가스압 소결(GPS) 조건이 질화규소의 기계적 특성에 미치는 영향

이수완,김성호,정용선 한국결정성장학회 1997 韓國結晶成長學會誌 Vol.7 No.4

$Si_3N_4$에 2 wt% $Al_2O_3$와 6 wt% $Y_2O_3$을 첨가한 분말을 가스압소결 방법으로 시편을 제조하였다. 이때 소결시 조건(온도, 압력, 시간) 변화에 대한 기계적 특성 변화를 비교하였다. 이때 나타난 결과에 의하면 $1900^{\circ}C$, 3 MPa에서 1시간 동안 유지시켰을 때 최적의 조건을 갖는다는 것을 보여주었다. 이는 온도를 높여 주거나 유지 시간을 길게 하였을 때 입자 조대화에 의해 기계적 특성이 떨어지는 것을 볼 수 있었다. 그러나 압력을 증가시킬 때에는 미세한 조직을 가지므로 기계적 특성은 좋아짐을 나타내지만 파괴 인성이 떨어지는 것을 볼 수 있었다. 이로 인해 소결시 최적의 조건을 찾는 것이 중요함을 알 수 있었다. $Si_3N_4$ powder with 2 wt% $Al_2O_3$ and 6 wt% $Y_2O_3$additives was gas pressure sintered (GPS). Characterization of the mechanical properties was compared with sintering conditions (temperature, pressure, time). Based on experimental result , the optimal condition of gas pressure sintering was found at $1900^{\circ}C$, 3 MPa for 1 hour. It is assumed that mechanical properties were degraded due to the grain coasening effects with increasing temperature or holding time. However, the grain size was decreased with increasing pressure, resulted in better strength, but lower fracture toughness. Present results suggested that optimization of processing parameters was impotant for better mechanical properties of $Si_3N_4$.

전립선 비대증의 수술방법의 비교분석 : 경요도적 절제술과 절개적 적출술

이수완,최희석 大韓泌尿器科學會 1989 Korean Journal of Urology Vol.30 No.6

방전가공용 질화규소의 미세조직이 내마모에 미치는 영향

이수완,김성호,이명호 한국결정성장학회 1998 韓國結晶成長學會誌 Vol.8 No.1

질화규소는 고경도, 고인성 세라믹 재료이기 때문에, 기계적 가공성은 매우 나쁘며, 또한 질화규소는 높은 전기 저항을 갖는다. 매우 높은 전기저항을 띠는 질화규소에 30wt% 이상의 TiN 분말이 첨가되었을 때 전도성 세라믹 복합체가 된다. 높은 전기 전도도를 가질 때 세라믹을 방전가공방법(EDM)을 이용하여 정밀한 가공을 할 수 있다. 높은 전기 전도도를 갖는 $Si_3N_4-TiN$ 세라믹 복합체는 EDM 방법을 이용하여 금속 가공 tool을 만드는데 이용되며, 이러한 tool 재료들은 산화뿐만 아니라 심각한 마모문제를 갖는다. 상압소결후 post HIP 소결방법으로 $Si_3N_4-TiN$ 복합체를 만들었으며, TiN의 양의 변화에 따른 $Si_3N_4$ 복합체의 마모특성을 상온의 대기중에서 조사하였다. 경도, 파괴인성, 강도값을 마모량과 비교하였다. 마모흔의 SEM 관찰로 $Si_3N_4-TiN$ 복합체의 마모기구를 설명하였다. Silicon nitride is hard and tough ceramic material. Hereby, mechanical machinability is very poor. It has also high electrical resistance. Silicon nitride of extremely high electrical resistivity becomes conductive ceramic composite by adding 30 wt% TiN. Ceramics with high electrical conductivity can be electrical discharge machined. Using by the Electrical Discharge Machining (EDM) technique. $Si_3N_4-TiN$ ceramic composite with high electrical conductivity is utilized to make metal working tool. These tool materials have severe wear problem as well as oxidation. Post HIP processing after sintering $Si_3N_4-TiN$ ceramic composites was performed. The tribological property of $Si_3N_4-TiN$ composite as a function of content of TiN was investigated in air, at room temperature. The hardness, fracture toughness, and flexural strength were compared with the wear volume. SEM observation of wear tracks can make an explanation of wear mode of $Si_3N_4-TiN$ composite.

Wear Mechanism of Silicon Nitride

이수완 선문대학교 중소기업기술지원연구소 1997 선문공대 연구/기술 논문집 Vol.2 No.1

순수한 paraffin oil을 윤활유로 한 HIPping한 질화규소의 마찰과 마모거동은 sliding speed, normal load와 sliding time에 대하여 조사하였다. subsurface damage에 의해 생긴 mild에서 severe wear로의 전이는 이 실험조건에서 관찰되지 않았다. 이 실험의 결과에서, polishing process와 plastic deformation은 paraffin oil을 윤활유로 한 silicon notride에서 중요한 기구이다. 때때로, wear track에서 elongated grain의 흔적이 나타났다. 또한, 입자의 pull-out은 wear mode의 일부이다. The friction and wear behavior of HIPped silicon nitride lubricated with a purified paraffin oil has been investigated as a function of sliding speed, normal load, and sliding time. A transition from mild to severe wear caused by subsurface damage was not observed in the investigated test condition. On the basis of experimental results, polishing process and plastic deformation is the predominant mechanism in silicon nitride lubricated with paraffin oil. Occasionally traces of elongated grains in the wear tracks were revealed. Grain pull-out is also a partial wear mode.

