Influence of clay content on microstructure and flexural strength of in situ reaction bonded porous SiC ceramics

Polycarbosilane (PCS) and SiC powders, in which PCS acted as binder, were adopted as starting materials to fabricate porous SiC ceramics. During pyrolysis, PCS experienced an organicinorganic transformation and bonded SiC powders at a low temperature of 1273K. The flexural strength of porous SiC ceramics increased with increasing PCS content and shaping pressure, while the porosity decreased with increasing the PCS content, shaping pressure and particle size of SiC powders. The fracture surface of porous SiC ceramics was observed.

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Polycarbosilane Conversion Bonded Porous SiC Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.280-283.1267 ◽

2007 ◽

Vol 280-283 ◽

pp. 1267-1270 ◽

Cited By ~ 1

Author(s):

Su Min Zhu ◽

Ruo Ding Wang ◽

Na Li ◽

Hong'an Xi ◽

Qin Li ◽

...

Keyword(s):

Flexural Strength ◽

Inert Atmosphere ◽

Pyrolysis Process ◽

Critical Feature ◽

Sic Ceramics ◽

Sic Particles ◽

Heat Treated ◽

Powder Compacts ◽

Porous Sic ◽

Bonding Technique

Porous silicon carbide (SiC) ceramics were fabricated by a polycarbosilane (PCS) conversion bonding technique, in which PCS was used as a binder to bond SiC particles with each other. In the preparing process, SiC particles were first coated with PCS, and then the powder compacts were heat-treated in an inert atmosphere. During the heat-treatment, the PCS decomposed and gradually converted to inorganic covalent solids composed mainly of Si-C networks. The pyrolysis process of PCS, the pore structures and flexural strength of the as-prepared specimens were analyzed and discussed. Preparing temperature as low as 1100°C was adopted in this process and the porous SiC ceramics with a flexural strength of 20 MPa at an open porosity of 43% was obtained. Since PCS was used as a binder, the critical feature of this technique was that the preparation of porous SiC body was achieved at a low temperature.

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Effect of Al(OH)3 Addition on the Properties of SiC/Al2O3 Composite Porous Ceramics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.1208 ◽

2013 ◽

Vol 821-822 ◽

pp. 1208-1212

Author(s):

Cheng Ying Bai ◽

Zhang Min Liu ◽

Ya Ni Jing ◽

Xiang Yun Deng ◽

Jian Bao Li ◽

...

Keyword(s):

Phase Composition ◽

High Temperature ◽

Mechanical Strength ◽

Porous Ceramics ◽

Reaction Bonding ◽

Sic Ceramics ◽

Porous Sic ◽

Bonding Characteristics ◽

Bonding Technique

SiC/Al2O3composite porous ceramics were prepared by an in situ reaction bonding technique and sintering in air with SiC and A1(OH)3as starting materials. The pores in the ceramics were formed by stacking particles of SiC and A12O3. The surface of SiC was oxidized to SiO2at high temperature. With further increasing the temperature, SiO2reacted with A12O3to form mullite. The reaction bonding characteristics, phase composition, and mechanical strength as well as microstructure of porous SiC ceramics were investigated.

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Effects of Composite Sintering Additives: Al(OH)3+Y2O3+CaF2 on the Performance of Porous Mullite Oxide-Bonded SiC Ceramics

10.21203/rs.3.rs-577272/v1 ◽

2021 ◽

Author(s):

Zihe Li ◽

Zixuan Chang ◽

Xinran Liu ◽

Weimin Zhao ◽

Xu Zhang ◽

...

Keyword(s):

Flexural Strength ◽

Phase Evolution ◽

Sintering Additives ◽

Additive System ◽

Air Atmosphere ◽

Sintering Additive ◽

Sic Ceramics ◽

Porous Mullite ◽

Sintering Mechanisms ◽

Porous Sic

Abstract A composite sintering additive system: Al(OH)3+Y2O3+CaF2 was proposed for porous mullite oxide-bonded SiC ceramics. Small variations of sintering additives have significant influences on the phase composition, pore shape/size, density and flexural strength. Samples sintered at 1550 ℃ for 4 h in the air atmosphere realized both good mullite densification and no detectable cristobalite phase, which was difficult to be achieved at the same time. Besides, the composite sintering additive system also promoted the formation of columnar shape mullite, which acts as a reinforcement. Flexural strength as high as 108 MPa was achieved at an apparent porosity of 40.3 vol%, which is higher than that sintered by SPS technique. Moreover, those additives also act as pore formers determining the shape and size of pores. Around 8.9 µm strip-like, 11.8 µm continuous channel-like and 4.1 µm irregular pores were obtained for Al(OH)3, Al(OH)3-Y2O3 and Al(OH)3-Y2O3-CaF2 added samples, respectively. Corresponding phase evolution, sintering mechanisms and pore formation models were established. This work provides a simple way to modify the phase, pore size/shape, and strength of mullite oxide-bonded porous SiC ceramics by properly selecting sintering additives without any additional pore formers.

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