噴霧乾燥混合物からの針状ピロホウ酸マグネシウムの合成

抄録

We studied the preparation method of acicular magnesium pyroborate (Mg₂B₂O₅), especially in relation to the prevention of formation of agglomerates, which generally form by heating mortar-ground mixture of MgO-H₃BO₃-KCl.
Spray-drying of slurry, which contained reaction components and flux, gave a starting material with Mg and B in amorphous state and Mg and K almost uniformly distributed. The slurry was made by adding hot solution of H₃BO₃ and KCl to suspended solution of Mg (OH) ₂ with 2 : 3 : 7 mole ratio of Mg : B : KCl.
Heat treatment of the spray-dried mixture at 750°C gave small acicular crystals of Mg₂B₂O₅ less than ca. 1μm in length without by-product such as MgO and MgB₄O₇. The product obtained by heating the mixture at 850°C for 3hrs contained only acicular Mg₂B₂O₅ crystals ca. 5-15μm long and ca. 0.5μm thick, and did not contain agglomerates.