Polishing Disk Research Articles

Effects of polishing disc material and substrate surface temperature on the tribological behaviors and machining results of β-Ga2O3(100)

Effects of polishing disc material and substrate surface temperature on the tribological behaviors and machining results of β-Ga2O3(100)

Polishing performance and material removal mechanism in the solid-phase Fenton reaction based polishing process of SiC wafer using diamond gel disc

The use of SiC wafer is widespread in many fields, especially in aerospace, energy, 5 G communications, and microelectronics. Chemical-mechanical polishing (CMP) is the primary method used for achieving an ultra-smooth surface on SiC wafers. However, CMP suffers from low efficiency, leading to increased processing time and costs. To address this issue, we developed a novel diamond gel polishing disc that incorporates SiO2/Fe3O4 (S/F) powder. The disc enhances polishing efficiency through a solid-phase Fenton reaction between the disc and SiC. The research investigates the reaction mechanism and the material removal model of the polishing process using SEM, TEM, and XPS analysis. Experimental studies are conducted to assess the polishing performance and validate the effectiveness of the theoretical model. The findings indicate that SiC undergo a solid-phase Fenton reaction with polishing disc mixed S/F powder (SG-S/F disc) during polishing. The Fenton reaction generates hydroxyl radicals (·OH), which break the Si-C and Si-Si bonds in the crystal structure, leading to the formation of a softer nanoscale amorphous oxide layer on the SiC surface. The cyclic generation and removal of this oxide layer enable highly efficient polishing of SiC wafers. Compared to a gel disc without S/F (SG disc), SiC polished with the SG-S/F disc exhibits superior surface quality. Additionally, the material removal rate (MRR) of the SG-S/F disc reaches 1.42 μm/h, representing a 51.1 % improvement over that of the SG disc. These results clearly demonstrate that the solid-phase Fenton reaction significantly enhances the polishing performance of the gel polishing disc.

Optimization of MRP quartz glass process parameters based on BP-PSO

ABSTRACT The BP-PSO was used to obtain the optimal process parameters of magnetorheological polishing quartz glass. Specifically, the orthogonal experiments investigated the effect of process parameters on processing properties. A BP prediction model was constructed with process parameters as input and comprehensive evaluation Z as output. Based on the model, PSO was used to optimize process parameters, and experimental validation was conducted. It turns out that the relationship of MRR with workpiece speed is linear, with working gap and polishing disc speed are sinusoidal, and with yaw speed is quadratic. The relationship between Sa and four process parameters are quadratic. The R2 of the model is 0.9609. The error of the predicted Z is less than 3.45%. The optimal combination predicted is: workpiece speed 700r/min, working gap 3.1mm, yaw speed 115mm/min, and polishing disc speed 60r/min. The predicted Z is 39.96, the actual Z is 41.93, with an error of 4.9%.

Comparative study on the effects of different polishing methods on tooth surface microstructure and roughness following initial periodontal treatment.

To investigate the effects of different polishing methods on the surface microstructure and roughness of teeth following initial periodontal treatment. Teeth were divided into three groups (silica onegloss, polishing disc, and polishing strip) in vitro. Tooth surface microstructure was characterized via scanning electron microscopy. Roughness was measured by profilometry and laser scanning confocal microscopy (LSCM). According to the in vitro results, one group was chosen for further clinical trials. Effects of the chosen polishing method on patient plaque control and satisfaction were assessed via plaque staining and visual analog scale (VAS). Electron microscopy results revealed that the polishing disc group had smoother roots and crowns than did the other two groups. Roughness analysis revealed that the crown roughness with the polishing disc and silica onegloss was lower, and the root roughness with the polishing disc was the lowest (p < .05) The LSCM results showed that the pigment deposition depth with the polishing disc and silicon onegloss in the crowns and roots were significantly lower than those with the other two methods (p = .000). The polishing effect of the polishing disc was best among the three groups. Clinical trials were performed to verify the polishing disc effects. Plaque staining results showed that the decrease in plaque in the polishing disc group was greater than that ofthe rubber cup group (p = .020), which was similar to the results of LSCM. The VAS results showed that the polishing disc made teeth feel smoother, similar to the results of the roughness detection, and the procedure was more comfortable (p < .05). However, there was no significant difference between the two groups regarding foreign body sensation during pronunciation (p = .178). Combining in vitro and in vivo evaluations, the use of a polishing disc following periodontal treatment yielded superior polishing effects on teeth and was better accepted by patients.

