| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hardened product, excellent in fine resistance and heating thermal stability and capable of preventing a wall from falling off even when used in a building material by including or producing a specific amount of an alumina-based compound in a hardened gypsum. SOLUTION: This refractory gypsum hardened product is obtained by including gypsum as a principal material and one or more of aluminum oxide or aluminum compounds convertible into the alumina at high temperatures in an amount of >=1.0wt.% expressed in terms of the alumina in the gypsum. The high temperatures are 200-1,000 deg.C. The generic name of the aluminum oxide (alumina) is a substance represented by the chemical formula Al2 O3 , which may be any of Al2 O3 having other crystal structures so-called intermediate alumina finally convertible intoα-Al2 O3 by heating at high temperatures including theα-Al2 O3 , e.g.γ-Al2 O3 ,η-Al2 O3 orδ-Al2 O3 . A calcined gypsum,α-type hemihydrate gypsum, II type anhydrous gypsum, III type anhydrous gypsum and gypsum dihydrate, etc., are cited as the gypsum material. The gypsums are used alone or mixed for used according to the production method. |
