Pipit Fitriani | Yeungnam University (original) (raw)

Papers by Pipit Fitriani

Journal of the European Ceramic Society

This study examined the joining of monolithic SiC by Si-C reaction bonding using a 100 µm-thick f... more This study examined the joining of monolithic SiC by Si-C reaction bonding using a 100 µm-thick filler tape prepared using different SiC/C compositions (30/70, 50/50, and 70/30 wt. %). Joining was performed at 1450, 1500, and 1550ºC for 1 h in a vacuum without pressure after inserting the filler tape followed by molten-Si infiltration. The sample joined at 1500ºC using a SiC/C=70/30 filler tape revealed a dense joint morphology without pores or cracks, showing the highest joint strength of 254 MPa. A larger amount of SiC in the filler tape resulted in less residual Si at the joining interface and higher joint strength. Moreover, the distribution of residual stresses at the joint was simulated using finite element analysis, which was well-suited to experimental observations based on micro-Raman spectroscopy.

Research and reviews: journal of material sciences, Dec 26, 2017

Journal of Nuclear Materials, May 1, 2018

SiC f /SiC composites containing three different types of sintering additives viz. Scnitrate, Al ... more SiC f /SiC composites containing three different types of sintering additives viz. Scnitrate, Al 2 O 3-Sc 2 O 3 , and Al 2 O 3-Y 2 O 3 , were subjected to ion irradiation using 0.2 MeV H + ions with a fluence of 3×10 20 ions/m 2 at room temperature. Although all composites showed volumetric swelling upon ion irradiation, SiC f /SiC with Sc-nitrate showed the smallest change followed by those with the Al 2 O 3-Sc 2 O 3 and Al 2 O 3-Y 2 O 3 additives. In particular, SiC f /SiC containing the conventional Al 2 O 3-Y 2 O 3 additive revealed significant microstructural changes, such as surface roughening and the formation of cracks and voids, resulting in reduced fiber pullout upon irradiation. On the other hand, the SiC f /SiC with Scnitrate showed the highest resistance against ion irradiation without showing any macroscopic changes in surface morphology and mechanical strength, indicating the importance of the sintering additive in NITE-based SiC f /SiC for nuclear structural applications.

Research and reviews: journal of material sciences, Dec 27, 2017

physica status solidi (a)

Two‐dimensional titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nano... more Two‐dimensional titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nanosheets were synthesized by etching the Ti3AlC2 MAX phase using two kinds of etchants: potassium hydroxide (KOH) base and hydrofluoric (HF) acid. This study aimed to reduce the environmental side‐effects caused by the etchant in fabricating MXene nanosheets to extract strontium ions (Sr2+) from nuclear wastewater. Ti3C2Tx MXene synthesized using alkaline KOH etchant showed a 99% Sr2+ removal rate, which is much higher than that synthesized using the conventional HF etchant (82%). The enhanced Sr2+ removal rate associated with KOH etching was explained by unique surface termination, which offers more active adsorption sites for Sr2+ by the partial hydrolysis of Ti–C bonds on the surface of MXene nanosheets.This article is protected by copyright. All rights reserved.

Physical Chemistry Chemical Physics

Nitrogen and oxygen-based functionalized carbon dots (CDs) surfaces have attracted significant at... more Nitrogen and oxygen-based functionalized carbon dots (CDs) surfaces have attracted significant attention due to their ability to tailor the optical and electronic properties of CDs.

Indonesian Journal of Chemistry

This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sinte... more This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sintering by combining it with polysilazane (PSZ). SiC was mixed with PSZ in a 1:1 weight ratio and sintered at 1600, 1700, and 1800 °C in a hot-pressing furnace. A satisfactory density was obtained at sintering temperatures > 1600 °C. The grain sizes of the SiC/PSZ composites sintered at 1700 and 1800 °C were 112 and 125 nm, respectively. The grain shape of the SiC/PSZ composite sintered at 1700 °C was circular and mainly similar to the initial shape of the SiC powder. Grain shape accommodation was observed at a sintering temperature of 1800 °C. It is suggested that different sample shapes were affected by different liquid phase formations. Silicon oxynitride (Si2N2O) was formed and played an important role in densification and microstructure generation.

