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비정질 PEEK 필름의 Self-Bonding에 따르는 결정화도 변화
조범래,Jo, Beom-Rae,Kardos, J.L. 한국재료학회 1995 한국재료학회지 Vol.5 No.6
비정질 PEEK필름의 self-bonding공정시 조건 변화에 따르는 결정화도(crystallinlty)변화가 self-bonding강도에 미치는 영향을 고찰하기 위하여, 비정질 PEEK필름을 그 2차천이온도(Tg=143$^{\circ}C$)와 용융점(Tm=335$^{\circ}C$) 사이의 여러 온도에서 일정 압력 하에서 접합 시간을 달리하여 self-bonding시킨 후, 각 조건에서 개발된 self-bonding강도를 측정하고, 이에 따르는 결정화도 변화를 DSC를 이용하여 비교 분석하였다. 결정화도는 접합공정변수(시간과 온도)의 함수로서 증가하였고, 동일한 값의 결정화도를 보이는 시편들의 경우에도 접합공정의 조건에 따라 결과적인 self-bonding강도는 큰 차이가 있음을 보였다. 또한 접합후 시편을 상온으로 노냉시키는 동안에는 더 이상의 결정화 현상이 일어나지 않음이 DSC분석을 통하여 판명되었다. The relationship between the variation of crystallinity and the resultant self-bonding strength of PEEK was examined by using DSC in conjunction with the shear test. DSC measurement of the crystallinity produced at different bonding conditions demonstrated that even though PEEK specimens contain the same amount of crystallinity, the resultant self-bonding strength is sensitively dependent on bonding history. It also showed that all crystallization during the bending process occurs only in the healing and annealing stage and no additional crystallization occurs in the cooling stage.
복합재료 기지재용 무정형 PEEK 필름의 Self-Bonding에 따르는 계면 미세 조직 연구
조범래,Jo, Beom-Rae 한국재료학회 1998 한국재료학회지 Vol.8 No.5
무정형 PEEK 필름의 self-bonding 공정 시에 일어나는 결정화 현상이 접합 면에서 개발되어지는 self-bonding 강도에 미치는 영향을 주사전자현미경(SEM)을 이용하여 고찰하였다. 무정형 PEEK 필름의 결정화 현상은 접합 시의 공정변수에 따라 변화하며, self-bonding 공정 동안 접합 면을 가로질러 PEEK의 결정들이 성장함에 따라 접합이 일어남을 알 수 있었다. 접합온도가 높을수록 접합 면을 가로지르는 결정들의 성장 정도가 낮은 온도에서 접합시켰을 때의 경우보다 훨씬 커서 결과적으로 높은 self-bonding 강도를 보였다. 각각의 시편들을 전단 파괴시킨 후 행한 파단면 관찰에서는 self-bonding 강도가 점차 높아짐에 따라 더욱 조밀한 물결무늬 파면과 dimple 형태와 유사한 파면 형상들이 관찰되는 것으로 보아 접합공정 시 접합 면을 가로지르는 PEEK 결정들의 성장 정도가 self-bonding 강도에 커다란 영향을 미친다고 판단되었다.
전자부품용 메탈라이즈드 알루미나 세라믹스의 미세구조 제어
조범래,Jo, Beom-Rae 한국재료학회 2001 한국재료학회지 Vol.11 No.12
Composition effects on microstructure and metallizing properties of the alumina sintered body were evaluated to develop the metallized alumina tubes having superior properties for electronic devices. SEM observation revealed that resultant micrographs and fractographs were varied with composition chance of additives and $SiO_2$-rich specimens showed better microstructural characteristics with uniform distribution of fine and round particles than other CaO-rich or MgO-rich ones. The resultant interfacial microstructure of the $SiO_2$-rich metallized alumina tubes also showed good metallizing properties with no defects between layers and uniform thickness of metallizing layer.
SiO<sub>2</sub>와 Al<sub>2</sub>O<sub>3</sub> 첨가가 지르콘의 기계적 특성에 미치는 영향
조범래,Cho, Bum-Rae 한국재료학회 2011 한국재료학회지 Vol.21 No.4
Zircon has excellent thermal, chemical, and mechanical properties, but it is hard to make a dense sintered product because of dissociation during the sintering process. This study analyzes how the addition of $SiO_2$ and $Al_2O_3$ affects the mechanical properties of sintered zircon, particularly in regards to reducing the thermal dissociation and improving the mechanical properties of $ZrSiO_4$. Zircon specimens containing different amounts of $SiO_2$ and $Al_2O_3$ were prepared and sintered to observe how the mechanical properties of $ZrSiO_4$ changed according to the differing amount of $SiO_2$ and $Al_2O_3$. The $ZrSiO_4$ that was used for the starting material was ground by ball mill to an average particle size of 3 ${\mu}m$. The $SiO_2$ and $Al_2O_3$ that was used for additives were ground to an average particle size of 3 ${\mu}m$ and 0.5 ${\mu}m$, respectively. Adding $SiO_2$ resulted in transformation in the liquid phase at high temperatures, which had little effect on suppressing the thermal dissociation but enhanced the mechanical properties of $ZrSiO_4$. When $Al_2O_3$ was added, the mechanical properties of $ZrSiO_4$ decreased due to the formation of pores and abnormal grains in the microstructure of the sintered zircon.
Effect of composition change on sintering and metallizing of alumina ceramics
조범래,Jung-Jin Lee,강승규 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
The effects of flux additions on the sintering and metallizing properties of alumina ceramics were investigated. Experimental results showed that the addition of SiO2, CaO and MgO as a flux increases the sintering ability of alumina. An increment in the amount of MgO seems to produce a more uniform and finer grain distribution. CaO and MgO addition seemed to promote a glassy state of the SiO2 easily at a lower temperature. Alumina containing the proper amount of flux additions showed a higher metal-to-bond strength than nearly pure alumina ceramics. This was explained by the fact that the glassy state of SiO2 migrated into the porous metallizing layer during the metallization process. The effects of flux additions on the sintering and metallizing properties of alumina ceramics were investigated. Experimental results showed that the addition of SiO2, CaO and MgO as a flux increases the sintering ability of alumina. An increment in the amount of MgO seems to produce a more uniform and finer grain distribution. CaO and MgO addition seemed to promote a glassy state of the SiO2 easily at a lower temperature. Alumina containing the proper amount of flux additions showed a higher metal-to-bond strength than nearly pure alumina ceramics. This was explained by the fact that the glassy state of SiO2 migrated into the porous metallizing layer during the metallization process.