polished surface
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2021 ◽  
Author(s):  
Jianwei Ji ◽  
Khan M. Ajmal ◽  
Zejin Zhan ◽  
Rong Yi ◽  
Hui Deng

Abstract Electrochemical polishing (ECP) is widely used for scratch- and damage-free finishing of metal components. Though the polishing effect of ECP has been confirmed in many researches, the influence of polishing parameters on evolution of surface roughness is still ambiguous owing to the use of different ECP systems. In this paper, the universal factor determining the evolution of surface roughness during ECP is studied by theoretical analysis as well as experiments. Theoretical analysis based on viscous layer mechanism demonstrates that the material removal thickness is the key parameter governing the roughness evolution of the polished surface regardless of other parameters including the voltage, current and electrolyte concentration and so forth. A series of experiments were designed and carried out to verify the proposed hypothesis. Both the experimental results and already published researches proved the validity and universality of the newly developed hypothesis on surface roughness evolution. This work is of great significance for further understanding the finishing mechanism of ECP and process control for its practical applications.


2021 ◽  
Vol 14 (1) ◽  
pp. 1-5
Author(s):  
Fikriyatul Azizah Su'ud ◽  
Suminar Pratapa ◽  
Musyarofah Musyarofah

This study was aimed to know the effect of B2O3(boria) addition on the phase composition and physical properties of zircon ceramics.The raw zircon powder used in the study was a purified natural zircon sand from Kereng Pangi, Central Kalimantan, Indonesia. The zircon ceramics were prepared by a solid state reaction method with variation of B2O3 addition of 3 wt%, 6 wt% and 9 wt% and sintered at 1300 °C for 5h. The phase composition, density and microstructure were characterized using X-ray diffraction (XRD), densimeter and Scanning Electron Microscope (SEM), respectively. Vickers Hardness measurement was perfomed at the polished surface of the ceramics. Results showed that all samples contained pure zircon phase, i.e. there was no effect of B2O3 addition on the phase composition. In general, the density and hardness increased with increasing B2O3 addition, but addition up to 9 wt% is not optimum to achieve ultra-dense zircon ceramics. Furthermore, the SEM image also showed no significant difference in average grain size. The crystallite size has grown nearly eight times (325 nm) of its original powder. The Vickers hardness of the ceramics is not significantly influenced by the addition of boria. It appears that the boria failure to increase densification also results in the extent of contact between grains which then produces relatively large zircon grains.


2021 ◽  
Vol 9 ◽  
Author(s):  
Chengyuan Yao ◽  
Wanfu Shen ◽  
Xiaodong Hu ◽  
Chunguang Hu

The sesquioxide Lu2O3 single crystal has attracted tremendous attention as potential host material for high-power solid-state lasers. As polishing is the terminal process of conventional ultra-precision machining, the quality of polished crystal directly impacts the crucial performance indicators of optics. The high melting point of Lu2O3 single crystal makes crystal preparation difficult. Therefore, investigations on the surface/subsurface quality inspection of polished Lu2O3 single crystal are scarce. In this paper, we utilize the quasi-Brewster angle technique (qBAT) based on ellipsometry to inspect the quality of polished Lu2O3 single crystal, achieving fast, non-destructive, and high-sensitive surface/subsurface damage assessment. A systematic crystal processing scheme is designed and polished Lu2O3 crystal samples are obtained. To verify the results of qBAT, the surface and subsurface quality are tested using optical profilometer and transmission electron microscope, respectively. The consistency of the test results demonstrates the feasibility, high sensitivity, and accuracy of the qBAT. To our knowledge, this is the first time that the qBAT is applied to investigate the polished surface/subsurface quality of Lu2O3 single crystal. In conclusion, this method provides a powerful approach to the high-precision characterization of the surface/subsurface quality of Lu2O3 single crystal, and has significant potential for material property study and process optimization during ultra-precision machining.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7536
Author(s):  
Patrycja Osak ◽  
Joanna Maszybrocka ◽  
Maciej Zubko ◽  
Jan Rak ◽  
Sylwia Bogunia ◽  
...  

Titanium Grade 4 (Ti G4) is widely used in medicine for dental implants. The failure-free life of implants depends on their properties such as resistance to wear and friction processes. This paper presents an analysis of the influence of sandblasting on tribological wear of commercial dental implants made of TiG4 in artificial saliva. Tribological wear measurements were performed in a reciprocating motion in the ball-on-disc system. The scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) method was used to characterize the surface of the implants before and after the tribological wear test. The microhardness of Ti G4 was measured before and after sandblasting by the Vickers method. The contact angle was determined by the method of sitting drop in air. The residual stress test using the X-Ray Diffraction (XRD) single-{hkl} sin2ψ method was carried out. The compressive residual stress of 324(7) MPa and surface hardening of Ti G4 was revealed after sandblasting with Al2O3 particles of 53–75 μm in diameter. It was found that sandblasting changes the surface wettability of Ti G4. The intermediate wettability of the mechanically polished surface and the hydrophobicity of the sandblasted surface was revealed. Sandblasting reduces the tribological wear and friction coefficient of Ti G4 surface in saliva. The three-body abrasion wear mechanism was proposed to explain the tribological wear of Ti G4 in saliva.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7280
Author(s):  
Mayumi Maesako ◽  
Takafumi Kishimoto ◽  
Shigetaka Tomoda ◽  
Taku Horie ◽  
Mitsuyoshi Yamada ◽  
...  

