• 한국결정학회지
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• 제6권1호
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• pp.14-26
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• 1995

Hot Filament CVD법에 의해 증착된 다이아몬드 박막의 기판온도와 증착시간 변화에 따르는 표면형상 변화를 관찰함으로써 그 증착기구를 규명하고자 하였다. 기판온도가 낮을 경우에는 비정질 탄소 및 DLC(diamond like carbon)가 증착되고 기판온도가 증가함에 따라 사가형의 (100)명으로 구성된 입자를 가지는 다이아몬드 박막이 증착되었으며 매우 높은 기판온도에서는 (100)명과 (111)명으로 이루어진 결정외형을 가지는 입자들로 구성되는 다이아몬드 박막이 증착되었다. 다이아몬드 박막의 (100) 우선배향성은 증착시의 비교적 높은 과포화도에 기인하는 것으로 생각되며, 이러한 (100) 우선배향성을 가지는 박막은 결정면내에 twin을 함유하지 않으므로 단결정박막으로의 성장가능성이 크다. 기판온도가 증가해도 다이아몬드 박막의 입자크기는 증가하지 않았으며 시간에 따른 증가양상도 온도에 관계없이 비슷한 경향을 보였다. 그러나 필라멘트 온도가 일정할 때 다이아몬드 박막의 핵 밀도는 기판온도가 높을수록 증가하였으며 시간에 따른 증가폭도 기판온도가 높을수록 더 크게 나타났다.

• 한국정밀공학회지
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• 제14권3호
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• pp.21-27
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• 1997

This paper aims to clarify the effects of grinding conditions in form grinding of Sr-ferrite with the electro-plated diamond wheel. The main conclusions obtained were as follows. (1) The flexural strength and surface roughness of ferrite became the best at the peripheral wheel speed of 1700 m/min. (2) In the case of the depth of cut larger than 0.4mm, crack layers is induced in the ground surface, and the fracture type of chips exhibits slight ductile mode in the depth of cut smaller than 0.2mm. (3) Whe the depth of cut exceeds 0.6mm, the wheel life becomes extremely severe due to the large chipping and brack- age in the diamond grains. However, at the depth of cut .leq. 0.05mm, the diamond grain shows abrasive wear. (4) The decrease of flexural strength and the increase of surface roughness is in proportion to the increase of the feed rate. (5) Most effective nozzle setting angles with various delivery conditions of the grinding fluid, such as nozzle position .PHI. , flow rate Q, etc., were made clear.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.29-33
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• 1996

This paper aims to clatify the potimum grinding condition for the electroplated diamond wheel in form grinding of Sr-ferrite. The main conclusions obtained were as follows. (1) The flexural strength and surface roughness of ferrite became the highest at the peripheral wheel speed of 1700m/min. (2) In the case of depth of cut larger than 0.4mm, crack layers is induced in the ground surface, the fracture type of chips exhibits slight ductile mode in the depth of cut smaller than 0.2mm. (3) When the depth of cut exceed 0.6mm, the tool life becomes extermely short due to large chipping and brackage. However, at the depth of cut .geq. 0.05mm, the diamond grain shows abrasive wear. (4) The flexural strength and surface roughness increases in proportion to the feed rate.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.67-74
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• 1998

Two kinds of polished and unpolished freestanding films prepared by DC plasma CVD method were impacted by SiC particles to understand erosion mechanism. Erosion damage caused by solid impact was characterized by surface profilometer, scanning electron microscopy and Raman spectroscopy. Gradually decrease of surface roughness and sharp reduction of crystallinity for unpolished CVD films were observed with increasing erosion time. It was found that smaller grains of the diamond were removed in early stage of erosion process and larger grains were eroded with further impingement. By introduction of re-growth method on polished diamond, further understanding of erosion mechanism was achieved. Most of the surface fractures were initiated at the grain boundary.

• 한국기계가공학회지
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• 제19권3호
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• pp.105-110
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• 2020

Alumina, a typical ceramic material used for semiconductors and display parts, is the subject of research and development efforts for mineral material processing. Alumina is extremely difficult to process since it is brittleness to either fine ceramics material. We have studied the shape of diamond particles and their use in machinability for alumina processing. Our study was carried out under various processing conditions, including cutting speed, table speed, and the surface roughness of the work piece. We also analyzed the wear characteristics of the tool by total cutting.

