Downward continuation of airborne gravimetry data based on Poisson integral iteration method

The research and application of airborne gravimetry technology has become one of the hottest topics in gravity field in recent years. Downward continuation is one of the key steps in airborne gravimetry data processing, and the quality of continuation results directly influence the further application of surveying data. The Poisson integral iteration method is proposed in this paper, and the modified Poisson integral discretization formulae are also introduced in the downward continuation of airborne gravimerty data. For the test area in this paper, compared with traditional Poisson integral discretization formula, the continuation result of modified formulae is improved by 10.8 mGal, and the precision of Poisson integral iteration method is in the same amplitude as modified formulae. So the Poisson integral iteration method can reduce the discretization error of Poisson integral formula effectively. Therefore, the research achievements in this paper can be applied directly in the data processing of our country's airborne scalar and vector gravimetry

Effects of Matrix Silicon Content on the Plasma Electrolytic Oxidation of Al-Si Alloys Using Different Power Modes

The plasma electrolytic oxidation (PEO) of pure Al and Al alloys containing 4, 9, 12, or 15 wt.% Si were investigated under pulsed bipolar current and pulsed bipolar voltage modes, respectively. It was determined that the discharge sparks preferentially occurred on the SiO2 relative to the Al2O3 during the initial stage of PEO processing regardless of the power mode. Following 30 min of PEO treatment under the two modes, the thicknesses of the layers decreased, whereas their specific energy consumption increased with increasing Si content in the matrix. The presence of primary Si in the alloy with 15 wt.% Si had a significantly negative effect on the PEO process in the pulsed bipolar current mode: The layer thickness decreased by 45%, and its specific energy consumption increased by 52%, compared with those on pure Al. However, in the pulsed bipolar voltage mode, the layer thickness on the evaluated samples only decreased slightly, and it became much more similar after treatment

Influence of Electrolyte Temperature on the Color Values of Black Plasma Electrolytic Oxidation Coatings on AZ31B Mg Alloy

A coating was prepared on an AZ31B Mg alloy substrate via black plasma electrolytic oxidation (PEO). The colorant NH4VO3 was added to Na2SiO3–(NaPO3)6 electrolyte at different temperatures (5, 15, 25, and 35 °C). The influences of electrolyte temperature on the structures, compositions, and color values of black PEO coatings were studied by UV–Visible, XRD, XPS, Raman, and SEM techniques. The results showed that the relative content of V2O3 and V2O5 was the key factor affecting the coating color value. At higher temperatures, more NH3 escaped from the electrolyte and the NH3 quantity participating in the reaction decreased, resulting in a decrease of V2O3 content, an increase in color value, and a darker coating. In the PEO process, VO3− mainly reacted to form V2O5, and then, the generated V2O5 reacted with NH3 to form V2O3

Titanium, zirconium and vanadium conversion coatings (TZVCCs) on AZ91D magnesium alloy sheets

This paper reports the preparation, characterization, and corrosion resistance of an eco-friendly titanium/zirconium/vanadium-based conversion coating (TZVCC) on an AZ91D magnesium alloy sheet. The TZVCC microstructure and composition were investigated by SEM, EDS, and XPS. The corrosion behavior of treated and untreated magnesium alloy sheets was observed by potentiodynamic polarization and EIS. The coatings are found to be rapidly formed on the alloy exterior within 90 s and optimal conversion treatment time at 50 s. The primary components of the TZVCC were MgO, Mg(OH) _2 , V _2 O _5 , V _2 O _3 , MgF _2 , TiO _2 , ZrO _2 and metal-organic complexation. The coating was also shown to markedly enhance the corrosion resistance performance of magnesium alloys