Polishing Quality Research Articles

A Normal Displacement Model and Compensation Method of Polishing Tool for Precision CNC Polishing of Aspheric Surface

The position accuracy of the polishing tool affects the surface quality of the polished aspheric surface. The contact deformation among the polishing tool, abrasives, and aspheric part can cause a displacement, which, in turn, will cause a position error of the polishing tool, which will lead to a significant change in the polishing force. In order to resolve this error, this paper proposed a method of normal displacement compensation for a computer numerical controlled (CNC) polishing system by controlling the polishing force. Firstly, the coupling principle between the polishing force and the position of the polishing tool is expounded, and the relationship between normal displacement and deformation is analyzed. Based on Hertz’s theory, a model of normal displacement is established. Then, on the basis of the decoupled polishing system developed, a normal displacement compensation method was proposed. Finally, a group of comparative experiments was carried out to verify the effectiveness of the proposed method. Compared with no displacement compensation, when the part was polished with the normal displacement compensation method, the value of roughness decreased from 0.4 µm to 0.21 µm, and the unevenness coefficient of surface roughness decreased from 112.5% to 19%. The experimental results show that the polishing quality is improved greatly, and the aspheric surfaces can be polished more uniformly with the method proposed in this paper.

Effects of Frequency on the Performance of Ultrasonic Vibration Assisted Chemical Mechanical Polishing for Sapphire

Abstract Sapphire (Al2O3) is renowned for its exceptional properties, yet its unique natural presents a surface processing challenge. To enhance the polishing quality and efficiency, the sapphire ultrasonic vibration assisted chemical mechanical polishing (UV-CMP) has been proposed. This paper employs computational fluid dynamics (CFD) simulation and polishing experiments to investigate the action and mechanism of ultrasonic frequency on sapphire UV-CMP. The CFD simulation reveals that an increase in frequency can effectively elevate the fluid velocity, pressure, and cavitation. The enhancement in pressure, Z-direction, and resultant velocity has a positive impact on the cutting ability and utilization rate of nano-abrasives. A high frequency can enhance the physical fields of slurry, but it suppresses the growth of cavitation bubbles, and is detrimental to the number and size of abrasive particles. The best processing performance of sapphire UV-CMP is obtained at 40 kHz due to coordinated physicochemical interactions. X-ray photoelectron spectroscpy proves the product of solid-solid chemical reaction between nano-SiO2 and sapphire is softer Al2Si2O7 instead of Al2SiO5, which is beneficial to the material removal. This article provides theoretical and practical guidance for sapphire UV-CMP.

The Effect of Sodium Hexametaphosphate on the Dispersion and Polishing Performance of Lanthanum-Cerium-Based Slurry.

A lanthanum-cerium-based abrasive composed of CeO2, LaOF, and LaF3 was commercially obtained. The effect of sodium hexametaphosphate (SHMP) on powder dispersion behavior was systematically investigated using the combined techniques of liquid contact angle, turbidity, zeta potential (ZP), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) combined with Rietveld refinements, X-ray photoelectron spectroscopy (XPS), and polishing tests. The results indicated that the addition of 0.5 wt.% SHMP dispersant to the 5 wt.% lanthanum-cerium-based slurry produced the most stable suspension with a high turbidity of 2715 NTU and a low wetting angle of 45°. The as-obtained slurry displayed good surface polishing quality for K9 glass, with low surface roughness (Ra) of 0.642 and 0.515 nm (in the range of 979 × 979 μm2) at pH = 6 and 11, respectively, which corresponds to the fact that it has local maximum absolute values of ZP at these two pH values. SEM images demonstrated that after appropriate grafting of SHMP, the particle aggregation was reduced and the slurry's dispersion stability was improved. In addition, the dispersion mechanism was explained based on the principle of complexation reaction, which reveals that the dispersant SHMP can increase the interparticle steric hindrance and electrostatic repulsions. In an acidic environment, steric hindrance dominates, while electrostatic repulsion prevails under alkaline conditions. As expected, this polishing slurry may find potential applications in manufacturing optical devices and integrated circuits.

