Preparation And Characterization Of Micropowder Aluminium Hydroxide

Micropowder aluminium hydroxide which is applied in material field such as rubber and plastic, fire retardant devoloped rapidly in recent years because of its special performance.However, the domestic technology of micropowder production is in a poor position relativly, and its micropowder production with low and instable quality.Therefore, aiming at the status quoand technical characteritics of Micropowder aluminium hydroxide in china, it is necessary to study the effects of precipitation condition on precipitation ratio, the crystallization and particle size of micropowder aluminium hydroxide, to explore crystal form of product, and to describe the crystal microstructure of aluminium hydroxide quantitatively, on the basis of production status and technique characters which is produced micropowder aluminium hydroxide of high quality.At first, the technological conditions of the decomposition of sodium aluminate solution of micropowder aluminum hydroxide were studied through the orthogonal experimental design.It mainly investigated four factors including initial decomposition temperature, decomposition time, seed crystal coefficient and solution molecular proportion. And the products which were obtained by the orthogonal experiment carried on the X-ray diffraction analysis, Raman analysis, grading analysis and the analysis of Na impurities. Take the micropowder aluminum hydroxide crystal crystallinity and the content of the impurity Na in the products as main evaluating indicators and the granularity as the reference indicators. Carried on the range analysis of the indicators separately and determined the optimal technique condition of the products.Second, the single factor test was used to study the effect of the initial temperature of the production process, the seed coefficient, ak and the decomposition time in the production of the aluminum hydroxide powder.The influence rule to the rate of dissociation, the product aluminum hydroxide granularity, the intensity and the crystal crystallinity was proved. It found that the decomposition craft used the temperature decrease system with73-55℃, the seed crystal coefficient at4%, the ak of1.8and the decomposition time of10h can obtain the aluminum hydroxide powder products which has better granularity intensity and crystal crystallization in good condition. The influence of the ultrasonic wave to the decomposition process, the product granularity and the crystal crystallinity in the decomposition process was studied in this paper.It found that the ultrasonic wave can significantly reduce the powder particle size, enhance the product performance and promote the growth of the aluminum hydroxide crystal structure unit. It proved in the frequency range which the ultrasonic wave can produce strengthen results in the process of the aluminum hydroxide powder, the high-frequency ultrasonic condition has the more remarkable invigoration effect to the sodium aluminate solution seed crystal decomposition.This article simultaneously selected three different kinds of seed crystals which were produced in the optimal conditions for the decomposition test. The effects of the different seed crystals to the fine powder product granularity and the crystal crystallization condition were discussed. It found that the powder crystal which was produced by the sand blast law, neutro-dyne system and precipitation has bigger activeness and the decomposition product granularity were smaller, the crystal crystallizes were better than the precipitation.