Study On Preparation And Mechanism Of Magnesium Borate Whisker

Whiskers have been widely used in the field of composite materials synthesis, asits excellent refractory, noncorrosive, good mechanical, high strength, highstrength, high elastic modulus and higher hardness properties. However, thedeveloped carbon whiskers, silicon carbide whiskers, silicon nitride whiskers dueto process complexity and high cost, have been greatly limited the applicationsof civilian industry, such as machinery, electronics, automotive and otherindustries. Magnesium borate whisker is a new generation of high-strength,low-cost whiskers, and its price is only1/20-1/30of the carbon whiskers, siliconcarbide whiskers, silicon nitride whiskers. Since the successful development of thelast century in the late1990s, because of its high cost performance magnesiumborate whisker show a broad application prospects in civilian industry, so it becomesa hotspot of the composite reinforced materials research field.In a variety of magnesium borate whisker preparation process, the ClassicNaCl-KCl flux method with its simple process, low-cost, easy to industrialization isthe most promising method. However this method still exist many problems, such asthe whisker morphology uneven, low aspect ratio, pollution of theenvironment, flux agents difficult to recycle etc. Magnesium borate whiskerhas so far rarely achieved industrialization.In order to solve the problem met in Classic NaCl-KCl flux method, this paperput forward a new method, like-sol-gel method. The diameter of the whiskers was0.5-2μm, and length was20-40μm, and its purity can reach99.06%.The process hasthe following characteristics:(1)The problem of high energy consumption and molten salt corrosion can be solved by using the WT flux system, and the synthesis reaction temperature could bereduced from850℃to620℃.(2)The preparation process used the Mg(OH)2and H3BO3as raw materials,none HCl emission, so the problem of pollution and corrosion in the whiskersynthesis could be solved.(3)The problem of synthetic raw materials mixed uneven could be solved byusing the like-sol–gel method.(4)The raw materials are not introducing impurity ions, so the flux agents couldbe easy recycling.(5)The uniform morphology of the whiskers products can be synthesized by theprecursor sintering at450℃for3-5h.