| With automobile exhaust pollution growing, the government enacted emission regulations more stringent. At present, the ceramic honeycomb and the metal honeycomb are widely used in catalyst, but there are some shortcomings in them. It has been difficult to reach the stringent requirements of emissions standards. Researching and developing a new generation of catalyst materials become imperative. That is in order to improve the catalytic converter purification efficiency and service life. In this study, as the current ceramic honeycomb and metal honeycomb carriers has their problems, a method is presented for making ceramics/metal composite of the honeycomb material, which has the advantages of both ceramic and metal monolithic.The paper presented:adding Al2O3 powder in metal powder prepared Al2O3/ iron-based honeycomb, that is use of mixing-extrusion-sintering. The process of extrusion-sintering honeycomb and analysis of microstructure and performance were studied, research and results are as follows:(1) By mixing, Al2O3 powder is added in the metal powder, and then Al2O3/ iron-based honeycomb is manufactured by extrusion-sintering.(2) During extrusion, the factors on extruding are explored. The quality of metal honeycomb formability is affected extrusion dies, feeding rings, mix ratio, etc. In experiment, the best choice is 32.4mm or 32.2mm for feeding rings, the best ratio of solid powder was 80% and 81%.(3) The influence of sintering conditions was analyed on Al2O3/iron-based honeycomb. The results show that:on the same conditions of sintering atmosphere, if the sintering temperature was increased or sintering time was prolonged, the honeycombs volumetric shrinkage and apparent density would be increased. Sintered honeycomb in hydrogen is denser than sintered honeycomb in argon. The optimum sintering conditions in argon gas is 1200℃ for 120min.(4) In argon, the volume shrinkage and apparent density increased and decreased with Al2O3 content increasing.5% Al2O3 reached the top. Al2O3 content is not more than 5%, which can increase the rate of antioxidation. It makes the matrix phase sinter closer.(5) The structure of sintered Al2O3/iron-based honeycomb was analyzed. For Al2O3/iron-based honeycomb sintered in a hydrogen atmosphere, the matrix phase is a solid solution of y-Fe (NiCr). Al2O3 is present in the sintered mesh gap. There is low-melting compound SiO2; in argon, Al2O3/iron-based honeycomb occurs oxidation. Cr is oxidized from the matrix phase γ-Fe (NiCr). The matrix phase becomes y-Fe (Ni). Al2O3 exists around the grid and SiO2 appears.(6) In the experimental, Al2O3/iron-based honeycomb is determined by structural parameters, surface area, surface adsorption, oxidation resistance and mechanical performance. The results showed that:there are many pores in cellular carrier surface, which makes the honeycomb have the larger specific surface area and improve the binding properties with the catalyst. With the Al2O3 content increased, the surface adsorption of cellular carrier is enhanced and oxidation resistance is also increases. The mechanical properties of the sintered honeycomb in hydrogen is 2-3 times strength than the sintered honeycomb in argon; in argon,5% Al2O3/iron-based honeycomb reached 25.8MPa on sintering temperature 1200℃ is the highest strength. |
PDF Full Text Request