Enhanced material removal modeling in cylindrical bonnet tool polishing: Incorporating time-dependent pad wear effects

To enhance the accuracy and stability of the material removal model for cylindrical bonnet tool polishing (CBTP), this study introduces a model incorporating the time-varying wear effect of the polishing pad. Initially, the functional principles of the CBTP method are systematically outlined. An advanced material removal model is then proposed, which accounts for the impact of pad wear on pressure and velocity distributions within the contact area. Experimental methods were employed to explore how pad wear affects the pad surface morphology, polishing quality, and material removal rates. Findings reveal that pad wear considerably influences both the depth of material removal and the quality of the polished surface. Validation experiments demonstrate that the enhanced model is accurate and stable. Including the time-varying factor, the discrepancy between the predicted and experimental values of the polishing spot size was 9.29 %, while the accuracy of the predicted material removal depth reached 90.74 %. Additionally, the removal profiles generated by the improved model closely matched those observed experimentally.

Exploration study of nickel slag/modified slag in the ultra-precision polishing of magnetic compound fluid

Nickel slag is the solid waste obtained from the nickel smelting process. Based on the magnetic elements in nickel slag, it is a potential ingredient that could be used in magnetic compound fluid (MCF) polishing. This work discusses polishing in MCF using nickel slag and modified slag. Investigations are conducted into how MCF is affected by the amount of modified slag and nickel slag present during polishing. The connections between shear force, position, material removal rate, morphological characteristics, and polishing quality are covered. Nickel slag is mixed with CaO, the alkalinity is adjusted, and the mixture is heated to 1500 °C to fully melt and oxidize it. The resulting product is modified slag. The morphological changes in MCF slurry before and after polishing were examined using an industrial camera, and the effect of different MCF slurry components on polishing performance was analyzed throughout the polishing process. In addition, the positioning of modified slag within the magnetic cluster formed during the polishing process was determined through a scanning electron microscope and by energy dispersive x-ray spectroscopy mapping of MCF slurry. The aforementioned research establishes the polishing mechanism for nickel slag and modified slag. The experimental results indicate that the polishing effect of the experimental group with added modified slag is better than that of added nickel slag. Under the same conditions, the surface roughness was reduced by 60% when modified slag was used instead of nickel slag. It was found that the optimal process is where the modified slag content is 10%, where the material removal rate is 1.207 × 108µm3/min and the surface roughness decrease rate is 95.482%. The polishing shear force is around 2.7N, which is twice as much as that of nickel slag.

Recent Patents for Optical Component Polishing Technology

Background: Fluid jet polishing, Airbag polishing, Magnetorheological polishing, and Ion beam polishing are all emerging polishing technologies commonly used for processing optical components, which can be used to manufacture various high-precision and high-quality optical components. Their processing mechanisms are to remove materials by high-speed jet impacting the surface of the workpiece; using a spherical flexible airbag as a polishing tool to obtain a super-smooth surface by adding polishing fluid containing fine abrasives; controlling the magnetic field to form a flexible polishing belt of Magnetorheological fluid, which undergoes relative motion to achieve material removal; using a neutral ion beam to bombard the surface of the workpiece to remove workpiece surface atoms and obtain a super-smooth surface through energy and momentum transfer between ions and workpiece atoms. The characteristics and removal mechanisms of various polishing methods are briefly described, and the advantages and key issues that need to be addressed for each polishing technology are pointed out, and suggestions and prospects for future research, application, and development are also given. Objective: In order to meet the growing demand for high-precision optical components and mass-manufactured optical components, this paper aims to study the various polishing technologies that are continuously improved and suggestions are made for future research and development directions. Method: This paper reviews the current patents related to various polishing technologies, such as Fluid jet polishing, Airbag polishing, Magnetorheological polishing and Ion beam polishing and other representative polishing technologies. Results: Various types of polishing technologies have been studied, and the main problem at the current stage is the lack of accuracy. The problem of the polishing device, such as fluid jet polishing, only considers the change of fluid velocity and pressure to construct the removal function model for analysis and summary, and suggestions for the latest research progress of various polishing technologies are given. Conclusion: The improvement and optimization of polishing technology are beneficial to improving the polishing accuracy and quality of optical components and have great help for the future development of related patents.

