A novel sintering additive system for porous mullite-bonded SiC ceramics: High mechanical performance with controllable pore structure

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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Porous mullite composite with controlled pore structure processed using a freeze casting of TBA-based coal fly ash slurries

Resources Conservation and Recycling ◽

10.1016/j.resconrec.2009.12.012 ◽

2010 ◽

Vol 54 (11) ◽

pp. 816-820 ◽

Cited By ~ 35

Author(s):

T.Y. Yang ◽

H.B. Ji ◽

S.Y. Yoon ◽

B.K. Kim ◽

H.C. Park

Keyword(s):

Fly Ash ◽

Pore Structure ◽

Coal Fly Ash ◽

Freeze Casting ◽

Porous Mullite

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Rheological Behavior and Microstructure Characteristics of SCC Incorporating Metakaolin and Silica Fume

Materials ◽

10.3390/ma11122576 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2576 ◽

Cited By ~ 7

Author(s):

Gang Ling ◽

Zhonghe Shui ◽

Tao Sun ◽

Xu Gao ◽

Yunyao Wang ◽

...

Keyword(s):

Pore Structure ◽

Silica Fume ◽

Mechanical Performance ◽

Free Water ◽

Hydration Product ◽

Replacement Ratio ◽

Microstructure Characteristics ◽

Beneficial Effects ◽

Slump Flow ◽

Strength And Durability

This study explores the effects of metakaolin (MK) and silica fume (SF) on rheological behaviors and microstructure of self-compacting concrete (SCC). The rheology, slump flow, V-funnel, segregation degree (SA), and compressive strength of SCC are investigated. Microstructure characteristics, including hydration product and pore structure, are also studied. The results show that adding MK and SF instead of 4%, 6% and 8% fly ash (FA) reduces flowability of SCC; this is due to the fact that the specific surface area of MK and SF is larger than FA, and the total water demand increases as a result. However, the flowability increases when replacement ratio is 2%, as the small MK and SF particles will fill in the interstitial space of mixture and more free water is released. The fluidity, slump flow, and SA decrease linearly with the increase of yield stress. The total amount of SF and MK should be no more than 6% to meet the requirement of self-compacting. Adding MK or SF to SCC results in more hydration products, less Ca(OH)2 and refinement of pore structure, leading to obvious strength and durability improvements. When the total dosage of MK and SF admixture is 6%, these beneficial effects on workability, mechanical performance, and microstructure are more significant when SF and MK are applied together.

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Microstructure and mechanical performance of porous mullite ceramics added with TiO2

Ceramics International ◽

10.1016/j.ceramint.2019.12.078 ◽

2020 ◽

Vol 46 (6) ◽

pp. 8438-8443 ◽

Cited By ~ 1

Author(s):

Xiangong Deng ◽

Wanchun Zhang ◽

Jiaqiang Yin ◽

Chaoheng Deng ◽

Shaowei Zhang ◽

...

Keyword(s):

Mechanical Performance ◽

Porous Mullite ◽

Mullite Ceramics

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The Mechanical Properties and Chloride Resistance of Concrete Reinforced with Hybrid Polypropylene and Basalt Fibres

Materials ◽

10.3390/ma12152371 ◽

2019 ◽

Vol 12 (15) ◽

pp. 2371 ◽

Cited By ~ 4

Author(s):

Xinyu Hu ◽

Yihong Guo ◽

Jianfu Lv ◽

Jize Mao

Keyword(s):

Pore Structure ◽

Mechanical Performance ◽

Single Fibre ◽

Fibre Volume ◽

Negative Effects ◽

Basalt Fibre ◽

Structure Characteristics ◽

Chloride Resistance ◽

Hybrid Fibre ◽

Curing Age

This paper aims to investigate the effect of the polypropylene fibre (PP) and basalt fibre (BF), singly or in hybridization, on the workability, mechanical, chloride resistance and pore structure characteristics of concrete. Sixteen mixtures consisting of PP and BF, both at volume content of 0.0, 0.1, 0.2 and 0.3%, were fabricated, and the slump, compressive, splitting tensile, flexural and charge passed were tested. The results show the hybridization of the PP and BF can improve three types of strength of concrete in comparison to their single fibre. Nevertheless, the hybridization is not always conducive, and the synergy of fibres is proposed and divided into positive and negative effects. The combination of the PP and BF both at content of 0.1% achieves the best mechanical performance, and is recommended for practical usage. Incorporating fibres reduces the chloride resistance of concrete, and the hybridization is helpless to this phenomenon; even the reduction is intensified at a highly hybrid fibre volume. However, increasing the curing age can mitigate this adverse effect caused by fibres. Furthermore, the microstructures were explored to elucidate the macro-properties of concrete in terms of interface and pore structure.

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In vitro biodegradable and mechanical performance of biphasic calcium phosphate porous scaffolds with unidirectional macro-pore structure

Ceramics International ◽

10.1016/j.ceramint.2014.01.031 ◽

2014 ◽

Vol 40 (6) ◽

pp. 8293-8300 ◽

Cited By ~ 31

Author(s):

Dong-Hyun Kim ◽

Kyeong-Lok Kim ◽

Ho-Hwan Chun ◽

Tae-Wan Kim ◽

Hong-Chae Park ◽

...

