• Tribology and Lubricants
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• 제40권3호
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• pp.71-77
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• 2024

Hydrogen has emerged as an eco-friendly and sustainable alternative to fossil fuels. However, the utilization of hydrogen requires high-pressure compression, storage, and transportation, which poses challenges to the durability of compressor components, particularly the diaphragm. This study aims to improve the durability of 304 stainless steel diaphragms in hydrogen compressors by optimizing their surface roughness and corrosion resistance through wet etching. The specimens were prepared by immersing 304 stainless steel in a mixture of sulfuric acid and hydrogen peroxide, followed by etching in hydrochloric acid for various durations. The surface morphology, roughness, and wettability of the etched specimens were characterized using optical microscopy, surface profilometry, and water contact angle measurements. The friction and wear characteristics were evaluated using reciprocating sliding tests. The results showed that increasing the etching time led to the development of micro/nanostructures on the surface, thereby increasing surface roughness and hydrophilicity. The friction coefficient initially decreased with increasing surface roughness owing to the reduced contact area but increased during long-term wear owing to the destruction and delamination of surface protrusions. HCl-30M exhibited the lowest average friction coefficient and a balance between the surface roughness and oxide film formation, resulting in improved wear resistance. These findings highlight the importance of controlling the surface roughness and oxide film formation through etching optimization to obtain a uniform and wear-resistant surface for the enhanced durability of 304 stainless steel diaphragms in hydrogen compressors.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.170-170
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• 2013

We present a novel etching technique for 2-dimentional (2-D) hexagonal boron nitride (h-BN) by using capacitively coupled plasma (CCP) of oxygen combined with a post-treatment by de-ionized (DI) water. Oxygen CCP etching process for h-BN has been systematically studied. It is found that a passivation layer was generated to obstruct further etching while it can be easily and radically removed by DI water. An essential cleaning effect also has been observed in the etching process, organic residues are successfully removed and the surface roughness has much decreased. Considering h-BN is the most important 2-D dielectric material and its potential application for graphene to silicon-based electronic devices, such an etching method can be widely used to control the 2-D h-BN thickness and improve the surface quality.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.725-730
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• 1996

The key process in silicon surface micromachining is the selective etching of a sacrificial layer to release the silicon microstructure. The newly developed anhydrous HF/$CH_3$OH gas phase etching of TEOS (teraethylorthosilicate) sacrificial layers onto the polysilicon and the nitride substrates was employed to release the polysilicon microstructures. A residual product after TEOS etching onto the nitride substrate was observed on the surface, since a SiOxNy layer is formed on the TEOS/nitride interface. The polysilicon microstructures are stuck to the underlying substrate because SiOxNy layer does not vaporize. We found that the only sacrificial etching without any residual product and stiction is TEOS etching onto the polysilicon substrate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.667-667
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• 2013

Optimizing morphology of the front surface with three dimensional structures (3D) in solar cell is essential element for not only effectivelight harvesting but also carrier collection and separation without the cost burden in process. We designed a three-dimensionally ordered front surface with wet chemical etching. Wet chemical etching is a proper way to have three dimensional structures. The method efficiently transmits the incident light at the front surface to a Si absorber and has competitive price in manufacturing when comparing with reactive ion etching (RIE) to have three dimensional structures. This indicates that optimized front surface with three dimensional structures by wet chemical etching will bring effective light management in solar cells.

• 한국표면공학회지
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• 제32권3호
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• pp.410-415
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• 1999

The adhesion strength of sputtered copper films to Inconel substrates has been studied using the scratch test. The effects of substrate treatments before deposition such as chemical or ion bombardment etching were investigated by means of a mean critical load derived from a Weibull-like statistical analysis. It was found that the mean critical load was very weak unless the amorphous layer produced by mechanical polishing on the substrate surface was eliminated. Chemical etching in a nitric-hydrochloric acid bath was shown to have practically no effect on the enhancement of the adhesion. In contrast, the addition in this bath of nickel and copper sulphates allowed removal of the amorphous layer and an increase in the values of the mean critical load. However, it was observed that excessive chemical etching could cancel out the mean critical load enhancement. The results obtained in the case of ion bombardment etching pretreatments could be far higher than those obtained with chemical etching. Moreover, for a sufficiently long period of ion bombardment etching, the adhesion strength was so high that it was impossible to observe evidence of an adhesion failure.

• 전기전자학회논문지
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• 제25권1호
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• pp.128-132
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• 2021

본 논문에서는 표면 Texturing 방법 중 습식 에칭법을 이용하여 태양전지에 사용되는 전극의 표면을 거칠게 처리하였고, 표면 처리 후 TiO2 산화물 반도체를 사용한 염료 감응 태양전지를 제작하였다. 표면 처리된 전극을 에칭 시간에 따른 분광특성을 측정 분석하였으며, 에칭 시간에 따라 제작한 TiO2 염료 감응 태양전지의 전기적 특성을 평가함으로써 표면 처리에 따른 태양전지의 효율 향상에 관한 연구를 진행하였다. 결과적으로 전극 표면을 10분간 에칭 처리한 태양전지의 경우 기존 효율과 비교하였을 때, 약 27.46[%] 개선됨을 확인할 수 있었다.