SAL5087 bright welding wire two acid polishing process and its effect on surface roughness

Abstract In order to obtain bright aluminum alloy wires and eliminate the environmental and human hazards of traditional chemical polishing, the H3PO4-H2SO4 system chemical polishing process was developed for SAL5087, and the surface roughness was measured by laser confocal microscopy and the surface morphology was observed by sweeping electron microscopy as the evaluation index of the polishing quality. The process optimization was carried out by orthogonal experiments and the role of each component was analyzed. The experiments showed that phosphoric acid dominates the polishing process, which can effectively enhance the polishing effect under the synergistic effect with various additives. The surface roughness of the polished wire was reduced to 0.257 μm in the optimum process, and the surface was free of defects such as burrs and scratches.

Numerical Analysis in Double-Sided Polishing: Mechanism Exploration of Edge Roll-Off

Understanding the mechanism of stress concentration effects on the surface of semiconductor substrate materials—silicon wafers—in Double-Sided Polishing (DSP) is particularly important for improving polishing quality. In this study, a two-dimensional finite element model is established to study the effect of contact state and stress concentration during polishing on edge roll-off (ERO) and polishing rate uniformity. The variation in this contact state is influenced by changes in wafer thickness and the gap between it and the carrier. The model is validated by experiments and helps to further analyze and interpret the experimental results, identifying six stages of contact states during the polishing process. The research indicates that the phenomenon of stress concentration at the edge of a wafer is caused by the pads creating a large amount of compression at the edge of the wafer. Additionally, there appears to be a threshold value during the polishing process, below which the stress concentration on the wafer changes, thereby altering the magnitude of edge roll-off and, ultimately, affecting overall flatness. This study provides a basis for optimizing the process design.

Pulsed Unipolar-Polarisation Plasma Electrolytic Polishing of Ni-Based Superalloys: A Proof of Conception

The enhanced performance of aerospace equipment drives parts development towards integration, complexity, and structural optimization. This advancement promotes metal near-net fabrication technologies like wire electrical discharge machining (WEDM) and 3D printing. However, the high initial surface roughness from WEDM or 3D printing poses significant challenges for the high-performance surface finishing required. To effectively reduce the surface roughness of the workpieces with high initial surface roughness, this paper proposes pulsed unipolar-polarisation plasma electrolytic polishing (PUP-PEP). The study examined the material removal mechanisms and surface polishing quality of PUP-PEP. This technique combines the high current density and material removal rate of the electrolytic polishing mode with the superior surface polishing quality of PEP through voltage waveform modulation. For an Inconel-718 superalloy part fabricated by WEDM, PUP-PEP reduced surface roughness from Ra 7.39 μm to Ra 0.27 μm in 6 min under optimal conditions. The roughness decreased from Ra 7.39 μm to Ra 0.78 μm in the first 3 min under pulsed unipolar-polarisation voltage, resulting in a remarkable 233% increase in efficiency compared to that with conventional PEP. Subsequently, the voltage output voltage is transformed into a constant voltage mode, and PEP is continued based on PUP-PEP to finally reduce the workpiece surface roughness value to Ra 0.27 μm. The proposed PUP-PEP technology marks the implementation of ‘polishing’ instead of conventional rough-finish machining processes, presenting a new approach to the surface post-processing of metal near-net fabrication technologies.

