scholarly journals Polymer Microchannel and Micromold Surface Polishing for Rapid, Low-Quantity Polydimethylsiloxane and Thermoplastic Microfluidic Device Fabrication

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2574
Author(s):  
Chia-Wen Tsao ◽  
Zheng-Kun Wu
Keyword(s):  
Surface Roughness ◽  
Microfluidic Device ◽  
Surface Defects ◽  
Device Fabrication ◽  
Mechanical Polishing ◽  
Numerical Control ◽  
Chemical Polishing ◽  
Surface Polishing ◽  
Mechanical Methods ◽  
Reduced Surface

Polymer-based micromolding has been proposed as an alternative to SU-8 micromolding for microfluidic chip fabrication. However, surface defects such as milling marks may result in rough microchannels and micromolds, limiting microfluidic device performance. Therefore, we use chemical and mechanical methods for polishing polymer microchannels and micromolds. In addition, we evaluated their performance in terms of removing the machining (milling) marks on polymer microchannel and micromold surfaces. For chemical polishing, we use solvent evaporation to polish the sample surfaces. For mechanical polishing, wool felt polishing bits with an abrasive agent were employed to polish the sample surfaces. Chemical polishing reduced surface roughness from 0.38 μm (0 min, after milling) to 0.13 μm after 6 min of evaporation time. Mechanical polishing reduced surface roughness from 0.38 to 0.165 μm (optimal pressing length: 0.3 mm). As polishing causes abrasion, we evaluated sample geometry loss after polishing. Mechanically and chemically polished micromolds had optimal micromold distortion percentages of 1.01% ± 0.76% and 1.10% ± 0.80%, respectively. Compared to chemical polishing, mechanical polishing could better maintain the geometric integrity since it is locally polished by computer numerical control (CNC) miller. Using these surface polishing methods with optimized parameters, polymer micromolds and microchannels can be rapidly produced for polydimethylsiloxane (PDMS) casting and thermoplastic hot embossing. In addition, low-quantity (15 times) polymer microchannel replication is demonstrated in this paper.

scholarly journals Singularities of Polishing Substrates GaAs by Chemo-Dynamical and Non-Contact Chemo-Mechanical Methods

2015 ◽  
Vol 16 (3) ◽  
pp. 560-564
Author(s):  
G.A. Pashchenko ◽  
M.J. Kravetsky ◽  
O.V. Fomin
Keyword(s):  
Surface Morphology ◽  
Substrate Surface ◽  
Etching Rate ◽  
Comparative Investigation ◽  
Mechanical Polishing ◽  
Chemical Polishing ◽  
Line Defect ◽  
Surface Etching ◽  
Gaas Substrates ◽  
Mechanical Methods

The comparative investigation of two chemical polishing methods as applied to GaAs substrates is carried out. In both cases the equal etchant Br2+HBr was used. The comparison of etching rates and of surface morphology is carried out. It is revealed that numerous etching pits arise during chemo-dynamical polishing of GaAs (111) В samples but not arise during non-contact chemo-mechanical polishing of the same samples. Besides, last method allows to raise appreciably etching rate as compared with the method of chemo-dynamical polishing. That is, the same etchant behaves as selective or polishing depending on method of polishing. On the basis of worked out model of substrate surface etching near line defect the simulating of etching pit arising is carried out. The results of simulation are consistent with the idea that there are two competing ways of GaAs etching in the etchant Br2+HBr .

scholarly journals Experimental Investigation on the Wear and Damage Behaviors of Machined Wheel-Rail Materials under Dry Sliding Conditions

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 540
Author(s):  
Peijie Liu ◽  
Yanming Quan ◽  
Junjie Wan ◽  
Lang Yu
Keyword(s):  
Surface Roughness ◽  
Surface Defects ◽  
Numerical Control ◽  
Wear Loss ◽  
Wear Property ◽  
Initial Surface ◽  
Surface Microhardness ◽  
Machined Surface ◽  
Dry Conditions ◽  
Grinding Machine

