Papers by Keyword: CrN

Abstract: The nitriding process is a well-known technology for increasing of wear resistance of steel. The conventional gas nitriding process of stainless steel is difficult in the case of surface passivation and formation of Cr₂O₃. The using of plasma enables to form hard surface area during the nitriding process. The plasma nitriding process was developed using Ionit Metaplas device. The kinetic growth was analysed in 2, 4, 6 and 8 h processes. The plasma gasses composition was selected for formation only diffusion layer without “white area” of nitrides. The microstructure, chemical and phase composition were analysed. As a result, the diffusion layer was formed. The iron nitrides formed the precipitations in the diffusion layer. The obtained results showed that 4h process enables to form nitride layer with required composition and hardness. The relationship between process time and nitride layer thickness and its hardness was observed.

Abstract: The CrN ceramic thin films were deposited using DC reactive magnetron sputtering system on silicon wafer substrate. Oxidation behavior was carried out in air at evaluated temperatures ranging from 500 °C up to 900 °C for 2 h. The structure and element composition of the films at different thermal annealing temperatures ranging were investigated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), respectively. The oxidation activation energies of the films were calculated using Arrhenius equation. The changes in the crystal structure from CrN to Cr₂O₃ phase were investigated from XRD results. The accumulation of grains on surface was confirmed by FESEM micrographs. The cross-section analysis showed an apparent columnar feature with dense structure for the film annealed at low temperature, and becomes porous when increasing the annealing temperature. The thickness was increased from 1.43 to 2.67 μm. The EDS studies indicated the existence of Cr, N and O with different elements compositions on the deposited thin films. The oxidation activation energy for the CrN thin films is 124.4 kJ/mol.

Abstract: CrVN coatings between 10 and 26 at.-% V were prepared by PVD to investigate the effect of V on the properties of CrN system. The films were analysed using, DRX, X microanalysis, AFM SEM, scratch, tribometer and nanoindentation testers.The DRX spectrum shows the formation of (CrN-VN) phases and the examinations morphology show that the progressive change in the structure mode with adding V. The study of mechanical behavior shows degradation in the hardness and elastic modulus. On the other hand, the Cr-V-N film has a good wear resistance which remains lower than that of CrN film. Detachment of the Cr-V-N layer is observed at the all scratch trace while the CrN film exhibits best adhesion performance.

Abstract: In this study, CrN_x thin films were prepared on 304 stainless steel substrate by DC reactive magnetron sputtering technique. Different N₂ gas partial pressure from 10 to 30% was employed in the sputtering process while sputtering power, sputtering pressure and total film thickness were kept constant. In order to improve structural, morphological, and mechanical properties, vacuum annealing process was adopted on the CrN_x thin films at the temperature of 400 oC. The standard characterization techniques such as X-ray diffraction, scanning electron microscope, atomic force microscope and hardness (load force of HV0.1) were used to reveal the properties of as-deposited and annealing films. The as-deposited films show two-phase crystal structure of Cr₂N and CrN depending on N₂ gas partial pressure. After the annealing process, the films effectively enhance the crystal structure and found the phases change from Cr₂N to CrN for the film deposited at low N₂ partial pressure. The surface roughness of the films was between 5 - 20 nm, and as expected the annealing films shows smoother surface than the as-deposited films. Hardness of the CrN_x films is in the range of 7 to 10 GPa. The mechanism of improvement in structural and mechanical properties of annealing films is introduced based on strain relaxation.

Abstract: The CrN thin films were deposited using reactive magnetron sputtering by varying base pressure to investigate the crystal structure, microstructure and composition of thin film. In this work, the films properties were characterized by XRD, FE-SEM and EDX techniques. The crystal structures were obtained the cubic of CrN with the crystal size between 23.23 – 28.25 nm and lattice parameters a = b = c = 4.142 - 4.160 Å. The XRD results indicated that the growth of preferred orientation was changed from (200) to (111) plane with increased the base pressure. The surface morphology of CrN thin films did not affected from base pressure. The thickness of CrN thin films which obtained from cross section analysis was decreased from 1788 to 1745 nm by varying the base pressure. The columnar pattern acccompany with the dense structure were investigated from the cross-section analysis. The Cr composition was substantly decreased whereas theN₂ composition were increased which observed from EDX technique.

