Cordierite, silicon carbides

Foam monoliths can be produced from a broad variety of materials. Commercially available are ceramic foams made of alumina, mullite, cordierite, silicon carbide, or zirconia, but numerous other oxides, carbides, nitrides, and... 

Use of the ceramic honeycomb packing structure in the recuperator keeps fuel and air substantially isolated as they travel through the recuperator. Various ceramic materials such as cordierite, mullite, alumina and silicon carbide can be used to fabricate honeycomb beds. While metallic materials have the potential to be used in honeycomb bed, corrosion resistance is a major issue... 

DPFs are important aftertreatment devices, enabling significant reduction in the emissions of PM. Typically, the filters are made of cordierite or silicon carbide materials, and can be either coated with a catalyst or left uncoated. The exhaust stream is forced to flow from one channel of the filter to an adjacent channel (see Fig. 37) the PM is filtered out by the wall of the filter. 

Ceramic Cordierite Steatite Silicon Carbide 1400 F 50 High temperature. Flexible. Energy efficient Prone to contaminants... 

An exploratory study was carried out with respect to the performance of a copper fuel additive in combination with monolithic wall flow filters for the removal of soot firom diesel exhaust gas. Cordierite filters, copper coated cordierite filters, and silicon carbide filters were studied. Model experiments have been performed to investigate the influence of contact between soot and catalyst on the oxidation rate. 

Metal based fuel additives, such as Ce [3], Cu [4, 5], Fe [6], and Mn [7, 8, 9] have been studied for use in combination with a particulate filter. In general, a wall flow monolith is applied as a particulate filter in this kind of operations. In this study the performance of a copper fuel additive in combination with a cordierite wall flow monolithic filter is compared with that of copper coated wall flow monolithic filters. Furthermore, the performance of a silicon carbide wall flow monolithic filter was compared with that of a cordierite one. 

The influence of the oven temperature on the collection behaviour has also been investigated. Several experiments have been performed with blank traps of cordierite and of silicon carbide, at different collection temperatures. For all these experiments, the additive concentration was 100 ppm. These experiments are listed in Table 2. 

Different refractory ceramics are used for the filter matrix. Most common are cordierite-, aluminum titanate-, and silicon carbide-based products [15, 17-21]. Typical physical properties for these materials are provided in Table 20.1. AU materials can withstand very high temperatures. Key differences between these... 

Aluminum titanate composition Cordierite composition Silicon carbide... 

Lanthanum chromite perovskite is another catalyst deposited on silicon carbide and cordierite honeycombs with the aim to investigate the oxidation of soot [56]. The perovskite was synthesized using a combustion synthesis method and showed promising activity. 

Honeycombs made of different materials (cordierite, mulUte, muUite-zirconia, alumina, silicon carbide, yttrium-stabilized zirconia) have been supplied by CTI Company [8] as supports to prepare catalysts for lab-scale reactors. They present square channels and a total volume between 1 and 2 cm. The external shape can be parallelepiped or cylindrical. The preparation of square-shaped monoliths for H2O2 decomposition has been presented at the previous Catalyst Preparation Symposium [5], focusing on the influence of the washcoat procedure and the nature of the active phase on the catalytic activity. Figure 4-b displays one example of such catalysts, as received and after washcoating, impregnation and reduction steps. 

Figure 7 displays the XRD profile of Pt-based catalysts prepared on cordierite or silicon carbide monoliths. The formation of metallic platinum is clearly evidenced from the profile of Pt diffraction peaks the average size is estimated about 13 nm. 

In addition to the initial work in the alumina and mullite matrix systems previously mentioned, SiC whiskers have also been used to reinforce other ceramic matrices such as silicon nitride,9-13 glass,14 15 magnesia-alumina spinel,16 cordierite,17 zirconia,18 alumina/zirconia,18 19 mullite/zirconia,18-21 and boron carbide.22 A summary of the effect of SiC whisker additions on the mechanical properties of various ceramics is given in Table 2.1. As shown, the addition of whiskers increases the fracture toughness of the ceramics in all cases as compared to the same monolithic materials. In many instances, improvements in the flexural strengths were also observed. Also important is the fact that these improvements over the monolithic materials are retained at elevated temperatures in many cases. 

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