There has been tremendous interest in the development of different innovative wear-resistant materials, which can help to reduce energy losses resulted from friction and wear by ≈40% over the next 10-15 years. This paper provides a comprehensive review of the recent progress on designs, properties, and applications of wear-resistant materials, starting with an introduction of various advanced technologies for the fabrication of wear-resistant materials and anti-wear structures with their wear mechanisms. Typical strategies of surface engineering and matrix strengthening for the development of wear-resistant materials are then analyzed, focusing on the development of coatings, surface texturing, surface hardening, architecture, and the exploration of matrix compositions, microstructures, and reinforcements. Afterward, the relationship between the wear resistance of a material and its intrinsic properties including hardness, stiffness, strength, and cyclic plasticity is discussed with underlying mechanisms, such as the lattice distortion effect, bonding strength effect, grain size effect, precipitation effect, grain boundary effect, dislocation or twinning effect. A wide range of fundamental applications, specifically in aerospace components, automobile parts, wind turbines, micro-/nano-electromechanical systems, atomic force microscopes, and biomedical devices are highlighted. This review is concluded with prospects on challenges and future directions in this critical field.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202003739

Recent Progress on Wear-Resistant Materials: Designs, Properties, and Applications.

High elastic moduli do not guarantee high hardness because upon finite shear electronic instabilities often occur that result in transformation to softer phases. Therefore, the author concentrates on the extrinsically superhard nanostructured materials, which are the most promising. Decreasing crystallite size results in strengthening and hardening because the grain boundaries impede the plasticity (e.g., Hall–Petch strengthening in case of dislocation activity). However, this hardening is limited to a crystallite size down to 10–15 nm below which softening due to grain boundary shear dominates. This softening can be reduced by forming low energy grain boundaries or a strong interfacial layer. In such a way, much higher hardness enhancement can be achieved. The emphasis will be on the understanding of the mechanisms of the hardness enhancement. A special section deals with examples of the present industrial applications of such coatings on tools for machining in order to illustrate that these materials ar...

Recent search for new superhard materials: Go nano!

Hard coatings are nowadays widely used for tool and automotive applications, to increase wear and oxidation resistance, and/or to reduce friction. The present chapter gives an overview on the chemical and physical vapor deposition technologies relevant for the synthesis of hard coatings as well as on the various coating materials and architectures. Vapor deposition allows one to synthesize coatings atom by atom, often under nonequilibrium conditions with kinetic limitations or exposure of the film surface to intense ion irradiation during growth. These conditions result in coatings often far away from thermodynamic equilibrium, with high defect densities and stresses, grain sizes in the nanometer range, and metastable phases. A huge variety of coatings based on transition metal nitrides and carbonitrides, carbides, borides, oxides, and diamond-like carbon has been investigated and many of them are nowadays standard materials in the coating business. The combination of sophisticated synthesis techniques with theoretical predictions of phase stabilities and properties enables to tailor coating materials and phase or layer architectures with unique property combinations.

PVD and CVD Hard Coatings

Mechanical, tribological and corrosion performance of WBN composite films deposited by reactive magnetron sputtering

This chapter has illustrated the importance of optimizing the ratio between hardness and elastic modulus (H/E) when developing coatings for wear resistance applications It has been shown that nanocomposite coatings offer specific attractions in this regard Metal-metal nanocomposites in particular are promising, because of not only their mechanical and tribological behavior, but also their corrosion properties and potential to compete cost-effectively with traditional coatings in terms of achievable thicknesses and deposition rates Finally, we have discussed how nanocomposite tribological coatings lend themselves to the goal of incorporating “adaptive” and “chameleon-like” attributes to permit self-optimization of performance during operation, particularly for extreme high-temperature applications— and in other severe environments

Optimization of Nanostructured Tribological Coatings

The composition, nanostructure, tribological and corrosion behaviour of reactive arc evaporated CrB x N y coatings have been studied and compared to CrN. The CrB x N y coatings were deposited on a commercial Oerlikon Balzers RCS coating system employing 80:20 Cr:B targets. To vary the composition, the nitrogen fraction was adjusted (N 2 fraction = N 2 /(Ar + N 2 )) and a moderate bias voltage of − 20 V was applied during coating growth. The coating composition and nanostructure was determined using time-of-flight elastic recoil detection analysis (TOF-ERDA), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Ball-on-disc dry sliding wear tests were conducted using an alumina ball counterface both at room temperature and at 500 °C with the relative humidity controlled at 20%. Potentiodynamic corrosion tests were undertaken in 3.5% NaCl aqueous solution. The wear tracks were examined using optical profilometry and scanning electron microscopy (SEM); the surface composition inside and outside of the wear tracks were investigated using Raman spectroscopy and XPS. All coatings exhibit nanocomposite structures and phase compositions which are in fair agreement with those expected from the equilibrium phase diagram. The lowest wear rate at room temperature and 500 °C was found for CrB 0.14 N 1.14 , which was shown to exhibit the highest hardness and possesses a nanocomposite nc-CrN/a-BN structure. CrB 0.12 N 0.84 coatings showed the lowest passive current density in potentiodynamic corrosion tests.

The nanostructure, wear and corrosion performance of arc-evaporated CrBxNy nanocomposite coatings

Copper-based bulk nanocrystalline and amorphous alloys offer attractive mechanical properties such as high hardness and fracture toughness—as well as good corrosion resistance. Such materials can potentially be used as thin film tribological coatings to improve the wear resistance of low strength steels and the light alloys. In this paper novel CrTiCu(B,N) glassy-metal coatings have been successfully deposited on Si-wafer, AISI 316 stainless and AISI M2 tool steel substrates, over a wide range of compositions, by hot-filament enhanced reactive magnetron sputtering. The majority of the coatings produced are X-ray amorphous and exhibit Knoop microhardness values above Hk 25g =2000 Kgf/mm 2 (i.e. ≥ 20 GPa). The coatings provide a significant improvement, by more than two orders of magnitude, in reciprocating sliding wear rate (compared to the stainless steel substrate) when tested against a 10 mm diameter SAE 52100 hardened steel ball counterface at 10 N normal load. In impact tests for 10 5 cycles against a 10 mm diameter WC–6% Co ball, at a maximum load of 1 kN, the coatings exhibit excellent resilience and ductility—with small impact cavities and little or no peripheral or radial cracking around the impact craters.

K. Kanakis

Papers

The nanostructure, wear and corrosion performance of arc-evaporated CrBxNy nanocomposite coatings

Mechanical and tribological properties of CrTiCu(B,N) glassy-metal coatings deposited by reactive magnetron sputtering

Small grain size zirconium-based coatings deposited by magnetron sputtering at low temperatures