TGA CHARACTERISTIC AND FABRICATION OF POROUS SiC CERAMICS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2863-2868
Author(s):  
SEONG HOON KIM ◽  
HAN KI YOON ◽  
SEON JIN KIM ◽  
YI HYUN PARK
Keyword(s):  
Particle Size ◽  
Carbon Fibers ◽  
High Strength ◽  
Porous Ceramics ◽  
Pressing Method ◽  
Sic Ceramics ◽  
Length Direction ◽  
Specific Temperature ◽  
Sic Composites ◽  
Porous Sic

The long-range aim of this research is to develop porous ceramics with high strength, excellent thermal resistance and chemical stability at high temperature in environmental industry. The C f / SiC was made by hot pressing method with SiC powder whose particle size is 50nm and less on the average also Al 2 O 3, Y 2 O 3 and SiO 2 as additive. The carbon fibers of oxidation property are investigated by TGA for finding out decarburization point. As a result, decarburization point selected the specific temperature of TGA curve and the C f/ SiC composites occurred perfectly decarburization at carbon fibers so the clearly porous SiC ceramics were formed many holes of 3-5µm diameters through length direction by its reaction.

Preparation and Characterization of Fe/SiC Ceramic-Metal Composites

2010 ◽  
Vol 434-435 ◽  
pp. 66-68 ◽  
Author(s):  
Zhong Sheng Liu ◽  
Gang Shao ◽  
De Liang Chen ◽  
Rui Zhang
Keyword(s):  
Bending Strength ◽  
Low Cost ◽  
High Hardness ◽  
High Strength ◽  
Precipitation Method ◽  
High Wear Resistance ◽  
Matrix Composites ◽  
Composite Powders ◽  
Pressing Method ◽  
Sic Composites

SiC is a perfect reinforced material, characteristic of high hardness, high wear- and corrosion-resistant property, and low cost. SiC-reinforced iron-matrix composites show high wear resistance, high hardness, high inflexibility and high strength, with wide applications as superior wear-resistant and high temperature materials. This paper reported a heterogeneous precipitation method to coat SiC with copper particles. The vacuum hot-pressing method was used to sinter the Fe/SiC composites with Cu-coated SiC powders. The techniques of XRD and SEM were used to characterize the compositions and microstructures of the samples. The Archimedes method was used to test the density. The results showed that SiC and Cu were homogeneously mixed in the composite powders obtained by the heterogeneous deposition method, and that the composites with 5wt% of SiC (Cu) obtained at 950°C have a high relative density of 96%, a high hardness of 4121 MPa and a high bending strength of 646 MPa. The enhanced properties of Fe/SiC composites could result from the improved interfacial consistency by using Cu-coated SiC powders, which could inhibit some adverse interfacial reactions.

Low Temperature Fabrication and Characterization of Porous SiC Ceramics Using Polycarbosilane as Binder

2007 ◽  
Vol 336-338 ◽  
pp. 1090-1092 ◽  
Author(s):  
Qing Song Ma ◽  
Xiao Dong Yu
Keyword(s):  
Particle Size ◽  
Low Temperature ◽  
Fracture Surface ◽  
Flexural Strength ◽  
Sic Ceramics ◽  
Fabrication And Characterization ◽  
Porous Sic

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.

Fabrication, Structure and Properties of Porous SiC Ceramics with High Porosity and High Strength

2010 ◽  
Vol 105-106 ◽  
pp. 608-611 ◽  
Author(s):  
Shao Feng Wang ◽  
Chang An Wang ◽  
Jia Lin Sun ◽  
Li Zhong Zhou ◽  
Yong Huang
Keyword(s):  
Compressive Strength ◽  
High Strength ◽  
Butyl Alcohol ◽  
Solid Loading ◽  
High Porosity ◽  
Reaction Bonding ◽  
Sintering Additive ◽  
Sic Ceramics ◽  
Tert Butyl Alcohol ◽  
Porous Sic

Porous SiC ceramics with high porosity and high strength were fabricated by gelcasting, with tert-butyl alcohol (TBA) as solvent, acrylamide (AM) as monomer, and in-situ reaction bonding with a-Al2O3 as sintering additive. SiC suspension with 10 vol% solid loading was successfully solidified by gel-casting to form high strength green body. The results showed that the compressive strength of the porous SiC ceramics increased with sintering temperature from 1300 to 1450°C, but porosity had little change, due to formation of more volume of cristobalite and mullite phases on the surface of SiC grains, accompanied by a large volume expansion effect. Very narrow single-peak distributions with about 2 mm median pore diameter could be found for the porous SiC ceramics. The porosity and compressive strength of the porous SiC ceramics sintered at 1450°C were 71.21 % and 12.14 MPa, respectively.

