive layer (CrN layer) on the backside. However, the contact points of the electrostatic pin chuck can make exfoliation of conductive CrN layer producing CrN particles. If these particles are present on the backside of the mask, CD or DOF may be affected during EUV exposure. The 1 μm particle can leads to a gap radius of 42mm [4]. Moreover, these backside particles may travel to the front side. Therefore, backside cleaning should be performed to remove particles from the mask backside surface.

Tailoring of the interface morphology of WS2/CrN bilayered thin film for enhanced tribological property

The WS2/CrN bilayered films with different interface morphologies between WS2 and CrN layer were prepared by physical vapor deposition. By controlling the deposition parameters, the surface of CrN interlayer exhibited compact granular structure when deposited under low partial pressure of Ar while a cone array-like surface appeared under high Ar partial pressure. The surface texture of the CrN interlayer had a great effect on the tribological performance of the WS2/CrN film. The compact CrN textured WS2 film exhibited a wear life about 2.6 × 105 cycles while the optimal cone array-like CrN textured WS2 film showed a much longer wear life reaching to 6.8 × 105 cycles, which was more than 2.6 times of that for compact CrN textured WS2 film and 3.5 times of that for WS2 film without the CrN interlayer. The improved tribological property of the optimal cone array-like CrN textured WS2 film was attributed to the high adhesion between the WS2 layer and the CrN interlayer. Meanwhile, the reservoir and replenishment of the WS2 lubricant by the CrN nanocones during the friction made a significant contribution for the long wear life.

Investigation of the Effect of Residual Stress Gradient on the Wear Behavior of PVD Thin Films

The control of residual stresses has been seldom investigated in multilayer coatings dedicated to improvement of wear behavior. Here, we report the preparation and characterization of superposed structures composed of Cr, CrN and CrAlN layers. Nano-multilayers CrN/CrAlN and Cr/CrN/CrAlN were deposited by Physical Vapor Deposition (PVD) onto Si (100) and AISI4140 steel substrates. The Cr, CrN and CrAlN monolayers were developed with an innovative approach in PVD coatings technologies corresponding to deposition with different residual stresses levels. Composition and wear tracks morphologies of the coatings were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and 3D-surface analyzer. The mechanical properties (hardness, residual stresses and wear) were investigated by nanoindentation, interferometry and micro-tribometry (fretting-wear tests). Observations suggest that multilayer coatings are composed mostly of nanocrystalline. The residual stresses level in the films has practically affected all the physicochemical and mechanical properties as well as the wear behavior. Consequently, it is demonstrated that the coating containing moderate stresses has a better wear behavior compared to the coating developed with higher residual stresses. The friction contact between coated samples and alumina balls shows also a large variety of wear mechanisms. In particular, the abrasive wear of the coatings was a combination of plastic deformation, fine microcracking and microspallation. The application of these multilayers will be wood machining of green wood.

Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10−17 (sliding with AISI 440C) and 2.64 × 10−17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

Correlation between damage evolution, structural and optical properties of Xe implanted CrN thin films

Polycrystalline CrN thin films were irradiated with Xe ions. The irradiation-induced modifications on structural and optical properties of the films were investigated. The CrN films were deposited on Si(100) wafers with the thickness of 280 nm, by using DC reactive sputtering. After deposition, the films were implanted at room temperature with 400 keV Xe ions with the fluences of 5-20?1015 ions/cm2. The films were then annealed at 700 ?C in vacuum for 2 h. The combination of Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) was used for structural analyses, while changes in optical properties were monitored by spectroscopic ellipsometry. We also measured the electrical resistivity of the samples using a four point probe method. RBS analysis reveals that the concentration of Xe in the layers increases with ion fluence reaching the value of around 1.5 at.% for the highest ion dose, at a depth of 73 nm. XRD patterns show that the irradiation results in the decrease of the lattice constant in the range of 0.4160-0.4124 nm. Irradiation also results in the splitting of 200 line indicating the tetragonal distortion of CrN lattice. TEM studies demonstrate that after irradiation the columnar microstructure is partially destroyed within _90 nm, introducing a large amount of damage in the CrN layers. Spectroscopic ellipsometry analysis shows that the optical band gap of CrN progressively reduces from 3.47 eV to 2.51 eV with the rise in ion fluence up to 20?1015 ions/cm2. Four point probe measurements of the films indicated that as the Xe ion fluence increases, the electrical resistivity rises from 770 to 1607 ?Wcm. After post-implantation annealing crystalline grains become larger and lattice distortion disappears, which influences optical band gap values and electrical resistivity of CrN.

