Fabrication And Optical Absorption Properties Of TiO₂ Nano Arrays On The Surface Of Ti₃SiC₂

Anodic oxidation has attracted much interest because of its simple,rapid and controllable for the preparation of nanomaterials.The layered ternary carbide Ti₃SiC₂ is widely used owing to its unique their unique combination of properties originating from both the metals and the ceramics such as excellent electrical and thermal conductivity,good machinability,high Young's modulus,and high resistance to thermal shock,oxidation,and corrosion.In this paper,Ti₃SiC₂ was prepared by reactive hot pressing sintering method.TiO₂ nanopore arrays and nanotube arrays were fabricated on Ti₃SiC₂ and Ti surfaces by anodic oxidation.The influence of the oxidation process parameters on the formation and surface morphology of the nano arrays and the effects of heat treatment temperature on the phase composition,surface morphology and optical absorption property were investigated by a variety of characterization methods.The current-time curves were recorded during anodic oxidation and the TiO₂ nano arrays prepared by anodic oxidation on Ti₃SiC₂ and Ti were compared and analyzed.?1?TiO₂ nanopore arrays were fabricated on the surface of Ti₃SiC₂ by anodic oxidation method.The results show that: Water content affects the rate of anodic oxidation,highly ordered TiO₂ nanopore arrays are formed when the water content is 5.0 vol%.With the increase of NH₄ F concentration,there is no significant effect on the average pore size of the nanopore.However,scattered TiO₂ nanotubes are formed when the concentration is 3.0 wt%.When the oxidation voltage is too high,the morphology of TiO₂ nanopore arrays is destroyed and the corrosion morphology is appeared.With the extension of oxidation time,it will lead to corrosion and shedding phenomenon due to the unique structure of the Ti₃SiC₂ substrate.?2?The heat treatment temperature has a certain influence on the phase composition,surface morphology and optical absorption property of the anodic oxidation Ti₃SiC₂ samples.When the heat treatment temperature is 500 ?,the amorphous TiO₂ transformed to anatase TiO₂.When the heat treatment temperature increased to 600?,the anatase TiO₂ transformed to rutile TiO₂ partially.At the same time,the grain size and volume changes owning to crystal transformation and phase transformation result in the spongy surface morphology of TiO₂ nanopore arrays.Oxidation products of the anodized Ti₃SiC₂ samples are TiO₂,Ti2O3 and SiO₂.The absorption ability at UV-visible light range of the anodized Ti₃SiC₂ samples decreases linearly and the absorption ability decreased with the increase of heat treatment temperatures.?3?TiO₂ nanotube arrays were fabricated on the surface of Ti by anodic oxidation method.The results show that: With the increase of water content,ordered nanopore arrays are formed.But too much water content lead to a small number of nanoparticles on the surface of nanopore array.NH₄ F concentration had no obvious effect on the average pore size of TiO₂ nanopore arrays.However,the chemical dissolution rate rapidly increases when the NH₄ F concentration is greater than 2.5 wt%,which results in the appearance of a large number of nanoparticles and corrosion morphology.Anodic oxidation voltage plays an important role in the formation of nanotube arrays.With the increase of voltage,the diameter and the length of nanotube increase,but there is no obvious change in the nanotube wall.?4?The heat treatment temperature has a certain influence on the phase composition and optical absorption property of the anodic oxidation Ti samples.With the increase of heat treatment temperature,the amorphous TiO₂ transformed into anatase TiO₂,then transformed from anatase TiO₂ to rutile TiO₂,and its oxidation product is only TiO₂.With the increase of heat treatment temperature,the absorption ability at UV-visible light range of the anodized Ti samples decreased.However,the basic trend at UV-visible light range is same.It has a strong absorption capacity in the ultraviolet band,when the wavelength is greater than about 387 nm,the absorption capacity was very low.?5?The structure and composition of the anode materials significantly influenced the surface morphology,oxidation products and light absorption characteristics of TiO₂ nano arrays under the same oxidation process parameters.TiO₂ nanopore and nanotube arrays are formed on the Ti₃SiC₂ and Ti surfaces,respectively.The oxidation products of anodized Ti₃SiC₂ samples are anatase and rutile mixed crystal TiO₂,and a small amount of Ti2O3 and SiO₂.While the oxidation products of anodized Ti samples is only mixed crystal TiO₂.The UV-Vis diffuse reflection absorption spectra of anodized Ti₃SiC₂ samples show a red shift,its absorption edge is 691 nm and the band gap is 1.79 eV.While the absorption edge and band gap of anodized Ti samples are 394 nm and 3.15 eV,respectively.