Circular Halbach array integrated using an abrasive circulating system during the ultra-precision machining of polymethyl methacrylate optical material

A novel approach to enhancing the efficacy and surface quality of magnetic polishing involves the incorporation of a magnetic liquid circulation system for abrasive particle regeneration in conjunction with a circular Halbach array. The continuous renewal of abrasive particles within the polishing zone is realised through a conveyor belt that transports new abrasive particles into the polishing liquid solution. This formation of a continuously circulating polishing system ensures uninterrupted magnetic finishing processes and maintains stability throughout the polishing operation. This study extensively explores polishing force distribution, magnetic field distribution and abrasive grain behaviour in the polishing area facilitated by the magnetic liquid solution. The application of the proposed polishing processes to polymethyl methacrylate, an optical lens material, aims to comprehend the characteristics and validate the feasibility of the polishing method. Key influencing factors in the magnetic polishing process, including abrasive grain size, magnetic particle, polishing distance and conveyor speed to surface quantity, are examined through experimental analysis. Results of the experimental polishing processes demonstrate that the utilisation of circular Halbach arrays with circulating abrasives produces a nanometric surface finish. Even in the polishing of polymethyl methacrylate with an initial rough surface (Ra = 464.895 nm), the process achieves an ultra-fine level with Ra below 9 nm without disruption in the material polishing processes of optical lenses.

FLAW DEFECTION ANALYSE OF THE SURFACE OF ACRYLIC BASE PLASTICS

This study examines the possibility of assessing the quality of removable orthopedic devices by measuring the smoothness of their surfaces and detecting microscopic defects. The methodology involves comparing standard samples of the base material with samples that have been intentionally defective, using defectoscopy techniques for analysis. Initially, twenty samples of basic acrylic plastic were selected: half of them were perfectly machined to dental standards and the other half were intentionally scratched with sandpaper. These samples were then examined by macrophotography and analyzed using Image J software for quantitative image measurement. This analysis provided numerical data on the polished surface's quality, focusing on metrics such as the total number of defects, and the average size and perimeter of these defects. Statistical evaluation through the JUSP program compared the two sets of samples, highlighting significant differences between them. From the most prominent data points provided by Image J, conclusions were made regarding the surface quality of the acrylic plastic and how it is affected by specific mechanical imperfections. This method of using optical flaw detection offers a new way to clinically evaluate the quality of detachable orthopedic devices (like base plastic) in terms of their susceptibility to bacterial buildup, which could lead to inflammation in the prosthetic bed's mucosal lining. The use of flaw detection analysis allows for a general assessment of the quality of the material surface polishing, detection of surface defects in its structure that may occur during the production stage or during operation, thereby preventing areas of biofilm accumulation. Light-optical flaw detection in the experiment proved its effectiveness and makes us pay attention to the prospects of its improvement and wider implementation in clinical practice.

Electrochemical polishing properties of AlMgScZr alloy produced by laser powder bed fusion in NaNO3 and NaCl solutions

Electrochemical polishing (ECP) is a potential process to improve the surface quality of AlMgScZr alloy components produced by laser powder bed fusion (LPBF). Replacing traditional acid electrolytes with environment-friendly electrolytes is of great significance to the environment and safety. This work aims to study the ECP properties of LPBF AlMgScZr alloy in environment-friendly electrolytes (NaNO3 and NaCl solutions). In ECP, the electrochemical dissolution behavior of anode materials determines the polished surface quality. To this end, the effect of electrolyte type, uneven microstructure and applied current density on the anodic dissolution behavior of LPBF AlMgScZr alloy was examined experimentally. The results provide information about the suitability of the electrolytes selected for the ECP of LPBF AlMgScZr alloy, the dissolved surface quality in NaNO3 solution is significantly better because of the existence of a dense passive film. In addition, a microstructure analysis reveals that the bimodal distribution of grain size is the main factor leading to an uneven dissolved surface. Finally, the inner surface of LPBF AlMgScZr alloy channel was successfully polished in NaNO3 solution, the semi-welding particles were completely removed, and the surface roughness Sa was reduced from 20.73 μm to 2.48 μm.