Rail grinding and wheel turning can effectively remove surface defects and unevenness, which is a crucial process for the safe and smooth operation of trains. Machined surface integrity of wheel/rail materials significantly influences their tribological property. In this study, firstly, the rail blocks were ground via a cylindrical grinding machine, and the wheel rings were turned by a computer numerical control (CNC) lathe with varied parameters. Then, the sliding wear and damage characteristics of the machined wheel/rail samples under dry conditions were studied by virtue of a block-on-ring tribometer. The results show that the surface microhardness of the ground rail blocks is larger than that of wheel rings, while the surface roughness and the thickness of the subsurface plastic deformation layer (SPDL) of rail blocks are much smaller than those of wheel rings. After sliding, the surface microhardness of wheel/rail samples increases remarkably. The thickness of the SPDL, the wear loss, and the increase degree of surface microhardness of rail blocks are larger than those of wheel rings. Surface microhardness, roughness and the SPDL of the machined wheel/rail samples impose a combined influence on the anti-wear property, and the tribological pair with proper initial surface roughness and microhardness engenders the smallest amount of total wear loss.

Variation of Surface Roughness of Ti3SiC2 Disk during Polishing in Water and Alcohols

2014 ◽  
Vol 602-603 ◽  
pp. 511-514
Author(s):  
Wan Xiu Hai ◽  
Jun Ling Zeng ◽  
Jun Hu Meng ◽  
Jin Jun Lu
Keyword(s):  
Surface Roughness ◽  
Hot Pressing ◽  
Mechanical Polishing ◽  
Polishing Process ◽  
Surface Polishing ◽  
3D Surface ◽  
Diamond Particles ◽  
Abrasive Disk ◽  
Reactive Hot Pressing

The surface polishing of Ti3SiC2 disk in fluids (water, ethanol, propanol, glycol, and glycerol) is conducted on a Buehler grinder/polisher and evaluated using surface roughness. Using Buehler automatic grinder/polisher, the Ti3SiC2 disks are grinded and polished in the as-mentioned lubricants by grinding disk of diamond with sizes of 45 μm to 3 μm. The surface roughnesses of Ti3SiC2 disks at each stage are measured by 3D surface profiler. The results show that the lowest surface roughness (Ra) of Ti3SiC2 disk obtained by mechanical polishing is 0.04 μm. The optimum polishing process of Ti3SiC2 disk is as follows: using water as lubricant, at a load of 5 N, for steps 1 to 4, the Ti3SiC2 and grinding disk rotates comparatively and the sizes of diamond particles on the abrasive disk are 45, 15, 9, and 3 μm, respectively. For step 5, the abrasive disk is woven cloth with no diamond particles. The duration of each step is 5 min. Using the same polishing process, the surface roughness of Ti3SiC2 disk by direct hot pressing is lower than that by in situ reactive hot pressing. Using the same polishing process but different lubricants, the surface roughness of the Ti3SiC2 disks increases in the order of water, ethanol, propanol, glycol, and glycerol. In water, the surface roughness of Ti3SiC2 disk decreases with the increasing quantity of water and polishing duration.

scholarly journals A Review on Precision Polishing Technology of Single-Crystal SiC

Crystals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 101
Author(s):  
Gaoling Ma ◽  
Shujuan Li ◽  
Feilong Liu ◽  
Chen Zhang ◽  
Zhen Jia ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Single Crystal ◽  
Chemical Mechanical Polishing ◽  
Surface Defects ◽  
Waste Treatment ◽  
Removal Rate ◽  
Research Direction ◽  
Mechanical Polishing ◽  
Neutral Salt ◽  
Single Crystal Sic

Single-crystal SiC is a typical third-generation semiconductor power-device material because of its excellent electronic and thermal properties. An ultrasmooth surface with atomic surface roughness that is scratch free and subsurface damage (SSD) free is indispensable before its application. As the last process to reduce the surface roughness and remove surface defects, precision polishing of single-crystal SiC is essential. In this paper, precision polishing technologies for 4H-SiC and 6H-SiC, which are the most commonly used polytypes of single-crystal SiC, such as chemical mechanical polishing (CMP), photocatalytic chemical mechanical polishing (PCMP), plasma-assisted polishing (PAP), electrochemical mechanical polishing (ECMP), and catalyst-referred etching (CARE), were reviewed and compared with emphasis on the experimental setup, polishing mechanism, material removal rate (MRR), and surface roughness. An atomically smooth surface without SSD can be obtained by CMP, PCMP, PAP, and CARE for single-crystal SiC. However, their MRRs are meager, and the waste treatment after CMP is difficult and expensive. Moreover, PAP’s operation is poor due to the complex polishing system, plasma generation, and irradiation devices. A high MRR can be achieved by ECMP. In addition, it is an environmentally friendly precision polishing process for single-crystal SiC since the neutral salt solution is generally used as the electrolyte in ECMP. However, the formation of the egglike protrusions at the oxide/SiC interface during anodic oxidation would lead to a bigger surface roughness after ECMP than that after PAP is processed. The HF solution used in CARE was toxic, and Pt was particularly expensive. Ultrasonic vibration-assisted single-crystal SiC polishing and electrolyte plasma polishing (EPP) were discussed; furthermore, the research direction of further improving the surface quality and MRR of single-crystal SiC was prospected.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