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

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.

scholarly journals Porous Design of SiCNWs/SiC Nanocomposites with High Strength and Low Thermal Conductivity

2021 ◽  
Author(s):  
Jing Ruan ◽  
Jinshan Yang ◽  
Jingyi Yan ◽  
Xiao You ◽  
Mengmeng Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Chemical Deposition ◽  
High Strength ◽  
Chemical Vapor Infiltration ◽  
Spherical Particles ◽  
Uniform Structure ◽  
Low Thermal Conductivity ◽  
Sic Composites ◽  
Porous Sic

Abstract Porous SiC composites with lightweight, high strength and low thermal conductivity design can be obtained by constructing porous silicon carbide nanowires (SiCNWs) network and controlling chemical vapor infiltration (CVI) process. The SiCNWs network with an optimized volume fraction (13.6%) and uniform structure is prepared by mixing SiCNWs and polyvinyl alcohol (PVA) firstly. SiCNWs reinforced porous SiC composite (SiCNWs/SiC) with a small uniform pore can be obtained by controlling the chemical deposition kinetics. The morphology of the grown SiC matrix, from the spherical particles to the hexagonal pyramid particles, can be influenced by the deposition parameters like temperature and reactive gas concentration. The strength of the lightweight SiCNWs/SiC composites reach 47.8 MPa with a porosity of 64% and thermal conductivity of 1.2 W/(m∙K), which shows the toughening effect and insulation design with low thermal conductivity.

Relation between Porosity and Permeability of Ceramic Membrane Supports

2006 ◽  
Vol 11-12 ◽  
pp. 39-42 ◽  
Author(s):  
Long Liang ◽  
Jian Bao Li ◽  
Hong Lin ◽  
Xiao Zhan Yang ◽  
Gang Feng Guo ◽  
...  
Keyword(s):  
Particle Size ◽  
Elevated Temperatures ◽  
Ceramic Membrane ◽  
Sic Ceramics ◽  
Sintering Time ◽  
Low Thermal Expansion ◽  
Dry Pressing ◽  
Porosity And Permeability ◽  
And Performance ◽  
Porous Sic

A membrane support provides mechanical strength to a membrane top layer to withstand the stress induced by the pressure difference applied over the entire membrane and must simultaneously have a low resistance to the filtrate flow. Due to their low thermal-expansion coefficient and good thermal-shock resistance as well as excellent mechanical and chemical stability at elevated temperatures, porous SiC ceramics have been widely used as catalyst supports and hot-gas or molten-metal filters. In this work, the influence of the particle size, sintering time and sintering temperature on the porosity and permeability of supports made by dry-pressing of micron-sized SiC powders is investigated. The present work presents a comparison of properties and performance data for samples made with different particle size. The effects of sintering time and temperature were analyzed in view of overall porosity and permeability. From calculations it becomes clear that optimum values exist for the material properties of the support.

Fabrication of Porous Cellular SiC Ceramics from Wood by Embedding in Si/SiO2 Powder Mixture

2007 ◽  
Vol 336-338 ◽  
pp. 1113-1116 ◽  
Author(s):  
Jung Soo Ha ◽  
Byong Gu Lim ◽  
Geum Hyun Doh ◽  
In Aeh Kang
Keyword(s):  
Powder Mixture ◽  
Cellular Structure ◽  
Porous Ceramics ◽  
Conversion Degree ◽  
Sic Ceramics ◽  
Sic Ceramic ◽  
Melt Infiltration ◽  
Porous Sic ◽  
Full Conversion ◽  
Good Retention

Wood has strongly anisotropic cellular structure with 50-80 vol% porosity. It can be converted into porous ceramics (e.g., SiC, SiC/Si, TiC, C/C, and TiO2) replicating the wood structure by various processes. Previously porous cellular SiC ceramic was prepared by reaction of wood charcoal with gaseous SiO generated remotely from an equimolar mixture of Si and SiO2. In the present work, poplar charcoal was simply embedded in the powder mixture of Si and SiO2 and heated at 1600°C for 1 h in Ar to produce porous SiC. Samples were also prepared by infiltration of Si melt (1500-1600°C, 2 h) and vapor (1700°C, 2 h) into the charcoal for comparison. Samples prepared by Si melt infiltration showed 15-52% conversion to SiC. Samples prepared by Si vapor infiltration showed severe damage such that the conversion degree could not be measured. In contrast, samples prepared by the embedding process showed full conversion to SiC (mostly β form) with good retention of the cellular structure of the original wood. The embedding process is a simple and efficient way to produce porous cellular SiC from wood.