Journal of the European Ceramic Society, 2018

We report microstructural evaluation in proton-irradiated SiC f /SiC up to a fluence level of 10 ... more We report microstructural evaluation in proton-irradiated SiC f /SiC up to a fluence level of 10 18 p + /m 2 (E = 20 MeV) performed at the Korea Multipurpose Accelerator Complex (KOMAC). To fabricate the SiC f /SiC, a SiC-based matrix with two different sintering additives, Sc-nitrate and Al 2 O 3-Y 2 O 3 , were infiltrated into the Tyranno ® SiC preform by electrophoretic deposition and subsequent hot pressing. Scanning (SEM) and high resolution (HREM) electron microscopy was used to probe crack formation, pore generation and surface amorphization upon irradiation. SiC matrix was comparatively more crack-resistant in the SiC f /SiC with Scnitrate than that with Al 2 O 3-Y 2 O 3. Subsurface porosity evolved in the form of continuous bands for Al 2 O 3-Y 2 O 3 and discrete pockets for Sc-nitrate additives. Selective leaching of Si from the grain surface leads to the formation of a graded structure and surface amorphization. Irradiation-induced roughness on the fibers facilitates easy debonding at the SiC f-PyC coating interface but no significant changes in the flexural behavior were observed.

Journal of the European Ceramic Society, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of the European Ceramic Society, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of the European Ceramic Society, 2019

SiC monoliths containing 5 wt.% Al 2 O 3-Y 2 O 3 additive were joined using a thin Ti 3 AlC 2, Ti... more SiC monoliths containing 5 wt.% Al 2 O 3-Y 2 O 3 additive were joined using a thin Ti 3 AlC 2, TiC, or Ti filler. After joining at 1900°C for 5 h under 3.5 MPa, the joint properties were compared in terms of the microstructure, phase evolution, joining strength, and possible elimination of the joining layer. Although all samples showed a sound joint, the microstructure differed according to the filler. SiC joined with Ti 3 AlC 2 filler showed an indistinguishable joining interface due to the filler decomposition followed by solid-state diffusion into the SiC base, whereas TiC filler remained at the interface without showing decomposition or diffusion. In contrast, the Ti filler showed a possible elimination of the joining layer because of the diffusion of Ti and the formation of TiC. The mean joining strengths for the Ti 3 AlC 2 , TiC, and Ti fillers were 300, 234, and 248 MPa, respectively, which were comparable to that of the base SiC material (250 MPa). with the base material [13]. Based on above background, this study compared the microstructure, phase generation, joining strength, and

Ceramics International, 2018

Polycarbosilane (PCS)/polysilazane (PSZ) preceramic mixtures with weight ratios of 100/0, 75/25, ... more 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 f /SiC to obtain high purity SiC at the joining region. SiC f /SiC was fabricated by the electrophoretic infiltration of a SiC-based matrix phase into Tyranno SA3 SiC fabrics followed by hotpressing at 1750 o C under 20 MPa for 2 h in an Ar atmosphere. Microstructural analysis confirmed a sound join without cracks after joining at 1750 o 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 3 N 4 along with the main SiC were observed in the join using PSZ. The flexural strengths of the butt-joint SiC f /SiC were 120 and 137 MPa for the samples joined using a pure PCS and PSZ at 1750 o C, respectively, whereas those joined using the mixture fillers showed relatively lower strength.