INFLUENCE OF PRETREATMENT ON DIAMOND-COATED TOOL NUCLEATION AND MACHINING PERFORMANCE

The CVD diamond film with favorable adhesion and relatively thinner thickness is essential facing for its application on drills for machining carbon fiber reinforced plastics (CFRP), with regard to either the tool lifetime or the machining quality. A 500-nm-thick CrN layer was deposited by the cathode arc technique on slight chemical etched WC–Co 6[Formula: see text]wt.% drill, and nano-crystalline diamond (NCD) is subsequently deposited by the hot filament chemical vapor deposition (HFCVD) technique. The same NCD film is also deposited on the drills pretreated only by the slight chemical etching or the CrN interlayer, which are adopted as comparisons in the present study. The nucleation and growth of diamond film and the cutting performance of the coated drills are systematically studied. The results show that the drill pretreated by the slight chemical etching and CrN interlayer can acquire highest nucleation density (ND) compared to the other pretreatment methods as it sufficiently prevents the Co diffusion. The diamond-coated drill with deep chemical etching was used for comparison to study the machining quality when drilling CFRP. During machining the CFRP, the failure mode of the diamond-coated drill is mainly the delamination and peeling off of the diamond film at areas with stress concentration, while the diamond-coated drill pretreated by slight chemical etching [Formula: see text] CrN interlayer can retard such failure. The exit hole quality of CRFP machined by drill pretreated with slight chemical etching [Formula: see text] CrN interlayer is better than that by drill pretreated with deep chemical etching, which is ascribed to the different cutting edges of the drills.

Microstructures and Mechanical Properties of TiN/CrN Multilayer Films

In order to study the relationship between mechanical properties and microstructure of TiN/CrN multilayer coatings, the TiN, CrN film and three TiN/CrN multilayer films with different periodicities were prepared on monocrystalline silicon by magnetron sputtering. Atomic force microscope and X-ray diffraction were adopted to analyze the surface morphology and phase constitution of the films, respectively. The hardness and indentation plasticity were studied using nanoindenter. Residual stress was measured by a curvature method. The results show that TiN/CrN multilayer films exhibit a mixture of TiN and Cr 2 N phases, the interface zone between TiN layer and CrN layer becomes small and sharp with the increasing of periodicity. Hardness and indentation plasticity of multilayer films are better than those of monolayer films, and increase as the bilayer period decreases. For multilayer films, the residual stress increases gradually with the increasing of periodicity. From the above observation, it can be concluded that the improvement in mechanical property depends on minor periodicity. The results agree well with Hall-Petch theory.

Influence of the bilayer thickness of nanostructured multilayer MoN/CrN coating on its microstructure, hardness, and elemental composition

Multilayer nanostructured coatings consisting of alternating MoN and CrN layers were obtained by vacuum cathode evaporation under various conditions of deposition. The transition from micron sizes of bilayers to the nanometer scale in the coatings under investigation leads to an increase in hardness from 15 to 35.5 GPa (with a layer thickness of about 35 nm). At the same time, when the number of bilayers in the coating decreases, the average Vickers hardness increases from 1267 HV0.05 to 3307 HV0.05. An increase in the value of the potential supplied to the substrate from–20 to–150 V leads to the formation of growth textures in coating layers with the [100] axis, and to an increase in the intensity of reflections with increasing bilayer thickness. Elemental analysis carried out with the help of Rutherford backscattering, secondary ion mass spectrometry and energy dispersion spectra showed a good separation of the MoN and CrN layers near the surface of the coatings.

