반도체 폐 Si 슬러지를 이용한 질화규소세라믹의 제조

이병택,유정호,김해두 공주대학교 자원재활용신소재지역협력센터 2000 2차년도 센터 사업 성과집 Vol.2000 No.1

반도체 폐 Si 슬러지를 이용하여 질화반응 및 post-sintering을 통해 제조된 질화규소세라믹의 미세조직 및 기계적 특성을 광학현미경, SEM 및 XRD를 이용하여 연구하였다. 상당량의 SiO2비정질상을 포함하는 폐 Si분말에서 많은 microcracks이 관찰되었다. 폐 슬러지를 사용한 Si 성형체의 질화율은 상용되고 있는 Si분말을 이용한 성형체의 값에 비해 낮은 값을 보였다. 그러나 질화온도가 증가함에 따라 질화율은 증가하였으며 1470℃에서 질화율은 98%를 보였다. 반응소결체내에 존재하는 Si3N4의 결정은 α와 β상으로 혼재되어 있으며 상당량의 산질화규소상이 검출되었다. 1950℃에서 후처리된 시료의 최대파괴인성 및 파괴강도 값은 각각 5.6 MPa · m1/2과 497 MPa로 H. C. Starck사의 Si을 이용한 것에 비해 낮은 값을 보였으며 이는 산질화규소 형성에 기인된 것으로 사료된다 The microstructures and mechanical properties of Si3N4 ceramics produced by nitridation and post-sintering using semiconductor-waste-Si sludge were investigated. Lots of microcracks were observed in the waste-Si powders which contained some amounts of amorphous SiO2. The nitridation rate of waste-Si compacts showed lower value than that of commercial Si powder compacts. The nitridation rate was increased with increasing nitridation temperature and then the percent of nitridation at 1470℃ showed 98%. The phases of Si3N4 in the reaction-bonded bodies were mixed with α and β-type, and small amounts of Si2N2O phase while those after post-sintering were β-Si3N4 and O'-Sialon. The sample post-sintered at 1950℃ showed the fracture toughness of 5.6 MPa · m1/2 and the fracture strength of 497 MPa which were lower than those of sintered body using commercial Si powder possibly due to the formation of O'-Sialon phase.

硏究開發課題의 選定과 評價에 관한 硏究

李五範,李光澤,高德弼,金炳泰 청주대학교 경상대학 1985 經商論叢 Vol.26 No.-

반도체 폐 Si 슬러지를 이용한 질화규소세라믹의 제조

이병택,김해두,유정호 공주대학교 자원재활용 신소재 연구센터 1999 1차년도 센터 성과집 Vol.1999 No.-

반도체 폐 Si슬러지를 이용하여 질화반응 및 post-sintering을 통해 제조된 질화규소세라믹의 미세조직 및 기계적 특성을 광학현미경, SEM 및 XRD를 이용하여 연구하였다. 상당량의 SiO₂비정질상을 포함하는 폐 Si분말에서 많은 microcracka이 관찰되었다. 폐 슬러지를 사용한 Si 성형체의 질화율은 상용되고 있는 Si분말을 이용한 성형체의 값에 비해 낮은 값을 보였다. 그러나 질화온도가 증가함에 따라 질화율은 증가하였으며 1470℃에서 질화율은 98%를 보였다. 반응소결체내에 존재하는 Si₁N₄의 결정은 α와 β상으로 혼재되어 있으며 상당량의 산질화규소상이 검출되었다. 1950℃에서 후처리된 시료의 최대파괴인성 및 파괴강도 값은 각각 5.6 MPa로 MPa로 H. C. Starcktk사의 Si을 이용한것에 비해 낮은 값을 보였으며 이는 산질화규소 형성에 기인된 것으로 사료된다. The microstructures and mechanical properties of Si₁N₄ceramics produced by nitridation and post-sintering using semiconductor-waster-SI sludge were investigated. Lots of microcracks were observed in the waste-Si powders which contained some amounts of amounts of amorphous SiO₂. The nitridation rate of waste-Si compacts showed lower value than that of commercial Si powder compacts. The nitridation rate was increased with increasing nitridation tempera ture and then the percent of nitridation at 1470℃ showed 98%. The phases of Si₁N₄in the reaction-bonded bodies were mixed wit αand β-type, and small amounts of Si₂N₂phase while those after post-sintering were β-Si₁N₄and α-Sialon. The sample post-sintered at 1950℃ showed the fracture toughness of 5.6 MPaㆍm1/2 and the fracture strength of 497 MPa which were lower than those of sintered body using commercial Si powder possibly dur to the for-mation of α-Sialon phase.

화학기상응축 공정으로 제조한 Fe 나노입자의 TEM 미세조직 및 결정화거동

김택수,이희정,오익현,한재길,최철진,이병택 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12

Iron and iron nitride nanoparticles were synthesized by chemical vapor condensation (CVC) process, using a precursor of Fe(CO)_(5) and carrier gas of NH₃. Phase change and crystallization behaviors of as received particles were mainly examined by TEM technique. Only α-Fe nanoparticles were formed at the lowest decomposition temperature of 500℃. As the temperature increased, the crystallization of α-Fe nanoparticles was suppressed and Fe₃N nanoparticles were begun to be formed. Finally full crystallization of Fe₃N was observed at 1000℃. Typical size of the α-Fe and Fe₃N particles was less than 30 nm in diameter.

