Solvothermal Synthesis Of The Key Factors In The Cbn Process

As the second hardest material known, cubic boron nitride possesses many merits, forinstance, high stability, high thermal conductivity, high hardness and wide band gapetc. Although the hardness ofcBN is inferior to that of diamond, its stability is higherthan the latter. Because of the above advantages, cBN can also be used in thefabrication of high-power semiconductor devices, short wavelength optoelectronicdevices, ultraviolet detectors, high power microwave devices, heat sinks and hightransparency windows etc.In practice, high temperature and high pressure method and CVD are used as the mainmeans ofcBN synthesis.On the consideration of that the cBN crystal has prospects in widely rangedapplications, while the existed preparation methods of it have inherent disadvantageswhich are hard to solve, we firstly established the Solvothermal Phase-Selective Reactionmethod, and researched a lot on the choice of reactants and solvents, the optimization ofexperiment conditions and the development of experiment equipment. On the basis of theexperiences before, we choose benzene as solvent, boron trichloride and lithium nitride asreactants. We set 260℃as reaction temperature, and pressure, times we load the reactant, and therate of the stirring device as parameters, so we can research how the conditions influence therelative content of cBN in three aspects. Here are the regulations we found:When the pressure is ranged from 1Mpa to 7Mpa, the relative content of cBN in the sample raisesalong with the rise of pressure. When we load the reactant twice, the result is better than when wedo that only once or three times. Keeping all parameters still except for the rate of the stirringdevice, we found that reduction of the rate could not improve the crystal quality of cBN, andresulted in a decrease of the relative content of cBN.At the end of the article, I concluded the problems maintained in experiments, and tried to givesolutions.