Study On The Synthesis Method Of High Length Aluminum Borate Whisker By Flux

Aluminum borate whisker with its excellent mechanical property and high cost-effective is widely used in metal base(aluminum 、 magnesium base), resin-based composite reinforcement, which can greatly improve the strength and mechanical property of materials. Thus it is one of the few inorganic whiskers for industrial applications.However, because the conventional synthetic methods of aluminum borate by flux are required for 1200℃and 5~6h to get aluminum borate whiskers, and its length is generally in 20~30μm. It is difficult to synthesize longer than 50μm aluminum borate whiskers. So some applications field that are required for high length whiskers has been greatly restricted,for example: enhancer context of aluminum、magnesium-based alloys, which need more than length of 50μm of aluminum borate whiskers. And in order to obtain high length aluminum borate whiskers, higher temperature and longer calcination time are required by conventional methods. In addition, a large mass(about 50% of the total reaction volume) of flux are needed to synthesis aluminum borate whiskers by traditional method. Moreover, it is very difficult to recover flux, which results in high costs and environmental pollution. It is the technical bottlenecks to synthesize aluminum borate whiskers.Aiming at the synthesis problems of aluminum borate whisker by flux method and based on the the traditional synthesis methods of aluminum borate whisker, this paper was committed to improving the technology especially for raw materials used in the preparation systems. Optimal raw materials were selected to synthesis aluminum borate whiskers at low temperature. A length of about 160μm aluminum borate whiskers was synthesized at low temperatures by adjusting the heating process、the ratios of raw materials and other process conditions. The above problems were solved, which were important for expanding the application scope of aluminum borate whiskers.This paper was further optimizing the synthesis conditions to synthesis the stable whisker products, and the process conditions were studied by using the testing methods of XRD, SEM and nano-microscopy. The growth factors of aluminum borate whisker were analyzed, the results were that the Al/B molar ratio, calcination temperature, holding time and process had a great influence on whisker growth. Some results were as follows by orthogonal test and studying on the different process conditions:(1) The optimum conditions for synthesis were that: Al/B molar ratio is 5:2, the flux in an amount of aluminum and boron molar amount of 1.2 times, at 910℃ for 3h;(2) Length of whisker reaches 160μm, diameter is in 1~2 μm, aspect ratio of aluminum borate whisker is up to 70;(3) The effect of the number of cycles of the flux on the impurities of flux was studied by recycling flux, and the results were that the number of cycles had a certain influence on purity of flux. So it is difficult to recover flux for the cycles;The synthesis mechanism of aluminum borate whisker was studied by the different sources of aluminum and flux at low temperature, and the results were that the growth mechanism of aluminum borate whiskers was just like L-S type. Besides the flux of potassium sulfate in the reaction process play a catalytic and flux role.