Fabrication and Polishing Performance of Diamond Self-Sharpening Gel Polishing Disk.

A diamond gel polishing disk with self-sharpening ability is proposed to solve the problem of glazing phenomenon in the gel polishing disks. Aluminum nitride (AlN) powder with silica sol film coating (A/S powder) is added to the polishing disk, and a specific solution is used to dissolve the A/S powder during polishing, forming a pore structure on the polishing disk. To realize the self-sharpening process, the dissolution property of the A/S powder is analyzed. The effect of A/S powder content on the friction and wear performance and the polishing performance of 4H-SiC wafers are investigated. Results showed that the friction coefficient of the polishing disk with 9 wt% A/S powder content is the most stable. The surface roughness Ra of 2.25 nm can be achieved, and there is no obvious glazing phenomenon on the polishing disk after polishing. The surface roughness of the 4H-SiC wafer is reduced by 38.8% compared with that of the polishing disk with no A/S powder addition after rough polishing, and the 4H-SiC wafer then obtained a damage-free surface with a Ra less than 0.4 nm after fine polishing by chemical mechanical polishing (CMP).

Effect mechanism of multi-phase coupling on particle behaviors in magnetorheological foam plane finishing process

In this study, the effect mechanism of multi-phase coupling on particle behaviors in magnetorheological foam plane finishing (MRFPF) was researched to realize the collaborative control of particle distribution uniformity and polishing quality. To reach the goal, particle behaviors in MRFPF under the effect of fluid-solid coupling in magnetorheological foam were numerically studied by molecular dynamics (MD) simulation based on the force analysis that considering pressure drop due to fluid flow in foam pores. According to the simulation results, the influence law of different processing parameters on the radial distribution uniformity of particles was analyzed based on experimental analysis method. The results show that the polishing disk rotation speed and foam porosity have a positive effect on the radial distribution uniformity of particles, while the foam aperture affects little, and the greatest influence is produced by foam porosity which followed by polishing disk rotation speed and foam aperture. What's more, an optimal parameter combination with foam porosity 0.7, polishing disk rotation speed 30 rpm, and foam aperture 1 mm was determined by comprehensively considering the fluidity of MRPF and self-excited characteristics of abrasive particles in MRPF. Moreover, the advantages of MRFPF in improving the particle distribution uniformity and surface finishing quality to that of magnetorheological finishing were verified from numerical simulations and experiments.

Investigation on influence of polishing disc materials in UV-catalytic polishing of single crystal diamond

The effects of three materials (Fe, SiO2, Al2O3) on the tribological behavior and material removal process of single crystal diamond (SCD) in a UV-catalyzed environment were investigated through ball-on-disc friction and wear experiments, as well as CMP experiments. The results indicate that the material removal rate (MRR) of SCD increases with the hardness of the polishing disc material. However, the surface roughness Ra is influenced by the synergistic effect of both chemical and mechanical actions. Strong chemical action leads to C-O corrosion on the surface, while strong mechanical action causes sp2 damage to surface C atoms. When using Al2O3 discs, the MRR is the highest, reaching 713.5 nm/h, while SiO2 discs result in a smooth surface with a surface roughness Ra of 0.26 nm. Therefore, the SCD can be rough polished with Al2O3 discs first and then fine polished with SiO2 discs to achieve a high material removal rate and superior surface quality simultaneously.