알루미나와 이트리아가 질화규소의 가공성에 미치는 영향

이수완,장태석,엄호성 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.3

The effect of sintering aids on the sinterability for silcion nitride has been studied by hundreds workers. However the effect of sintering aids on the machinability as the own trobles which is the major barrier for the field applications of the ceramic components has not been fully studied. in this study the contents of Al2O3 and Y2O3 in silicon nitride were varied from 0 to 8 wt% respectively. The physical and mechanical properties of the silcion nitride were measured. The optimal microstructure of silicon nitride balls with the excellent machinability by adding with various contents of sintering aids was studied by MGF(magnetic-fluid grinding)technique. An attempt to figure out how the mechanical properties influence the machinability of silicon-nitride ball was made.

Wear Mechanism of Silicon Carbide

이수완 선문대학교 1994 鮮文論叢 自然科學 編 Vol.- No.4

본고는 일단 기존의 축적된 논의들을 수용하면서 추사 문학의 불교적 측면을 살필 것이다. 대부분의 실학자들이 불교에 대하여 비판적이거나 부정적이었던 것과는 달리, 추사는 부분적으로 불교적 예술론을 상정하거나 당대 선객인 백파선사와의 선학 논쟁에 뛰어들었을 정도로 불교에 대하여 지대한 관심을 표명했다. 이는 추사가 불교신자였는가, 아니었는가와는 별개의 문제이다. 다만 그의 사유 체계에서 비롯된 기록이나 실제 문학작품을 통하여 추사의 불교의 관련 양상을 고찰하는 데 본고의 목적이 있기 때문이다. The objectives of the final phase of this study are to investigate the friction and wear behaviors of silicon carbide in simulated gas ?fuel engine environment and to understand the wear mechanisms for the silicon carbide operated under different conditions. The wear characterization of silicon carbide were examined in detail as function of normal load and speed. To better understanding of various wear behaviors of silicon carbide in dry and paraffin oil. Detailed wear mechanisms were investigated by observing the worn surface, using optical microscopy, scanning electron microscopy (SEM). A linear fracture mechanics wear model has been tried with the experimental data. Agreement between theory and experimental results is good. The model contains a dimensionless parameter derived from the linear fracture theory, which is consisted of the degree of wear severity (S_(ct)), the applied load, fracture toughness, coefficient of friction, and the average grain size.

가스압 소결조건에 따른 질화규소볼의 가공성에 대한 연구

이수완,김성호,정용선 한국세라믹학회 1998 한국세라믹학회지 Vol.35 No.2

The effect of sintering conditions on the sinterability for silicon nitride has been studied by many in-vestigators. However the effect of sintering conditions on the machinability which is the major barrier to the field applications of the ceramic components has not been fully studied. In this study the sintering con-ditions such as temperature gas pressure and time in silicon nitride were varied. The physical and mechan-ical properties of the gas pressure sintered (GPS) silicon nitride were measured. The optimum mi-crostructure of silicon nitride with the excellent machinability was investigated by MFG(magnetic-fluid grinding) technique. An attempt was made to figure out how the mechanical properties influence upon the machinability of silicon nitride ball.

질화규소의 가스압 소결 (GPS) 시간에 따른 마모거동

이수완,김성호,Lee, Su-Wan,Kim, Seong-Ho 한국재료학회 2000 한국재료학회지 Vol.10 No.1

$Si_3N_4$에 2wt% $Al_2O_3$와 6wt% $Y_2O_3$을 첨가한 분말을 가스압 소결 방법으로 시편을 제조하였다. 이때 소결시 시간변화에 따른 공기 중에서 마모 특성을 비교하였다. 소결 시간에 따른 마모 특성의 변화는 기계적 성질, 즉, 파괴인성 등이 영향을 주는 것으로 나타났다. 소결 시간이 길어지면 큰 elongated 입자의 과잉성장에 따라 곡강도 및 파괴인성이 낮아져 이 결과 마모가 증가되었다. 이때 나타난 결과에 의하면 공기 중에서 질화규소의 마모특성에 영향을 주는 인자는 여러 가지 기계적 특성 중에서 파괴인성 및 곡강도가 미치는 영향이 크게 나타났다. $Si_3N_4$ powder with 2wt% $Al_2O_3$ and 6wt% $Y_2O_3$ additives was sintered by gas pressure sintering (GPS) technique. The variations in the unlubricated wear behavior depending on sintering time were compared. Tribological properties depending on sintering time are associated with fracture toughness as well as flexural strength of materials. When increasing the sintering time, the larger elongated grains were formed as a result of exaggerated grain growth. As the fracture toughness and flexural strength decreased, the wear volume increased. On the basis of these experimental results, the unlubricated wear properties of silicon nitride were found to be governed mostly by both the fracture toughness and the flexural strength of the material.

여성요도의 평활근종 1례

이수완,지창하,노충희,최희석,고일향,김주홍 大韓泌尿器科學會 1988 Korean Journal of Urology Vol.29 No.3

부고환에 발생한 유선종 1례

이수완,최홍용,노충희,최희석 인제대학교 1986 仁濟醫學 Vol.7 No.4

The term adenomatoid tumor was applied by Golden and Ash to certain Small, circumscribed, benign vision of the genital tract in recognition of their somewhat adenomators structure. Adenomatoid tumors are generally found in the epididymis, tunica vaginalis or spermatic cord in the male and fallopian tube, uterus, ovary in the female. But most the tumors are found near or in epididymis. The histogenesis of the adenomatoid tumor has been controversial. But the possibility of an origin from mesothelium are considered recently. Adenomatoid tumors are usual solid, asymptomatic neoplasm, its size are less then 2 cm usually. Histogically the tumor consists of tubular and gland pattern lined with cuboidal or flattened cell and a fibrous stroma. Recently we experienced a painful adenomatoid tumor of epididymis after trauma.