• 한국정밀공학회지
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• 제25권12호
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• pp.47-54
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• 2008

Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

• 한국진공학회지
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• 제8권2호
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• pp.158-158
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• 1999

ME-ARE법에 의해 합성된 c-BN 박막의 초기성장층 및 이의 계면구조를 개선하고 밀착력을 향상 시키고자 후처리로서 질소이온을 주입$(PSII-N^+)$하였다. 이온 주입량이 c-BN 박막의 미세구조, 계면구조에 미치는 영향에 대하여 조사하였으며 이와 함께 박막의 경도 및 박리특성에 미치는 효과를 고찰하였다. 질소이온 주입시 약 $5.0{\times}10_15atoms/cm^2$ 이상의 주입량에서부터 IR스펙트럼의 변화가 보이기 시작하였으며 $5.0{\times}10_16atoms/cm^2$ 이상의 주입량 이상에서부터 급격한 c-BN$c-BN{\to}h-BN$상전환이 일어났다. HRTEM관찰 결과, 이온주입에 의해 $sp^2$ 결합을 하고 있는 취약한 초기성장층의 결정구조 개선을 확인할 수 있었으며 이온주입된 박막의 경도 및 박리거동을 비교하여 이온주입 및 주입량에 따른 경도 및 박리 상관관계를 설명하였다.

• 한국세라믹학회지
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• 제26권2호
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• pp.179-186
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• 1989

The preparation of the fine BN powders by ammonia-nitridation of ammonia-decaborane derivate was attempted at temperature between 300 to 150$0^{\circ}C$. The formation mechanism of BN was examined and the resulant BN powder was characterized by means of IR, XRD, SEM and PSA method. In the nitridation below 80$0^{\circ}C$ bonding materials were identified with mainly BH and NH but above 80$0^{\circ}C$ with BN by IR spectra and X-ray patterns. Crystalite size, lattice constant and particle size distribution of hexagonal BN prepared at 1, 50$0^{\circ}C$ were La=470$\AA$, Lc=180$\AA$, a=2.5062$\pm$1$\AA$, c=6.8285$\pm$2$\AA$ and 2.0-5.4${\mu}{\textrm}{m}$, respectively.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2002년도 춘계학술발표회 초록집
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• pp.12-12
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• 2002

hexagonal Boron Nitride (hBN), rhombohedral Boron Nitride (rBN)과 고밀도의 wurzitic Boron N Nitride (wBN), cubic Boron Nitride (cBN) 등의 다양한 상을 갖는 Boron nitride는 그 결정구조에 따라 저밀도, 고밀도 박막으로 분류되며 이중 hBN과 rBN은 층간 결합이 약한 $sp^2$ 결합특성을 가지고, wBN 과 cBN은 강한 $sp^3$ 결합특성을 가지고 있다. 현재까지 $sp^3$결합을 갖는 BN의 우수한 특성을 응용하기 위한 수 많은 연구들이 있어왔다. 특히 cBN은 다이아몬드에 버금가는 높은 경도뿐만 아니라 높은 화 학적 안정성 및 열전도성 등 우수한 물리화학적 특성을 가지고 있어 마찰.마모, 전자, 광학 등의 여러 분야에서의 산업적 응용이 크게 기대되고 있다. 그러나 이와 같이 BN박막의 기계적 물성과 관련한 연 구는 많이 진행되어 왔으나 전기.전자적, 광학적 특성에 관한 연구는 미비한 실정이다. 따라서 본 연구에서는 BN박막의 또 다른 웅용 분야를 탐색하고자 ME - ARE (Magnetically Enhanced A Activated Reactive Evaporation)법 에 의 해 합성 된 BN박막의 광학적 특성 에 관하여 조사하였다. BN박 막합성 은 전자총에 의 해 증발된 보론과 질소.아르곤 플라즈마의 활성 화반응증착(Activated Reactive E Evaporation)에 의해 이루어졌다. 기존의 ARE장치와 달리 열음극(hot cathode)과 양극(anode)사이에 평 행자기장을 부가하여 플라즈마의 증대시켜 반웅효율을 높였다. 합성실험용 모재로는 기본적인 특성 분 석을 위해 p-type으로 도핑된 (100) Si웨이퍼를 $30{\times}40mm$크기로 절단 후, 10%로 희석된 완충불산용액 에 10분간 침적하여 표면의 산화층을 제거한 후 사용하였으며, 광학특성 분석을 위해 $30{\times}30mm$의 glass를 아세톤으로 탈지.세척한 후 사용하였다. 박막합성실험에서 BN의 광학적 특성에 미치는 공정변수의 영향을 파악하기 위하여, 기판바이어스 전압, discharge 전류, $Ar/N_2$가스 유량비 등을 달리하여 증착하였다. 증착된 박막은 FTIR 분석을 통하 여 결정성을 확인하였으며, AFM 분석을 통하여 코팅층의 두께를 측정하였고, UV - VIS spectormeter를 이용하여 투광특성을 평가하였다.

• 한국결정성장학회지
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• 제24권3호
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• pp.127-132
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• 2014

$Y_2O_3$-BN 세라믹 복합체를 제작하기 위해서, 분말 입도 $3{\sim}10{\mu}m$인 $Y_2O_3$ 분말을 분산한 슬러리에 pH 조절제인 NaOH를 첨가하였으며 결합제로는 PVA, 가소제로는 PEG를, BN 분말과 혼합하고, 분무건조(spray drying)공정을 거쳐 $Y_2O_3$ 혼합 분말을 제조하였다. ${\O}14mm$ 크기의 $Y_2O_3$-BN 시편을 성형하고, $1550^{\circ}C$ 및 $1600^{\circ}C$에서 소결하여 $Y_2O_3$-BN 복합체를 제작하였다. BN 투입량과 소결온도의 변수에 따른 미세구조, 순도, 꺽임강도, 열팽창계수, 밀도, 체적저항, 내플라즈마 특성을 조사하였다.

