Effect of granulated sugar as pore former on the microstructure and mechanical properties of the vitrified bond cubic boron nitride grinding wheels

Abstract

For vitrified bond cubic boron nitride (CBN) grinding wheel, introduced pores play a very important role for its mechanical properties and performance. In this paper, granulated sugar was used as pore former of the vitrified bond in CBN grinding wheel. The effects of content and particle size of the granulated sugar on the porosity and the flexural strength of the sintered vitrified bond CBN wheel samples have been investigated. It was found that the porosity of the vitrified bond CBN wheel is positively correlated with the content of the granulated sugar. The smaller and more irregular shaped pores are uniformly distributed in the bond when the content of granulated sugar is between 1 and 3wt.%. Larger and more non-uniform pores and pore channels appear as the content of granulated sugar is increased from 5 to 7wt.%. The flexural strength of the vitrified bond CBN wheel specimens decreases with an increase in pore former’s content and the porosity. With the increase of pore former’s particle size at the content of 3wt.%, the flexural strength reaches to a peak value of 49MPa with average particle size of granulated sugar is 250μm. When the average size of granulated sugar is from 100 to 125μm, the pores’ size is similar with the size of pore former and distributed homogeneously. The larger granulated sugar with the size from 160 to 500μm can introduce different size of pores which could be smaller or larger than the size of pore former.