https://iopscience.iop.org/article/10.1088/1468-6996/15/1/014402/pdf

Effects of surface coating on reducing friction and wear of orthopaedic implants

Chromium nitride (CrN) films are superior to the titanium nitride film in corrosion and wear resistances, and friction behavior. CrN has been widely applied to the molding dies, machine parts and sliding part. In the present paper, additions of aluminum and vanadium into CrN films were performed with an expectation of improvement in tribological properties. CrN, CrAlN and CrVN were deposited by a cathodic arc ion plating. Deposited films were characterized by X-ray diffraction for crystal structure identification and energy-dispersive X-ray spectroscopy for chemical composition analysis. Diffraction peaks that appeared were similar in position and orientation in all films because the crystal structure and the lattice constant for CrN, VN and AlN are close to each other. The composition of the film deposited with Al and V was estimated to be Cr70Al30N and Cr50V50N, respectively. Knoop hardness test showed that CrAlN was harder than CrN and CrVN. Friction and wear tests were carried out by a ball-on-disk tribometer with stainless steel and cemented carbide balls as a counter material, with and without lubricant. Flaking occurred on CrN with stainless steel ball in wear tests without lubrication by ball-on-disk tribometer, but that did not occur on CrAlN and CrVN films. In the case of the wear test with cemented carbide ball, depth of wear track on CrN film reached to the substrate. The friction coefficient was almost the same for CrN and CrAlN films; however, that for CrVN film was lower than other films, in motor oil. V addition into CrN film successfully improved its tribological properties.

Friction and wear properties of CrAlN and CrVN films deposited by cathodic arc ion plating method

Comparative tribological behaviors of TiN, CrN and MoNCu nanocomposite coatings

CrN–Ag composite films, 2.5–4 μm thick, were deposited by reactive magnetron sputtering on Si and stainless steel substrates in a 0.4 Pa pure nitrogen atmosphere at 500 °C. The layer composition was controlled by the relative power to 7.5-cm-diameter Ag and Cr targets to be 0, 3, 12, and 22 at.% Ag. The layers exhibit a dense columnar microstructure where the Ag is homogeneously distributed in the CrN matrix. The coatings were vacuum annealed for t a  = 5–60 min at temperatures ranging from T a  = 600–700 °C, to study the Ag-lubricant transport to the surface. Ag surface segregation during annealing is negligible for layers with 3 at.% Ag content. However, Ag diffuses to the surface of layers with ≥ 12 at.% Ag and forms particles with diameters ranging, as a function of T a and t a , from 50 to 1100 nm. Statistical analyses provide average particle sizes of 110 and 375 nm, and surface particle densities of 2 × 10 7 and 1.7 × 10 6 mm − 2 , for the 12 and 22% Ag samples, respectively. The Ag diffusive transport occurs 2–3 times faster for the 22% than for the 12% sample. We attribute the increase in Ag transport as a function of the total Ag concentration to a network of pores that form during deposition due to Ag segregation into nanometer-size pockets. The pores grow in width and connectivity as the total Ag concentration is increased, leading to a faster Ag transport at elevated Ag concentrations. Room-temperature micro-scratch tests show that the average friction coefficients and wear track depths monotonically decrease, by 27 and 56%, respectively, when the Ag concentration is increased from 0 to 22 at.%.

/pdf/crn-ag-self-lubricating-hard-coatings-4b3tahaucn.pdf

CrN-Ag self-lubricating hard coatings

Friction and wear phenomena encountered in mechanical systems with moving components are directly related to efficiency, reliability and life of the system. Hence, minimizing and controlling these phenomena to achieve the desired system performance is crucial. Among the numerous strategies developed for reducing friction and wear, coatings have been successfully utilized in various engineering applications to mitigate tribological problems. One of the benefits of coatings is that they may be fabricated using a variety of materials in several different forms and structures to satisfy the requirements of the operating conditions. Among many types, coatings that are comprised of a combination of materials in the form of a multilayer have been gaining much interest due to the added degree of freedom in tailoring the coating property. In this paper, the properties and development status of multilayer coating systems for tribological applications were reviewed with the aim to gain a better understanding regarding their advantages and limitations. Specifically, focus was given to Ti-based and Cr-based coatings since Ti and Cr were identified as important elements in multilayer coating applications. Emphasis was given to materials, design concepts, mechanical properties, deposition method, and friction and wear characteristics of these types of coatings.

https://link.springer.com/content/pdf/10.1007%2Fs40544-017-0181-7.pdf

Z.L. Leu

Papers

Comparison of tribological behavior of three films—TiN, TiCN and CrN—grown by physical vapor deposition