Synthesis of Chrysotile Fibers with Addition of Alkali Halides especially Potassium and Magnesium Bromides under Hydrothermal Condition

Abstract

Formation and growth of chrysotile fibers were investigated under hydrothermal conditions with addition of alkali halides to chrysotile composition of raw materials mixture of silicic unhydride and magnesium hydroxide.
At first, formation of serpentine was studied by X-ray diffraction for short period of reactions at relatively low temperatures. Then serpentine was formed with addition of potassium bromide, but not formed only from raw materials. Moreover for prolonged reaction time at elevated temueratlire, 50μ length of the fiber was easily produced with that addition.
By adding magnesium bromide, about 3mm of the fiber was grown under the same condition as the above. In this case, however, slurry of the mixture was weakly acidic by hydrolysis of magnesium bromide, therefore the slurry was gradually dehydrated in process of the reactions with iron metal placed in the bottom of autoclave.
For the above results, the effect of bromide for formation of chrysotile was deduced that structure of magnesium bromide was the same CdI₂ type as brucite which was outer layer of chrysotile. And also at process of formation and growth, the slurry was concentrated by the dehydration to state as sol, where would be thought that dissolved polysilicic acid combined brucite with Br partially substituting to site of (OH).