ANALYSIS OF SURFACE QUALITY IN BASE ACRYLIC PLASTIC USING FLAW DETECTION METHOD

Before scanning the surface of the base acrylic plastic, ten samples were selected with a surface that had undergone all stages of finishing according to the proper dental protocol and ten samples that had previously been artificially damaged with scratches using sandpaper. This study addresses the assessment of the quality of removable orthopedic appliances concerning surface polishing and detection of microdefects. The research employs a comparative analysis of reference samples of base plastic and artificially damaged samples using flaw detection analysis. Prior to scanning the surface of the base acrylic plastic, ten samples underwent all stages of finishing according to dental protocol, while another ten samples were intentionally damaged with scratches using sandpaper. The macrophotographs obtained were processed using the "Image J" program, allowing for quantitative analysis of images, enabling the evaluation of surface quality through various parameters. This included evaluating the total number of defects, as well as the average area and perimeter of the defects. Statistical analysis conducted in the JUSP program enabled comparison between the two groups of samples, identifying significant quantitative differences. Based on the prominent indicators available in the Image J program, conclusions were drawn regarding the quality of the acrylic plastic surface and the factors influencing its condition through specific mechanical defects. The proposed method of light-optical flaw detection expands the clinical assessment capabilities of removable orthopedic structures (base plastic), particularly concerning potential bacterial contamination, which can serve as a significant factor in the formation of inflammation foci on the mucous membrane of the denture-supporting oral tissues. Flaw detection analysis enables a comprehensive assessment of material surface polishing quality and the detection of surface defects that may arise during production or use, thus preventing biofilm accumulation. The experiment demonstrated the effectiveness of light-optical flaw detection and highlights the potential for its further improvement and broader implementation in clinical practice.

Theoretical and experimental investigation on magnetorheological shear thickening polishing force using multi-pole coupling magnetic field

The magnetorheological shear thickening polishing method, with its dual-stimulus response of shear thickening and magnetization enhancement, has emerged as a promising magnetic field-assisted polishing technology. However, in existing theories and experimental studies on polishing forces, the phenomenon of magnetization enhancement was mainly considered. The shear thickening effect has not yet to be incorporated into. Furthermore, there have been few systematic investigations on the polishing mechanism considering variations of force characteristics. The study aims to fill in these research gaps by developing theoretical models for both normal and tangential forces, and revealing the microscopic polishing mechanism during the magnetorheological shear thickening polishing process. Both normal and tangential polishing force models were established through taking the rheological properties of polishing media under magnetic field and plastic indentation theory into account. Polishing force measurement experiments under a multi-pole coupling magnetic field were conducted to reveal the variations of the polishing forces with different polishing parameters and to validate the established models. Furthermore, the microstructural evolutions of the polishing media components and the surface morphologies after polishing were combined with in-depth analysis to elucidate the polishing mechanism. The polished surface quality was significantly improved without visible scratches. The surface roughness of 48 nm was achieved from the initial value of 245 nm under the normal force of 3.36 N and the tangential force of 2.42 N. The study provides deep insights into the polishing forces characteristics and the polishing mechanism, which contributes to a theoretical guidance for optimizing polishing parameters and improving polishing quality.

Evaluation of Electropolishing Characteristics of 316L Stainless Steel Tube in Contaminated Electrolyte

In the electropolishing process, the polishing quality of the metal surface varies according to the contamination of the electrolyte. In this study, the electrolyte was evaluated according to the usage time, and the effect of each factor on electropolishing was investigated. As the electrolyte is contaminated, the concentration of metal ions in the electrolyte increases and the ion conductivity decreases. In addition, the pH and specific gravity of the electrolyte increase due to the metal sludge formed as the metal ion concentration increases. When the electrolyte usage time was more than 5 days, many scratches remained on the surface of 316L stainless steel, and relatively high surface roughness was measured. The surface roughness improvement rate compared to the initial specimen was 30% for the unused electrolyte, 26% on the 3rd day, 19% on the 5th day, and 17.5% on the 13th day. Since the low current density due to electrolyte contamination causes a decrease in polishing efficiency, initial scratches on the metal surface still exist on the polished surface. Therefore, it is necessary to manage the electrolyte to maintain the quality of electropolishing.

