Microstructure and tribological behavior of tungsten-containing diamondlike carbon coated rubbers

Abstract

Articles you may be interested inStudy of the fatigue wear behaviors of a tungsten carbide diamond-like carbon coating on 316L stainless steel J. Vac. Sci. Technol. A 30, 051506 (2012); 10.1116/1.4737619 Superhard behaviour, low residual stress, and unique structure in diamond-like carbon films by simple bilayer approach J. Appl. Phys. 112, 023518 (2012); 10.1063/1.4739287 Temperature dependent properties of silicon containing diamondlike carbon films prepared by plasma source ion implantation J. Appl. Phys. 107, 083307 (2010); 10.1063/1.3394002 Structure and corrosion behavior of platinum/ruthenium/nitrogen doped diamondlike carbon thin filmsTungsten-containing diamondlike carbon ͑W-DLC͒ coatings have been deposited on FKM ͑fluorocarbon͒, ACM ͑acrylate͒, and HNBR ͑hydrogenated nitrile butadiene͒ rubbers via unbalanced magnetron reactive sputtering from a WC target in C 2 H 2 / Ar plasma. The surface morphology and fracture cross sections of coated rubbers have been scrutinized by high resolution scanning electron microscopy ͑SEM͒. The random crack networks formed due to the large difference in the coefficients of thermal expansion break down the W-DLC coatings into segments of a couple of hundred micrometers in size, facilitating good flexibility if the interfacial adhesion between the coating and a rubber substrate is strong enough. The size and density of growth defects in the W-DLC coatings strongly depend on the surface roughness of the rubber sheets. The tribological behavior of uncoated and coated rubbers has been investigated with ball-on-disk tribotest under dry sliding condition against a 6 mm 100Cr6 ball. Uncoated rubbers exhibited a very high coefficient of friction ͑Ͼ0.9͒. W-DLC coated FKM did not considerably reduce the friction because the coating was damaged due to poor adhesion. W-DLC coated HNBR and ACM exhibited excellent tribological performance, and very low coefficients of friction ͑Ͻ0.24͒ were achieved even at high normal load of 5 N. After tribotests, the W-DLC coatings on HNBR and ACM were intact and no serious damage was observed on the wear tracks.

Flexible diamond-like carbon films on rubber: On the origin of self-acting segmentation and film flexibility

“…When the segments adhere strongly to the rubber substrate, they are pushed against each other during the shrinkage of the rubber substrate and bend inwards along the edge where the highest compressive strain occurs. It must be emphasized that the inwardly bent edge of the DLC film segments and the close crack network are crucial for avoiding the impact between the surface asperities of the sliding counterpart and the otherwise sharp edges of open cracks in a film, thus preventing the formation of a large amount of wear debris that can cause wear and high friction in practical applications [2]. In addition, the groove network may also serve as a microreservoir for lubricants for dynamic rubber seals in heavy work conditions.…”

“…Under heavy working conditions, rubber seals are subjected to severe wear leading to an increase in clearance, which is often the cause of loss of function and failure of the lubrication system. Applying a wear-resistant coating with low friction is an advanced solution to enhance the performance of rubber seals [1][2][3].…”

“…However, there are technical problems with this approach: the size of the film segments is limited to the sub-millimeter range, and there are open gaps of at least tens of micrometers (equal to the thickness of the grid) between the film segments. Experimental results revealed that the impact between the asperity on the surface of the sliding counterpart and the sharp edges of the open cracks in the films produced a large amount of debris that led to high friction and severe wear of the coated rubber [2].…”

Flexible DLC film coated rubber: friction and the effect of viscoelastic deformation of rubber substrate

“…Both terms are directly related to the viscoelastic properties of a rubber [1]. By applying a chemically inert coating such as diamond-like carbon (DLC) film on rubber substrates, the interfacial adhesion between the sliding counterparts may be largely restrained [2,3]. On the other hand, a thin film may only reduce partially the inevitable viscoelastic i i deformation of coated rubbers and thus the associated energy dissipation via internal damping, which are affected by the loading/sliding conditions.…”

“…In the past a tile-like patterned films on rubber was proposed and deposited by using a net mask in front of the substrate [4]. Obviously, there are technical problems with this approach: the size of film segments is rather limited to submillimeter and especially the open gap that produced a large amount of debris and led to a high friction and severe wear of coated rubber [3]. Another approach was recently developed for depositing micro-segmented DLC films of superior flexibility on rubber [5].…”