Ceramics International, 2019

We demonstrate that AC-EPD, using an aqueous slurry system followed by sintering in air, is an ef... more We demonstrate that AC-EPD, using an aqueous slurry system followed by sintering in air, is an effective technique to form thick ceramic coatings on porous Si-SiC cellular ceramic substrates. As an example, CeO 2 particles with high surface area dispersed in water have been deposited successfully on Si-SiC foams by optimizing the zeta potential and dispersion conditions. Moreover, the parameters for AC-EPD were determined by controlling voltage, frequency, time, and degree of signal asymmetry to minimize water electrolysis in this aqueous system. The microstructure of CeO 2 layer has been controlled by adjusting sintering conditions to obtain porous and dense layers at 1200 and 1400 °C, respectively. The grain growth of the CeO 2 deposit upon the heat treatment was explained by the diffusion of SiO 2 into the CeO 2 coating layer, which resulted in a firm joining with the Si-SiC substrate.

Journal of the European Ceramic Society, 2018

This paper reports the joining of SiC monoliths using a thin MAX phase tape filler, such as Ti3Al... more This paper reports the joining of SiC monoliths using a thin MAX phase tape filler, such as Ti3AlC2 and Ti3SiC2, 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 Ti3AlC2 filler. The base SiC monolith, showing ≥ 99% density, was fabricated by hot pressing SiC powder after adding 5 wt. % Al2O3-Y2O3 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 o C using a thin Ti3AlC2 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.

Ceramics International, 2018

This study examined the joining of SiC fiber-reinforced SiC matrix composites (SiC f /SiC) using ... more This study examined the joining of SiC fiber-reinforced SiC matrix composites (SiC f /SiC) using a Ti 3 AlC 2 MAX phase filler and the possibility of eliminating the joining layer via solidstate diffusion upon the decomposition of Ti 3 AlC 2. The base SiC f /SiC was fabricated by electrophoretic deposition (EPD) combined with hot pressing after adding a 10 wt. % Al 2 O 3-Y 2 O 3 sintering additive. Two types of base SiC f /SiC with a density of 93 and 96 % were prepared by hot pressing at 1750 o C without and with SiC tape insertion, respectively, followed by joining at 1700 or 1900 o C for 5 h under 3.5 MPa in an Ar atmosphere. The SiC f /SiC with tape insertion showed feasible elimination of the joining layer after joining at 1900 o C, whereas the composite joined at 1700 o C revealed the presence of a joining filler due to incomplete decomposition of the Ti 3 AlC 2 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 f /SiC joints were explained by the surface roughness, microstructure, and phase evolution upon decomposition of the Ti 3 AlC 2 filler.

Journal of the Korean Ceramic Society, 2017

SiC 2 , indicating the joining by solid-state diffusion. The results showed sound joining interfa... more SiC 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

Ceramics International, 2017

This study examined the processing feasibility of electrophoretic deposition (EPD), as an effecti... more This study examined the processing feasibility of electrophoretic deposition (EPD), as an effective matrix infiltration method, in conjunction with hot-pressing to fabricate dense and tough SiC f /SiC materials. Flat and tubular specimens were fabricated by hot pressing at 1750°C and 20 MPa after infiltrating a SiC-based matrix phase into Tyranno ® SA3 SiC fabrics, which can be used as the core structural components for the next generation fission reactors and as blanket materials for future fusion reactors. For the tubular specimens, two types of preforms were compared: filament wound and jelly-rolled with different woven structures. The incorporation of SiC green tapes between the successive layers of SiC fabrics allowed better control over the composite density and pore distribution. The macro-architecture of the composites was optimized in terms of the slurry composition, sintering additives, and phase evolution. Fractography revealed considerable debonding at the SiC fiber-PyC coating interface and fiber pull-out with pronounced tail extension behavior when tested in flexure. Joining of the flat-tube and flat-flat SiC f /SiC was performed using a range of filler systems; the structures integrated using the Ti-based MAX fillers at 1750°C and 3.5 MPa for 1-2 h soaking time are discussed.

