Boron nitride/titanium nitride laminar-lubricating coating deposited by pulsed laser ablation on polymer surface

摘要

Pulsed laser deposition technique was applied for covering elastic cast-polyurethane membranes with titanium nitride and boron nitride layers.The deposition process was realized using a Nd:YAG laser with Qswitch in stages;firstly the membranes were coated with ultra-thin titanium nitride layer(Ti_xN)by evaporation of a metallic titanium disk in nitrogen gas atmosphere and then a layer of boron nitride(BN)was deposited by ablation of hexagonal h-BN target in argon atmosphere.The surface morphology was observed by scanning electron microscopy.Chemical composition was analyzed by energy dispersive X-ray spectrometry.The phase analysis was performed by means of grazing incidence X-ray diffraction and attenuated total reflection infrared spectroscopy.The crystallographic texture was measured.The wear test was performed by pin-on-disk method.Hexagonal boron nitride layers with(0001)[uvtw]texture with flake-like grains were fabricated.The structure and texture of boron nitride was identical irrespectively of substrate roughness or BN thickness.Pin-on-disk wear tests showed that the coatings effectively decreased the friction coefficient from two to even four times comparing to pure polyurethane and polyurethane covered with graphite.This proved that deposited layers can replace graphite as a lubricating material used to protect polymer surfaces.