The role of formamidine acetate as a complexing agent in the chemical mechanical polishing process of Ta-based barrier layers for through-silicon vias wafers

The complex agent can form a soluble complex with tantalum to improve the removal rate of tantalum (Ta), but the removal rate of tantalum is less than 1000 Å/min when the traditional complex agents such as citric acid, acetic acid, phosphoric acid, ammonium salt and oxalic acid are added to the slurry, which cannot meet the requirements of through-silicon via (TSV) process. Due to the various bonding forms of amidine and the easy modification of the substituent group on the terminal nitrogen atom, the metal complexes of amidine have different stereo effects and electronic properties, and are called "universal ligands". Formamidine acetate (FA) is a new complexing agent with great potential, which is suitable for the removal of TSV tantalum materials. In order to improve the rate selection ratio of Ta and copper (Cu) in the chemical mechanical polishing (CMP) of TSV wafer barrier materials, the effect of FA as a complexing agent on the removal rate of Ta and Cu and the rate selection ratio was investigated under the conditions of working pressure of 3 psi, polishing head speed of 87 r/min, polishing disk speed of 93 r/min, and flow rate of 300 mL/min. The complexation mechanism of FA on Ta and Cu was investigated by electrochemistry, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and density functional theory (DFT), and the surface quality before and after polishing was compared by using atomic force microscope (AFM). The results showed that with an FA concentration of 1.5 wt%, the removal rates of Ta and Cu were 1503 Å/min and 516 Å/min respectively, which verified the obvious effect of FA on improving the rate selection ratio of Ta and Cu. Surface roughness for both metals decreased from pre-polishing values of 0.793 nm to post-polishing values of 0.210 nm for Ta; from pre-polishing values of 4.32 nm to post-polishing values of 0.381 nm for Cu indicating significant improvement in surface quality after treatment with FA.

Assessing micrometer-scale contamination from organic materials in serpentinite analysis

Serpentinization of peridotite provides a significant source of energy for the subseafloor biosphere and abiotic organic synthesis. The presence of diverse micrometer-scale organic matter in serpentinites offers insights into deep carbon cycling and the origin of life on Earth. It is critical to maintain stringent lab protocols in analyzing serpentinite samples, limiting the contact with organic materials that could contaminate serpentinites and cause misinterpretations. However, the extent to which these organic materials (e.g. latex gloves or nylon polishing disc) can introduce contamination remains unclear. Here we subject serpentinite samples from the Yap Trench in the western Pacific Ocean to multi-stage cutting and polishing procedures prior to analysis. Our findings from electron microscopy reveal that micrometer-scale organic matter in serpentinites is randomly distributed either on the sample surface or within Cr-spinel fractures. Further analysis using Raman spectroscopy indicates that the organic matter contains several hydrogen bonding moieties, similar to those found in the latex gloves or nylon polishing disc used during the treatment of serpentinite samples. Our results suggest that the detected organic matter is likely due to contamination from the organic materials involved during sample processing. Thus, future studies need to carefully assess micrometer-scale organic contamination and limit the use of organic materials when analyzing organic compounds hosted in serpentinites, not only on Earth but also on other rocky planets.

Understanding the microstructure evolution of Fe-induced diamond with DFT study: Etching and graphitization

Studying diamond graphitization is a crucial issue in ultra-precision machining because it sheds light on the reason for material removal during polishing. The polishing disc made of cast iron is usually used to process diamonds, and a high-quality surface can be obtained. However, the graphitization mechanism induced by iron (Fe) is still obscure. This paper employs the density-functional theory (DFT) method to elucidate the mechanism by which Fe induces diamond graphitization. The results demonstrated that Fe atoms at the metastable adsorption sites (P3) on the surface could change some C–C interactions between layers. Notably, multiple Fe atoms at the P3 sites could alter the region of surface graphitization and the structural dissociation direction. The surface area close to Fe atoms became stable, while the surrounding surface areas were susceptible to oblique dissociation into graphite-like structures. Moreover, we speculated that the material removal rate was related to the moving activation energy of Fe atoms. Based on the charge-transfer and microstructural evolution, the phenomenon of Fe-atom-induced diamond graphitization was attributed to varying the connections between sixfold chair rings and promoting their weakening and dissociation rather than breaking the structure of sixfold chair rings.

