A review on the joining of SiC for high‑temperature applications

Dang‑Hyok Yoon,Ivar E. Reimanis 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.3

A review on the joining of SiC is given in response to the interest surge on this material for a number of applications. Because the engineering design for the majority of applications requires complicated shapes, there has been a strong demand for the development of reliable joining techniques for SiC, especially for high-temperature applications. However, the joining of SiC-based materials is inherently difficult because of the high degree of covalent bonding in SiC and the low self-diffusivity. This review discusses basic mechanisms and properties of the SiC joining techniques developed to date; they are divided into eight different categories. In addition, critical assessment is given for each technique in the context of high-temperature application (≥ 1000 °C). Finally, comments are provided for the use of these techniques in advanced nuclear reactors where stringent irradiation stability under neutron irradiation as well as hermeticity and joint strength are required.

BaTiO3 properties and powder characteristics for ceramic capacitors

Dang-Hyok Yoon,BurtrandI.Lee 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.2

Barium titanate (BaTiO3) is one of the most widely used ceramic raw materials in the electro-ceramic industry, especially in multi-layer ceramic capacitors (MLCCs). In this paper recent information on basic dielectric properties, the effect of particle size on phase transition, and powder characteristics resulting from various synthetic methods of producing BaTiO3, including the hydrothermal method are reviewed.

Fabrication of Mullite-Bonded Porous SiC Using Ti₃AlC₂ MAX Phase

Septiadi, Arifin,Yoon, Dang-Hyok The Korean Ceramic Society 2019 한국세라믹학회지 Vol.56 No.2

This study assessed the feasibility of a Ti₃AlC₂ MAX phase as an Al-source for the formation of a mullite bond in the fabrication of porous SiC tubes with high strength. The as-received Ti₃AlC₂ was partially oxidized at 1200℃ for 30 min before using to minimize the abrupt volume expansion caused by oxidation during sintering. Thermal treatment at 1100-1400℃ for 3 h in air led to the formation of Al₂O₃ by the decomposition of Ti₃AlC₂, which reacted further with oxidation-derived SiO₂ on the SiC surface to form a mullite phase. The fabricated porous SiC tubes with a relative density of 48 - 62 % exhibited mechanical strengths of 80 - 200 MPa, which were much higher than those with the Al₂O₃ filler material. The high mechanical strength of the Ti₃AlC₂-added porous SiC was explained by the rigid mullite neck formation along with the retained Ti₃AlC₂ with good mechanical properties.

Effects of post-sintering annealing on the microstructure and toughness of hot-pressed SiC_f/SiC composites with Al₂O₃-Y₂O₃ additions

Fitriani, Pipit,Yoon, Dang-Hyok,Sharma, Amit Siddharth Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.16

<P><B>Abstract</B></P> <P>This study examined the effects of post-sintering heat treatment on enhancing the toughness of SiC<SUB>f</SUB>/SiC composites. Commercially available Tyranno<SUP>®</SUP> SiC fabrics with contiguous dual ‘PyC (inner)-SiC (outer)’ coatings deposited on the SiC fibers were infiltrated with a SiC + 10wt% Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> slurry by electrophoretic deposition. SiC green tapes were stacked between the slurry-infiltrated fabrics to control the matrix volume fraction. Densification of approximately 94% ρ<SUB>theo</SUB> was achieved by hot pressing at 1750°C, 20MPa for 2h in an Ar atmosphere. Sintered composites were then subjected to isothermal annealing treatment at 1100, 1250, 1350, and 1750°C for 5h in Ar. The correlation between the flexural behavior and microstructure was explained in terms of the in situ-toughened matrix, phase evolution in the sintering additive, role of dual interphases and observed fracture mechanisms. Extensive fractography analysis revealed interfacial debonding at the hybrid interfaces and matrix cracking as the key fracture modes, which were responsible for the toughening behavior in the annealed SiC<SUB>f</SUB>/SiC composites.</P>

Metal oxide additives for the sintering of silicon carbide: Reactivity and densification

Noviyanto, Alfian,Yoon, Dang-Hyok Elsevier 2013 Current Applied Physics Vol.13 No.1

Effect of hexagonal-BN on phase transformation of additive-free Si3N4/SiC nanocomposites prepared from amorphous precursor

NOVIYANTO, Alfian,YOON, Dang-Hyok,LEE, Kyungseok,KIM, Young Moon,KIM, Doo-In,JEONG, Young-Keun,KIM, Kwang Ho,KWON, Sehun,HAN, Young-Hwan Elsevier 2013 Transactions of Nonferrous Metals Society of China Vol.23 No.2

