scholarly journals Polishing Sapphire Substrates by 355 nm Ultraviolet Laser

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
X. Wei ◽  
X. Z. Xie ◽  
W. Hu ◽  
J. F. Huang
Keyword(s):  
Surface Roughness ◽  
High Efficiency ◽  
Laser Energy ◽  
Incident Angle ◽  
High Hardness ◽  
Scanning Speed ◽  
Sapphire Crystal ◽  
Initial Surface ◽  
Ultraviolet Laser ◽  
Nanosecond Pulses

This paper tries to investigate a novel polishing technology with high efficiency and nice surface quality for sapphire crystal that has high hardness, wear resistance, and chemical stability. A Q-switched 355 nm ultraviolet laser with nanosecond pulses was set up and used to polish sapphire substrate in different conditions in this paper. Surface roughnessRaof polished sapphire was measured with surface profiler, and the surface topography was observed with scanning electronic microscope. The effects of processing parameters as laser energy, pulse repetition rate, scanning speed, incident angle, scanning patterns, and initial surface conditions on surface roughness were analyzed.

scholarly journals Investigation of Multiparameter Laser Stripping of AlTiN and DLC C Coatings

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 951
Author(s):  
Tomáš Primus ◽  
Josef Hlavinka ◽  
Pavel Zeman ◽  
Jan Brajer ◽  
Martin Šorm ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Efficiency ◽  
Steel Substrate ◽  
Cutting Tools ◽  
High Hardness ◽  
Working Time ◽  
Nanosecond Laser ◽  
Altin Coating ◽  
Successful Removal ◽  
Frequency Laser

The lifetime and properties of cutting tools and forming moulds can be prolonged and enhanced by the deposition of hard, thin coatings. After a certain period of usage, the coating will deteriorate. Any remaining coating must be removed prior to successful recoating. Laser stripping is a fast and environmentally friendly coating removal method. In this paper, we present laser removal of two types of coatings deposited on a 1.2379 tool steel substrate, namely, an AlTiN coating with high hardness and a DLC C coating with a small coefficient of friction (COF). A powerful nanosecond laser was employed to remove the coating from the substrate with high efficiency, along with suitable residual surface roughness. Measurements were taken of surface roughness, removed depth, and working time on a stripped area of 1 cm2. The samples were evaluated under a microscope, with a 3D profilometer, and by EDS chemical analysis. Successful removal of the coating was confirmed by optical analysis, but detailed chemical characterisation showed that about 30% of the coating element may remain on the surface. Moreover, a working time of less than 7.5 s per cm2 was obtained in this study. In addition, it was shown that the application of a second low energy, high frequency laser beam pass leads to remelting of the peaks of the material and reduced surface roughness.

Cr12MoV Die Repair Experiment Based on Laser Cladding with Wire

2019 ◽  
Vol 814 ◽  
pp. 137-143 ◽  
Author(s):  
Yan Yin ◽  
Yun Wang ◽  
Zhong Rui Tan ◽  
Wei Jie Yu
Keyword(s):  
Surface Roughness ◽  
Laser Cladding ◽  
Light Trapping ◽  
Steel Wire ◽  
High Hardness ◽  
Scanning Speed ◽  
Surface Damage ◽  
Cladding Layer ◽  
Wire Feeding ◽  
Process Factors

In this paper, SKD11 steel wire has been deposited on Cr12MoV plate using Nd: YAG pulsed laser for repairing the die surface damage. The effects of laser power, wire feeding speed, scanning speed and surface roughness on clad geometry have been studied with OM and LSCM. hardness distribution of the cladding layer is also obtained by microhardness tester. Experiment results indicate that the surface roughness is important for clad characteristics due to the light trapping effect. With the increases of roughness, the laser absorption ratio can be raised, both the clad depth and the dilution rate increase, the height decreases. The essence of influence mechanism is effective body energy Ev and specific filling rate ω, and can be used as critical process factors. When Ev is 80~100 J/mm3 and ω is 1~3, a flat cladding layer can be obtained with low dilution, less fusion defects and high hardness. Keywords: Cr12MoV, laser cladding with wire, surface roughness, clad geometry, hardness

