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Fabrication of CNT-Reinforced HAp Composites by Spark Plasma Sintering
Sarkar Swapan Kumar,Youn Min-Ho,Oh Ik-Hyun,Lee Byong-Taek 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Carbon nanotube (CNT) reinforced hydroxyapatite (HAp) composites were fabricated by using the spark plasma sintering process with surfactant modified CNT and HAp nano powder. Without the dependency on sintering temperature, the main crystal phase existed with the HAp phase although a few contents of (Tri calcium phosphate) phase were detected. The maximum fracture toughness, was obtained in the sample sintered at and on the fracture surface a typical intergranular fracture mode, as well as the pull-out pmhenomenon of CNT, was observed.
Fabrication of CNT-Reinforced HAp Composites by Spark Plasma Sintering
Sarkar, Swapan Kumar,Youn, Min Ho,Oh, Ik Hyun,Lee, Byong Taek Trans Tech Publications, Ltd. 2007 Materials science forum Vol.534 No.-
<P>Carbon nanotube (CNT) reinforced hydroxyapatite (HAp) composites were fabricated by using the spark plasma sintering process with surfactant modified CNT and HAp nano powder. Without the dependency on sintering temperature, the main crystal phase existed with the HAp phase although a few contents of β-TCP (Tri calcium phosphate) phase were detected. The maximum fracture toughness, (1.27 MPa.m1/2) was obtained in the sample sintered at 1100 oC and on the fracture surface a typical intergranular fracture mode, as well as the pull-out pmhenomenon of CNT, was observed.</P>
Sarkar, Swapan Kumar,Kim, Young-Hee,Kim, Min-Sung,Min, Young-Ki,Yang, Hun-Mo,Song, Ho-Yeon,Lee, Byong-Taek The Korean Ceramic Society 2008 한국세라믹학회지 Vol.45 No.10
A porous $Al_2O_3$, scaffold coated with tricalcium phosphate(TCP) was fabricated by replica method using polyurethane(PU) foam as a fugitive material. Successive coatings of $Al_2O_3$ and hydroxyapatite(HAp) were applied via dip coating onto polyurethane foam, which has a slender and well interconnected network. A porous structure was obtained after sequentially burning out the foam and then sintering at $1500^{\circ}C$. The HAp phase was changed to TCP phase at high temperature. The scaffold showed excellent interconnected porosity with pore sizes ranging from $300{\sim}700{\mu}m$ in diameter. The inherent well interconnected structural feature of PU foam remained intact in the fabricated porous scaffold, where the PU foam material was entirely replaced by $Al_2O_3$ and TCP through a consecutive layering process. Thickness of the $Al_2O_3$ base and the TCP coating was about $7{\sim}10{\mu}m$ each. The TCP coating was homogeneously dispersed on the surface of the $Al_2O_3$ scaffold.
Fabrication and Characterization of Porous TCP coated Al2O3 Scaffold by Polymeric Sponge Method
Swapan Kumar Sarkar,김영희,김민성,민영기,양훈모,송호연,이병택 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.10
A porous Al2O3 scaffold coated with tricalcium phosphate (TCP) was fabricated by replica method using polyurethane (PU) foam as a fugitive material. Successive coatings of Al2O3 and hydroxyapatite (HAp) were applied via dip coating onto polyurethane foam, which has a slender and well interconnected network. A porous structure was obtained after sequentially burning out the foam and then sintering at 1500oC. The HAp phase was changed to TCP phase at high temperature. The scaffold showed excellent interconnected porosity with pore sizes ranging from 300~700 μm in diameter. The inherent well interconnected structural feature of PU foam remained intact in the fabricated porous scaffold, where the PU foam material was entirely replaced by Al2O3 and TCP through a consecutive layering process. Thickness of the Al2O3 base and the TCP coating was about 7~10 μm each. The TCP coating was homogeneously dispersed on the surface of the Al2O3 scaffold.