Ceramics International, 2017

This study examined the effects of post-sintering heat treatment on enhancing the toughness of Si... more This study examined the effects of post-sintering heat treatment on enhancing the toughness of SiC f /SiC composites. Commercially available Tyranno ® SiC fabrics with contiguous dual 'PyC (inner)-SiC (outer)' coatings deposited on the SiC fibers were infiltrated with a SiC + 10 wt% Al 2 O 3-Y 2 O 3 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 theo was achieved by hot pressing at 1750°C, 20 MPa for 2 h in an Ar atmosphere. Sintered composites were then subjected to isothermal annealing treatment at 1100, 1250, 1350, and 1750°C for 5 h 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 f /SiC composites.

Journal of the European Ceramic Society, 2017

Please cite this article in press as: P. Fitriani, et al., Fabrication of tough SiC f /SiC compos... more Please cite this article in press as: P. Fitriani, et al., Fabrication of tough SiC f /SiC composites by electrophoretic deposition using a fabric coated with FeO-catalyzed phenolic resin,

Journal of the Korean Ceramic Society, 2015

This study examined carbon layer coating on silicon carbide (SiC) fibers by utilizing solid-state... more This study examined carbon layer coating on silicon carbide (SiC) fibers by utilizing solid-state and wet chemistry routes to confer toughness to the fiber-reinforced ceramic matrix composites, as an alternative to the conventional pyrolytic carbon (PyC) interphase layer. Electrophoretic deposition (EPD) of carbon black nanoparticles using both AC and DC current sources, and the vacuum infiltration of phenolic resin followed by pyrolysis were tested. Because of the use of a liquid phase, the vacuum infiltration resulted in more uniform and denser carbon coating than the EPD routes with solid carbon black particles. Thereafter, vacuum infiltration with controlled variation in phenolic resin concentration, as well as the iterations of infiltration steps, was improvised to produce a homogeneous carbon coating having a thickness of several hundred nanometers on the SiC fiber. Conclusively, it was demonstrated that the carbon coating on the SiC fiber could be achieved using a simpler method than the conventional chemical vapor deposition technique.

Journal of the European Ceramic Society

This study examined the joining of monolithic SiC by Si-C reaction bonding using a 100 µm-thick f... more This study examined the joining of monolithic SiC by Si-C reaction bonding using a 100 µm-thick filler tape prepared using different SiC/C compositions (30/70, 50/50, and 70/30 wt. %). Joining was performed at 1450, 1500, and 1550ºC for 1 h in a vacuum without pressure after inserting the filler tape followed by molten-Si infiltration. The sample joined at 1500ºC using a SiC/C=70/30 filler tape revealed a dense joint morphology without pores or cracks, showing the highest joint strength of 254 MPa. A larger amount of SiC in the filler tape resulted in less residual Si at the joining interface and higher joint strength. Moreover, the distribution of residual stresses at the joint was simulated using finite element analysis, which was well-suited to experimental observations based on micro-Raman spectroscopy.

Research and reviews: journal of material sciences, Dec 26, 2017

Journal of Nuclear Materials, May 1, 2018

SiC f /SiC composites containing three different types of sintering additives viz. Scnitrate, Al ... more SiC f /SiC composites containing three different types of sintering additives viz. Scnitrate, Al 2 O 3-Sc 2 O 3 , and Al 2 O 3-Y 2 O 3 , were subjected to ion irradiation using 0.2 MeV H + ions with a fluence of 3×10 20 ions/m 2 at room temperature. Although all composites showed volumetric swelling upon ion irradiation, SiC f /SiC with Sc-nitrate showed the smallest change followed by those with the Al 2 O 3-Sc 2 O 3 and Al 2 O 3-Y 2 O 3 additives. In particular, SiC f /SiC containing the conventional Al 2 O 3-Y 2 O 3 additive revealed significant microstructural changes, such as surface roughening and the formation of cracks and voids, resulting in reduced fiber pullout upon irradiation. On the other hand, the SiC f /SiC with Scnitrate showed the highest resistance against ion irradiation without showing any macroscopic changes in surface morphology and mechanical strength, indicating the importance of the sintering additive in NITE-based SiC f /SiC for nuclear structural applications.