Transmission and nanohardness studies of ternary GaAs1-xPx layers grown from the vapor phase by heteroepitaxy

Transmission measurements in the 0.5–25-μm spectral range are performed on thin (<350-μm) GaAsP layers grown by Hydride Vapor Phase Epitaxy (HVPE) on plain (100) GaAs substrates. Comparison with calculations taking into account multiple reflections reveals the role of the surface polishing quality on the clear transmission window and the wavelength dependent losses. A measurement of a 5-mm thick epitaxially grown GaP underlines more realistic spectral limitations on the application of orientation-patterned structures based on GaP and GaAsP for nonlinear optical frequency conversion. The mid-IR cut-off wavelength for the ternary GaAsP layers is almost independent of the composition and corresponds to the same two-phonon absorption limit observed in the binary GaP. Nanohardness and Young's modulus are measured for the same samples to evaluate their compositional dependence. The nanohardness dependence on the P-content obeys a second order polynomial law with a maximum around P = 0.8. Young's modulus depends linearly on the P-content, similar to the trend observed in other ternary systems, such as InxGa1−xAs and InxGa1-xP. The evolution of the band-gap, estimated from the transmission measurements, with the composition of the ternary compounds is linear in the range of 0–0.5 for the P content. In this same range the nanohardness can be considered to be linearly proportional to the band-gap.

Concealing Meets Healing in the Treatment of Toenail Onychomycosis: A Review of Concurrent Nail Polish Use With Topical Efinaconazole 10% Solution

Introduction: Females are more likely than males to seek help or treatment for onychomycosis and are more likely to camouflage affected nails with nail polish. Between 2016 and 2022, over half of prescriptions for topical efinaconazole 10% solution were written for females, suggesting that there may be particular interest in the interaction between nail polish use concurrent with efinaconazole treatment for onychomycosis.&#x0D; Methods: Review in vitro data on effects of nail polish on nail penetration of efinaconazole 10% solution and clinical studies on the impact of nail polish use on efficacy of topical efinaconazole in the treatment of toenail onychomycosis.&#x0D; Results: Only 4 small studies have assessed interactions between efinaconazole 10% solution and concurrent nail polish use. In vitro, penetration of efinaconazole 10% solution through cadaverous human nails coated with traditional nail polish was similar to penetration through uncoated nails. In a 1-year clinical study, once-daily efinaconazole treatment for 48 weeks was associated with improvements in onychomycosis severity and clear toenail growth that were similar for participants who used traditional nail polish and those who did not use nail polish. In a second, 6-month clinical study, participants received once-daily efinaconazole treatment concurrent with monthly gel nail polish pedicures. After 6 months, 100% of participants tested negative for fungal infection (mycological cure) and all participants experienced visible improvements in their treated toenails. In clinical and in vitro studies, efinaconazole application was associated with degradation of traditional nail polish texture and appearance as well as color transfer to the applicator and unused medication. In contrast, efinaconazole did not affect the duration, quality, or texture of gel nail polish.&#x0D; Conclusions: Application of nail polish did not prevent penetration of efinaconazole 10% solution through human nails or its successful use in the treatment of toenail onychomycosis. Further, efinaconazole did not impact the texture or appearance of gel-polished nails. To our knowledge, these findings represent the only available data on topical treatment of toenail onychomycosis with concurrent nail polish use, and may be of particular importance when selecting treatment options for female patients with onychomycosis.&#x0D; Funding: Ortho Dermatologics

Influence of SiO2–ZnO mixed soft abrasive on tribological behavior and polishing performance of sapphire wafer