• The Korean Journal of Ceramics
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• 제1권3호
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• pp.155-159
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• 1995

Borosilicate, $B_2O_3$ and BN derived from liquid precursors have been tested as shielding materials for the long period of oxidation resistance of C/BN composites at $650^{\circ}C$. Borosilicate coating displayed excellent oxidation resistance and low moisture absorbance, while $B_2O_3$ and BN were less effective in elevating the oxidation resistance. The enhancement of the oxidation resistance was explained as self-healing effect by viscous flow of the borosilicate glass over Tg, resulting in the reduction of the exposed carbon fibers in a BN matrix.

• 한국표면공학회지
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• 제41권2호
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• pp.43-47
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• 2008

Cubic boron nitride(c-BN) films were deposited on tungsten carbide insert tool by microwave plasma enhanced chemical vapor deposition(MPECVD) from a gas mixture of triethyl borate$(B(C_2H_5O)_3)$, ammonia $(NH_3)$, hydrogen$(H_2)$ and argon(Ar). The qualities of deposited thin film were investigated by x-ray diffrac-tion(XRD), field emission scanning electron microscopy(FE-SEM) and micro Raman spectroscope. The surface morphologies of the synthesised BN as well as crystallinity appear to be highly dependent on the flow rate of $B(C_2H_5O)_3$ and $(NH_3)$ gases. The deposited film had more crystallized phases with 5 scem of $B(C_2H_5O)_3$ and $(NH_3)$ gases than with 2 sccm, and the phase was identified as c-BN by micro Raman spectroscope and XRD. The adhesion strength were also increased with increasing flow rates of $B(C_2H_5O)_3$ and $(NH_3)$ gases.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.33-34
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• 2007

카본과 BN의 합성조건을 제어하여 고경도 상과 저경도 상을 다층박막화하기 위하여 시편에 인가하는 바이어스 전압을 조절하여 박막을 합성하였다. 합성된 다층박막은 카본의 경우 흑연상을 많이 함유한 단일층 박막과 유사한 경도와 탄성계수를 보였으나 마찰계수는 $2{\sim}3$배 개선되었다. BN의 경우에도 2층박막화된 박막에서 FTIR분석 결과로는 50%이상의 c-BN이 합성된 것으로 나타났으며, 마모특성도 c-BN박막과 유사하였다.

• Carbon letters
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• 제12권2호
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• pp.116-119
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• 2011

C/SiC composites were prepared by boron nitride (BN)-assisted liquid silicon infiltration (LSI), and their anti-oxidation and mechanical properties were investigated. The microstructures, bulk densities, and porosities of the C/SiC composites demonstrated that the infiltration of liquid silicon into the composites improved them, because the layered-structure BN worked as a lubricant. Increasing the amount of BN improved the anti-oxidation of the prepared C/SiC composites. This synergistic effect was induced by the assistance of BN in the LSI. More thermally stable SiC was formed in the composite, and fewer pores were formed in the composite, which reduced inward oxygen diffusion. The mechanical strength of the composite increased up to the addition of 3% BN and decreased thereafter due to increased brittleness from the presence of more SiC in the composite. Based on the anti-oxidation and mechanical properties of the prepared composites, we concluded that improved anti-oxidation of C/SiC composites can be achieved through BN-assisted LSI, although there may be some degradation of the mechanical properties. The desired anti-oxidation and mechanical properties of the composite can be achieved by optimizing the BN-assisted LSI conditions.

• Journal of Microbiology and Biotechnology
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• 제17권8호
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• pp.1284-1290
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• 2007

This study was conducted to investigate the antibacterial activity and shelf-life extension effect of iceberg lettuce packed in BN/PE film. The BN/PE film has a strong microbial suppression effect on pathogenic bacteria such as Escherichia coli, Salmonella enteritidis, and S. typhimurium. The number of psychrophiles and mesophiles during 5 days of cold storage of fresh-cut iceberg lettuce at $10^{\circ}C$ packaged in BN/PE film was strictly suppressed in comparison with other tested films (OPP, PE, and PET film). When fresh processed iceberg lettuce was processed and stored under the current conditions, the shelf-life of the product was longer than 5 days in the BN/PE film package, whereas the shelf-life when using the other films tested, PE, OPP and PET, was no longer than 3-4 days. The decay rates of the iceberg lettuce packed in the BN/PE film was maintained at $29.8{\pm}2.1%$ on the 5th day of preservation. The samples packed in BN/PE film maintained an excellent visual quality during the 3 days of storage without significant differences in comparison with the initial visual quality. No browning was observed in the samples packed in BN/PE film for up to 3 days. The texture of shredded iceberg lettuce packaged in BN/PE film remained unchanged up to 3 days, and then a moderate decrease in texture was observed after 4 days of storage. In addition, the overall acceptability of fresh-cut iceberg lettuce packaged in BN/PE film did not change for up to 3 days, whereas the samples packaged in the other films were inedible by 3 days of storage. In conclusion, the shelf-life of fresh-cut iceberg lettuce packaged in the BN/PE film was extended to more than 5 days at $10^{\circ}C$, whereas that in the other films was 2 days at $10^{\circ}C$. Therefore, the shelf-life extension effect of the fresh-cut iceberg lettuce in BN/PE film packaging was very effective compared with the other films tested.