Reported by (6)
Effect of variation of electropolishing parameters on surface properties of 316L stainless steel
2017, Applied Surface Science
Therefore, in order to reduce the inflammatory and immune response at the implant/tissue interface, surface modification of implant materials such as stainless steel is considered extremely important . Electropolishing is an electrochemical surface treatment process that involves the anodic dissolution of a metal or alloy in a suitable electrolyte to restore a smooth, defect-free surface . During electropolishing, simultaneous surface melting and brightening result in a mirror-like smooth surface.
The corrosion resistance and biocompatibility of 316L stainless steel implants depend on the surface characteristics and the nature of the passive film. The effects of electropolishing on surface topography, surface free energy, and surface chemistry were determined by atomic force microscopy, contact angle counter, and X-ray photoelectron spectroscopy. Electropolishing of 316L stainless steel is performed at the oxygen evolution potential (EPO) and below the oxygen evolution potential (EPBO). Compared to mechanically polished (MP) and EPO, the EPBO sample has a lower surface roughness (Ra=6.07 nm) and a lower surface free energy (44.21 mJ/m2).Relatively low corrosion rate (0.484mpy) and low passive current density (0.619µA/cm2) was determined by circular polarization scanning to be associated with OH, Cr(III), Fe(0), Fe(II) and Fe(III) species present on the surface. These species ensure the existence of a relatively uniform passivating oxide film on the EPBO surface. In addition, the relatively large charge transfer (Rct) and passive film resistance (Rto eat) recorded from EPBO samples by impedance spectroscopy, confirming its better electrochemical performance. The in vitro response of these polished samples to MC3T3 preosteoblast cell proliferation was found to be directly related to their surface and electrochemical properties.
Dependence of the pore size of the AAO film on the surface roughness of the Al-1050 sheet controlled by electropolishing combined with partial factorial design
2007, Technology of surfaces and coatings
The annealed aluminum plates were then electropolished in an ethanol-perchloric acid solution using a direct current (DC) source (ABM 9603D, GW, Taiwan) according to the experimental conditions of the FFD study. Based on the literature review [3,4,14–22] and our preliminary study, the following electropolishing variables that may affect the surface roughness of aluminum foil were investigated: (A) stirring speed (rpm); (B) solution polishing temperature (°C). (C) Applied potential (V); (D) Polishing time. (E) Volume percentage (v %) of perchloric acid in ethanol-HClO4 solution. The fixed levels of these five variables are listed in Table 1 .
The effects of electropolishing variables such as stirring speed, solution temperature, applied potential, electropolishing time and volume percentage of perchloric acid in an ethanol-perchloric acid solution on the surface roughness of commercially pure aluminum plates (Al-1050, 99.5 %) using a fractional systematic factorial study design (FFD). Solution temperature, applied potential and electropolishing time were found to be the key factors affecting the surface roughness of Al-1050 plates, while the volume percentage of perchloric acid (or ethanol) showed complex interactions with these key factors. When performing electropolishing at 4 °C (ie low temperature solution level). These polished sheets can be effectively formed into a highly uniform, self-aligned anodized aluminum oxide (AAO) by performing an anodizing process in an aqueous solution consisting mainly of sulfuric and oxalic acids. The AAO pore size gradually decreases from approx. When the surface roughness of the aluminum plate increases from 3 to 30 nm, it is 90 to 60 nm.
Electropolishing and shaping of microscale metal shapes
Electrochemical Mechanical Polishing Technology: Recent Developments and Future Research and Industry Requirements
2016, International Journal of Advanced Manufacturing Technology
A new mechatronic design of an electrochemical mechanical end effector for robotic surface polishing
2016, 2015 IEEE/SICE International Symposium on Systems Integration, SII 2015.
Featured Articles (6)
Magnesium in mouse arteries: detection of corrosion products
Acta Biomaterials, Volume 10, Number 3, 2014, Pages 1475-1483
Numerous publications provide information on physiological and pseudophysiological corrosion of magnesium and its alloys for bioresorbable implants, but little attention has been paid to the properties of explanted materials. In this work, commercially pure magnesium wires were corroded in rat arteries for up to 1 month, then removed, and the major and surface products were characterized. Characterization of the surface using infrared spectroscopy revealed a dual structure consisting of highly magnesium-substituted hydroxyapatite, which later transformed into type A (carbonate-substituted) hydroxyapatite. To explain this transition, an ion exchange mechanism has been proposed. Elemental distribution of bioerosion products revealed Ca, P, Mg and O in the outer layer and Mg, O and P in the inner layer. No significant amount of carbon from the inner regolith was observed, suggesting that carbonates are not a ubiquitous weathering product. Cross-sectional electron backscatter shows that the thinning or loss of hydroxyapatite in the later stage of decomposition is associated with local thickening of the internal corrosion layer. Based on these experimental observations, a mechanism is proposed to describe the quasi-steady-state corrosion and final degradation process of magnesium samples.
Physical modeling of tool steel CCT Figure 1.2343
Procedia Structural Integrity, Volume 43, 2023, Pages 270-275
This article deals with the phase transformation and austenitizing behavior of tool steel 1.2343. Dilation analysis of a series of samples with different cooling rates, selected within a range of 10°C s−1do 0,05°C·s−1The obtained experimental data are used to estimate the expansion curves for mapping the temperature scale for the transformation of austenite to pearlite, bainite or martensite. Microstructural analysis and hardness measurements were then performed on all experimental samples from the dilatation analysis to characterize the microstructure and hardness for each heat treatment regime investigated. At the end of the work, the generated CCT maps were compared with the JMatPro software to assess the accuracy.