Clustering of gold particles in Au implanted CrN thin films: The effect on the SPR peak position

We report on the formation of gold particles in 280nm thin polycrystalline CrN layers caused by Au+ ion implantation. The CrN layers were deposited at 150°C by d.c. reactive sputtering on Si(100) wafers and then implanted at room temperature with 150keV Au+ ions to fluences of 2×1016cm−2 to 4.1×1016cm−2. The implanted layers were analysed by the means of Rutherford backscattering spectrometry, X-ray diffraction, atomic force microscopy and spectroscopic ellipsometry measurements. The results revealed that the Au atoms are situated in the near-surface region of the implanted CrN layers. At the fluence of 2×1016cm−2 the formation of Au particles of ∼200nm in diameter has been observed. With increasing Au ion fluence the particles coalesce into clusters with dimensions of ∼1.7μm. The synthesized particles show a strong absorption peak associated with the excitation of surface plasmon resonances (SPR). The position of the SPR peak shifted in the range of 426.8–690.5nm when the Au+ ion fluence was varied from 2×1016cm−2 to 4.1×1016cm−2. A correlation of the shift in the peak wavelength caused by the change in the particles size and clustering has been revealed, suggesting that the interaction between Au particles dominate the surface plasmon resonance effect.

초고강도강판 프레스성형용 금형의 CrN 코팅층 마모수명 예측

In this study, a wear test method was proposed to predict the wear life of the CrN layer coated on the surface of the press tools for manufacturing the auto-parts with ultra high strength steel (UHSS) with a tensile strength of 1.5 GPa. The pin-on-disc type wear test was carried out to confirm the feasibility and the reproducibility of the wear amount according to the test conditions such as the normal force, the sliding velocity, and the sliding speed. The test conditions were obtained from the finite element stamping analysis and the wear simulation. With the wear amount from the wear test, a prediction model of the wear depth in the CrN coating layer was proposed according to the test conditions with the design of experiments such as Taguchi method and the response surface method. The derived prediction model was then compared to the result of the Archard wear model, fully describing that the proposed model can effectively predict the wear life of the press tools for the auto-parts with UHSS.

The relationship between substrate temperature and mechanical properties of CrN/Si3N4 nanolayered coatings deposited by magnetron sputtering

ABSTRACTThe polycrystalline CrN/Si3N4 multilayer films were deposited by magnetron sputtering. We have investigated the effects of substrate temperature on the microstructural, interfacial and mechanical properties. X-ray reflectivity and diffraction (XRR and XRD), and nanoindentation were used to characterize the structures and mechanical properties for the coatings. It was found that the hardness enhancement is caused by the modulus difference in the interface between layer CrN and Si3N4. The elastic modulus is related to the composition of crystalline orientation and distortion. The sharp interface is good for improving the mechanical properties for CrN/Si3N4 multilayer. The variation of hardness and modulus are attributed to the changes in grain size and modulus variation caused by crystalline distortion. Compared to sample at room temperature, the yield stress (resistance to plastic deformation) and fracture toughness (resistance to crack propagation) would be improved by increase of substrate temperature.

Hydrogen permeability of diamondlike amorphous carbons

The hydrogen barrier properties of the coatings of nitride and diamondlike amorphous carbon (DLC) were evaluated. Using plasma chemical vapor deposition and sputtering, ZrN, TiAlN, AlCrN, CrN, and DLC coatings were deposited with a thickness of about 3 μm. It was confirmed that all coatings have an impact on decreasing the hydrogen permeation rate. Specifically, by coating stainless steel with a DLC coating, the hydrogen permeation rate was reduced to 1/1000 or lower compared to that without a coating. By providing a buffer layer of Cr-N, the hydrogen barrier function was improved. DLC coatings with high hydrogen content had an especially high hydrogen barrier function. For hydrogen diffusion in coatings, the movement of atoms through hydrogen trap sites is important. There are both sp3 and sp2 bonds in DLC coatings, and excess hydrogen can be found in the interstitial space and the above-mentioned hydrogen trap sites. It is suggested that the hydrogen trap sites in a DLC coating with high hydrogen content are likely already filled with hydrogen atoms, and the movement of new hydrogen atoms could be limited.