A precision dimple grinder-polisher produced by 3D printing

A precision dimple grinder-polisher has been designed and constructed using 3D printing. The purpose of the device is to produce a thin central area in 3 mm round samples for transmission electron microscopy before ion milling to electron transparency. The device can be self-made by any laboratory with a 3D printer for scientific research or teaching, and when combined with recycling and use of biodegradable filaments it can help labs reach their sustainable development goals. A novel sample holder design allows sample alignment without a monocular and thickness detection by light transmission. Novel solutions are developed for aligning the grinding disc and sample rotation motors and for fixing the polishing cloth to the polishing disc. The diameter-depth relationship is investigated for steel and plastic grinding discs. Design principles and materials are discussed, and the tool is evaluated by preparing samples from copper, silicon and tungsten, which are then examined in the transmission electron microscope to evaluate their quality.

Effect of mouthwash on color change and solubility of composite resins

Aims: This study aimed to evaluate the effects of currently available mouthwashes on color changes and solubilities of composite resins by comparing them. Methods: Three different types of composite resins, namely nanofill, nanohybrid, and microhybrid resins (Filtek Ultimate, Estelite Sigma Quick, and Filtek Z250, respectively), were used in thisstudy. A total of 120 samples, with 40 foreach composite material, were prepared. The composite resins were placed in plastic molds of 10 mm × 2 mm with round disc shapes and polymerized with an LED light device. After finishing and polishing them with a polishing disc, the prepared samples were stored in distilled water. Initial color measurements were performed using the VITA Easyshade V device (VITA, Germany) for color stability evaluations. For solubility measurements, the dry weights of the samples were measured and their diameters and thicknesses were recorded with a caliper. Samples from each group were then immersed in three different mouthwashes (Kloroben, Listerine Advanced White, and Colgate Plax) twice a day for 2 minutes for 14 days. After 14 days, color and weight measurements were repeated for all samples. Kruskal-Wallis and Mann-Whitney U tests were used in the statistical analysis of the data. Results: Significant color changes were detected in all samples as a result of color measurements (p&lt;0.05). Significant differences were observed for all solution groups in terms of color change, but the lowest amount of color change was observed with the Colgate Plax solution. Comparisons of composite groups revealed that Filtek Ultimate was the composite with the lowest amount of color change. Positive solubility values were recorded for all samples as a result of solubility measurements. Although no significant difference was observed among composite groups in terms of solubility, higher solubility levels were detected with the Kloroben, Listerine Advanced White, and Colgate Plax solutionscompared to the control group. Conclusion: In thisstudy, in all evaluated composite groups, acceptable levels of color change and solubility were detected, with values varying depending on the composite material after immersion in the mouthwashes.

DESIGN AND FABRICATION OF VARIABLE SPEED ABRASIVE GRINDING AND POLISHING MACHINE FOR METALLOGRAPHIC SAMPLE PREPARATION

The polishing machine is one of the most useful pieces of metallography equipment for the grinding and polishing of metallic materials, particularly, surfaces of specimens. This is required in order to produce a flat, smooth and mirror-like surface before determine their physical structure using microscopy. This paper reports the design and construction of a variable speed abrasive polishing machine for physical metallographic applications. The machine design and construction are principled on using locally available materials for its fabrication. The machine consists of an electrical powered motor, pulleys, belt, rotating shaft, light aluminium alloy polishing disk plate, bush bearing, pillow bearings enclosed in metal casing. The test-running and evaluation of the machine was carried out at different speeds, grits of abrasive papers and on variety of materials (metal alloys, composites, plastic, ceramics) for both dry and wet operating conditions. Testing the machine was done with and without specimen on the rotating table for grinding and polishing. The machine is simple and safe to operate and requires minimum maintenance cost. The specimen size should not be less than 25mm diameter by 10mm thickness for easy hand held polishing operation.

Effect of different polishing systems and speeds on the surface roughness of resin composites.