Grinding Performance of Diamond Grinding Tools for Sapphire Crystal

2014 ◽  
Vol 1017 ◽  
pp. 544-548 ◽  
Author(s):  
Yu Zhang ◽  
Shang Gao ◽  
Ren Ke Kang ◽  
Xiao Guang Guo ◽  
Zhi Fu Lin
Keyword(s):  
Surface Roughness ◽  
High Efficiency ◽  
Removal Rate ◽  
Resin Composite ◽  
Sapphire Crystal ◽  
Grain Sizes ◽  
Diamond Grinding ◽  
Grinding Performance ◽  
Ultra Precision ◽  
The Cost

In order to improve the efficiency and reduce the cost of sapphire crystal machined by loose abrasive lapping, the fixed-abrasive diamond grinding tools for sapphire grinding were investigated in this paper. Four vitrified-resin composite bond diamond grinding tools with different grain sizes (40μm, 20μm, 7μm, 2.5μm) were developed. The grinding experiments were performed with the developed diamond grinding tools and the grinding performance of four grinding tools were evaluated by comparing the surface roughness and the material removal rate (MRR) of sapphire. The experiment results show that with the increase in grain size, both the MRR and the surface roughness increase. A high-efficiency and high-quality ultra-precision grinding process using diamond grinding tools with different grain sizes was proposed.

Study on Mechanism of Polishing Sapphire Crystal by Laser

2011 ◽  
Vol 341-342 ◽  
pp. 133-137
Author(s):  
Yongan Luo
Keyword(s):  
Laser Energy ◽  
Interaction Mechanism ◽  
Optical Element ◽  
High Hardness ◽  
Substrate Material ◽  
Green Laser ◽  
Sapphire Crystal ◽  
Contact Method ◽  
Laser Polishing ◽  
Laser Experiments

Single sapphire crystal is an important optical element and semiconductor substrate material, widely used in industry, national defense and scientific research, etc. But, high hardness and good chemical stability of the sapphire make it hard to be polished by applying mechanical chemical polishing and other contact methods. Therefore, laser polishing will be one of polishing methods which are supposed to replace contact method polishing sapphire. This essay, based on the summary of the study on laser polishing mechanism and technique of processing sapphire by laser, from the perspective of the interaction mechanism of the laser and the substance, analyzes in theory the interaction of laser and sapphire during the sapphire is polished by the short-wavelength laser. Experiments proved that under the cases of 20mJ and 40mJ laser energy when green laser polishes sapphire, the main material removal mechanism is fracture, at the same time, light melt mechanism exists.

scholarly journals On-chip trans-dimensional plasmonic router

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3357-3365 ◽  
Author(s):  
Shaohua Dong ◽  
Qing Zhang ◽  
Guangtao Cao ◽  
Jincheng Ni ◽  
Ting Shi ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Incident Angle ◽  
Reciprocal Lattice ◽  
Plasmonic Waveguide ◽  
Optical Diffraction ◽  
Local Dynamic ◽  
Phase Gradient ◽  
On Chip ◽  
Plasmon Polaritons

AbstractPlasmons, as emerging optical diffraction-unlimited information carriers, promise the high-capacity, high-speed, and integrated photonic chips. The on-chip precise manipulations of plasmon in an arbitrary platform, whether two-dimensional (2D) or one-dimensional (1D), appears demanding but non-trivial. Here, we proposed a meta-wall, consisting of specifically designed meta-atoms, that allows the high-efficiency transformation of propagating plasmon polaritons from 2D platforms to 1D plasmonic waveguides, forming the trans-dimensional plasmonic routers. The mechanism to compensate the momentum transformation in the router can be traced via a local dynamic phase gradient of the meta-atom and reciprocal lattice vector. To demonstrate such a scheme, a directional router based on phase-gradient meta-wall is designed to couple 2D SPP to a 1D plasmonic waveguide, while a unidirectional router based on grating metawall is designed to route 2D SPP to the arbitrarily desired direction along the 1D plasmonic waveguide by changing the incident angle of 2D SPP. The on-chip routers of trans-dimensional SPP demonstrated here provide a flexible tool to manipulate propagation of surface plasmon polaritons (SPPs) and may pave the way for designing integrated plasmonic network and devices.

