Electrolytic Polishing Process Research Articles

Low current density electropolishing and corrosion resistance study of 304 stainless steel

In response to the challenge posed by electrical breakdown occurrences during the conventional current density electrolytic polishing of large-scale stainless steel workpieces, this investigation delved into the parameters of low current density electrolytic polishing process. The study scrutinised the surface morphology and corrosion resistance of 304 stainless steel, employing tools such as metallographic microscopy, a roughness gauge, and an electrochemical workstation. Within a sulphuric acid–phosphoric acid-based electrolyte characterised by a volume ratio of 1:2, the optimal mass concentration ratio of salicylic acid and saccharin was ascertained to be 3:3. By configuring the process parameters to 10 A dm−2 and 20 min, outcomes of electrolytic polishing were obtained that stood on par with the conventional current density approach. The stainless steel surface exhibited a surface roughness measuring a mere 0.08 µm and characterised by a corrosion current density of 1.907 × 10−8 A cm−2 and a corrosion potential of −0.0965 V.

Random Sequential Simulation of the Resulting Surface Roughness in Plasma Electrolytic Polishing of Stainless Steel

Plasma electrolytic polishing (PeP) is an electrochemical method for surface treatment. Unlike electrochemical polishing, PeP requires higher voltage and uses environment friendly aqueous solutions of salts. This process can be realised by immersing a workpiece inside an electrolyte bath or by using an electrolyte jet (Jet-PeP process).In this work a new stochastic method for modelling the plasma electrolytic polishing process is presented. The model was developed to predict the possible achievable surface roughness based on the defined initial one after PeP and Jet-PeP processes. The model describes the workpiece surface and the plasma-gas layer in 2D. The method formulation is based on the assumption, that PeP can be described as an electrochemical process. The physical parameters of the plasma-gas layer were calculated based on the experimental data.To realise the surface roughness change during PeP process a random method for the generation of the initial rough surface and a random method for the removal process were developed. The rough surface generation is based on the random deposition method and the Monte Carlo method. Initial Ra roughness is given as an input parameter.The removal process is simulated using locally defined probability. This probability is based on the Poisson point process depending on the current density on the surface. The simulation model uses the finite difference method (FDM) for the calculation of the electric potential and electric field.In this work, the calculation of various surface roughness variables is implemented and the results of polishing simulation are discussed. It is shown that with the help of the developed stochastic method it is possible to simulate the surface roughness change during the PeP process.

Process Understanding of Plasma Electrolytic Polishing through Multiphysics Simulation and Inline Metrology.

Currently, the demand for surface treatment methods like plasma electrolytic polishing (PeP)—a special case of electrochemical machining—is increasing. This paper provides a literature review on the fundamental mechanisms of the plasma electrolytic polishing process and discusses simulated and experimental results. The simulation shows and describes a modelling approach of the polishing effect during the PeP process. Based on the simulation results, it can be assumed that PeP can be simulated as an electrochemical machining process and that the simulation can be used for roughness and processing time predictions. The simulation results exhibit correlations with the experimentally-achieved approximation for roughness decrease. The experimental part demonstrates the results of the PeP processing for different times. The results for different types of roughness show that roughness decreases exponentially. Additionally, a current efficiency calculation was made. Based on the experimental results, it can be assumed that PeP is a special electrochemical machining process with low passivation.

Assessment of the influence of selected electrolytic polishing process parameters on the surface roughness of casts made of the CoCrMo alloy.

To fabricate some prosthetic restorations, such as metal alloy frameworks for removable partial dentures (RPDs), casting techniques must be used. The penultimate stage of the cast finishing procedure is electropolishing. The aim of the study was to assess the influence of selected electrolytic polishing process parameters on the resulting surface smoothness of the cobalt-chromium-molybdenum (CoCrMo) alloy. The CoCrMo alloy, 3 experimental and 2 name-brand electrolytes, were used in the study. A total of 25 samples, 63 mm × 10 mm × 1 mm in size, were cast using the Nautilus® equipment. The cast samples were shaped using metal cutters and carborundum stones and separators, and were sandblasted. The prepared samples were placed in an electrolysis cell as an anode. For each sample, measurements were made by changing the potential of the electrode by 0.2 V in the range from 1.2 V to 7.0 V. The surface of the samples was analyzed using a profilometer. An optical microscope and a scanning electron microscope (SEM) were used to examine the structure of the surface. An analysis of the obtained results showed no statistically significant differences between the BEGO Wirolyt® electrolytic polishing liquid (WB) and experimental electrolytes K15, K8 and K13, all of which were significantly better than the Dentaurum Electrolyt® polishing solution (ED). The microscope images indicated differences in the surface structure of the samples; in the SEM images, inclusions were also visible. The experimental electrolytes did not differ in quality from one of the name-brand electrolytes and were even better than the other one. The obtained surface roughness values (Ra) did not differ significantly from those achieved by other researchers.