Reduced Surface Roughness of P3HT: PCBM Thin Films with Different Ratios by Electrospray Deposition Methods

2013 ◽  
Vol E96.C (3) ◽  
pp. 362-364
Author(s):  
Takeshi FUKUDA ◽  
Kenji TAKAGI ◽  
Norihiko KAMATA ◽  
Jungmyoung JU ◽  
Yutaka YAMAGATA
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Electrospray Deposition ◽  
Reduced Surface

OPTIMISATION OF SAND CASTING PROCESS FOR IMPELLER USING TAGUCHI METHODOLOGY

2020 ◽  
Vol XVII (2) ◽  
pp. 23-33
Author(s):  
Faisal Hafeez ◽  
Salman Hussain ◽  
Wasim Ahmad ◽  
Mirza Jahanzaib
Keyword(s):  
Surface Roughness ◽  
Surface Defects ◽  
A356 Alloy ◽  
Casting Process ◽  
Sand Casting ◽  
Gate Length ◽  
Taguchi Methodology ◽  
Confirmatory Tests ◽  
Binder Ratio ◽  
Response Measures

This paper presents the study to investigate the effects of binder ratio, in-gate length and pouring height on hardness, surface roughness and casting defects of sand casting process. Taguchi methodology with L9 orthogonal array was employed to design the experimentation. Sand casting of six blade impeller using A356 alloy was performed and empirical models for all the above response measures were formulated. Confirmatory tests and analysis of variance results confirmed the accuracy of the model. Binder ratio was found to be the most significant parameter affecting casting surface defects and surface roughness. This was followed by pouring height and in-gate length.

scholarly journals Investigation into the Effect of Cutting Conditions in Turning on the Surface Properties of Filament Winding GFRP Pipe Rings

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 16
Author(s):  
Gabriel Mansour ◽  
Panagiotis Kyratsis ◽  
Apostolos Korlos ◽  
Dimitrios Tzetzis
Keyword(s):  
Surface Roughness ◽  
Glass Fiber ◽  
Process Parameters ◽  
Filament Winding ◽  
Numerical Control ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

There are numerous engineering applications where Glass Fiber Reinforced Polymer (GFRP) composite tubes are utilized, such as desalination plants, power transmission systems, and paper mill, as well as marine, industries. Some type of machining is required for those various applications either for joining or fitting procedures. Machining of GFRP has certain difficulties that may damage the tube itself because of fiber delamination and pull out, as well as matrix deboning. Additionally, short machining tool life may be encountered while the formation of powder like chips maybe relatively hazardous. The present paper investigates the effect of process parameters for surface roughness of glass fiber-reinforced polymer composite pipes manufactured using the filament winding process. Experiments were conducted based on the high-speed turning Computer Numerical Control (CNC) machine using Poly-Crystalline Diamond (PCD) tool. The process parameters considered were cutting speed, feed, and depth of cut. Mathematical models for the surface roughness were developed based on the experimental results, and Analysis of Variance (ANOVA) has been performed with a confidence level of 95% for validation of the models.

Analysis of tape surface roughness by magnetic recording and mechanical methods

2000 ◽  
Vol 36 (1) ◽  
pp. 189-194 ◽  
Author(s):  
Peng Luo ◽  
Sanwu Tan ◽  
H.N. Bertram ◽  
G. Hughes ◽  
F.E. Talke
Keyword(s):  
Surface Roughness ◽  
Magnetic Recording ◽  
Mechanical Methods
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