Effect of electrochemical polishing time on surface topography of mild steel

The variation in altitude density function （ADF） of the surface topography of mild steel during electrochemical polishing （ECP） was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distri- butions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.

The Effect of Electrochemical Polishing Time on Surface Topography of Mild Steel

This paper investigated the variation of the altitude density function （ADF） and the autocorrelation function （ ACF） about the surface profile of mild steel during electrochemical polishing （ECP）. The results show that the variation features of ADF with polishing time are fiat-steep-fiat, and the variation features of A CF with polishing time are random-regular-random. There is a fine surface smoothness at the special period of ECP. Both the original surface and the full ECP surface show an obvious roughness.

Characteristics of Micro Electrochemical Polishing to Improve the Surface Quality of the Stainless Steel Tube

Electrochemical polishing is the anodic dissolution process without contact with tools,is a surface treatment method to make a surface planarization using an electrochemical reaction with low applied current.The surface quality is mainly affected by the many process parameters.To improve the surface quality,the control of parameters is very important.The aim of this study is to investigate the characteristic of electrochemical polishing effect for inner diameter of Stainless Steel Tube.In order to analyze the characteristics of surface quality were measured in terms of temperature, applied current and machining time.The investigation can enhance the surface quality of inner diameter Stainless Steel Tube.Therefore,we have verified improved results by using selected optimal conditions.

Magnetic Electrochemical Finishing Machining

How to improve the finishing efficiency and surface roughness have been all along the objective of research in electrochemical polishing. However, the research activity, i.e. during electrochemical polishing, directly introduce the magnetic field to study how the magnetic field influences on the finishing efficiency, quality and the electrochemical process in the field of finishing machining technology, is insufficient. When introducing additional magnetic field in the traditional electrochemical polishing, due to the co-action of Lorentz’ force and electric field force, the ions arriving the machined surface by way of a curvilinear motion result in the electric current density distribution on the surface even more non-uniform, then the dissolving velocity of the peak points or side faces and the diffusion velocity of the product are enhanced, and the forcible agitation is happened on the electrodes surface by magnetic field, the removal rate of peak points are still more greater, and efficiency is also still more higher. Compared with the electrochemical polishing, in the magnetic electrochemical finishing machining, the finishing speed at peak points is higher, but at valley points it is lower, therefore after machining, both the highness at peak points and finishing depth at valley points are smaller, the results are propitious to minish initial wear quantity caused by friction and wear when machined workpiece employing in practice, and increase contact stiffness of workpiece, and from the viewpoint of microcosmic theory, this phenomenon is also of advantage to reduce damage to substrate. It can also be seen from the equation presented in the paper that the track of ionic movement relates to the electrodes gap, potential and magnetic induction intensity and furthermore; under the given conditions, the movement also relate to the electrolyte. it can be inferred that there must be an optimum value in respect of the magnetic induction intensity influencing the efficiency of finishing machining, and at the same time, the rational matching among the interelectrodes voltage, gap sizes and magnetic induction intensity can raise the efficiency and quality as well as improve the surface roughness to the maximum. In short, the co-action of the Lorentz’ force and electric field force change the motion track of anions and make more uneven distribution of the electric current density on the anodes surface, thus the dissolving velocity and product diffusion velocity of the peak points or side faces of the anode are raised. All those and the forced agitation of magnetic field towards the electrode surface are the principal mechanism for surface finishing. This point has been proved from the experimental results in this paper.

Electrolyte composition and galvanic corrosion for ruthenium/copper electrochemical mechanical polishing

Electrochemical mechanical polishing(ECMP)is a new and highly promising technology.A specific challenge for integrating Ru as barrier in Cu interconnect structures is the galvanic corrosion of Cu that occurs during ECMP.To mitigate the problem,the benzotriazole(BTA)and ascorbic acid(AA)were chosen as selective anodic and cathodic inhibitors for Cu and Ru,respectively.The optimization of electrolytes at different pHs including BTA,hydroxyethylidenediphosphoric acid(HEDP),and AA were investigated using electrochemical methods.The Ru/Cu removal rate and the planarization efficiency during Ru/Cu ECMP can be approximated using electrochemical measurements of the removal rate,with and without surface abrasion.Chemical systems that exhibit a 1:1 selectivity between the barrier layer and copper would be ideal for the barrier removal step of ECMP.Optimized slurry consists of 20.0 wt%HEDP,0.5 wt%BTA,and 0.3 wt%AA at pH 2.2.Using the optimized slurry,the selectivity of Ru to Cu is near 1.Electrochemical measurements of open circuit potentials,potentiodynamic polarization,and impedance spectroscopy were performed to investigate the galvanic corrosion between ruthenium and copper.

Isotropic Tuning of Electrochemical Etching forthe Nanometric Finishing of Metals

Isotropic etching polishing(IEP)based on the merging of isotropic etch pits has been proposed as a generic metal finishing approach.In this work,the tuning of the etching isotropy of various metals,which is the key to realizing the finishing effect of IEP,is studied by theoretical analysis and etching experiments.The isotropic etching of various metals can be realized through mass transfer polarization by adjusting the electrochemical parameters.The addition of sulfuric acid in the electrolyte is the most effective for tuning the isotropy of electrochemical etching.It can decrease the diffusion coefficient of metal ions,thereby increasing the resistance of mass transfer and transforming the electrochemical dissolution of metal into mass transfer polarization.In this study,the atomic and close-to-atomic scale surface finishing of various metals and alloys has been successfully achieved through isotropic etching.After etching at a current of 1.5 A for 3 min,the surface Sa roughness of TA2 is drastically reduced from 242 to 3.98 nm.After etching for 1 min at a current of 3 A,the surface Sa roughness of pure tungsten,NiTi,and CoCrNi decreases from 9.33,76.4,and 37.6 nm,respectively,to 1.16,2.01,and 2.51 nm,respectively.

Characterization of Compositionally Complex Hydrides in a Metastable Refractory High-Entropy Alloy

Here,we study the hydride formation in a metastable Ti-33Zr-22Hf-11Ta(at.%)refractory high entropy alloy(RHEA).Deviating to non-equiatomic compositions of RHEAs promotes the formation of transformation-induced plasticity where the body-centered cubic phase transforms to hexagonal close-packed(HCP)phase.It is found that the phase transformation capability assists the hydride formation due to the low solubility of hydrogen within the HCP phase.In this study,hydrogen is charged via electrochemical polishing and the corresponding phase transformation is activated in the metastable RHEAs.The newly formed HCP phase interacts with hydrogen to form a face-centered cubic hydride verified by electron energy loss spectroscopy.This work provides a primary exploration of the formation of compositionally complex metal hydrides in the metastable RHEAs,which are potential candidates for future hydrogen storage material design.