scholarly journals Experimental Investigation and Comparison of the Thermal Performance of Additively and Conventionally Manufactured Heat Exchangers

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 574
Author(s):  
Ana Vafadar ◽  
Ferdinando Guzzomi ◽  
Kevin Hayward
Keyword(s):  
Surface Roughness ◽  
Thermal Performance ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Experimental Studies ◽  
Manufacturing Method ◽  
Industrial Sectors

Air heat exchangers (HXs) are applicable in many industrial sectors because they offer a simple, reliable, and cost-effective cooling system. Additive manufacturing (AM) systems have significant potential in the construction of high-efficiency, lightweight HXs; however, HXs still mainly rely on conventional manufacturing (CM) systems such as milling, and brazing. This is due to the fact that little is known regarding the effects of AM on the performance of AM fabricated HXs. In this research, three air HXs comprising of a single fin fabricated from stainless steel 316 L using AM and CM methods—i.e., the HXs were fabricated by both direct metal printing and milling. To evaluate the fabricated HXs, microstructure images of the HXs were investigated, and the surface roughness of the samples was measured. Furthermore, an experimental test rig was designed and manufactured to conduct the experimental studies, and the thermal performance was investigated using four characteristics: heat transfer coefficient, Nusselt number, thermal fluid dynamic performance, and friction factor. The results showed that the manufacturing method has a considerable effect on the HX thermal performance. Furthermore, the surface roughness and distribution, and quantity of internal voids, which might be created during and after the printing process, affect the performance of HXs.

scholarly journals Effect of Optical and Morphological Control of Single-Structured LEC Device

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 843
Author(s):  
Woo Jin Jeong ◽  
Jong Ik Lee ◽  
Hee Jung Kwak ◽  
Jae Min Jeon ◽  
Dong Yeol Shin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Surface Roughness ◽  
Surface Properties ◽  
High Efficiency ◽  
High Surface ◽  
Reduction Rate ◽  
Operating Characteristics ◽  
Emission Layer ◽  
Light Emitting ◽  
Stable Operating

We investigated the performance of single-structured light-emitting electrochemical cell (LEC) devices with Ru(bpy)3(PF6)2 polymer composite as an emission layer by controlling thickness and heat treatment. When the thickness was smaller than 120–150 nm, the device performance decreased because of the low optical properties and non-dense surface properties. On the other hand, when the thickness was over than 150 nm, the device had too high surface roughness, resulting in high-efficiency roll-off and poor device stability. With 150 nm thickness, the absorbance increased, and the surface roughness was low and dense, resulting in increased device characteristics and better stability. The heat treatment effect further improved the surface properties, thus improving the device characteristics. In particular, the external quantum efficiency (EQE) reduction rate was shallow at 100 °C, which indicates that the LEC device has stable operating characteristics. The LEC device exhibited a maximum luminance of 3532 cd/m2 and an EQE of 1.14% under 150 nm thickness and 100 °C heat treatment.

scholarly journals A Hierarchical Architecture of Functionalized Polyaniline/Manganese Dioxide Composite with Stable-Enhanced Electrochemical Performance

2021 ◽  
Vol 5 (5) ◽  
pp. 129
Author(s):  
Yapeng Wang ◽  
Yanxiang Wang ◽  
Chengjuan Wang ◽  
Yongbo Wang
Keyword(s):  
Electrochemical Performance ◽  
Manganese Dioxide ◽  
Specific Capacitance ◽  
Current Density ◽  
Electrode Materials ◽  
High Efficiency ◽  
Scanning Speed ◽  
Hierarchical Architecture ◽  
Electrochemical Window ◽  
A Current