Investigation of microstructure evolution and low-temperature fracture resistance of AA2219 VPTIG weld metal after post-weld heat treatment
Materials and Design, Volume 113, 2017, Pages 54-59
In this paper, the effect of post-weld heat treatment (solution + artificial aging) on the microstructure and low-temperature fracture toughness of weld metal of VPTIG-welded AA2219 joints was investigated using the Crack Tip Opening Displacement (CTOD) Method. There are three classes: (i) Weld metal of welded joints, designated as Sample A. (ii) Weld metal for heat treated joints after welding, designated as Sample B. iii) Base metal is used for comparison and designated as BM. The results show that solid solution treatment dissolves the θ phase, and artificial aging treatment causes redeposition of the θ phase. After post-weld heat treatment, the strength of the weld metal increases, while the plasticity and fracture toughness decrease slightly. Regardless of the sample type, 77K tests are more intense than 298K due to lower frequencies of lattice vibrations and lower energy fluctuations. Also, the plasticity at 77 K is greater than that at 298 K because the Peierls-Nabarro force is insensitive to temperature. Therefore, fracture resistance is also better at 77K.
Two-dimensional chromatography-mass spectrometry: quantification of chiral shifts in propranolol metabolism in bioassays
Journal of Chromatography A, Volume 1617, 2020, Article 460828
In this study, an impressive 2D-LC method was successfully developed and optimized for the differentiation and quantification of (S)-propranolol, (R)-propranolol and its hydroxy metabolites, namely the isomer (S)-4'-hydroxypropranolol, (R)-4' -hydroxypropranolol in chromatographic analysis, (S)-5'-hydroxypropranolol Er, (R)-5'-hydroxypropranolol, (S)-7'-hydroxypropranolol and (R)-7'-hydroxypropranolol. Therefore, experiments to study the chiral discrimination of propranolol ring hydroxylation became feasible.
After a single oral dose of 40 mg of propranolol, analysis of human urine samples clearly showed pronounced chiral changes of propranolol and its 4'-, 5'- and 7'-hydroxy metabolites. In addition, the excretion rates of the individual (S)- and (R)-enantiomers were continuously monitored for 24 hours after dosing.
Investigations were carried out on a triple quadrupole mass spectrometer using a coupled 2D-LC system. The chromatographic system consists of a reverse phase column (phenyl-hexyl) in the first dimension and a column of chiral teicoplanin in the second dimension. The method has been extensively validated and successfully evaluated as robust. Calibrated to an accuracy between 80% and 120%. (S)-propranolol, (R)-propranolol, (S)-4'-hydroxypropranolol, (R)-4'-hydroxypropranolol, (S)-5'-hydroxypropranolol, (R)-5'-Maximum excretion rates of H -hydroxypropranolol and (R)-7'-hydroxypropranolol were 237 ng/min, 281 ng/min, 4 ng/min, and 4 ng/min, 1 ng/min, 9 ng/min, and 3 ng/min, respectively.
Degradation and bioactivity of magnesium films used in dental surgery
Materials Letters: X, Volume 2, 2019, Article 100007
Bioabsorbable materials are being investigated for their promising properties for application as implant materials. This study deals with the degradation and bioactive behavior of the magnesium scales that make up the dental ligament. Degradation behavior, including indentation during immersion tests, can be accurately observed using micro-computed tomography. Using bioactivity tests according to Kokub, it was shown that magnesium has a strong calcium phosphate layer formation associated with high degradability. Therefore, magnesium flakes seem to have great potential in the application of bone implants.
The effect of SiO2 content on the microstructure and mechanical properties of reaction sintered lithium hydrogen silicate glass ceramics
Journal of Amorphous Solids, Volume 512, 2019, p. 148-154 (view, other).
An attempt to prepare lithium hydrogen silicate glass ceramics through a solid state reaction between Li2silicon dioxide3Crystals and silicon2Glass. Add 0.5 mol Li2i2this one5With glass as a binder, the mixture was hot pressed at 840°C for 1 hour. The role of silicon2Effect of content (1-2mol) on reaction sintering, microstructure and mechanical properties of Li2i2this one5Glass ceramics were studied. Partial silicon2The glass is crystallized in quartz so that at least 1.5 mol of SiO2Requires complete reaction with 1 mole of LM crystal. Li particle size2i2this one5The crystal increases with SiO2The content depends on the degree of reaction. The flexural strength and fracture toughness of the samples first increased and then decreased with increasing SiO2After the reaction, Lee Rod2i2this one5Crystals tens of microns long can be obtained, several times larger than crystals crystallized directly from the mother glass. Such a reaction forms Li2i2this one5These crystals apparently have an effective hardening effect without sacrificing other properties. Since 1mol of Li reacts completely2silicon dioxide3The crystals consist of 1.5 mol of SiO2Glass in sample M1S1.5D0.5 has a higher bending strength of 373±12 MPa and a higher fracture strength of 3.35±0.12 MPa∙m1/2is acquired. The improved properties are mainly attributed to flexural crack hardening and grain bridging mechanisms.
Copyright © 2002 Published by Elsevier Inc. All rights reserved.