Keyword(s):

Calcium Phosphate ◽

Pore Structure ◽

Biphasic Calcium Phosphate ◽

Mechanical Performance ◽

Porous Scaffolds

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Properties and Application of Oriented Porous SiC as Transpiration Cooling Materials

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.336-338.1109 ◽

2007 ◽

Vol 336-338 ◽

pp. 1109-1112 ◽

Cited By ~ 1

Author(s):

Jie Tang ◽

Yu Feng Chen ◽

Ji Guo Sun ◽

Hua Wang ◽

Hai Lin Liu ◽

...

Keyword(s):

Pore Structure ◽

Pore Size ◽

Cooling System ◽

Casting Process ◽

Solid Loading ◽

Transpiration Cooling ◽

Rocket Engines ◽

Intrinsic Permeability ◽

Sic Ceramics ◽

Porous Sic

This paper describes the fabrication of porous reaction-bonded SiC ceramics with radial directed pores and the application of these materials to transpiration cooling system of rocket engines. A special mold is designed for freeze-casting process to prepare SiC cylinders with radial directed pores. Green bodies with well-oriented pore structure are obtained from slurry with solid loading up to 47vol%. The pore size is in the level of several tens micron. Green bodies with various porosities are infiltrated with different amount of liquid Si. The intrinsic permeability of each sample is measured with air as flowing media. It is concluded that permeability has relationship with not only the porosity but also the pore structure of samples.

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Physical and Chemical Influence of Polyacrylate Latex on Cement Mortars

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.261-263.807 ◽

2011 ◽

Vol 261-263 ◽

pp. 807-811 ◽

Cited By ~ 1

Author(s):

Ye Tian ◽

Zong Jin Li ◽

Hong Yan Ma ◽

Xian Yu Jin ◽

Nan Guo Jin

Keyword(s):

Pore Structure ◽

Cement Hydration ◽

Bending Strength ◽

Mechanical Performance ◽

Air Entrainment ◽

Hydration Products ◽

Cement Mortars ◽

Cement Based Materials ◽

Physical And Chemical ◽

Chemical Influence

In this research, the physical and chemical influence of polyacrylate (PA) latex on cement-based materials were studied using polymer modified mortars with polymer/cement (P/C) ratios of 0%, 5% and 10%. Physically, the mechanical performance of PA latex modified mortars was investigated with compression toughness energy and bending strength. Further more, a comparison of the pore structure and porosity between PA latex modified and unmodified mortars was conducted. The chemical reactions between PA polymer and cement hydrates were clarified with thermogravimetric (TG) analysis. It can be concluded from this research that PA polymer can refine the pore structure of cement mortars and link the cement hydration products together chemically. While, at the same time, PA latex addition can cause air entrainment which will weaken the physical behavior of cement mortars. So there is an optimum P/C ratio to achieve the best mechanical properties. And in this research, the optimum P/C ratio is 5%.

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Effect of Structure on the Thermal-Mechanical Performance of Fully Ceramic Microencapsulated Fuel

Computation ◽

10.3390/computation8010013 ◽

2020 ◽

Vol 8 (1) ◽

pp. 13 ◽

Cited By ~ 1

Author(s):

Yi Zhou ◽

Zhong Xiao ◽

Shichao Liu ◽

Ping Chen ◽

Hua Pang ◽

...

Keyword(s):

Silicon Carbide ◽

Hoop Stress ◽

Mechanical Performance ◽

Maximum Temperature ◽

Sic Ceramics ◽

Decomposition Point ◽

The Matrix ◽

Maximum Hoop Stress ◽

Triso Particles ◽

Effect Of Structure

The effect of non-fuel part size on the thermal-mechanical performance of fully ceramic microencapsulated (FCMTM) Fuel was investigated, and the non-fuel part size was selected according to integrity maintaining of non-fuel part and silicon carbide (SiC) layers. The non-fuel part size can affect the FCMTM temperature and stress distribution greatly by changing the distance between tristructural isotropic (TRISO) particles. The maximum temperature of SiC matrix increased from 1220 K to 1450 K with the non-fuel part size increasing from 100 μm to 500 μm, and the matrix temperature of all the samples was lower than the decomposition point of SiC ceramics. The maximum hoop stress decreased with non-fuel part size, but the inner part exhibiteda crosscurrent trend. The inner part of the SiC matrix lost structure integrity because of the large hoop stress caused by the deformation of TRISO particles, however, the non-fuel parts of FCMTM pellet may maintain their integrity when the non-fuel part size was larger than 300 μm. SiC layers hoop stress increased with non-fuel part size, and the failure probability of SiC layer was lower than 2.2 × 10−4 for the FCMTM pellet with small non-fuel part size. The integrity of non-fuel and SiC layers can be maintained for the FCMTM pellet with the non-fuel part size from 300 μm to 400 μm.

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