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.

Low Pressure Joining of SiC_f/SiC Composites Using Ti₃AlC₂ or Ti₃SiC₂ MAX Phase Tape

Septiadi, Arifin,Fitriani, Pipit,Sharma, Amit Siddharth,Yoon, Dang-Hyok The Korean Ceramic Society 2017 한국세라믹학회지 Vol.54 No.4

$SiC_f/SiC$ composites were joined using a $60{\mu}m-thick$ $Ti_3AlC_2$ or $Ti_3SiC_2$ MAX phase tape. The filler tape was inserted between the $SiC_f/SiC$ composites containing a 12 wt.% $Al_2O_3-Y_2O_3$ sintering additive. The joining was performed to a butt-joint configuration at $1600^{\circ}C$ or $1750^{\circ}C$ in an Ar atmosphere by applying 3.5 MPa using a hot press. Microstructural and phase analyses at the joining interface confirmed the decomposition of $Ti_3AlC_2$ and $Ti_3SiC_2$, indicating the joining by solid-state diffusion. The results showed sound joining interface without the presence of cracks. Joining strengths higher than 150 MPa could be obtained for the joints using $Ti_3AlC_2$ or $Ti_3SiC_2$ at $1750^{\circ}C$, while those for joined at $1600^{\circ}C$ decreased to 100 MPa approximately without the deformation of the joining bodies. The thickness of initial filler tape was reduced significantly after joining because of the decomposition and migration of MAX phase owing to the plasticity at high temperatures.

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>

Joining of SiC monoliths using a thin MAX phase tape and the elimination of joining layer by solid-state diffusion

Fitriani, Pipit,Septiadi, Arifin,Hyuk, Jeong Dong,Yoon, Dang-Hyok Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.10

<P><B>Abstract</B></P> <P>This paper reports the joining of SiC monoliths using a thin MAX phase tape filler, such as Ti<SUB>3</SUB>AlC<SUB>2</SUB> and Ti<SUB>3</SUB>SiC<SUB>2</SUB>, and the subsequent phenomena leading to the elimination of the joining layer via solid-state diffusion of the MAX phase into the SiC base material, particularly with the decomposition of the Ti<SUB>3</SUB>AlC<SUB>2</SUB> filler. The base SiC monolith, showing ≥ 99% density, was fabricated by hot pressing SiC powder after adding 5 wt. % Al<SUB>2</SUB>O<SUB>3</SUB>-Y<SUB>2</SUB>O<SUB>3</SUB> sintering additive. A butt-joint configuration was prepared and joined by hot pressing under a pressure of 3.5 MPa. The effects of the experimental parameters, including the type and thickness of the joining filler, temperature as well as the holding time, were examined carefully in terms of the microstructure, phase evolution and joining strength. The joining interface could be eliminated from the SiC base when the SiC monoliths were joined at 1900 °C using a thin Ti<SUB>3</SUB>AlC<SUB>2</SUB> tape, showing a high joining strength ∼300 MPa. Moreover, fracture during the mechanical test occurred mainly at the base material rather than the joining interface, indicating excellent joining properties. These findings highlight the elimination of the joining interlayer, which might be ideal for practical applications because the absence of a joining filler helped preserve the excellent SiC mechanical properties of the joint.</P>

Joining of SiC_f/SiC using polycarbosilane and polysilazane preceramic mixtures

Jeong, Dong-Hyuk,Septiadi, Arifin,Fitriani, Pipit,Yoon, Dang-Hyok Elsevier 2018 CERAMICS INTERNATIONAL Vol.44 No.9

<P><B>Abstract</B></P> <P>Polycarbosilane (PCS)/polysilazane (PSZ) preceramic mixtures with weight ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 were used as a filler for the joining of SiC<SUB>f</SUB>/SiC to obtain high purity SiC at the joining region. SiC<SUB>f</SUB>/SiC was fabricated by the electrophoretic infiltration of a SiC-based matrix phase into Tyranno SA3 SiC fabrics followed by hot-pressing at 1750 °C under 20 MPa for 2 h in an Ar atmosphere. Microstructural analysis confirmed a sound join without cracks after joining at 1750 °C for 2 h under a pressure of 10 MPa. SiC was the only phase remaining at the joint when PCS was used, while a small amount of Si<SUB>3</SUB>N<SUB>4</SUB> along with the main SiC were observed in the join using PSZ. The flexural strengths of the butt-joint SiC<SUB>f</SUB>/SiC were 120 and 137 MPa for the samples joined using a pure PCS and PSZ at 1750 °C, respectively, whereas those joined using the mixture fillers showed relatively lower strength.</P>

Fabrication of tubular SiC_f/SiC using different preform architectures by electrophoretic deposition and hot pressing

Fitriani, Pipit,Sharma, Amit Siddharth,Septiadi, Arifin,Park, Ji-Yeon,Yoon, Dang-Hyok Elsevier 2017 Ceramics international Vol.43 No.10

<P><B>Abstract</B></P> <P>This paper reports the processing feasibility of electrophoretic deposition combined with hot pressing in the fabrication of dense tubular SiC<SUB>f</SUB>/SiC composites using a cylindrical mold. A simulation of pressure distribution using ANSYS software was performed by varying the angular inclinations in a cylindrical mold with an ‘out → in’ configuration so as to ensure a maximum and uniform conversion of vertical hot press force to the lateral side of a centrally-located preform through graphite powder. The simulation revealed an inhomogeneous pressure distribution along the height of the preform, which could be minimized by mold optimization to achieve a more uniform tube density. To verify this, two different preform architectures such as 0/90° woven 2-D fabric rolled in a jelly state and filament winding with two plies having an inter-ply angle of 55° were hot-pressed using a mold fabricated based on the simulation after infiltrating the matrix phase by electrophoretic deposition. The density of the tube could be increased with more uniform microstructures. Although the tube using a filament winding preform exhibited a lower flexural strength (105MPa) and relative density (90%) than those with the preform rolled in a jelly state (221MPa, 95%), the results revealed a high degree of fiber pull-out due to the PyC coating on the SiC fiber.</P>