Formation and phase transformation of aluminide coating prepared by low-temperature aluminizing process

A low-temperature aluminizing process involving a surface slurry pre-coating and powder embedded aluminizing process, with AlCl3 as the chosen activator, was developed to avoid changes in the mechanical properties of the substrate at high temperatures. An electrolytic polishing process using an acidic electroplating solution was further adopted to improve the average surface roughness of the aluminide coating and the smoothing mechanism was explained. Heat treatment promotes the diffusion of iron into the coating and aluminum into the substrate, the phase structure of the coating changed simultaneously. After a 30h heat treatment at 700°C, the brittle phases of Fe2Al5 and FeAl3 disappeared and the aluminide coating completely transformed into the Fe3Al and FeAl phases no cracks were observed inside the coating. Through the above processes, a dense and ductile aluminide coating was obtained with a thickness of about 60μm.

Study on surface shape control of pure Ti fabricated by electron beam melting using electrolytic polishing

Titanium parts in special industries such as vacuum, catalyst and medical application require a variety of surface properties with a unique structure for high efficiency. In this study, the unique surface of commercially pure titanium (CP Ti) parts fabricated using Electron Beam Melting (EBM) in the process of additive manufacturing is post-treated by the electrolytic polishing process under conditions ranging from 10 to 30V and 10–600s in order to study the surface characteristics. The possibility of controlling microstructural surface shape according to electrolytic polishing process conditions is presented from the increase of surface area through the formation of micro-dimples on protruding residual powder on the surface to the flattening of entire surface.

Electrochemical polishing of monocrystalline silicon with specific crystallographic planes

In this study, an electrolytic polishing experimental system was developed to obtain a uniform, flat-surfaced monocrystalline silicon with specific crystallographic planes. Several key factors reflecting specific electrolytic polishing on monocrystalline silicon with specific crystallographic planes were summarized. These factors, including electrolyte, conduction mode, Schottky barrier, semiconductor body resistance, and unidirectional conductivity, were analyzed comprehensively through energy spectrum analysis, theoretical modeling, and potential simulation. The effects of electrolytic polishing process were obtained, and corresponding solutions were proposed. Finally, the electrolytic polishing experiment for monocrystalline silicon with specific crystallographic planes was conducted. A uniform, flat-surfaced monocrystalline silicon with no metamorphic layer was then obtained. The flatness error of the center area was less than 0.201µm. Furthermore, the crystallographic planes of monocrystalline silicon wafers showed no change.

Research on the electrolytic-magnetic abrasive finishing of nickel-based superalloy GH4169

Due to stable performance and great hardness of nickel-based superalloy, single magnetic abrasive finishing (MAF) is difficult to polish the nickel-based superalloy workpiece, which makes the grinding efficiency decrease. The effective combination of electrolytic polishing process (EPP) and magnetic abrasive finishing process can improve processing efficiency by reducing the influence of material hardness. In order to verify the feasibility of this method, large numbers of experiments on the electrolytic-magnetic abrasive finishing (EMAF) of nickel-based superalloy GH4169 were carried out. Experimental results show that the EMAF can change the surface component content of workpiece to reduce the material hardness and make the surface roughness value reduce significantly and the surface morphology smoother; the processing efficiency is improved by 50 %.

비이온계 계면활성제기반 고순도 알루미늄 습식식각을 통한 균일한 마이크로패턴 어레이 제작

ABSTRACT In this paper, the effects of a nonionic surfactant on the etch uniformity and the etch profile during the wet-etching process of high-purity aluminum were investigated for the fabrication of uniform micropattern arrays. To improve the surface roughness of a high-purity aluminum plate, a mechanical lapping process and an electrolytic polishing process were used. After electrolytic polishing process, the surface roughness, Ra, of the high-purity aluminum plate was improved from 1.25 ㎛ to 0.02 ㎛. A photoresist was used as an etching mask during the aluminum etching process, where the mixture of phosphoric acid, acetic acid, nitric acid, a nonionic surfactant and water was used as the aluminum etchant. Different amounts of the Triton X-100 nonionic surfactant were added to the aluminum etchant to investigate the effect of a nonionic surfactant during the wet-etching process of high-purity aluminum. The etch rate and the etch profile were measured by an optical interferometer and a scanning electron microscope.

