• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.4
• /
• pp.48-56
• /
• 2004

Ceramics are very difficult-to-cut materials because of its high strength and hardness. Their machining mechanism is characterized by cracking and brittle fracture. In this paper, to give good machinability to the ceramics, h-BN powders are added to $Si_3N_4$, by volume of 20, 25 and 30%. And the machinability of the produced ceramics is tested using micro drilling system. Through required experimental works, it is shown that the micro drilling machinability is varied along with the volumetric percentage of h-BN powders. Also, it is verified that the obtained results can be used to develop new machinable ceramics of good material properties and machinability.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.69.1-69.1
• /
• 2012

원자 한층 또는 수층의 두께를 가진 그래핀과 2차원 나노물질들은 그들의 적층형태의 3차원 물질들과는 두드러지게 다른 전기적, 전자적, 광학적, 화학적, 기계적 성질을 지닌다. 그래핀은 탄소원자들간에 sp2공유결합을 형성하여 뛰어난 기계적, 윤활적 특성을 가지고 있으며, 이황화몰리브덴 또한 좋은 윤활적 특성을 가지고 있다. 본 발표에서는 원자현미경을 이용해서 그래핀, 이황화몰리브덴, 질화붕소, 니오븀 다이셀레나이드 등의 원자 두께 수준의 2차원 나노물질들에서 나타나는 특이한 마찰적 특성들을 보고한다. 특별히 원자수준으로 얇아짐으로 두께에 따른 마찰력의 변화와 2차원물질의 주름에 따른 방향성있는 마찰특성 그리고, 기판에 따른 마찰력의 특성변화를 보고하도록 한다.

• Journal of the Korean Ceramic Society
• /
• v.26 no.2
• /
• pp.179-186
• /
• 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.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.4
• /
• pp.29-34
• /
• 2008

Application of ceramic has increased due to excellent mechanical properties, and machining of ceramic has demanded gradually a precision surface machining. For decreasing the surface roughness, the control of IED lapping parameters is very important. This paper deal with the analysis of the process parameters such as applied forces, percentage of h-BN and IED lapping time, developed based on Taguchi method. Also, SEM was used for monitoring of a machinable ceramic surface.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.4
• /
• pp.1216-1224
• /
• 1996

In the use of glass fiber reinforced plastics it is often necessary to cutting the components, but the cutting GFRP is often made difficult by the delamination of composites and the short tool life. In this paper, the machinability of GFRP by mean of tool materials and type was experimentally investigated. By proper selection of cutting tool material and type excellent machining of this workpiece is achieved. The surface quality relate closely with the feed rate and cutting tools.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.05a
• /
• pp.216-217
• /
• 2012

QM/MM 혼성 이론 방법인 ONIOM 계산을 통해, $CO_2$가 $B_N$-BNNT 벽면에서의 흡착 반응과 $H_2CO_3$로의 전환 반응 메커니즘을 규명함으로써 $B_N$-BNNT가 효과적인 $CO_2$ 흡착제와 $H_2CO_3$ 생성 반응 촉매로 개발 가능함을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.925-929
• /
• 2001

Ultra-abrasives such as diamond and CBN have used to maintain accuracy and form deviation for superalloy etc. This study contains the dry cylindrical grinding of metals with Vitrified-bond CBN wheel and Resinoid-bond CBN wheel. For various conditions of grinding speed, workpiece speed, grinding depth and feed speed of table, the grinding resistance, the surface roughness, and the material removal are measured and discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.315-320
• /
• 2001

Ultra-abrasives such as diamond and CBN have used to maintain accuracy and form deviation for superalloy etc. This study contains the dry cylindrical grinding of metals with Vitrified-bond CBN wheel and Resinoid-bond CBN wheel. For various condition of grinding speed, workpiece speed, grinding depth and feed speed of table, the grinding resistance, the surface roughness, and material removal are measured and discussed.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.2
• /
• pp.97-105
• /
• 1985

Phosphorus and boron diffusion from doped PECVD oxide films into silicon have been studied. CVD PSG was also prepared to parallelly compare the diffusion characteristics of CVD PSG with that in PECVD PSG, The phosphorus diffusion experiments were performed in N2 and O2 ambient at the temperatures of 100$0^{\circ}C$, 105$0^{\circ}C$ and 110$0^{\circ}C$ The parameters of boron diffusion have been investigated from the doped film prepared by changing B2 H6 flow rate and deposition temperature. The diffusivities and diffusion profiles of the dopant into silicon were calculated by applying Barry's model using the measured parameters such as diffusion depth and surface concentration.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.3 no.1
• /
• pp.15-21
• /
• 2004

The machining process of ceramics can be characterized by cracking and brittle fracture. In the machining of ceramics, edge chipping and crack propagation are the principal reasons to cause surface integrity deterioration. Such phenomenon can cause not only poor dimensional and geometric accuracy, but also possible failure of the ceramic parts. Thus, traditional ceramics are very difficult-to-cut materials. To overcome such problems, in this paper, h-BN powder, which gives good cutting property, is added for the fabrication of machinable ceramics by volume of 5, 10, 15, 20, 25 and 30%. The objectives of this paper is to evaluate the fracture phenomenon of the tungsten carbide tool and the variation of surface integrity of the manufactured machinable ceramics under various cutting conditions during end mill machining With CNC machining center.