| TiO2 films are recognized as a kind of catalytic material because of its high photocatalytic activity,insolubility,non-toxicity and low cost.Its photohydrophilic properties are used for self-cleaning.TiO2 films also has good corrosion resistance,wear resistance,oxidation resistance and good photoelectric performance.It has been widely used in the fields of micro-computer electro-mechanical friction reduction,photo-catalytic degradation,photoelectrochemistry,etc.It is very important to study the properties of the TiO2 films so that the TiO2 films play a better role.The traditional preparation methods of TiO2 films are complicated,which can be made up by using electrohydrodynamic jet(E-jet)deposition.In this paper,E-jet technology combined with TiO2 sol was used to prepare TiO2 films,and the samples were calcined at the various temperatures.The physical and mechanical properties and microstructure of TiO2 films were studied,and the friction and corrosion of the films were studied.TiO2 sol with various physical parameters satisfying the conditions of E-jet deposition was prepared.The effects of deposition height and flow rate on the formation of E-jet mode were studied,and the parameters of E-jet deposition were optimized.Samples of TiO2 films which annealed at 700?(STT1),annealed at 800?(STT2),annealed at 900?(STT3)and annealed at 1000?(STT4)were prepared.The results show:(1)Different jet modes will be formed under different flow rates and different distances between the nozzle and the base.(2)The voltage ranges of the stable cone jet modes are different under different flow rates.With the increase of flow rates,the voltage ranges of the stable cone jet modes changed.The stable cone jet regions correspond to a lower and upper voltage limt,respectively.When the voltage was less than the minimum voltage micro-droplet or spindle mode would be formed,and more than the maximum voltage the multi-strand jet mode formed.(3)Distances also affect cone-jet mode.Breakdown was easy to occur when the distance between the base and the pin is too small,the voltage is hard to control so that the stable electric field cannot be formed.However,the density and smoothness of the films were increases.(4)The optimum deposition parameters were determined as follows:distance between nozzle and base was 5 mm,flow rate was 8 ?l/min,and voltage was 3.5?4.6 kV.The physical and mechanical properties and microstructure of TiO2 films were studied by SEM,XRD,nanomechanical testing system.The results show:(1)With the increase of calcined temperature,the crystal structure of TiO2 gradually changes from anatase to rutile,and the grain size gradually increases.But when the temperature reaches a certain value,the change of particle size is no longer obvious.The thickness of the TiO2 films increases,which is consistent with the change of particle size.(2)The hardness and elastic mode of the films increased.The friction and wear test were carried out.The wear morphology and elements were analyzed by SEM and EDS.The corrosion resistance of the TiO2 films was tested by electrochemical workstation.The results show:(1)Under the conditions of small load and slow sliding speed,the films which annealed at 700? showed the highest friction coefficient wass 0.62,the films which annealed at 1000? showed the lowest friction coefficient of was 0.25,which is only about 40.3%of the former;However,under the conditions of large load and fast sliding speed,the films which annealed at 700? showed the lowest friction coefficient was 0.43 and the films which annealed at 900? showed the highest friction coefficient was 0.55.(2)The corrosion resistance test showed that under the same corrosion potential,the corrosion current density of films which annealed at 900? was significantly lower than films which annealed at 700?,the current density is reduced by about one order of magnitude.The films which annealed at 900? showed the better corrosion resistance. |
PDF Full Text Request