Fabrication of micro-lenticular patterns using WEDM-grooving and electrolytic polishing

Lenticular pattern panels have been used for displaying 3D effects and their precise fabrication methods have attracted great attention. In this study, we present a novel fabrication method for lenticular patterns on a stainless steel mold (AISI 304). The fabrication process was composed of two steps. First, the lenticular shape groove was machined by wire-electrical discharge machining (EDM) (WEDM-grooving). In this step, EDM was adopted because it is useful for machining hard-to-cut material such as WC-Co, stainless steel and titanium, and a newly developed wire grooving system ensures highly accurate machining. Second, electrolytic polishing was carried out afterward to improve the surface quality since the machined surface resulting from the WEDM-grooving was rough. The entire fabrication processes required a single machine and deionized water only; thus, the step change time was minimized and the method was eco-friendly. Parametric tests for the WEDM-grooving conditions as well as for the proper electrolytic polishing conditions (voltage, offset and feedrate) were executed to fabricate the grooves with fine surface. Excessive electrolytic polishing conditions caused pitting and damage from the additional sparks on the surface of the mold. On the other hand, inadequate machining conditions resulted in an incomplete electrolytic polishing process. Using this multi-step process, a lenticular pattern mold with high surface quality was machined. The lenticular pattern PDMS lens was successfully produced using the stainless steel mold.

Electrolytic polishing process

Electrolytic polishing process

Study on the characteristics of Magneto-Electrolytic-Abrasive Polishing by using the newly developed nonwoven-abrasive pads

Recently, advanced technologies in general industry demand that the production of precision parts is much more precise and efficient. However, most of the precision finishing technologies cannot satisfy both the finishing efficiency and surface finishing at the same time. Magneto-Electrolytic-Abrasive Polishing (MEAP) is a new ultra precision machining technology, which combined many kinds of energy, has been deeply investigated under this urgent demand and its effect has been much improved. The method of MEAP for those difficult-to-cut materials has become an important technique in the precision machining field. In particular, the nonwoven abrasive pad, which is a kind efficient matching polishing material used in MEAP system, has been developed. Because nonwoven abrasive pads can cut off the oxide membrane which appears during electrolytic polishing process without time delay and there are no scratches left on workpiece surface, it has been proved that it is a high efficiency and economic polishing material. In this study, the basic properties of nonwoven abrasive pads have been explained and the developed processes for SiC and Al 2O 3 nonwoven abrasive pads have also been described. Their polishing abilities on difficult-to-cut materials of Cr-coated rollers have been tested according to different kinds of pad. Through using the life test experiment, their economic benefits in Magneto-Electrolytic-Abrasive Polishing systems will be discussed.

Performance characteristics of a circular multicusp neutral beam source

The performance of the Heliotron-E neutral beam system, composed of intense cylindrical magnetic multipole bucket sources and beam line facilities, has been investigated. The investigation of the influence of the filament shape on the arc discharge stability shows that a wide-hairpin shaped filament results in more stable arc discharge without increasing the arc voltage than does a narrow-hairpin filament. An electrolytic polishing process has been tested for surface treatment of the Molybdenum grid and found to be very effective in reducing the number of conditioning shots. Beam extraction experiments show that a single bucket source can deliver the total beam current of 35 A at the accelerating voltage of 30 kV with the corresponding power transmission efficiency of more than 85% at the focal point of the grid curvature, the minimum beam divergence is less than 1.15° and the proton yield of the source is above 85%. Measurements of the equivalent gas line density in the neutralizer cell suggest the existence of the gas flow process different from a standard vacuum model.

THE PREPARATION OF TRANSMISSION ELECTRON MICROSCOPE SPECIMEN BY ELECTROLYTIC POLISHING METHOD

The transmitting and reflecting optical microscopy has been used in the electrolytic polishing process for monitoring the polished specimen to obtain the optimum polishing condition. The intermittent current device has been employed in the electric circuit so that the control of the polishing condition becomes more feasible. The efficiency and reproducibility of specieen preparation have been improved. The transmission electron microscopy specimen of some superconducting and amorphous materials have been pre-pared by this technique and the electron microscopy and selected area electron diffrac-tion observations have been made.