| 摘要 |
PURPOSE:To obtain a titled large-sized ceramic having uniform thickness and formed conditions without any warpage and with closed cells by making a powdery ceramic material which melts into a glassy state at a specified temp. into fine granules, and calcining the granules. CONSTITUTION:An adequate amt. of a flux, a foaming agent, or a plasticizer is added to a powdery ceramic material which melts into a glassy state at a specified temp. such as volcanic ashes, e.g., SIRASU (white sandy deposit) and KOKASEKI (porous lava), or feldspar, and a powdery admixture is prepared. The admixture is kneaded with water, and spray-dried into fine granules having <=1mm. granule diameter which are placed uniformly on a large-sized shelf made of a refractory in 20-50mm. specified thickness. Said shelves are piled up on a carriage in several stages, passed through a tunnel kiln, and calcined at a temp. higher than the softening or melting temp.
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