Microstructure, micro-mechanical and tribological properties of the nc-WC/a-C nanocomposite coatings magnetron sputtered on non-hardened and oxygen hardened Ti–6Al–4V alloy (original) (raw)
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Metallurgical and Materials Transactions A, 2014
In this paper, we show that duplex surface treatment, combining oxygen diffusion hardening with the subsequent deposition of thick, low-friction nanocomposite nc-MeC/a-C coatings to improve the tribological properties of the Ti-6Al-4V alloy. We have synthesized, in a magnetron sputtering process, the nanocomposite nc-MeC/a-C coatings (where Me denotes W or Ti transition metal) consisting of two dissimilar materials (nanocrystallites of transition metal carbides MeC and an amorphous carbon matrix a-C). The nano and microstructure of the substrate material and coatings were examined with the use of scanning and transmission electron microscopy as well as by X-ray diffractometry. It was found that different carbide nanocrystals of the same transition metal were embedded in an amorphous carbon matrix of both coatings. The HRTEM analysis indicated that the volume fraction of tungsten carbides in the nc-WC/a-C coating was equal to 13 pct, whereas in the nc-TiC/a-C one the volume fraction of the titanium carbides was equal to just 3 pct. The tribological properties, hardness, and scratch resistance of the coatings were investigated as well. The coefficient of friction (COF) of the coatings during dry sliding against 6 mm diameter alumina ball reached very low value, 0.05, in comparison with an oxygen-hardened alloy, whose COF was equal to 0.8. This lowfriction effect of the coatings has been attributed to the formation of a self-lubricating film in sliding contact. The coatings exhibited similar failure morphology in the scratch tests. Even though the hardness was rather low, the coatings exhibited a very good wear resistance during sliding friction. The wear rate of the nc-WC/a-C coating was equal to 0.08 9 10 À6 mm 3 N À1 m À1 and for the nc-TiC/a-C one it was 0.28 9 10 À6 mm 3 N À1 m À1 .
The Ability of Nanocomposite Carbon Coatings to Withstand Friction Under Severe Conditions
Tribologia, 2019
The paper presents an analysis of the micromechanical properties of selected thin, hard anti-wear coatings of the type nc-TiN/a-C and nc-TiC/a-C, which were deposited by magnetron sputtering on a steel substrate. The load carrying capacity of the nanocomposite coatings was analysed in point contact with the use of indentation method, a scratch test, and friction test in contact with a ceramic ball. The hardness and modulus of elasticity of the coatings were determined by an instrumented indentation method using a Vickers indenter. The coating adhesion to the substrate was examined in a scratch test. Tribological tests in sliding contact with an Al2O3 ball were made at various loads to determine the limit load in which normal friction occurs. The results of tribological tests were compared with the resistance to plastic deformation index (H3/E2). It was found that the basic micromechanical parameters of coatings provide important information concerning durability and load carrying ca...
Low friction and wear resistant nanocomposite nc-MeC/aC and nc-MeC/aC: H coatings
Purpose: Elaboration of nanocomposite, low friction and wear resistant coatings in order to increase the lifetime and reliability of friction couples especially in aviation industry, car industry and of cutting tools. These coatings consist of nanocrystallites of chromium or titanium carbides built into amorphous carbon matrix. Design/methodology/approach: Coatings type nc-MeC/a-C and nc-MeC/a-C:H (where Me means Cr or Ti transition metal) are deposited by a PVD method based on magnetron sputtering of pure Ti or Cr and pure graphite targets in the atmosphere of Ar or Ar+H 2 , respectively. The coatings are deposited onto the surface of quenched and tempered HSS steel Vanadis23 and diffusion hardened titanium alloy Ti6Al4V. Findings: Depending on deposition parameters, like the power ratio of transition metal to carbon targets or the substrate bias, it is possible to obtain different morphological and tribological properties of coatings. These latter are very important for designing friction couples in mechanical applications.
