ABSTRACT
In recent years, electrolytic plasma polishing technology has attracted wide attention due to its advantages of shape adaptability, high efficiency, better precision, environmental friendliness, and non-contact polishing. However, the lack of research on the evolution mechanism of the gas layer at the anode interface restricts the improvement of the material removal mechanism and the regulation of the polishing effect. Firstly, the thermodynamic conditions of gas layer formation were analyzed based on the Clapeyron-Clausius equation, and the key parameters affecting the gas layer were identified. Secondly, the laws of voltage and electrolyte temperature on the dynamic evolution of the gas layer and its polishing effect were revealed. Additionally, the influence of the gas layer on the voltage-current characteristics was also investigated by analyzing the experimental phenomena. The results indicate that the optimal polishing effect is achieved at a voltage level of 300 V resulting in a decrease in Ra from 0.451 µm to 0.076 µm. Similarly, superior polishing results are obtained when the electrolyte temperature is 80 °C, with a decrease in Ra from 0.451 µm to 0.075 µm. This study provides theoretical guidance for the further development and application of electrolytic plasma polishing technology.
ABSTRACT
Thioglycollic acid was employed as a molecular linker to prepare CdS and/or Ag2S quantum dots (QDs) for the co-sensitization of TiO2 nanotube arrays through the successive ionic layer adsorption and reaction (SILAR) method. The microstructure, chemical composition, and photoabsorption of the prepared samples were analyzed by using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DAS). The interfacial separation and transport of photoinduced charge carries were also examined by applying current-voltage characteristics (J-V), electrochemical impedance spectroscopy (EIS), transient open circuit potential plots, and Mott-Schottky techniques. The sizes of the CdS and Ag2S QDs were found to be 6 and 4 nm, respectively. The co-sensitized samples demonstrate significantly enhanced photo absorption, greatly reduced charge transfer resistance at the semiconductor interfaces, positive shift of the flat band, elongated electron lifetimes, and accelerated interfacial separation and transport of the photoinduced charge carriers. A critical operation sequence is to first carry out the deposition of the CdS QDs that are less mismatched with TiO2 crystal lattice, followed by the deposition of Ag2S QDs. The samples prepared in this manner presented the best optoelectronic characteristics with a short photocurrent density of 9.5 mA·cm(-2). This value is 7.6% higher than 8.83 mA·cm(-2) of the sample prepared by depositing the more mismatched Ag2S QDs followed by deposition of CdS. This value is 18.8% higher than 8 mA·cm(-2) of the Ag2S-only sensitized sample, and 22.6% higher than 7.75 mA·cm(-2) of the CdS-only sensitized sample.