The critical raw materials in cutting tools for machining applications: a review

A variety of cutting tool materials are used for the contact mode mechanical machining of components under extreme conditions of stress, temperature and/or corrosion, including operations such as drilling, milling turning and so on. These demanding conditions impose a seriously high strain rate (an order of magnitude higher than forming), and this limits the useful life of cutting tools, especially single-point cutting tools. Tungsten carbide is the most popularly used cutting tool material, and unfortunately its main ingredients of W and Co are at high risk in terms of material supply and are listed among critical raw materials (CRMs) for EU, for which sustainable use should be addressed. This paper highlights the evolution and the trend of use of CRMs) in cutting tools for mechanical machining through a timely review. The focus of this review and its motivation was driven by the four following themes: (i) the discussion of newly emerging hybrid machining processes offering performance enhancements and longevity in terms of tool life (laser and cryogenic incorporation); (ii) the development and synthesis of new CRM substitutes to minimise the use of tungsten; (iii) the improvement of the recycling of worn tools; and (iv) the accelerated use of modelling and simulation to design long-lasting tools in the Industry-4.0 framework, circular economy and cyber secure manufacturing. It may be noted that the scope of this paper is not to represent a completely exhaustive document concerning cutting tools for mechanical processing, but to raise awareness and pave the way for innovative thinking on the use of critical materials in mechanical processing tools with the aim of developing smart, timely control strategies and mitigation measures to suppress the use of CRMs

Critical Raw Materials Saving by Protective Coatings under Extreme Conditions: A Review of Last Trends in Alloys and Coatings for Aerospace Engine Applications

Several applications, where extreme conditions occur, require the use of alloys often containing many critical elements. Due to the ever increasing prices of critical raw materials (CRMs) linked to their high supply risk, and because of their fundamental and large utilization in high tech products and applications, it is extremely important to find viable solutions to save CRMs usage. Apart from increasing processes’ efficiency, substitution, and recycling, one of the alternatives to preserve an alloy and increase its operating lifetime, thus saving the CRMs needed for its manufacturing, is to protect it by a suitable coating or a surface treatment. This review presents the most recent trends in coatings for application in high temperature alloys for aerospace engines. CRMs’ current and future saving scenarios in the alloys and coatings for the aerospace engine are also discussed. The overarching aim of this paper is to raise awareness on the CRMs issue related to the alloys and coating for aerospace, suggesting some mitigation measures without having the ambition nor to give a complete overview of the topic nor a turnkey solution

Multilayer design of CrN/MoN protective coatings for enhanced hardness and toughness

We report on CrN/MoN multilayer coatings, their structure, elemental and phase composition, residual stresses, mechanical properties and their dependence on deposition conditions. The hardness and toughness were considered as main parameters for improvement of the protective properties of coatings. Multilayers with varying bilayer periods, ranging from 40 nm to 2.2 mm, were obtained by using cathodic arc physical vapour deposition (Arc-PVD) on stainless steel substrate. The elemental analysis was performed using wavelength-dispersive X-ray spectroscopy (WDS). The surface morphology and cross-sections were analysed with scanning electron microscopy (SEM). The X-ray diffraction (XRD) measurements, including grazing incidence X-ray diffraction (GIXRD), in-plane diffraction analysis and electron backscatter diffraction (EBSD), were used for microstructure characterisation. Mechanical properties of deposited films were studied by measuring hardness (H) and Young's modulus (E) with micro-indentation, H/E and H3/E2 ratios were calculated. The dependences of internal structure and, hence, mechanical properties, on layer thickness of films have been found. Significant enhancement of hardness and toughness was observed with decreasing individual layer thickness to 20 nm: H = 38-42 GPa, H/E = 0.11The study was partly financed by the Foundation of Science and Technology (FCT) of Portugal, project UID/NAN/50024/2013, budget project of Ministry of Education and Science of Ukraine “Physical basics of forming the composition and properties of transition metals boride, nitride and boride-nitride films for application in machine-building” (number 0116U002621) and Erasmus Mundus scholarship from European Commission (grant number 2013-2526/001-001). B.O. Postolnyi is also grateful to Arlete Apolinário from LEPABE, Department of Chemical Engineering, Faculty of Engineering of the University of Porto, and to João H. Belo from IFIMUP and IN - Institute of Nanoscience and Nanotechnology, Physics and Astronomy Department, Faculty of Sciences of the University of Porto, for help and useful discussion.info:eu-repo/semantics/publishedVersio

Structure and Properties of (Zr–Ti–Cr–Nb)N Multielement Superhard Coatings

Structure and properties of (Zr–Ti–Cr–Nb)N multicomponent nanostructured coatings fabricated by a vacuumarc deposition have been investigated. It has been found that the coatings thickness attained 6.2 μm, hardness and indentation load that is responsible for the stress exceeding cohesion strength of coatings were H = 43.7 GPa and Lc = 62.06 N, respectively. In coatings structures have been identified that consist of three interstitial phases having cubic, hexagonal, and tetragonal lattices. The nanocrystallites sizes were from 4 to 7.3 nm. The results of the SEM, TEM, EDS, and XRD analysis have been also considered

Fabrication and Research of Superhard (Zr–Ti–Cr–Nb)N Coatings

This work presents the results of (Zr–Ti–Cr–Nb)N superhard coatings research. The samples were fabricated by the vacuum-arc deposition method (Arc-PVD). Structure, composition and properties of these coatings were studied. The study of coatings was carried out using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Hardness measurements and adhesion tests were performed. The coatings thickness was up to 6.2 m, nanocrystallites sizes ranged from 4 to 7.3 nm. Values of hardness and cohesive streng