Research and reviews: journal of material sciences, Dec 27, 2017

physica status solidi (a)

Two‐dimensional titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nano... more Two‐dimensional titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nanosheets were synthesized by etching the Ti3AlC2 MAX phase using two kinds of etchants: potassium hydroxide (KOH) base and hydrofluoric (HF) acid. This study aimed to reduce the environmental side‐effects caused by the etchant in fabricating MXene nanosheets to extract strontium ions (Sr2+) from nuclear wastewater. Ti3C2Tx MXene synthesized using alkaline KOH etchant showed a 99% Sr2+ removal rate, which is much higher than that synthesized using the conventional HF etchant (82%). The enhanced Sr2+ removal rate associated with KOH etching was explained by unique surface termination, which offers more active adsorption sites for Sr2+ by the partial hydrolysis of Ti–C bonds on the surface of MXene nanosheets.This article is protected by copyright. All rights reserved.

Physical Chemistry Chemical Physics

Nitrogen and oxygen-based functionalized carbon dots (CDs) surfaces have attracted significant at... more Nitrogen and oxygen-based functionalized carbon dots (CDs) surfaces have attracted significant attention due to their ability to tailor the optical and electronic properties of CDs.

Indonesian Journal of Chemistry

This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sinte... more This paper reports a route to suppress the grain growth in silicon carbide (SiC) during its sintering by combining it with polysilazane (PSZ). SiC was mixed with PSZ in a 1:1 weight ratio and sintered at 1600, 1700, and 1800 °C in a hot-pressing furnace. A satisfactory density was obtained at sintering temperatures > 1600 °C. The grain sizes of the SiC/PSZ composites sintered at 1700 and 1800 °C were 112 and 125 nm, respectively. The grain shape of the SiC/PSZ composite sintered at 1700 °C was circular and mainly similar to the initial shape of the SiC powder. Grain shape accommodation was observed at a sintering temperature of 1800 °C. It is suggested that different sample shapes were affected by different liquid phase formations. Silicon oxynitride (Si2N2O) was formed and played an important role in densification and microstructure generation.

Journal of the European Ceramic Society, 2018

We report microstructural evaluation in proton-irradiated SiC f /SiC up to a fluence level of 10 ... more We report microstructural evaluation in proton-irradiated SiC f /SiC up to a fluence level of 10 18 p + /m 2 (E = 20 MeV) performed at the Korea Multipurpose Accelerator Complex (KOMAC). To fabricate the SiC f /SiC, a SiC-based matrix with two different sintering additives, Sc-nitrate and Al 2 O 3-Y 2 O 3 , were infiltrated into the Tyranno ® SiC preform by electrophoretic deposition and subsequent hot pressing. Scanning (SEM) and high resolution (HREM) electron microscopy was used to probe crack formation, pore generation and surface amorphization upon irradiation. SiC matrix was comparatively more crack-resistant in the SiC f /SiC with Scnitrate than that with Al 2 O 3-Y 2 O 3. Subsurface porosity evolved in the form of continuous bands for Al 2 O 3-Y 2 O 3 and discrete pockets for Sc-nitrate additives. Selective leaching of Si from the grain surface leads to the formation of a graded structure and surface amorphization. Irradiation-induced roughness on the fibers facilitates easy debonding at the SiC f-PyC coating interface but no significant changes in the flexural behavior were observed.