Resin composites employing structural coloration have recently been developed. These resins match to various tooth shades despite being a single paste. To accomplish this, the filler and base resin are tightly bonded, which is thought to provide excellent discoloration resistance. Here, we investigated the surface properties of one of these resins, including the discoloration of the repolished surface. We developed an innovative in vitro method to adjust the repolished surface, in which structural degradation is removed according to scanning electron microscopy (SEM) observation rather than by the naked eye. The resin samples (20 mm (length) × 10 mm (width) × 4 mm (depth)) were manufactured using this resin material. After accelerated aging of the resin by alkaline degradation, the resin was repolished and the discoloration (ΔE*ab), surface roughness (the arithmetic mean roughness (Ra)), and glossiness (the 60° specular) were measured. SEM observation showed that the appearance of the bond between the organic composite filler and base resin on the repolished surface was different from that on the mirror-polished surface. This revealed that according to our in vitro method it was difficult to make the repolished surface structurally identical to the mirror-polished surface. Among the properties of the repolished surface, the degree of discoloration did not change despite the rougher and less glossy surface. It can be concluded that the factors that induce discoloration in this resin composite are independent of the surface roughness and glossiness.


2021 ◽  
Author(s):  
Abhinav Kumar ◽  
Suraj Kumar ◽  
Manas Das

Abstract Maraging steel 300 is widely used in aircraft, tools, and automotive industries, which requires a polished surface for better performance. In conventional methods of polishing, the abrasives directly contact the workpiece surface and deteriorate its property. Thus, a non-conventional method like Electropolishing (EP), is utilized to finish maraging steel with acetic acid (99.7 wt.%) and perchloric acid (70 wt.%) mixed in the volume of 3:1. Linear sweep voltammetry (LSV) is performed to determine the passive region that gives the best electropolishing performance. Different parameters, namely temperature, agitation, and polishing time and their effect on surface roughness and surface reflectance, are observed during EP. The optimized process parameters which give the best EP performance are the temperature at 60ºC, rotation of magnetic stirrer at 400 rpm, and polishing time of 6 minutes. An improvement of 56% in surface roughness and 60% in surface reflectance from its initial value of 21% is observed. EP makes the surface hydrophilic as the contact angle changes from 111.2º to 68.6º. Energy-Dispersive X-Ray Spectroscopy analysis suggests that after EP, a metal oxide layer forms on the surface which helps in increasing corrosion resistance.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chen Sun ◽  
Weijie Xu ◽  
Yongqi Tan ◽  
Yuqing Zhang ◽  
Zengqi Yue ◽  
...  

AbstractWith the ChemCam instrument, laser-induced breakdown spectroscopy (LIBS) has successively contributed to Mars exploration by determining the elemental compositions of soils, crusts, and rocks. The American Perseverance rover and the Chinese Zhurong rover respectively landed on Mars on February 18 and May 15, 2021, further increase the number of LIBS instruments on Mars. Such an unprecedented situation requires a reinforced research effort on the methods of LIBS spectral data analysis. Although the matrix effects correspond to a general issue in LIBS, they become accentuated in the case of rock analysis for Mars exploration, because of the large variation of rock compositions leading to the chemical matrix effect, and the difference in surface physical properties between laboratory standards (in pressed powder pellet, glass or ceramic) used to establish calibration models and natural rocks encountered on Mars, leading to the physical matrix effect. The chemical matrix effect has been tackled in the ChemCam project with large sets of laboratory standards offering a good representation of various compositions of Mars rocks. The present work more specifically deals with the physical matrix effect which is still lacking a satisfactory solution. The approach consists in introducing transfer learning in LIBS data treatment. For the specific application of total alkali-silica (TAS) classification of rocks (either with a polished surface or in the raw state), the results show a significant improvement in the ability to predict of pellet-based models when trained together with suitable information from rocks in a procedure of transfer learning. The correct TAS classification rate increases from 25% for polished rocks and 33.3% for raw rocks with a machine learning model, to 83.3% with a transfer learning model for both types of rock samples.


2021 ◽  
Author(s):  
Jinwei Fan ◽  
Xingfei Ren ◽  
Ri Pan ◽  
Peitong Wang ◽  
Haohao Tao

Abstract As an advanced finishing technology, magnetic compound fluid finishing (MCFF) is considered to be able to achieve damage-free finishing of low-hardness materials such as copper alloys with appropriate finishing parameters. However, ignoring the influence of the material removal amount on the dimensional accuracy when optimizing the finishing parameters may result in excessive material removal and a reduction in the workpiece's dimensional accuracy. Thus, a novel finishing parameters optimization method considering dimensional accuracy is proposed in this paper. Firstly, the MCFF experiments are planned and carried out for modeling. Secondly, a MCFF model is established based on the integrated learning theory. The established model is a multi-layer neural network fusion model comprised of a prediction layer and a fusion layer, which can accurately predict the polished surface quality and material removal amount. Thirdly, taking the effect of material removal amount on the dimensional accuracy into account, the finishing parameters are optimized by the multi-objective particle swarm optimization algorithm. Finally, the model's prediction accuracy and the superiority of the optimized parameters are compared and verified by experiments. The results demonstrate that the developed model can correctly predict the finishing effect, and the high-quality polished surfaces and high dimensional accuracy can be obtained with the optimized finishing parameters.


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