Micromechanical and Tribological Properties of Nanocomposite nc-TiC/a-C Coatings
Solid State Phenomena, 2011
The nanocomposite coatings composed of nanocrystalline TiC grains embedded in hydrogen free amorphous carbon a-C matrix (nc-TiC/a-C) were deposited by magnetron sputtering on the two substrates, oxygen hardened Ti-6Al-4V alloy and heat treated VANADIS 23 steel. The Ti-6Al-4V alloy was oxygen hardened by plasma glow discharge. Micro-mechanical and tribological properties as well as coating adhesion to the substrates were investigated. Micro/nanostructure of the coatings and the substrates were examined using scanning- and transmission electron microscopy methods as well as X-ray diffractometry. Nano-, microhardness tests performed for the coated materials showed average hardness 13.4-14.7 GPa and modulus of elasticity 160 GPa. Scratch test revealed good adhesion of coatings to the both substrates. The nanocomposite coatings significantly improved tribological properties of the titanium alloy and steel, increased wear resistance and decreased friction coefficient.
Wear resistant multilayer nanocomposite WC1-x/C coating on Ti-6Al-4V titanium alloy
Tribology International
A significant improvement of tribological properties on Ti-6Al-4V has been achieved by developed in this study multilayer treatment method for the titanium alloys. This treatment consists of an intermediate 2 ?m thick TiCxNy layer which has been deposited by the reactive arc evaporation onto a diffusion hardened material with interstitial O or N atoms by glow discharge plasma in the atmosphere of Ar+O2 or Ar+N2. Subsequently, an external 0.3 ?m thin nanocomposite carbon-based WC1-x/C coating has been deposited by a reactive magnetron sputtering of graphite and tungsten targets. The morphology, microstructure, chemical and phase compositions of the substrate material after treatment and coating deposition have been investigated with use of AFM, SEM, EDX, XRD, 3D profilometry and followed by tribological investigation of wear and friction analysis. An increase of hardness in the diffusion treated near-surface zone of the Ti-6Al-4V substrate has been achieved. In addition, a good adhes...
The processing and testing of new and advanced materials for wear resistant surface coatings
Journal of Materials Processing Technology, 1997
In the search of wear resistant coatings for applications such as cutting tools and turbine refurbishing, we have produced and tested a wide range of coatings including nanocrystalline metals (At, Ti, Cu), nanolaminated composites, containing alternating layers of metal-ceramic (AI 2 0] and TiffiN) or metal-metal (Ti/Cu), and monolithic coatings (TiN). These coatings were produced using an r.f. magnetron sputtering system except for the monolithic TiN which was commercially produced using an ion plating system. All these coatings were tested for their tribological (friction and wear) and mechanical (hardness) properties using a pin-on-disc type wear rig and an ultra-microindentation system, respectively. The tribological properties that were used to compare the relative performance of these materials were the coefficients offriction (both peak and steady-state) and the wear rates (volume loss pef unit sliding distance) in both the severe and mild wear regimes. The optimum combination of a low coefficient of friction and low wear rate in the steady-state regime was exhibited by TiffiN nanolaminated composite coating with a 150 nm Ti layer thickness and a 20 nm TiN layer thickness. This material also exhibited the highest hardness ofthe composite coatings. The micromechanisms responsible for the differences in hardness and wear resistance of these materials are discussed and recommendations are made on future directions for producing improved wear resistant coatings.
Experimental analysis and modelling for reciprocating wear behaviour of nanocomposite coatings
Wear
This paper presents the study of wear responses of nanocomposite coatings with a steel ball under oscillatingreciprocating state. Nanocomposite coatings for this study include: Nickel-Alumina (Ni/Al 2 O 3), Nickel-Silicon Carbide (Ni/SiC), Nickel-Zirconia (Ni/ZrO 2) and Ni/Graphene. Ni/ZrO 2 exhibited maximum wear rate followed by Ni/SiC, Ni/Al 2 O 3 and Ni/Graphene respectively which was also assured by Scanning Electron Microscopy (SEM) micrographs, grain sizes, hardness, porosity, surface stresses, frictional coefficients behaviours and "Ushaped" wear depth profiles. The "U-shaped" profiles were utilised to calculate the energy distribution (Archard factor density) along the interface. A novel mechano-wear model incorporating the energy distribution equations with the mechanics equations was developed for analysing the effects of intrinsic mechanical properties (such as grain sizes, hardness, porosity, surface stresses of the nanocomposite coatings) on the wear response. The predictions showed close agreement with the experimental results. In conclusion Ni/Graphene exhibited better anti-wear properties compared to other nanocomposite coatings. The high anti-wear behaviour of Ni/Graphene composite is due to enhanced strengthening effects in the presence of graphene. The importance of this work is evident from various industrial applications which require reliable modelling techniques to predict coatings failures due to wear. This work will bring significant impact to precision manufacturing, wind turbine industries, automotive, locomotive and aerospace in overcoming critical wear failures.