Journal of the European Ceramic Society, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of the European Ceramic Society, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Journal of the European Ceramic Society, 2019

SiC monoliths containing 5 wt.% Al 2 O 3-Y 2 O 3 additive were joined using a thin Ti 3 AlC 2, Ti... more SiC monoliths containing 5 wt.% Al 2 O 3-Y 2 O 3 additive were joined using a thin Ti 3 AlC 2, TiC, or Ti filler. After joining at 1900°C for 5 h under 3.5 MPa, the joint properties were compared in terms of the microstructure, phase evolution, joining strength, and possible elimination of the joining layer. Although all samples showed a sound joint, the microstructure differed according to the filler. SiC joined with Ti 3 AlC 2 filler showed an indistinguishable joining interface due to the filler decomposition followed by solid-state diffusion into the SiC base, whereas TiC filler remained at the interface without showing decomposition or diffusion. In contrast, the Ti filler showed a possible elimination of the joining layer because of the diffusion of Ti and the formation of TiC. The mean joining strengths for the Ti 3 AlC 2 , TiC, and Ti fillers were 300, 234, and 248 MPa, respectively, which were comparable to that of the base SiC material (250 MPa). with the base material [13]. Based on above background, this study compared the microstructure, phase generation, joining strength, and

Ceramics International, 2018

Polycarbosilane (PCS)/polysilazane (PSZ) preceramic mixtures with weight ratios of 100/0, 75/25, ... more 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 f /SiC to obtain high purity SiC at the joining region. SiC f /SiC was fabricated by the electrophoretic infiltration of a SiC-based matrix phase into Tyranno SA3 SiC fabrics followed by hotpressing at 1750 o C under 20 MPa for 2 h in an Ar atmosphere. Microstructural analysis confirmed a sound join without cracks after joining at 1750 o 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 3 N 4 along with the main SiC were observed in the join using PSZ. The flexural strengths of the butt-joint SiC f /SiC were 120 and 137 MPa for the samples joined using a pure PCS and PSZ at 1750 o C, respectively, whereas those joined using the mixture fillers showed relatively lower strength.

Ceramics International, 2019

We demonstrate that AC-EPD, using an aqueous slurry system followed by sintering in air, is an ef... more We demonstrate that AC-EPD, using an aqueous slurry system followed by sintering in air, is an effective technique to form thick ceramic coatings on porous Si-SiC cellular ceramic substrates. As an example, CeO 2 particles with high surface area dispersed in water have been deposited successfully on Si-SiC foams by optimizing the zeta potential and dispersion conditions. Moreover, the parameters for AC-EPD were determined by controlling voltage, frequency, time, and degree of signal asymmetry to minimize water electrolysis in this aqueous system. The microstructure of CeO 2 layer has been controlled by adjusting sintering conditions to obtain porous and dense layers at 1200 and 1400 °C, respectively. The grain growth of the CeO 2 deposit upon the heat treatment was explained by the diffusion of SiO 2 into the CeO 2 coating layer, which resulted in a firm joining with the Si-SiC substrate.

Journal of the European Ceramic Society, 2018

This paper reports the joining of SiC monoliths using a thin MAX phase tape filler, such as Ti3Al... more This paper reports the joining of SiC monoliths using a thin MAX phase tape filler, such as Ti3AlC2 and Ti3SiC2, 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 Ti3AlC2 filler. The base SiC monolith, showing ≥ 99% density, was fabricated by hot pressing SiC powder after adding 5 wt. % Al2O3-Y2O3 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 o C using a thin Ti3AlC2 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.

Ceramics International, 2018

This study examined the joining of SiC fiber-reinforced SiC matrix composites (SiC f /SiC) using ... more This study examined the joining of SiC fiber-reinforced SiC matrix composites (SiC f /SiC) using a Ti 3 AlC 2 MAX phase filler and the possibility of eliminating the joining layer via solidstate diffusion upon the decomposition of Ti 3 AlC 2. The base SiC f /SiC was fabricated by electrophoretic deposition (EPD) combined with hot pressing after adding a 10 wt. % Al 2 O 3-Y 2 O 3 sintering additive. Two types of base SiC f /SiC with a density of 93 and 96 % were prepared by hot pressing at 1750 o C without and with SiC tape insertion, respectively, followed by joining at 1700 or 1900 o C for 5 h under 3.5 MPa in an Ar atmosphere. The SiC f /SiC with tape insertion showed feasible elimination of the joining layer after joining at 1900 o C, whereas the composite joined at 1700 o C revealed the presence of a joining filler due to incomplete decomposition of the Ti 3 AlC 2 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 f /SiC joints were explained by the surface roughness, microstructure, and phase evolution upon decomposition of the Ti 3 AlC 2 filler.

