| The structure of vitreous bonded cubic boron nitride (cBN) grinding tool is composed of bond, pore and abrasive. A kind of reasonable vitrified bond with low vitrification temperature and high strength is choosed. The samples are prepared in hot pressing. By means of XRD, SEM, EDS and bending strength, the performance of bond and the effect of filler are studied. The effect of pore inducers on the tool structure is researched. The relationship between the cBN surface state and performance of tool is investigated and an optimum coating material is selected.The results show the appropriate bond is alumina-borosilicate ceramic bonding system: The molar ratio of alkali oxides to B2O3 is 0.35:0.23, and that of B203 to SiO2 is 0.23:0.90. The refractoriness is 700 ℃. When sintering with corundum the coefficient of thermal expansion is 4.15x106/℃. If adding BJS or M1 alone, the bending strength of sample increases. But adding both of them together, the bending strength decreases obviously.The function mechanisms of CaCO3 and graphite are different. The strength of sample with graphite depends on the shape and content of graphite greatly. As to the sample with CaCO3, the bending strength doesn't change obviously. The pore is spheroidal and distributes homogeneously. The size of pore varies with the content of CaCO3.The combination of corundum-coated cBN abrasive with vitrified bond is better than that of Ti-coated or un-coated cBN. And the buffer layer from cBN abrasive, corundum coating to bond is perfect because part of corundum coating melts into vitrified bond to build dentation combination.
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