Preparation Of Submicron Boron Carbide By Mechanical Alloying

Boron Carbide has unique physical, chemical and mechanical properties, and get extensive application in many fields. For the reason of rigorous preparation requirement, the research of convenient and low-cost preparation method for B4C particle materials is necessary. Since 1970s, duo to its notable advantages in the preparation of advanced materials, mechanical alloying (MA) has attracted much attention of researcher interests in the field of synthesis of advanced materials. In this thesis, the MA method has been used to synthesize B4C particles materials, and the working mechanisms in MA process, and the developments and its applications of MA technique have been reviewed.Using B₂O₃, C and Mg particles smaller than 3mm as raw materials, B4C and MgO particles were prepared by planetary ball milling for 72 hours. Submicron B₄C particle materials was obtained by purifying and cleaning the B4C and MgO particles using hydrochloric acid and water. The submicron B4C particle materials was characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), electronic probe (EPMA). The crystal structure of the submicron B4C particle materials has been anaylsized by crystallography, and the theoretical analysis indicated that the submicron B4C particles has hexagonal crystal structure with lattice constants of a=5.628A and c=12.186A.In order to finding the effect of the size change of boron oxide particles in the milling process, the grinding of boron oxide by the planetary mill was studied. The rate of breakage and the distribution parameter of breakage of different size interals are obtained by experiments. A model of grinding process has been built. The calculation results showed that the grinding of boron oxide has transit behaviour.From all of the work and experiments, the following conclusion could be drawn: At normal temperature, B4C and MgO particles can be prepared successfully by ball-milling with B₂O₃, C and Mg particles smaller than 3mm as raw materials. Submicron B4C particle materials was obtained by purifying and cleaning the B4C and MgO particles using hydrochloric acid and water, and the submicron B4C particles has hexagonal crystal structure with lattice constants of a=5.628A and c=12.186A. The grinding of boron oxide has transit behaviour.