• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.171-172
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• 2015

$Ni-W-Si_3N_4$ alloy composite coatings were prepared by pulse electro-deposition method using nickel sulfate bath with different contents of tungsten source, $Na_2WO_4.2H_2O$, and dispersed $Si_3N_4$ nano-particles. The structure and micro-structure of coatings was separately analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results indicated that nano $Si_3N_4$ and W content in alloy had remarkable effect on micro-structure, micro-hardness and scratch resistant properties. Tungsten content in Ni-W and $Ni-W-Si_3N_4$ alloy ranged from 7 to 14 at.%. Scratch test results suggest that as compared to Ni-W only, $Ni-W-Si_3N_4$ prepared from Ni/W molar ratio of 1:1.5 dispersed with 20 g/L $Si_3N_4$ has shown the best result among different samples.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.232-233
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• 2006

In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

• 한국표면공학회지
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• 제54권5호
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• pp.285-293
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• 2021

High-entropy TiAlCrSiN nano-composite coating was designed to improve mold life for high temperature liquid molding. Alloy design, powder fabrication and single alloying target fabrication for the high-entropy nano-composite coating were carried out. Using the single alloying target, an arc ion plating method was applied to prepare a TiAlCrSiN nano-composite coating had a 30 nm TiAlCrSiN layers are deposited layer by layer, and form about 4 ㎛-thickness of multi-layered coating. TiAlCrSiN nano-composite coating had a high hardness of about 39.9 GPa and a low coefficient of friction of less than about 0.47 in a dry environment. In addition, there was no change in the structure of the coating after the dissolution loss test in the molten metal at a temperature of about 1100 degrees.

• 소성∙가공
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• 제28권4호
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• pp.219-225
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• 2019

This study deals with the effect of austempering temperature and time on the microstructures and mechanical properties of high-carbon nano-bainite steels. Although all the austempered specimens are mainly composed of bainite, martensite, and retained austenite, the specimens which are austempered at lower temperatures contain finer packets of bainite. As the duration for austempering increases, bainite packets are clearly seen due to larger amount of carbon atoms being redistributes into bainite and retained austenite during bainite transformation. As the austempering time increases, the hardness of the specimens gradually decreases as a result of lower martensite volume fraction, and later increases again due to the formation of nano-bainite structure. The Charpy impact test results indicate that the impact toughness of the austempered specimens can be improved if the formation of nano-bainite structure and the transformation induced plasticity effect of retained austenite are optimized at higher austempering temperature.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.132.1-132.1
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• 2005

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.925-926
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• 2009

• 한국생산제조학회지
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• 제21권5호
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• pp.848-854
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• 2012

SCM420 steel cutting gear to improve the durability is quenched. When quenching, increases surface hardness, a change of the physical properties and machinability or fall. This study, using a solid carbide hobs skiving hobbing gear cutting finishing. And cutting tool solid carbide TiAlN coating hove when TiAlN coating on the surface of multi-con polishing hob conducted aero lap nano polishing for each cutting. Experimental results conducted aero lap nano coating on the surface polishing tool machinability was excellent. And aero lap nano polishing tool results were reduced 2.5 times the tool wear compared to TiAlN coated tools. Excellent results were 1.42 times longer tool life.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.155-155
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• 2014

The oxide film was formed in hydrogen induced cracking (HIC) environment by potentio-dynamic method. Corrosion potentials and rates of the X-65 and X-80 line pipe steels were -0.3495 $V_{SHE}$, $2.833{\times}10^{-3}A/cm^2$ and 0.2716 $V_{SHE}$ and $2.533{\times}10^{-3}A/cm^2$, respectively. Surface composition analysis of the oxide film contained sulfur. Thermodynamic analysis of the HIC solution chemistry suggested that the oxide phase consisted of iron sulfate. Dynamic nano-indentation method applied to determine nano-hardnesses of the oxide film and base metal hardness.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.187-187
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• 2014

In this study, we investigated mechanical properties and surface characteristics of Ti-25Ta-xHf alloys. The samples were manufactured for composition of Ti-25Ta-xHf(x=0 to 15 wt. %) alloys. Each alloy was melted twenty times in an arc-melting vacuum furnace. The microstructural phases and phase transformation of Ti-25Ta-xHf alloys were identified with the aid of an XRF, XRD and DSC. And mechanical properties were investigated using Vickers hardness, nanoindentation, and tensile test.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.108-111
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• 2007

It's important to measure quantitative properties about thermal-nano variation conduct of polymer for producing high quality components using NIL process. NanoScale indents can be used ad cells for molecular electronics and drug deliver, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, it's to evaluate mechanical characteristic of polymer such as PMMA and PC at high temperature for manufacture of nano/micro size of polymer using indenter at high temperature. At high temperature mechanical properties of polymer have extreme variation. Because heating the polymer, it becomes softer than room temperature. In this case it is especially important to study for mechanical properties of polymer at high temperature.