The objective of this study was to compare surface roughness of a nano-spherical resin composite using four different multi-step polishing disc systems at five different speeds. In total, 154 discs samples were prepared using a supra-nano spherical resin composite. The samples were divided into negative and positive control groups and the following four finishing and polishing disc systems: Sof-Lex, Bisco Finishing Discs, OptiDisc, and Super-Snap. Each polishing disc system was applied at five different speeds (2000, 5000, 10,000, 15,000, and 20,000 revolutions per minute [RPM]) (n = 7). The surface roughness of samples was measured using a profilometer. One sample from each group was evaluated by scanning electron microscopy and atomic force microscopy. Two-way analysis of variance was used to evaluate the average roughness (Ra) data from the profilometric experiments using statistical software (GraphPad Prism4-GraphPad Software; La Jolla, CA, USA). The mean values were compared using the Bonferroni test (P = 0.05). The mean roughness ranged from 0.07 μm to 0.41 μm. The smoothest surfaces were obtained with OptiDisc at 20,000 RPM and Super-Snap at 20,000 RPM. The Bisco Finishing Discs group at 2,000 RPM showed the highest surface roughness values. For all polishing systems, the roughness at 20,000 RPM was lower than that at other speeds. Within the limitations of the present in vitro study, it can be concluded that the polishing performance was in the following order: Super-Snap > OptiDisc > Sof-Lex > Bisco Finishing Discs. In addition, the surface roughness decreased as the polishing speed increased.

Comparison of Different Finishing and Polishing Systems on Surface Roughness and Bacterial Adhesion of Resin Composite.

Insufficient dental restoration finishing and polishing may lead to plaque accumulation, gingival inflammation, staining, caries, and esthetic impairment. Here, the effect of two finishing and polishing systems on surface roughness and bacterial adhesion were evaluated. Two finishing and polishing kits were evaluated: diamond burs (Shine 1-2, Strauss & Co, Raanana, Israel) and paper discs (Sof-Lex 3M ESPE, Seefeld, Germany) (n = 30 each). For each group surface roughness was evaluated using an optical profilometer (Contour GT-K1, Bruker, Billerica, MA, USA) (n = 10). Surface bacteria were evaluated for biofilm biomass using crystal violet (CV) staining (absorbance measured at 538 nm) and viable counts (CFU/mL) (n = 20). The control group included polymerized discs against a Mylar strip (n = 30). Student's t test and one-way ANOVA were used for statistical evaluation. Diamond burs, paper discs, and control average surface RA were 169.4 ± 45.2 µ, 364 ± 77.7 µ, and 121.2 ± 18.1 µ, respectively. There was a significant difference found between all groups (p &lt; 0.00001). Bacterial biomass on diamond burs, paper discs, and control samples were 0.458 ± 0.161, 0.507 ± 0.139, and 0.446 ± 0.142, respectively (p = 0.257). Viable bacterial counts (CFU/mL) on diamond burs, paper discs, and control samples were 2.25 × 104, 2.95 × 104, and 2.75 × 104, respectively (p = 0.856). A comparison between two finishing and polishing kits showed that the shine 1-2 diamond bur kit produced a smoother surface than the polishing disc kit. No differences were found in the biofilm biomass quantification and bacterial viable count between the groups.

Simulation of Magnetorheological Plane Polishing Scratch Creation Process and Suppression Method

This study was conducted to simulate the causes of, and suppress, the scratch damage on the workpiece surface during magnetorheological surface polishing. The molecular dynamics method combined with polishing contact trajectory modeling was used to simulate the scratch damage formation process, and the scratch damage morphology model was established by analyzing the scratch damage distribution characteristics in the magnetorheological plane polishing process. The effect of different process parameters on the scratch damage characteristics was predicted by simulation, and orthogonal experiments were designed to explore the preferred polishing process parameters that could suppress the scratch damage formation. Finally, it was further verified that the formation of scratch damage can be effectively suppressed by controlling the workpiece speed, polishing disc speed, and magnetic field generator speed, and adjusting the magnetic field eccentricity distance under the premise of ensuring the surface roughness and flatness of the workpiece.