Sintering additives for SiC based on the reactivity: A review

Raju, Kati,Yoon, Dang-Hyok Elsevier 2016 CERAMICS INTERNATIONAL Vol.42 No.16

<P><B>Abstract</B></P> <P>Silicon carbide (SiC) is one of the most attractive materials for high temperature applications, being used in many areas, such as gas turbines, heat exchangers, and space shuttles, because of its excellent strength, oxidation resistance and chemical stability at high temperatures. Moreover, SiC and its composites are being considered as structural materials for advanced fission reactors and future fusion reactors owing to its additional low induced radioactivity under neutron irradiation conditions. On the other hand, pure SiC can only be densified by sintering at high temperatures and pressures because of its high covalent bonding nature and low self-diffusivity. Therefore, the addition of sintering additives is essential for enhancing the densification of SiC. This paper reviews the criteria for the selection of effective SiC sintering additives based on the Gibbs free energy to predict the reactivity between the sintering additive and SiC, particularly for liquid phase sintering at 1700–1900°C. The thermodynamic simulation was verified by offering the experimental results for various types of sintering additives, such as main group metals, metal oxides, and rare earth elements. This review suggests a guideline for the selection of sintering additives for SiC.</P>

Joining of SiC_f/SiC using a Ti₃AlC₂ filler and subsequent elimination of the joining layer

Fitriani, Pipit,Yoon, Dang-Hyok Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.18

<P><B>Abstract</B></P> <P>This study examined the joining of SiC fiber-reinforced SiC matrix composites (SiC<SUB>f</SUB>/SiC) using a Ti<SUB>3</SUB>AlC<SUB>2</SUB> MAX phase filler and the possibility of eliminating the joining layer via solid-state diffusion upon the decomposition of Ti<SUB>3</SUB>AlC<SUB>2</SUB>. The base SiC<SUB>f</SUB>/SiC was fabricated by electrophoretic deposition (EPD) combined with hot pressing after adding a 10 wt% Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> sintering additive. Two types of base SiC<SUB>f</SUB>/SiC with a density of 93% and 96% were prepared by hot pressing at 1750 °C without and with SiC tape insertion, respectively, followed by joining at 1700 or 1900 °C for 5 h under 3.5 MPa in an Ar atmosphere. The SiC<SUB>f</SUB>/SiC with tape insertion showed feasible elimination of the joining layer after joining at 1900 °C, whereas the composite joined at 1700 °C revealed the presence of a joining filler due to incomplete decomposition of the Ti<SUB>3</SUB>AlC<SUB>2</SUB> filler. All samples showed fracturing at the joining interface during the flexural test, showing a joining strength of 180–255 MPa depending on the preparation conditions. The properties of the SiC<SUB>f</SUB>/SiC joints were explained by the surface roughness, microstructure, and phase evolution upon decomposition of the Ti<SUB>3</SUB>AlC<SUB>2</SUB> filler.</P>

Fabrication of tough SiC_f/SiC composites by electrophoretic deposition using a fabric coated with FeO-catalyzed phenolic resin

Fitriani, Pipit,Septiadi, Arifin,Yoon, Dang-Hyok,Sharma, Amit Siddharth Elsevier 2017 Journal of the European Ceramic Society Vol.37 No.4

<P><B>Abstract</B></P> <P>A hybrid processing route based on vacuum infiltration, electrophoretic deposition, and hot-pressing was adopted to fabricate dense and tough SiC<SUB>f</SUB>/SiC composites. The as-received Tyranno SiC fabric preform was infiltrated with phenolic resin containing 5wt.% FeO and SiC powders followed by pyrolysis at 1700°C for 4h to form an interphase. Electrophoretic deposition was performed to infiltrate the SiC-based matrix into the SiC preforms. Finally, SiC green tapes were sandwiched between the SiC fabrics to control the volume fraction of the matrix. Densification close to 95% ρ<SUB>theo</SUB> was achieved by incorporating 10wt.% Al<SUB>2</SUB>O<SUB>3</SUB>-Sc<SUB>2</SUB>O<SUB>3</SUB> sintering additive to facilitate liquid phase sintering at 1750°C and 20MPa for 2h. X-ray diffraction and Raman analyses confirmed the catalytic utility of FeO by the formation of a pyrolytic carbon phase. The flexural response was explained in terms of the extensive fractography results and observed energy dissipating modes.</P>

Fabrication of SiC_f/SiC Composites using an Electrophoretic Deposition

Lee, Jong-Hyun,Gil, Gun-Young,Yoon, Dang-Hyok The Korean Ceramic Society 2009 한국세라믹학회지 Vol.46 No.5

Continuous SiC fiber-reinforced SiC composites ($SiC_f$/SiC) were fabricated by electrophoretic deposition (EPD). Nine types of slurries with different powder contents, binder resin amounts and slurry pH were deposited on Tyranno$^{TM}$-SA fabrics by EPD at 135 V for ten minutes to determine the optimal conditions. Further EPD using the optimum slurry conditions was performed on fabrics with four different pyrolitic carbon (PyC) thicknesses. The density of the hot-pressed composites decreased with increasing PyC thickness due to the difficulty of infiltrating the slurry into the narrow gaps between the fibers. On the other hand, the mechanical strength increased with increasing PyC thickness despite the decrease in density, which was explained by the enhanced crack deflection with increasing PyC thickness. The $SiC_f$/SiC composites showed the highest density and flexural strength of 94% and 342 MPa, respectively, showing EPD as a feasible method for dense $SiC_f$/SiC fabrication.