As one of the most outstanding high-efficiency and environmentally friendly energy storage devices, the supercapacitor has received extensive attention across the world. As a member of transition metal oxides widely used in electrode materials, manganese dioxide (MnO2) has a huge development potential due to its excellent theoretical capacitance value and large electrochemical window. In this paper, MnO2 was prepared at different temperatures by a liquid phase precipitation method, and polyaniline/manganese dioxide (PANI/MnO2) composite materials were further prepared in a MnO2 suspension. MnO2 and PANI/MnO2 synthesized at a temperature of 40 °C exhibit the best electrochemical performance. The specific capacitance of the sample MnO2-40 is 254.9 F/g at a scanning speed of 5 mV/s and the specific capacitance is 241.6 F/g at a current density of 1 A/g. The specific capacitance value of the sample PANI/MnO2-40 is 323.7 F/g at a scanning speed of 5 mV/s, and the specific capacitance is 291.7 F/g at a current density of 1 A/g, and both of them are higher than the specific capacitance value of MnO2. This is because the δ-MnO2 synthesized at 40 °C has a layered structure, which has a large specific surface area and can accommodate enough electrolyte ions to participate the electrochemical reaction, thus providing sufficient specific capacitance.

Broadband, High‐Efficiency and Wide‐Incident‐Angle Anomalous Reflection in Groove Metagratings

2021 ◽  
pp. 2100149
Author(s):  
Chuanbao Liu ◽  
Jingjin He ◽  
Ji Zhou ◽  
Jianchun Xu ◽  
Ke Bi ◽  
...  
Keyword(s):  
High Efficiency ◽  
Incident Angle ◽  
Anomalous Reflection

scholarly journals The behaviour of composites, glass ionomers and compomers in erosive conditions – in vitro study

2014 ◽  
Vol 60 (5) ◽  
pp. 200-203
Author(s):  
Andreea Borş ◽  
Cristina Molnar-Varlam ◽  
Melinda Székely
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Erosive Wear ◽  
In Vitro Study ◽  
Vitro Study ◽  
Initial Surface ◽  
Dental Filling ◽  
Filling Materials ◽  
Restorative Materials

Abstract Objective: The aim of this in vitro study was to evaluate the influence of erosive conditions on the wear resistance of aesthetic direct restorative materials. Methods: Six dental filling materials were tested: two composites (Filtek Z550 and X-tra fil), two compomers (Dyract Extra and Twinky Star) and two glass ionomers (Ketac Molar and Fuji II LC). Twenty disks (10mm×2mm) of each material were prepared (n=120) and kept in artificial saliva at 37˚C for 24 hours. Specimens were cycled in acidic soft drink (Coca-Cola) 5×/day, for 5’, over 30 days. Initial surface roughness ISR (Ra-μm) and final surface roughness FSR were measured using a profilometer. The wear rate was calculated as difference of final minus the initial roughness (ΔSR=FSR-ISR). For statistical analysis t-test and one-way ANOVA test were used by GraphPad Prism version 5.03 statistical software. The level of significance was set at p<0.05. Results: The erosive wear rates (mean±SD, μm) after exposure to acidic beverage were: 0.30±0.03 (Ketac Molar), 0.28±0.04 (Fuji II LC), 0.27±0.00 (Filtek Z550), 0.23±0.01 (X-tra fil), 0.20±0.00 (Twinky Star) and 0.14±0.01 Dyract Extra, respectively. There were significant differences between the tested materials (p<0.05). Conclusions: Dental filling materials had different behaviour under the same erosive condition, however all investigated aesthetic restorative materials showed surface degradation. These findings suggest that erosive wear resistance of tooth coloured restoratives could influence their longevity in intraoral acidic conditions. Acknowledgements: The study was supported by the Internal Research Grant no. 5/30.01.2013 of the University of Medicine and Pharmacy of Tirgu Mureş.

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