• 대한치과기공학회지
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• 제43권4호
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• pp.160-167
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• 2021

Purpose: In this study, when the etching treatment method, which is a chemical surface treatment method, is applied to colored zirconia, the shear bond strength between the veneering ceramic material and colored zirconia is compared with that without surface treatment, and the fracture type is observed to evaluate the etching treatment effect of colored zirconia. Methods: Experiments were conducted after dividing the study sample into two groups, which are the zirconia control group without surface treatment using colored zirconia blocks (without etching zirconia, NZC group) and the zirconia group treated with a commercially available etching solution (etching liquid zirconia, EZC group). Results: The mean shear bond strength of the NZC group was 20.31±2.32 Mpa, and that of the EZC group was 25.95±2.34 Mpa, and the difference between these two values was statistically significant (p<0.05). Further, the surface roughness Ra value was higher in the EZC group than in the NZC group. In the fracture pattern, cohesive fractures were dominant, and adhesive fractures and cohesive fractures were mixed. Conclusion: The bond strength was significantly higher in the group treated with colored zirconia. The fracture pattern was mostly cohesive failure in the group not treated with etching and changed to mixed failure as the etching treatment progressed.

• Journal of Electrical Engineering and information Science
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• 제2권5호
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• pp.108-113
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• 1997

In this paper, the optimum condition of (110) Si etching with the potassium hydroxide(KOH) etchant is presented. Although several researches on (110) Si anisotropic etching have been studied, there has been lack of effects of mask quality and etching conditions on the selectivity and the roughness o the etched surface. Three kinds of masks (film, emulsion and E-beam mask) were used in order to verify the effect of etching properties. Anisotropic bulk etching depends on the crystalline orientation and the concentration and temperature of the etchant. In order to investigate the effect of etching conditions on selectivity and the roughness of the etched surface, the concentration of the etchant was varied from 35 to 45 per cent in weight with increments by 5 per cent and the temperature was changed from 70 to 90$^{\circ}C$ with increments by 10$^{\circ}C$. The combination of the temperature of 70$^{\circ}C$ and the concentration of 40wt.% was found to be the optimum etching condition for high selectivity. Etched surfaces show minimum surfaces show minimum surface roughness at a temperature of 80$^{\circ}C$ and a concentation of 40wt.%. Comb structures with various comb widths were fabricated and the lengths of the combs wree measured with several etching time durations. A micro comb structure 525$\mu\textrm{m}$ high was fabricated for MEMS application.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.38.1-38.1
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• 2009

Plasma etching is an essential process for electronic device industries and the particulate contamination during plasma etching has been interested as a big issue for the yield of productivity. The oxynitride glasses have a merit to prevent particulate contamination due to their amorphous structure and plasma etching resistance. The YSiAlON oxynitride glasses with increasing nitrogen content were manufactured. Each oxynitride glasses were fluorine-plasma etched and their plasma etching rate and surface roughness were compared with reference materials such as sapphire, alumina and quartz. The reinforcement mechanism of plasma etching resistance of the YSiAlON glasses studied by depth profiling at plasma etched surface using electron spectroscopy for chemical analysis. The plasma etching rate decreased with nitrogen content and there was no selective etching at the plasma etched surface of the oxynitride glasses. The concentration of silicon was very low due to the generation of SiF4 very volatile byproduct and the concentration of aluminum and yttrium was relatively constant. The elimination of silicon atoms during plasma etching was reduced with increasing nitrogen content because the content of the nitrogen was constant. And besides, the concentration of oxygen was very low on the plasma etched surface. From the study, the plasma etching resistance of the glasses may be improved by the generation of nitrogen related structural groups and those are proved by chemical composition analysis at plasma etched surface of the YSiAlON oxynitride glasses.

• 한국표면공학회지
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• 제49권3호
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• pp.231-237
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• 2016

This article reports a new chemical bath for preparing a mirror-like surface of AZ31 Mg alloy. In order to find an appropriate chemical polishing solution, four different acidic solutions of sulphuric acid, nitric acid, acetic acid and a specially designed mixture of nitric acid and acetic acid were investigated in view of the changes in surface appearance, roughness and dissolution rate of AZ31 Mg alloy. The surface scales on AZ31 Mg alloy were readily removed by all the acidic solutions, but a reflective surface was produced only by etching in the specially designed solution, and only after a specific etching time. The surface roughness increased with etching time in sulphuric acid, nitric acid, and acetic acid, but it lowered after a specific etching time in the specially designed mixture of nitric acid and acetic acid. Dissolution rate of the alloy in the specially designed mixture of nitric acid and acetic acid appeared to be more than twice than that in separate nitric acid or acetic acid. In this work, we recommend the mirror-like surface of AZ31 Mg alloy obtained by polishing for an optimum time in a mixture of nitric acid and acetic acid for following surface finishings, chemical conversion coating, electroplating, electrophoretic painting and anodizing treatment.