The use of reactive soft abrasives, capable of undergoing solid-state reactions with sapphire, is a promising approach for low-damage and low-contamination machining of sapphire wafers. This study calculates the Gibbs free energy change of these chemical reactions based on thermodynamic principles. SiO2–ZnO mixed soft abrasives were selected for the polishing of sapphire wafers. Friction and wear experiments were conducted to explore the tribological behavior of sapphire wafers with various mixed abrasives, leading to the optimization of the abrasive composition. The results show that mixed abrasives significantly enhance the material removal rate (MRR) of sapphire wafers. As the proportion of SiO2 in the mixture increases, the MRR correspondingly rises. Specifically, an SiO2–to–ZnO ratio of 2:1 in the mixed abrasives results in a 91.68% increase in MRR compared to using SiO2 abrasives alone. Based on these findings, five grinding discs with different abrasive ratios were prepared using a resin binder for mechanical–chemical polishing experiments on sapphire wafers. The polishing results corroborate those of the friction and wear experiments, confirming that an increased SiO2 content in the mixed abrasive discs leads to higher MRR. With a 2:1 ratio of SiO2 to ZnO in the mixed abrasive disc, the MRR is enhanced by 342.9% compared to discs with only SiO2 abrasives, while reducing the surface roughness to 3.21 nm. In the SiO2–ZnO mixed abrasives, the inclusion of ZnO enhances chemical reactions during polishing. Aided by the mechanical removal efficacy of SiO2, this approach significantly increases MRR while maintaining superior polishing quality.

Magnetorheological Polishing Based on Honing Vertical Mechanism for Inner Surface of Titanium Alloy Pipes

Recently, high internal surfaces for titanium alloy pipes have been required due to the increment of various applications such as aerospace components. In this work, vertical magnetorheological polishing (VMRP) is carried out to achieve high polishing performance on the internal surface of the titanium alloy pipe. A series of comparative experiments were conducted to investigate the polishing mechanism of magnetorheological polishing (MRP) fluid and enhance the polishing performance. It is shown from the experimental results that the VMRP method under the opposite polarity arrangement improves the surface roughness from 47.85% to 83.34% by reducing unwanted vibration and noise during operation. This provides nanoscale surface polishing quality, while such a precision cannot be achieved from the previous horizontal MR polishing apparatus method. It is found that under a 2700 cycle polishing time, a polishing process combining a rough and fine polishing approach with a combination of different particle diameters results in an axial surface roughness of 0.05 μm and circumferential surface roughness of 0.038 μm, respectively. It is also identified that the axial surface roughness of 0.04 μm–0.041 μm is achieved through the combination of high- and low-speed polishing process after 1602 cycles.

The processing properties of photocatalysis assisted magnetorheological polishing based on TiO2–CI composite particles

With the development of optoelectronic wafers tend to be high brittleness, high hardness and high chemical stability, a single magnetorheological polishing is difficult to meet the application requirements of optoelectronic wafers. The quality and efficiency of magnetorheological polishing (MRP) of photoelectric wafer can be further improved by electric field assisted polishing or photocatalysis assisted polishing. In this paper, TiO2–CI functional composite particles were synthesized by sol-gel method, and a variety of polishing fluid with magnetic, electric and optical multi field effects were prepared. Silicon wafer and fused silica glass were polished by fixed-point centering polishing method, and the mechanism of photocatalytic assisted magnetorheological polishing (PMRP) was studied by comparing the polishing performance of the polishing fluid under different applied fields. The results show that when the polishing fluids prepared by oil-based liquid, the material removal rate is high under the action of a single magnetic field, but the polishing quality is poor. After polishing for 60 min, the height difference in surface profile ΔRz of fused silica glass is 0.67 μm. When the 2.5 kV/mm electric field is applied, the abrasive distribution can be controlled by electromagnetic composite field, and the stiffness distribution of polishing pad is more uniform, but it will reduce the material removal rate (MRR). Compared with the single magnetic field, the height difference in surface profile ΔRz is reduced by 73.1 % to 0.18 μm under the magnetoelectric compound field, which can obtain a more flattened surface quality. When light field and magnetic field are applied, water-based polishing fluid is used for polishing. Because UV light can induce photocatalytic reaction, the strong oxidation group ·OH generated in the photocatalytic reaction can oxidize the materials of workpiece surface into the lower hardness materials. Therefore, the material removal rate is increased by 249 % to 13.4 mg/h compared with that without light field, and the surface roughness was reduced by 69.32 % to 1.05 nm.