Chemical mechanical polishing exploiting metal electrochemical corrosion of single-crystal SiC

A chemical mechanical polishing (CMP) method of single-crystal SiC is proposed based on metal electrochemical corrosion. The oxidation mechanism of SiC by electrochemical corrosion of metals and the mechanism of surface material removal are revealed by corrosion and polishing experiments. The metallic aluminum sheet that is in contact with single-crystal SiC was immersed in sodium sulfate (Na2SO4) electrolyte solution, and the morphological and elemental changes of single-crystal SiC surface were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Then, polishing experiments were conducted on single-crystal SiC using different metal polishing discs and different polishing solutions. The XPS and EDS results show that single-crystal SiC can electrochemically corrode to generate a silica reaction layer. The use of metal polishing discs in CMP significantly improved the material removal rate (MRR) of SiC, with the highest MRR of 1011.43 nm/h for aluminum polishing discs, followed by that for iron polishing discs, and the lowest MRR for copper and alumina ceramic polishing discs. When metal polishing discs were used, the addition of electrolyte solution significantly improved the MRR and reduced the surface roughness of the SiC surface. Polishing with Na2SO4 solution when the polishing disc was aluminum disc, the MRR was higher than that for using deionized water by 105%, and the surface roughness Ra decreased by 37.8% to 2.8 nm. The metal electrochemical corrosion reaction can promote the oxidation of single-crystal SiC and generate a soft SiO2 reaction layer on the SiC surface, thereby improving the polishing efficiency of single-crystal SiC.

Exploring structural evolution and graphitization of the interface between tungsten and diamond (1 1 1) surface: A DFT study

In the ultra-precision machining field, tungsten (W) is a promising material as a polishing disc for machining diamond, which is easier to obtain high-quality diamond surfaces than cast iron. The removal mechanism of the diamond during high-speed polishing is considered surface graphitization. In this work, the diamond graphitization mechanism induced by tungsten is revealed by the density functional theory (DFT). The results show that the W adatoms at the fcc sites can activate the interlayer C-C bonds, causing the surface carbon atoms to separate. Notably, the electron transfer of W atoms and the structure contraction of the diamond surface cause the graphitization. Moreover, the movement of W adatoms intensifies the diamond surface structure transformation and graphitization process. It is worth noting that the W adatoms of the fcc and hcp sites have different contributions to the surface carbon atom separation during the interfacial sliding process. When the W atoms cross the hcp sites, the pulling force of the W-C bonds promotes the reconfiguration of the separated surface carbon atoms. The diamond-to-graphite transition is attributed to catalyst activation by W adatoms, diamond surface structure contraction, and mechanical tensile stress by the W-C bonds.

Theoretical and experimental research into a novel method of cluster magnetorheological finishing based on a circular array polishing disk

Theoretical and experimental research into a novel method of cluster magnetorheological finishing based on a circular array polishing disk

Surface Quality Control Strategy of Aspherical Mold Based on Screw Feed Polishing of Small Polishing Tool.

For small aspherical molds, it is difficult for the existing polishing method to take into account the correction of the surface error and the control of the uniformity of the surface roughness (SR) distribution, because the polishing tool is always larger than the small mold. Therefore, we used viscoelastic polyester fiber cloth to wrap the small steel ball as a polishing tool to adapt to the surface shape change of the aspherical mold, and designed a semi-flexible small polishing disc tool with microstructure, which can better adapt to the curvature change of aspherical surface and obtain better SR Ra. At the same time, a combined polishing method of constant speed and variable speed for screw feed was proposed to improve the uniformity of SR distribution in the paper. Then, a series of theoretical analysis and experimental verification were carried out in this paper to predict the tool influence function (TIF) of the two polishing tools and the effectiveness of the combined polishing method. In the experiment, a TIF bandwidth of about 0.46 mm was obtained with a small spherical polishing tool, which favors the surface shape correction of the small aspherical mold. The experiment of uniform removal with a small polishing disc tool was carried out to quickly reduce the Ra. Finally, the surface quality of the aspherical mold was effectively improved, combined with the constant speed and variable speed polishing modes of screw feed of the small spherical polishing tool and the smoothing effect of the small polishing disc tool. The peak valley (PV) of two small aspherical molds with an optical effective diameter less than 13 mm converged from 0.3572 μm and 0.2075 μm to 0.1282 μm and 0.071 μm, respectively. At the same time, the SR dispersion coefficient was reduced from 27.9% and 41.6% to 14.2% and 12.7%, respectively. The study provides a good solution for the surface quality control of small aspherical molds.