scholarly journals Porous Design of SiCNWs/SiC Nanocomposites with High Strength and Low Thermal Conductivity

2021 ◽  
Author(s):  
Jing Ruan ◽  
Jinshan Yang ◽  
Jingyi Yan ◽  
Xiao You ◽  
Mengmeng Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Chemical Deposition ◽  
High Strength ◽  
Chemical Vapor Infiltration ◽  
Spherical Particles ◽  
Uniform Structure ◽  
Low Thermal Conductivity ◽  
Sic Composites ◽  
Porous Sic

Abstract Porous SiC composites with lightweight, high strength and low thermal conductivity design can be obtained by constructing porous silicon carbide nanowires (SiCNWs) network and controlling chemical vapor infiltration (CVI) process. The SiCNWs network with an optimized volume fraction (13.6%) and uniform structure is prepared by mixing SiCNWs and polyvinyl alcohol (PVA) firstly. SiCNWs reinforced porous SiC composite (SiCNWs/SiC) with a small uniform pore can be obtained by controlling the chemical deposition kinetics. The morphology of the grown SiC matrix, from the spherical particles to the hexagonal pyramid particles, can be influenced by the deposition parameters like temperature and reactive gas concentration. The strength of the lightweight SiCNWs/SiC composites reach 47.8 MPa with a porosity of 64% and thermal conductivity of 1.2 W/(m∙K), which shows the toughening effect and insulation design with low thermal conductivity.

The Effect of Bond Phase Additive and Sintering Temperature on the Properties of Mullite Bonded Porous SiC Ceramics

2020 ◽  
Vol 978 ◽  
pp. 454-462
Author(s):  
Dulal Das ◽  
Nijhuma Kayal
Keyword(s):  
High Temperature ◽  
Structural Properties ◽  
Sintering Temperature ◽  
High Strength ◽  
Secondary Phases ◽  
Reaction Bonding ◽  
Sintering Additives ◽  
Sic Ceramics ◽  
Porous Sic ◽  
Very High

Currently, porous SiC ceramics have been a focus of interesting research in the field of porous materials due to their excellent structural properties, high strength, high hardness, and superb mechanical and chemical stabilities even at high temperatures and hostile atmospheres. Porous SiC ceramics have been considered as suitable candidate materials for catalyst supports [1-2], hot gas or molten metal filters [3], high temperature membrane reactors [4], thermal insulating materials [5], gas sensors [6] etc. Porous SiC ceramics are fabricated by various methods including partial sintering [7], carbothermal reduction [8-9], replication or pyrolysis of polymeric sponge [10-12], reaction bonding [13] etc. In all these methods SiC needs to be sintered which requires a very high temperature due to the strong covalent nature of the Si-C bond, selective sintering additives, expensive atmosphere, costly and delicate instrumentation. Processing of porous SiC ceramics at low temperature using a simple technique thus becomes necessary. Bonding of SiC can be done at low temperatures by use of different oxide and non-oxide secondary phases. They include silica, mullite, cordierite, silicon nitride, etc. Various sintering additives are used for the formation of variety of secondary oxide bond phases for formations for porous SiC [14-19] Choice of mullite as a bond for SiC has many advantages. Mullite possesses a high melting point (Tm= 1850°C) and a low oxygen diffusion coefficient (5.6 x 10-14 m2/sec at 50°C). It has a matching thermal expansion coefficient with SiC (CTEmullite= 5.3 ×10-6/K; CTESiC = 4.7 ×10-6/K at RT-1000 °C) and a high strength that can be retained up to a very high temperature. Different sources of aluminum, such as Al2O3, Al, AlN, and Al (OH)3 powders were used for the formation of mullite bonded porous SiC ceramics (MBSC) [20-21]. However, the mullitization temperature of 1550o C is still necessary. In this work, mullite bonded porous SiC ceramics were fabricated by an in situ reaction-bonding process; the mixture of clay and CaCO3 were chosen as sintering additives to lower the mullitization reaction between Al2O3 and oxidation-derived SiO2. The effect amount of alumina, sintering temperature and other sintering aids on material property such as porosity/pore size distribution mechanical and micro structural properties of porous oxide bonded SiC ceramics were studied.

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