Abstract: The CrN thin films were deposited on silicon (100) substrate using reactive magnetron sputtering technique. The films were characterized by XRD, FE-SEM, EDS and nanoindentation techniques to examine the effect of deposition time on crystal structure, compositions, microstructure and hardness. The crystal structure, microstructure, element composition and hardness. The higher crystallinity through longer deposition time were investigated. The grain aggregration with columnar structure were obtained from FE-SEM. The Cr and N contents were not direct relationship with deposition time. The CrN coated sample performed hardness varied between 9 - 16 GPa.

Abstract: Chrome nitride (CrN) and CrN/Cr thin films were grown on EN ISO HS6-5-2 tool steel, which has been used as a substrate material. It is a high-speed Mo-W steel with high toughness. Chrome nitride thin films were deposited using a RF PA CVD/Magnetron Sputtering (MS) system at a gas flow ratio of 15/13 sccm of Ar/N₂. During the deposition process the pressure in the vacuum chamber was 0.9 Pa, the deposition Ubias and deposition time were different. The parameters of the process influence properties of the thin films were microstructure, hardness and adhesion to the substrate, etc. Optimal selection of process parameters is needed to achieve particular property combinations. The basis of the tribological measurements was the “ball-on-disc” testing method. Tribological testing (EN1071-13:2010) was conducted using a ball made from Si₃N₄ with a diameter of 6.350 mm, with a constant load of 3N at room temperature and humidity of 40±2 %. A Zeiss AXIO Imager M2 light optical microscope and a Dektak XT TM mechanical profilometer were used to evaluate the wear of the friction pairs at a load of 6mg and the size of the measured area of 200x1000 μm. The basis of the tribological measurements is the “ball-on-disc” testing method. Tribological testing (EN1071-13:2010) was conducted using a ball made from Si₃N₄ with a diameter of 6.350 mm, with a constant load of 3N at room temperature and humidity of 40±2 %. A Zeiss AXIO Imager M2 light optical microscope and a Dektak XT TM mechanical profilometer were used to evaluate the wear of the friction pairs at a load of 6mg and the size of the measured area of 200x1000 μm.

Abstract: Multilayer coating onto orthopedic implants has been studied extensively due to their excellence mechanical and biological properties. A multilayer coating was coated onto metal implants to prevent the leaching of metallic ions into human body. This paper aims to study the hardness of multilayer coatings of Chromium (Cr), Chromium Nitride (CrN), Chromium Carbonitride (CrCN) and Zirconium Nitride (ZrN) by Physical Vapour Deposition (PVD). The deposited multilayer coating was characterised by Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Energy Dispersive X-ray (EDX). Cr, CrN, CrCN and ZrN have been successfully deposited onto stainless steel substrates by PVD. XRD analysis detected major peak in preferred orientation of (200) and other peaks with (111), (220), (311) for CrN cubic phase. For CrCN, XRD analysis detected only low intensity peaks of Cr₇C₃ and ZrN peaks with preferred orientation of (111), (200) with other peak (220), (311) and (222). Microvickers Hardness results showed an increment in hardness value from substrates with 160HV to 174HV for Cr, 236HV for CrN, 362HV for CrCN, 364HV for ZrN and 370HV for multilayer coatings.

Abstract: The formation of anti-wear coatings on the inner surface of steel cylinders and pipes presents a difficult process-related problem for PA PVD methods. This problem is associated with a strictly limited geometry of the reaction space and dimensions of plasma sputtering-sources. Among the main factors behind physical and chemical phenomena occurring the reaction space, formed within a low-temperature plasma and at its boundaries with a solid object, there are type, concentration, unobstructed path for reacting substances, as well as values and geometry of electrical/magnetic/thermal fields [1-5]. In the research on the plasma-based technology in confined space, the lowest possible distance between the surface being modified and the source of ions of metallic and gaseous elements is taken into account.

Abstract: CrSiN coatings of different silicon content were deposited on 1Cr18Ni9Ti austenitic stainless by d.c. reactive magnetron sputtering in a closed field unbalanced system. Comparative studies on microstructure and mechanical properties between CrN and CrSiN coatings with various Si contents were carried out. The structure of the CrSiN coatings was found to change from crystalline to amorphous structure as the Si contents increased. Amorphous phase of Si₃N₄ compound was suggested to exist in the CrSiN coatings. The crystalline grain became smaller in CrSiN coatings. With the increasing Si content, the coating deposition rate slew down, while the hardness of coatings improved obviously and the best hardness was about 4200 HV_0.01 when the Si content was 1.13%.