Experimental Analysis and Modeling for Reciprocating Wear Behavior of Nanocomposite Coatings
2018
This paper presents the study of wear responses of nanocomposite coatings with a steel ball under oscillatingreciprocating state. Nanocomposite coatings for this study include: Nickel-Alumina (Ni/Al 2 O 3), Nickel-Silicon Carbide (Ni/SiC), Nickel-Zirconia (Ni/ZrO 2) and Ni/Graphene. Ni/ZrO 2 exhibited maximum wear rate followed by Ni/SiC, Ni/Al 2 O 3 and Ni/Graphene respectively which was also assured by Scanning Electron Microscopy (SEM) micrographs, grain sizes, hardness, porosity, surface stresses, frictional coefficients behaviours and "Ushaped" wear depth profiles. The "U-shaped" profiles were utilised to calculate the energy distribution (Archard factor density) along the interface. A novel mechano-wear model incorporating the energy distribution equations with the mechanics equations was developed for analysing the effects of intrinsic mechanical properties (such as grain sizes, hardness, porosity, surface stresses of the nanocomposite coatings) on the wear response. The predictions showed close agreement with the experimental results. In conclusion Ni/Graphene exhibited better anti-wear properties compared to other nanocomposite coatings. The high anti-wear behaviour of Ni/Graphene composite is due to enhanced strengthening effects in the presence of graphene. The importance of this work is evident from various industrial applications which require reliable modelling techniques to predict coatings failures due to wear. This work will bring significant impact to precision manufacturing, wind turbine industries, automotive, locomotive and aerospace in overcoming critical wear failures.
Researches on nanocomposite self-lubricated coatings
Metalurgia international
Present paper presents results of our research work for optimization of tribological properties by definition of selected parameters for reactive sputtering process conditions of self-lubricated MoS 2 doped Ti-Al-Cr-N coatings developed in multilayer structure. The coatings were deposited using DC reactive UM magnetron co-sputtering system with 3 magnetron targets (TiAl, Cr and MoS 2) by co-deposition of elements as a result of periodically movement of the substrates in front of targets. Paper presents XTEM, HRTEM, SAED, XRD, AES and micro Vickers hardness investigations of nanostructured multilayer coatings. Also, the paper presents the design of coating architecture and process parameters for deposition of nanocomposite multilayer coatings on the components of a spiroid gear.
Comparative performance of nanocomposite coatings of TiC or TiN dispersed in aC matrixes
Surface & Coatings Technology, 2008
Titanium carbide (TiC) and nitride (TiN) are two of the most used materials in the field of protective coatings, due to their optimal mechanical and tribological properties. The addition of the second phase can provide extra benefits to the coating, like improved hardness, reduced friction and/or oxidation resistance. In this work, we present two series of coatings in which hard crystalline TiC and TiN phases are mixed at the nanometric level with a soft lubricant phase like amorphous carbon (a-C). Both series of TiC/a-C and TiN/a-C nanocomposite coatings were prepared by double magnetron sputtering of C and Ti(N) targets in a Ar atmosphere (P =5×10 − 3 Torr) by changing the power ratio applied to each magnetron. The chemical composition has been measured by electron energy loss spectroscopy, and the phase composition changes gradually from pure C to pure TiC or TiN through nanocomposite structures with variable phase contents. These structures are confirmed by transmission electron microscopy and diffraction techniques, like X-ray diffraction and electron diffraction. The mechanical and tribological properties are found to be mainly controlled by the hard/soft phase ratio present in the coating. The changes in hardness values follow similar trends in both types of nanocomposite samples. Introducing a small amount of TiN or TiC into a-C matrix causes a hardness reduction, but further addition of crystalline phase makes increase the hardness. The best tribological properties are found for nanocomposite coatings (both TiN/a-C and TiC/a-C) with high amount of a-C (N 65%), showing low friction values (f ∼0.1) and high wear resistance (k about 10 − 7 mm 3 N − 1 m − 1 ). However, coatings with 50-60% a-C show a good compromise between tribological and mechanical properties.