• The Korean Journal of Ceramics
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• 제3권1호
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• pp.1-4
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• 1997

Diamond film (24$\mu\textrm{m}$) were prepared by Microwave Plasma Chemical Vapor Deposition method from a reactive CO/H$_2$ mixtures. Micro-Raman spectroscopy and micro-cathodoluminescence study were carried out along the crosssection and correlated to SEM observation. CL image of cross-section was also investigated. Peak position, FWHM of Raman spectrum were determined using Lorentzing fit. The stress in this sample is 0.4~0.7 GPa compressive stress, and along the distance the compressive stress reduced. The Raman peak broadening is dominated by phonon life time reduction at grain boundaries and defect sites. Defects and impurities were mainly present inside the film, not at Silicon/Diamond interface.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.194-194
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• 1999

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.58-58
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• 1999

The diamond films which can be applied to SOD (silicon-on-diamond) structure were deposited on Si(100) substrate using CO/H2 CH4/H2 source gases by microwave plasma chemical vapor deposition(MPCVD), and SOD structure have been fabricated by poly-silicon film deposited on the diamond/Si(100) structure y low pressure chemical vapor deposition(LPCVD). The phase of the diamond film, surface morpholog, and diamond/Si(100) interface were confirmed by X-ray diffraction(XRD), scanning electron microscopy(SEM), atomic force microscopy(AFM), and Raman spectroscopy. The dielectric constant, leakage current and resistivity as a function of temperature in films are investigated by C-V and I-V characteristics and four-point probe method. The high quality diamond films without amorphous carbon and non-diamond elements were formed on a Si(100), which could be obtained by CO/H2 and CH4/H2 concentration ratio of 15.3% and 1.5%, respectively. The (111) plane of diamond films was preferentially grown on the Si(100) substrate. The grain size of the films deposited by CO/H2 are gradually increased from 26nm to 36 nm as deposition times increased. The well developed cubo-octahedron 100 structure nd triangle shape 111 are mixed together and make smooth and even film surface. The surface roughness of the diamond films deposited by under the condition of CO/H2 and CH4/H2 concentration ratio of 15.3% and 1.5% were 1.86nm and 3.7 nm, respectively, and the diamond/Si(100) interface was uniform resistivity of the films deposited by CO/H2 concentration ratio of 15.3% are obtained 5.3, 1$\times$10-9 A/cm, 1 MV/cm2, and 7.2$\times$106 $\Omega$cm, respectively. In the case of the films deposited by CH4/H2 resistivity are 5.8, 1$\times$10-9 A/cm, 1 MV/cm, and 8.5$\times$106 $\Omega$cm, respectively. In this study, it is known that the diamond films deposited by using CO/H2 gas mixture as a carbon source are better thane these of CH4/H2 one.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.9-16
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• 2003

In this study, the decision of dressing time for diamond wheel was analyzed by observing with acoustic emission signals and surface roughness, and also obtained the machining characteristics by weibull distribution plot for the values of bending strength. From the experimental study, it was possible to predict the time of re-dressing for the diamond grinding wheel with the analysis of acoustic emission signals and surface roughness values, and following conclusions were obtained. The root-mem-square values of acoustic emission signals were obtained low as the increased of table speed for different abrasive grain size. This is caused by the lack of grinding power which is not able to get rid of all real grinding mass of depth as the table speed is increased. The values of bending strength for ground $Si_3 N_4$ specimens were decreased for gain size of #400 than that of #60, but it was found that the surface roughness values for gain size of #60 were better than that of #400. As compared the shape parameter of weibull distribution plot for the values of bending strength, it was found that the reliability of bending strength for grain size of #60 increased than that of #400.

• 한국세라믹학회지
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• 제21권1호
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• pp.27-32
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• 1984

During the last decade there have been many studies on the new ceramics especially engineering ceramics. Sintered silicon carbide is one of the main materials in engineering ceramics. This study shows the effects of surface treatment and microstructure especially the abnormal grain growth on the strength of sintered SiC. Surface of sintered SiC and treated with 400, 800 and 1200 grit diamond wheel. Grain growth is introduced by increasing the sintering times at 205$0^{\circ}C$. The $\beta$longrightarrow$\alpha$ transformation occurs during the sintering of $\beta$-starting materials and is often accompanied by abnormal grain growth. The overall strength distribution are estimated using the Weibull statistics. The results show that the strength of sintered SiC is limited by extrinsic surface flaws in normal-sintered specimens. And it is sound that the finer the surface finishing and the grain size the higher the strength results. But the strength of abnormal sintering specimens is limited by the abnormally-grown large tabular grains. The Weibull modulus increases with the decreasing grain size and the decreasing grit size of grinding.