• 동력기계공학회지
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• 제18권5호
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• pp.74-79
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• 2014

This article aims at investigating the effect of applied load and sliding speed on wear behavior of thermally spraryed STS316 coating. STS316 coatings were fabricated by flame spray process according to optimal parameters on steel substrates. Dry sliding wear tests were performed on STS316 coating using four different applied load as 10, 15, 20 and 25 N and four different sliding speed as 15, 30, 45 and 60 rpm. Wear behavior on worn surface was investigated using scanning electron microscope(SEM) and energy disperive X-ray spectroscopy(EDS). The dominant wear mechanism of STS316 coating under low applied load and sliding speed was oxidation on worn surface. However, under high applied load and sliding speed the principal wear mechanism was abrasion on oxidation film and damage of oxidation film.

• 펄프종이기술
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• 제39권3호
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• pp.52-59
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• 2007

This paper confirms that high solid coating can increase coating speed and reduce drying cost. Low solid coating color with the synthetic thickener and high solid coating color with the rheology modifier and with higher ratio of GCC were prepared. Coated paper was then produced with an industrial coater, varying coating speed and dryer temperature in order to keep the moisture content of the coated paper constant. Coating color concentration was able to be increased from 66% to 69% and from 68% to 71% without an adverse effect on coating color rheology. With a help of the rheology modifier, the increased ratio of GCC in high solid coating did not show harmful effects on the coated paper quality.

• 한국공작기계학회논문집
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• 제15권6호
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• pp.32-37
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• 2006

Micron size Co-alloy(T800) powder was coated on Inconel 718 by HVOF thermal spraying for the studies of the improvement of durability of high speed spindle by using Taguchi program for the parameters of spray distance, flow rates of hydrogen and oxygen and powder feed rate. The optimal coating process was determined by the studies of coating properties such as micro-structure, porosity, surface roughness and micro hardness. Friction and wear behaviors of coatings were investigated by sliding wear test at room temperature and $1000^{\circ}F(538^{\circ}C)$. At both room temperature and $538^{\circ}C$ the sliding wear debris and friction coefficients of the coating were drastically reduced compared with the surface of non-coated parent material. This shows that Co-alloy powder coating is highly recommendable for the durability improvement surface coating of high speed air-bearing spindle. At high temperature wear traces and friction coefficients of both coating and non-coating were drastically reduced compared with those of room temperature since the brittle oxides were formed easily on the surface, and the brittle oxide phases were attrited by the reciprocating sliding wear according to the complicated mixed wear mechanisms These oxide particles, partially melts and the melts play role as lubricant and reduce the wear and friction coefficient. This also shows that Co-alloy powder coating is highly recommendable far the durability improvement surface coating on the surface vulnerable to frictional heat such as high speed spindles.

• 대한기계학회논문집
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• 제19권3호
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• pp.705-712
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• 1995

The wear characteristics and wear mechanisms in TiN coating deposited on high speed steel and alloy tool steel by ion plating were investigated. Pin on V-block wear tester was used for a wear test method. The specimen was composed of three kinds of high speed steel and alloy tool steel which had different hardness by changing the heat treating condition. Three kinds of coating thickness were also applied to each specimen. Microscopic observation of worn surfaces was made by SEM. The scratch test of coating surface by the ion plating showed that critical load to break the coating interface was greater than 50N. The critical load increased with both substrate hardness and coating thickness. The wear resistance of TiN coated high speed steel became 10 times greater than that of non-coated ones. SEM observation showed that leading edge of contact was compressive and trailing edge was under maximum tensile stress and then surface cracking broke out perpendicular to sliding direction.

• Tribology and Lubricants
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• 제34권6호
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• pp.284-291
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• 2018

Ball-milling for reactant powders in advance and using an induction heating system for Ni-Al intermetallic coating process are known to enhance the reactivity of combustion synthesis. In this work, the effects of the charging weight ratio of ball to powder in ball-milling for reactant Ni-Al powders and the synthesizing temperature in induction heating on sliding wear behavior of the coating layers are investigated. Sliding wear behavior of the coating layers is examined against a tool steel using a pin-on-disc type sliding wear machine. As results, wear of the coating layer ball-milled without ball was severely worn out at the sliding speed of 2m/s, regardless of the synthesizing temperature in induction heating. However, the wear rate of the coating layers at the sliding speed was remarkably decreased with increasing the charging weight ratio of ball in ball-milling for reactant powders. This can be explained by the fact that the void in the coating layer is disappeared and the coating layer is densified by the ball-milling. The evidence showed that pitting damages were disappeared on the worn surface of ball-milled coating layer. Consequentially, the Ni-Al intermetallic coating layer could have better wear resistance at all sliding speed ranges with the ball-milling for reactant powders in advance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.308-313
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• 2006

The effect of coating time on surface properties of the TiN-coated high speed steel(SKH51) by arc ion plating is and presented in this paper. Surface roughness, micro-hardness, coated thickness, atomic distribution of TiN and adhesion strength are measured for various coating times. It has been shown that the coating time has a deep influence more than 60 minites on the micro-hardness, coated thickness, atomic distribution of Ti and adhesion strength of the SKH51 steels, but that the coating time has little influence on the surface roughness.