The effect of nanolayer thickness on the structure and properties of multilayer TiN/MoN coatings

The effect of nanolayer thickness on the structure and properties of nanocomposite multilayer TiN/MoN coatings is revealed. The multilayer (alternating) TiN/MoN coatings are prepared by the Arc PVD method. The selected thickness of the nanolayers is 2, 10, 20, and 40 nm. The formation of two phases—TiN (fcc) and γ-Mo2N—is found. The ratio of Ti and Mo concentrations varies with varying layer thickness. The maximum hardness value obtained for different thicknesses of the layers does not exceed 28– 31 GPa. The stability of TiN/MoN during cutting and tribological tests is significantly higher than that of products with TiN coatings. The nanostructured multilayer coatings with layer thicknesses of 10 and 20 nm exhibit the lowest friction coefficient of 0.09–0.12

Structure and Properties of Superhard (Zr-Ti-Cr-Nb)N Coatings

This work presents the results of superhard (Zr-Ti-Cr-Nb)N coatings research. Samples were fabricated by vacuum-arc deposition method (Arc-PVD). Structure, composition and properties of these coatings were studied. The study of coatings was performed using SEM, EDS and XRD. Hardness measurements and adhesion tests were provided. The coatings thickness was up to 6.2 mm. Nanocrystallites sizes ranged from 4 to 7.3 nm. Values of hardness and cohesive strength were H=43.7 GPa and LC=62.06 N respectively. The optimal conditions for coating’s deposition were found

Obtaining of TiN/MoN Nanocomposite Coatings and Their Research

At the nanometer scale multilayer nanostructured coatings show special properties due to the depositions conditions. This paper presents results of TiN/MoN nanocomposites obtaining and their research. Multilayer coatings based on TiN/MoN were deposited using vacuum arc evaporation cathode method (CPVD). Total thickness range of obtained coatings was 2, 10, 20 and 40 nm. We used vacuum-arc device “Bulat-6” for coatings deposition. Structure and properties of multilayer coatings were analyzed using XRD (Bruker D-8 Advance) in Cu-Kα radiation, high resolution transmission electron microscopy (HRTEM system) with diffraction CFEI EO Techai F200, SEM with EDX (JEOL-7001F). Scratch tests were carried out using Rockwell-C diamond indenter (CSM Revetest Instruments) with a tip radius of 200 μm. Besides this, ball-on-plate sliding test on UMT-3MT tribometer (CETR, USA) was used for additional investigation of friction and wear. This research allowed to reveal structural and properties depending on deposition conditions of TiN/MoN multilayer coatings. The nanocomposite hardness value increases when monolayer thickness decreases. This also reduced nanograins size. Measurement of the friction coefficient demonstrates smaller values for multilayer system in comparison with TiN or MoN nanostructured coatings. Formation of a (Ti, Mo)N solid solution and nanocrystals growing were observed during annealing. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3541

Structure and Properties of Multilayer Nanostructured Coatings TiN/MoN Depending on Deposition Conditions

This work presents the results of TiN/MoN coatings studying. These multilayer nanostructured coatings demonstrate dependence on depositions conditions on nanometer level. The influence of nanosized monolayer thickness on structure changing and properties of nanocomposite multilayer coatings TiN/MoN was found. Multilayer TiN/MoN coatings of the total thickness from 6.8 to 8.2 m were obtained using C-PVD method. Thicknesses of monolayers were 2, 10, 20, 40 nm. The structure of samples was studied using X-ray di raction (Bruker D-8 Advance) in Cu K radiation, high resolution transmission electron microscopy with diffraction CFEI EO TechaiF200, scanning electron microscopy with energy dispersive X-ray spectroscopy (JEOL-7001F), and microhardness measurements in dependence on indenter load. Scratch tests (friction, wear, etc.) were also provided using Rockwell-C diamond indenter (CSM Revetest Instruments) with a tip radius of 200 m. Friction and wear behavior were evaluated using ball-on-plate sliding test on a UMT-3MT tribometer (CETR, USA). With decreasing monolayer thickness the hardness value increases, and the size of nanograins reduces. The values obtained for the friction coeffcient of the multilayer system is much smaller than in nanostructured coatings of TiN (nc) or MoN (nc). Annealing showed formation of a (Ti,Mo)N solid solution and small growth of nanocrystals

Multilayered vacuum-arc nanocomposite TiN/ZrN coatings before and after annealing: Structure, properties, first-principles calculations

Nanoscale multilayered TiN/ZrN films were deposited using sequential vacuum-arc deposition of Ti and Zr targets in a nitrogen atmosphere. Studies of film's properties were carried out using various modern methods of analysis, such as XRD, STEM, HRTEM, SIMS combined with results of nanoindentation and tribological tests. To interpret the mechanical properties of the deposited multilayer films first-principles calculations of TiN(111), ZrN(111) structures and TiN(111)/ZrN(111) multilayer were carried out. To study the influence of thermal annealing, several samples were annealed in air at the temperature 700 °C. All deposited samples were highly polycrystalline with quite large 20–25 nm crystals. The crystalline planes were very ordinated and demonstrated an excellent coordinated growth. The nanohardness and elastic modulus of non-annealed coatings reached 42 GPa and 348 GPa, respectively. Annealing in air at the temperature 700 °C led to partial oxidation of the multilayered coatings, however hardness of the non-oxidized part of the coatings remained as high, as for initial coatings. All deposited coatings demonstrate good wear resistance