급속응고된 N-type Bi₂Te_(2.75)Se_(0.15) 열전재료의 미세조직과 열전특성에 미치는 압출비의 영향

김태경,이상일,임종호,손현택,김택수,천병선 대한금속재료학회 2005 대한금속·재료학회지 Vol.43 No.1

The n-Type thermoelectric compounds of Bi₂Te_(2.75)Se_(0.15) doped with 0.1 wt% SbI₃ were fabricated by gas atomization process and extruded under ratio of 16:1 and 28:1 at 450℃. The effect of extrusion ratio on the microstructures and thermoelectric properties were investigated by a combination of microscopy, XRD and thermoelectric properties. Grains of extruded bars are smaller than those of heated powder at extrusion temperature (450℃) due to the dynamic recrystallization but with increasing the amount of plastic deformation, grains of specimen extruded with 28:1 were slightly coarse. The compressive strength of hot extruded bar under 28:1 is 160 MPa and with decreasing the extrusion ratio to 16:1, the value is 250 MPa. The Seebeck coefficient a and electrical resistivity p were decreased with increasing ratio, while thermal conductivity x was increased. this results from decrease of carrier scattering and increase of carrier mobility. Extruded bar under ratio of 16:1 shows the higher value of figure of merit (Z=2.50x10^(-3)/K) than that of 28:1 (Z=2.07x10^(-3)/K). (Received June 24, 2004)

Microstructure and Indentation Fracture of Dysprosium Niobate

Lee, Byong-Taek,Kriven, Waltraud M. Published for the Materials Research Society by th 2005 Journal of materials research Vol.20 No.6

<P>The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.</P>

Fabrication of biphasic calcium phosphates/polycaprolactone composites by melt infiltration process

Lee, Byong-Taek,Van Quang, Do,Youn, Min-Ho,Song, Ho-Yeon Springer-Verlag 2008 Journal of materials science, Materials in medicin Vol.19 No.5

Effect of MgO-P₂O₅ Sintering Additive on Microstructure of Sintered Hydroxyapatite (HAp) Bodies and Their In-Vitro Study

Lee, Byong-Taek,Youn, Hyeong-Chul,Lee, Chi-Woo,Song, Ho-Yeon Materials Research Society of Korea 2007 한국재료학회지 Vol.17 No.2

The effects of $MgO-P_2O_5$ based sintering additive on the microstructure and material and biological properties of hydroxyapatite $(HAp,\;Ca_{10}(PO_4)_6(OH)_2)$ ceramic were investigated using XRD, SEM and TEM techniques. The $MgO-P_2O_5$ sintering additive improved the material properties and increased the grain size in the sintered HAp bodies. As the content of sintering additive increased over 4 wt%, a small amount of the HAp phase was decomposed and transformed to ${\beta}-TCP$. In the 2 wt% $MgO-P_2O_5$ content HAp sintered body, the maximum values of density and hardness were respectively about 3.10 gm/cc and 657 HV. However, the maximum fracture toughness in the HAp body containing 8 wt% $MgO-P_{2}O_{5}$ was about $1.02MPa{\cdot}m^{1/2}$ due to the crack deflection effect. Human osteoblast like MG-63 cells and osteoclast like raw 264.7 cells were well grown and fully covered all of the HAp sintered bodies. The osteoblast cells were grown with spindle-shaped and the osteoclast cells had a grape-like round shape.

Microstructural characterization of electroconductive Si_3N_4-TiN composites

Lee, Byong-Taek,Yoon, Yeu-Joo,Lee, KaP-Ho 공주대학교 자원재활용 신소재 연구센터 2002 센터사업 성과집 Vol.- No.1

Electroconductive Si_3N_4-TiN composites from Si and TiN powders have been fabricated by in situ reaction-bonding and post-sintering under N_2 atomosphere. The values of fracture strength and electrical resistivity in the Si_3N_4-50 wt % TiN composite were 531 MPa and 2.5×10 exp (-2) Ω ㎝, respectively. The dispersion of TiN particles inhibited the abnormal growth of rod-like Si_3N_4 grains with large size in diameter. An amorphous phase observed in most grain boundaries and triple points is attributed to liquid phase sintering. Many dislocations formed by the difference of thermal expansion coefficients were observed in Si_3N_4 and TiN grains.

Microstructures and fracture characteristics of spark plasma-sintered HAp–5vol.% Ag composites

Lee, Byong-Taek,Shin, Na-Young,Han, Jae-Kil,Song, Ho-Yeon Elsevier 2006 Materials science & engineering. properties, micro Vol.429 No.1

<P><B>Abstract</B></P><P>Microstructures and mechanical properties of SPSed HAp–5vol.% Ag composites, using ball-milled Ag and electroless-deposited Ag-coated HAp powders, were investigated by the XRD, SEM and TEM techniques. In the Ag ball-milled HAp powder, many cracks and shrinkage cavities were observed at the interfaces between HAp and large-sized Ag particles due to the mismatch of their thermal expansion coefficients. However, in the composite using 5vol.% Ag-coated HAp powder by electroless deposition process, no microcracks were found at the interfaces due to the homogeneous and fine distribution of Ag particles. The main fracture mode of ball-milled HAp–Ag composite was a transgranular type with flat fracture morphology although there were found some pulling-out and elongated phenomenon of large Ag particles. However, in electroless-deposited 5vol.% Ag-coated HAp composite, its fracture surface was appeared to be rougher than that of ball-milled HAp–Ag composite due to the homogenous dispersion of fine Ag particles in the HAp matrix.</P>