SILICON CARBIDE FORMATION FROM NATURAL WOODS

Processing of cellular ceramics with anisotropic pore structure by using silicon infiltration into carbonized template was investigated. Biomorphic silicon carbide (bioSiC) was produced by using two different types of natural woods which are Kapur and Dark Red Meranti. Carbon template was produced from a pyrolysis process followed by an infiltration process of melting silicon to produce bioSiC. The samples were dried in an oven in order to remove the moisture of the samples. The pyrolysis was done in two stages at a temperature of 500°C followed by 850°C. This study was to investigate the effect of infiltration temperature in the formation of SiC composites. Two different infiltration temperatures of 1500°C and 1600°C were used with constant holding time of 1 hour. The characteristic of the biomorphic silicon carbide was analyzed using the TGA, FESEM and EDX analysis. A wide variety of microstructures, densities and porosities were found depending on the type of wood used. Instead of carbon, it was found that both woods also reacted with nitrogen gas, which reduced the formation of SiC. The density of samples was increased as the working temperature increased. Dark Red Meranti was found to be denser and exhibit higher porosity than Kapur due to the higher formation of SiC.

Effect of Infiltration Temperature on the Composition and Mechanical Property of RMI C/C-SiC Composite

C/C-SiC composites were prepared by reactive melt infiltration process at different temperatures. The composition, microstructures and mechanical properties of the composites were investigated. The results showed that infiltration temperature could affect composite’s properties through regulating the chemical composition and interfacial bonding strength of the composites. The C/C-SiC composite prepared at 1650°C exhibited the relatively highest performance with density of 2.24 g·cm-3 and SiC content of 31.44 vol.%. The flexural strength and the fracture toughness were 238MPa and 10.04 MPa·m1/2, respectively.

SiC/Cu Composite Prepared by Spontaneous Infiltration of Copper Alloy into Porous SiC Ceramic

A porous SiC ceramic reinforced copper-matrix composite was fabricated by spontaneous infiltration of molten Cu-24at%Si alloy into the reinforcement. The influence of process parameters on the infiltration behavior and microstructure of the as-prepared SiC/Cu composite investigations showed that infiltration temperature had an important influence on the infiltration behavior, and higher infiltration temperature which decreased the viscosity of molten Cu-24Si was beneficial to the penetration. Besides, the degree of infiltration increased with the increase of dwelling time at 1600°C. SiC particles were bonded together by sintering additives to form the porous reinforcement, which can be maintained after spontaneous infiltration. The interfacial bond between SiC and Cu-24Si alloy was tight, and no obvious interfacial reaction layer was observed in the as-prepared composite.

Preparation of Anti-Static Ceramics by Fe-Infiltration on Sintered Zirconia Body

Anti-static materials are widely used in the fields of textile, petrochemical processing, aerospace and electronics. An innovative processing method for fabricating anti-static ceramics has been developed based on Fe-infiltration on the sintered zirconia body. The sintered zirconia ceramics infiltrated by metal Fe in the inner atmosphere showed both perfect anti-resistive and mechanical properties. In this study, infiltration temperature and time was optimized to control the surface resistivity. It was shown that the lower surface resistivity could be obtained at higher infiltration temperature and longer infiltration time. However, the surface hardness was decreased. The surface resistivity reached 5.6×107Ω/ at 1300°C for 12 hours. The phase transformation and microstructure changes were characterized by XRD and SEM. The existence state of Fe was analyzed by EDS.

The Study on Preparation of a B4C/Al Composite Fabricated by the Sponge Impregnant Method

In this work, B4C porous ceramics reinforced alumium composite was fabricated by the sponge impregnant method and pressureless infiltration technique. The wettability of aluminum on B4C, the component and the wear resistance of the composite were studied .The result indicates that the infiltration temperature is determined 1200 centigrade and there are mainly Al, B4C, Al3BC , no AL4C3in the experimental composite, the wear resistance of B4C/AL composite is 25 to 30 times higher than that of the alumium.