Electrochromic and auto-bleaching processes at the WO2 anodic film in 0. 5 mol/L H2SO4 solution were investigated by cyclic voltammetry, a. c. impedance technique and photocurrent spectrometry. The colouration mechani...Electrochromic and auto-bleaching processes at the WO2 anodic film in 0. 5 mol/L H2SO4 solution were investigated by cyclic voltammetry, a. c. impedance technique and photocurrent spectrometry. The colouration mechanism consists of hydrogen adsorption on the WO2 surface and the transport of H atoms in the WO, lattice. The bleaching process involves at least two steps: transport of interstitial H atoms and hydrogen desorption on the W surface, resulting in interstitial H+ ions; then extration of the H+ ions driven by the external electric field. The auto-bleaching arises from the hydroxylation due to both partial interstitial H atoms and a little of water contained in the film.展开更多
The W-La_(2)O_(3)-Y_(2)O_(3)-ZrO_(2)materials were prepared by vacuum hot pressing sintering process.The microstructure was characterized by scanning electron microscopy(SEM).The effects of sintering temperature,sinte...The W-La_(2)O_(3)-Y_(2)O_(3)-ZrO_(2)materials were prepared by vacuum hot pressing sintering process.The microstructure was characterized by scanning electron microscopy(SEM).The effects of sintering temperature,sintering pressure,holding time and heating rate on relative density,hardness and microstructure were studied.The sintering activation energy of the powder was calculated.Based on the result,the best sintering parameters by vacuum hot pressing sintering are as follows:sintering temperature of 1600℃,sintering pressure of 60 MPa and holding time of 60 min.The heating rate is 10℃·min^(-1)from room temperature to 1000℃and 4℃·min^(-1)from1000 to 1600℃.Using this process,the grain size is about3 lm in diameter with relative density at 99.7%,and the hardness is HV 528.5.The sintering characteristic index(n)of the specimen is 4,and the sintering mechanism mainly depends on the diffusion from the surface to the intragranular in the volume diffusion.The sintering activation energy of W-La_(2)O_(3)-Y_(2)O_(3)-ZrO_(2)material is286.2 k J·mol^(-1),which indicates that the powder has higher activity in sintering process.展开更多
基金The project Supported by National Natural Science Foundation of China.
文摘Electrochromic and auto-bleaching processes at the WO2 anodic film in 0. 5 mol/L H2SO4 solution were investigated by cyclic voltammetry, a. c. impedance technique and photocurrent spectrometry. The colouration mechanism consists of hydrogen adsorption on the WO2 surface and the transport of H atoms in the WO, lattice. The bleaching process involves at least two steps: transport of interstitial H atoms and hydrogen desorption on the W surface, resulting in interstitial H+ ions; then extration of the H+ ions driven by the external electric field. The auto-bleaching arises from the hydroxylation due to both partial interstitial H atoms and a little of water contained in the film.
基金the National Natural Science Foundation for Innovative Research Group Projects(No.51621003)。
文摘The W-La_(2)O_(3)-Y_(2)O_(3)-ZrO_(2)materials were prepared by vacuum hot pressing sintering process.The microstructure was characterized by scanning electron microscopy(SEM).The effects of sintering temperature,sintering pressure,holding time and heating rate on relative density,hardness and microstructure were studied.The sintering activation energy of the powder was calculated.Based on the result,the best sintering parameters by vacuum hot pressing sintering are as follows:sintering temperature of 1600℃,sintering pressure of 60 MPa and holding time of 60 min.The heating rate is 10℃·min^(-1)from room temperature to 1000℃and 4℃·min^(-1)from1000 to 1600℃.Using this process,the grain size is about3 lm in diameter with relative density at 99.7%,and the hardness is HV 528.5.The sintering characteristic index(n)of the specimen is 4,and the sintering mechanism mainly depends on the diffusion from the surface to the intragranular in the volume diffusion.The sintering activation energy of W-La_(2)O_(3)-Y_(2)O_(3)-ZrO_(2)material is286.2 k J·mol^(-1),which indicates that the powder has higher activity in sintering process.
