Abstract: A magnesium alloy material contains a complex made from a phosphate-containing magnesium, such as dittmarite and the like, and magnesium hydroxide, the complex being formed by a steam curing of the magnesium alloy material conducted using (i) at least one compound chosen among diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and triammonium phosphate, and (ii) water. In this way, it is possible to provide a magnesium alloy material having excellent corrosion resistance, shock resistance and the like, and to provide a method for treatment of surface of magnesium alloy material allowing the manufacture of a magnesium alloy material having excellent corrosion resistance, shock resistance and the like.

Abstract: Disclosed is an improvement in the process for the preparation of amorphous silicic acid particles useful, for example, as a filtration aid comprising the steps of a hydrothermal reaction to prepare calcium silicate particles and decalcification of the calcium silicate particles, after or without undertaking carbonation by the reaction of carbon dioxide, with an acid to form particles of amorphous silicic acid followed by drying of the amorphous silicic acid particles.

Abstract: A novel method is proposed for the preparation of a calcium silicate powder particularly useful as a filter aid in the filtration of an acidic aqueous liquid by virtue of the extremely high acid resistance of the calcium silicate powder. The inventive method comprises a hydrothermal reaction of a blend of a silica-containing material and calcium oxide or hydroxide in a specified molar ratio under specified reaction conditions to form calcium silicate, which is then subjected to a heat treatment at 800.degree.-1200.degree. C. for 0.5-2 hours. An improvement can be obtained in the clarity of the filtrate obtained by the filtration using the calcium silicate powder prepared by the inventive method as a filter aid when the hydrothermal reaction for the preparation thereof is conducted in an aqueous solution of potassium hydroxide in a specified concentration.

Abstract: An alkali-resistant glass composition which comprises 40 - 55% by weight of iO.sub.2, 6 - 12% by weight of Al.sub.2 O.sub.3, 8 - 30% by weight of CaO, 3 - 6% by weight of an alkali metal oxide of Na.sub.2 O and/or K.sub.2 O, 3 - 10%, by weight of ZrO.sub.2 and 2 - 20% by weight of ZnO together with or without 2 - 7% by weight of Fe.sub.2 O.sub.3. This glass composition has especially remarkable alkali-resistance and is excellent in fusibility, workability, spinnability and devitrification-resistance.