Abstract
Five porous cordierite-mullite ceramics with similar porosity and different neck characteristics were prepared from Al(OH)3, magnesite, silica and clay using an in-situ pore-forming technique. The phase composition, pore and neck characteristics and strength of the porous ceramics were investigated by an X-ray diffractometer (XRD), a scanning electron microscopy (SEM) and a microscopy measured method, etc. The experimental results showed that Al(OH)3 content had a significant effect on the pore size distribution and neck characteristics (neck size distribution, total value of neck size and phase composition) and then affecting the strength. With an increase in Al(OH)3 content, the median pore size decreased, the total length of necks and the uniformity of neck size increased, also the mullite content of necks increased, resulting in the increase of strength of the porous cordierite-mullite ceramics. When the Al(OH)3 content was 64.9 wt%, the porous cordierite-mullite ceramics had the best performance of high apparent porosity of 45.1 % and high compressive strength of 55.9 MPa.
Highlights
Porous cordierite ceramic has been widely used in insulating refractories due to its low thermal conductivity coefficient and high thermal-shock resistances at elevated temperatures [1,2,3]
Mullite has a high strength, a high refractoriness, as well as a good thermal-shock resistance [4, 5], the properties of porous cordierite can be improved by adding mullite as a reinforcing phase [6,7,8]
X-ray diffractometer (XRD) patterns of samples are shown in Fig. 1 and the relative phase contents are listed in Tab
Summary
Porous cordierite ceramic has been widely used in insulating refractories due to its low thermal conductivity coefficient and high thermal-shock resistances at elevated temperatures [1,2,3]. Mullite has a high strength, a high refractoriness, as well as a good thermal-shock resistance [4, 5], the properties of porous cordierite can be improved by adding mullite as a reinforcing phase [6,7,8]. A porous structure could be achieved by adding some pore-forming agents [9, 10], by gel-casting [11, 12] or by foaming method [13], etc. Benhammou [10] fabricated porous cordierite ceramics using oil shale as a natural poreforming agent.
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