Synthesis of titanium carbide coating on Ti15Mo alloy and its tribological behaviour

Ti15Mo alloy has been regarded as one of the most potential biomedical materials due to its excellent performance.However,the low hardness and poor wear resistance of titanium alloy limit the further application.Therefore,high temperature solid carburising technology was performed on the surface of Ti15Mo alloys to prepare titanium carbide(TiC)coating with graphene(G)as the carburising agent.The microstructure,mechanical properties,and tribological properties of TiC coating under different lubricants were investigated.Results showed that TiC coating was closely bonded to the titanium substrate.The maximum thickness of TiC coating treated with 1150°C was approximately 184.02μm,and the microhardness of alloys treated with 1100°C can achieve 1221.5 HV.All modified Ti15Mo alloys showed improved tribological performance compared to the original samples.The wear mechanisms of modified Ti15Mo alloys were abrasive wear and adhesive wear under the SBF lubricant,and the TiC coating was slightly peeled off.The overall friction coefficient and wear rate under 25%calf serum lubricant were lower than the SBF lubricant,and surface scratches were almost absent,and slight abrasive wear and adhesive wear occurred on the surface.

Correlated triple hybrid amplitude and phase holographic encryption based on a metasurface

Metasurface holography is becoming a universal platform that has made a considerable impact on nanophotonics and information optics,due to its advantage of large capacity and multiple functionalities.Here,we propose a correlated triple amplitude and phase holographic encryption based on an all-dielectric metasurface.We develop an optimized holographic algorithm to obtain quantitatively correlated triple holograms,which can encrypt information in multiple wavelength and polarization channels.We apply the“static”and“dynamic”pixels in our design,respectively.Two kinds of isotropic square nanofins are selected,one functioning as a transmitter and the other functioning as a blocker counterintuitively at both working wavelengths,while another anisotropic rectangle nanofin can transmit or block light in co-polarization selectively,mimicking“dynamic”amplitude switches.Meanwhile,such“dynamic”nanofins can simultaneously function as a phase modulator in cross-polarization only at the transmission wavelength.That is,through smart design,different dielectric meta-atoms functioning as spectral filters as well as phase contributors can compositely achieve triple hybrid amplitude and phase holograms.Such strategy promises to be applied in compact large-capacity information storage,colorful holographic displays,optical encryption,multifunctional imaging devices,and so on.