Journal of the Korean Ceramic Society, 2017

SiC 2 , indicating the joining by solid-state diffusion. The results showed sound joining interfa... more SiC 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

Ceramics International, 2017

This study examined the processing feasibility of electrophoretic deposition (EPD), as an effecti... more This study examined the processing feasibility of electrophoretic deposition (EPD), as an effective matrix infiltration method, in conjunction with hot-pressing to fabricate dense and tough SiC f /SiC materials. Flat and tubular specimens were fabricated by hot pressing at 1750°C and 20 MPa after infiltrating a SiC-based matrix phase into Tyranno ® SA3 SiC fabrics, which can be used as the core structural components for the next generation fission reactors and as blanket materials for future fusion reactors. For the tubular specimens, two types of preforms were compared: filament wound and jelly-rolled with different woven structures. The incorporation of SiC green tapes between the successive layers of SiC fabrics allowed better control over the composite density and pore distribution. The macro-architecture of the composites was optimized in terms of the slurry composition, sintering additives, and phase evolution. Fractography revealed considerable debonding at the SiC fiber-PyC coating interface and fiber pull-out with pronounced tail extension behavior when tested in flexure. Joining of the flat-tube and flat-flat SiC f /SiC was performed using a range of filler systems; the structures integrated using the Ti-based MAX fillers at 1750°C and 3.5 MPa for 1-2 h soaking time are discussed.

Ceramics International, 2017

This study examined the effects of post-sintering heat treatment on enhancing the toughness of Si... more This study examined the effects of post-sintering heat treatment on enhancing the toughness of SiC f /SiC composites. Commercially available Tyranno ® SiC fabrics with contiguous dual 'PyC (inner)-SiC (outer)' coatings deposited on the SiC fibers were infiltrated with a SiC + 10 wt% Al 2 O 3-Y 2 O 3 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 theo was achieved by hot pressing at 1750°C, 20 MPa for 2 h in an Ar atmosphere. Sintered composites were then subjected to isothermal annealing treatment at 1100, 1250, 1350, and 1750°C for 5 h 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 f /SiC composites.

Journal of the European Ceramic Society, 2017

Please cite this article in press as: P. Fitriani, et al., Fabrication of tough SiC f /SiC compos... more Please cite this article in press as: P. Fitriani, et al., Fabrication of tough SiC f /SiC composites by electrophoretic deposition using a fabric coated with FeO-catalyzed phenolic resin,

Journal of the Korean Ceramic Society, 2015

This study examined carbon layer coating on silicon carbide (SiC) fibers by utilizing solid-state... more This study examined carbon layer coating on silicon carbide (SiC) fibers by utilizing solid-state and wet chemistry routes to confer toughness to the fiber-reinforced ceramic matrix composites, as an alternative to the conventional pyrolytic carbon (PyC) interphase layer. Electrophoretic deposition (EPD) of carbon black nanoparticles using both AC and DC current sources, and the vacuum infiltration of phenolic resin followed by pyrolysis were tested. Because of the use of a liquid phase, the vacuum infiltration resulted in more uniform and denser carbon coating than the EPD routes with solid carbon black particles. Thereafter, vacuum infiltration with controlled variation in phenolic resin concentration, as well as the iterations of infiltration steps, was improvised to produce a homogeneous carbon coating having a thickness of several hundred nanometers on the SiC fiber. Conclusively, it was demonstrated that the carbon coating on the SiC fiber could be achieved using a simpler method than the conventional chemical vapor deposition technique.