Hard tissue regeneration using bone substitutes: an update on innovations in materials
Swapan Kumar Sarkar,이병택 대한내과학회 2015 The Korean Journal of Internal Medicine Vol.30 No.3
Bone is a unique organ composed of mineralized hard tissue, unlike any other body part. The unique manner in which bone can constantly undergo self-remodeling has created interesting clinical approaches to the healing of damaged bone. Healing of large bone defects is achieved using implant materials that gradually integrate with the body after healing is completed. Such strategies require a multidisciplinary approach by material scientists, biological scientists, and clinicians. Development of materials for bone healing and exploration of the interactions thereof with the body are active research areas. In this review, we explore ongoing developments in the creation of materials for regenerating hard tissues.
Sarkar, Swapan Kumar,Lee, Byong Taek Materials Research Society of Korea 2013 한국재료학회지 Vol.23 No.9
This paper investigates the effect of prolonged high temperature exposure on concentric laminated $Al_2O_3-ZrO_2$ composites. An ultrafine scale microstructure with a cellular 7 layer concentric lamination with unidirectional alignment was fabricated by a multi-pass extrusion method. Each laminate in the microstructure was $2-3{\mu}m$ thick. An alternate lamina was composed of 75%$Al_2O_3$-(25%m-$ZrO_2$) and t-$ZrO_2$ ceramics. The composite was sintered at $1500^{\circ}C$ and subjected to $1450^{\circ}C$ temperature for 24 hours to 72 hours. We investigated the effect of long time high temperature exposure on the generation of residual stress and grain growth and their effect on the overall stability of the composites. The residual stress development and its subsequent effect on the microstructure with the edge cracking behavior mechanism were investigated. The residual stress in the concentric laminated microstructure causes extensive micro cracks in the t-$ZrO_2$ layer, despite the very thin laminate thickness. The material properties like Vickers hardness and fracture toughness were measured and evaluated along with the microstructure of the composites with prolonged high temperature exposure.
Swapan Kumar Sarkar,Do-Van Tuyen,이병택 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.4
In this study, we investigated the formation behavior of spherical porous biphasic calcium phosphate (BCP)granules, in which PCL was both the binder and fugitive pore former. The formation of porous granules was based on the immiscibility of PCL slurry containing BCP powder and distilled water. The porosity was controlled by controlling the volume fraction of PCL. In addition, the effect of the composition on the rheological properties and consequently the droplet formation mechanism was examined. After drying and sintering, the resulting BCP granules had a porous structure, which could promote stronger cell in-growth behavior. The method developed in this study can be utilized to successfully fabricate granules with controlled porosity and size.
Mondal, Dibakar,Sarkar, Swapan Kumar,Oh, Ik-Hyun,Lee, Byong-Taek The Japan Institute of Metals 2011 Materials transactions Vol.52 No.7
<P>Sintering of Ti-biphasic calcium phosphate (BCP) is difficult because of the chemical instability of the phases at high temperature. When the sintering temperature is above 1273 K, Ti reacts with BCP and forms CaO, TiO<SUB>2</SUB>, CaTiO<SUB>3</SUB>, TiP etc. Conventional vacuum sintering is common for Ti powder but for Ti-BCP composites, spark plasma sintering in an inert atmosphere is a quick method to overcome the issues associated with a prolonged reaction time. In this study, the effect of two different sintering processes on the sintering reactions and mechanical and biological properties of Ti-30 vol%BCP composites were investigated and compared. Detailed micro-structural and morphological analyses were conducted using scanning electron microscopy (SEM). Mechanical properties were characterized by relative density, Vickers hardness and compressive strength measurement. Phase characteristics were analyzed by X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). Cell viability and biocompatibility were investigated using the MTT assay and by examining cell morphology. In this study, the mechanical properties and biocompatibility for both, spark plasma sintered Ti-Ca-P composites were excellent compare to vacuum sintered composites.</P>