• Tribology and Lubricants
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• 제32권4호
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• pp.125-131
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• 2016

In recent years, thick ta-C coating has attracted considerable interest owing to its existing and potential commercial importance in applications such as automobile accessories, drills, and gears. The thickness of the ta-C coating is an important parameter in these applications. However, the biggest problems are achieving efficient coating and uniformity over a large area with high-speed deposition. Feasibility is confirmed for the ta-C coating thickness of up to 9.0 µm (coating speed: 3.0 µm/h, fixed substrate) using a single FCVA cathode. The thickness was determined using multiple coating cycles that were controlled using substrate temperature and residual stresses. In the present research, we have designed a coating system using FCVA plasma and produced enhanced thick ta-C coating. The system uses a specialized magnetic field configuration with stabilized DC arc plasma discharge during deposition. To achieve quality that is acceptable for use in automobile accessories, the magnetic field, T-type filters, and 10 pieces of a multi-cathode are used to demonstrate the deposition of the thick ta-C coating. The results of coating performance indicate that uniformity is ±7.6 , deposited area is 400 mm, and the thickness of the ta-C coating is up to 5.0 µm (coating speed: 0.3 µm/h, revolution and rotation). The hardness of the coating ranges from 30 to 59 GPa, and the adhesion strength level (HF1) ranges from 20 to 60 N, depending on the ta-C coating.

• 한국초지조사료학회지
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• 제28권1호
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• pp.35-40
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• 2008

본 실험은 표준화된 피복종자를 생산하기 위하여 피복통의 회전속도를 20, 30, 40, 45, 55, 60 rpm으로 하여 소형 피복통으로 레드클로버와 톨페스큐 종자를 피복하였다. 고형물질로는 vermiculite를 사용하였고 접착제는 polyvinyl alcohol을 사용하였다. 피복 후 통에서 회수된 단립 피복종자 무게, 서로 달라붙어 덩어리진 피복종자 무게, 피복되지 않고 회수된 미 피복물질 무게, 충격에 의한 피복층 탈락성 및 피복종자의 백립중 등을 조사하여 피복종자의 물리적 특성을 평가하였으며, 이 자료를 근거로 피복효과를 종합적으로 표현하는 피복지수를 산출하였다. 레드클로버 종자는 통의 회전속도 45 rpm에서 회수된 단립 종자 무게가 제일 높았으며(p<0.01), 덩어리진 종자 수가 적고 피복물질의 탈락율이 적었으며, 피복종자의 백립중도 가장 무거웠다. 톨페스큐 종자는 피복통 회전속도 40 rpm에서 회수된 단립 종자 무게가 제일 높았으며(p<0.01), 덩어리진 종자 수가 적고 피복물질의 탈락율이 적었으며, 피복종자의 백립중도 가장 무거웠다. 통의 회전속도별 피복지수는 레드클로버는 45 rpm에서(p<0.01), 톨페스큐는 40 rpm에서 제일 높았다(p<0.01). 피복통의 회전속도는 피복종자의 물리적 성질에 크게 영향을 미치기 때문에 종자피복 전에 종자나 피복제에 따른 피복통 회전속도의 표준화가 필수적이라 하겠다.

• 펄프종이기술
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• 제44권5호
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• pp.39-45
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• 2012

For a fundamental study for high concentration pigment coating, the effects of alkali swellable emulsion (ASE) type rheology modifier and surface adsorption emulsion (SAE) type rheology modifier on both the stability and the viscoelastic behavior of a coating color were elucidated. The coating color prepared with SAE type rheology modifier showed superior thermal and mechanical stability than that with ASE type. In the high concentration and high speed coating process, the mechanical stability of a coating color was a key parameter since both impact force and shear force were increased with the increase of coating color concentration and coating speed, respectively.

• 반도체디스플레이기술학회지
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• 제18권3호
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• pp.12-18
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• 2019

The protective double layer polymer coatings on silica optical fibers are realized by wet-on-wet liquid coating process and they play an important role in final quality of mass produced optical fibers. This numerical study aims to analyze the effects of secondary coating die design parameters by employing two dimensional axisymmetric model of coating cup and coating die geometry and computational fluid dynamics simulations which include temperature dependent viscosity of polymer coating liquids and viscous dissipation heating. Under high speed fiber drawing conditions and pressurized coating liquid supply, the effects of converging die angle are investigated in order to appreciate the change of coating liquid flow patterns such as flow recirculation zone near coating die as well as primary and secondary coating layer thicknesses. The auxiliary coating die to converging coating die is also tested and the results find that this concept is advantageous in achieving stable double layer coatings on silica glass fiber.