The effect of ELID grinding on the flexural strength of silicon nitride

Advanced structural ceramics, such as silicon nitride-based materials, are of significant interest due to their excellent physical and mechanical prop erties. However the cost of grinding these ceramics, an integral part of th eir fabrication, is very high and can result in surface and subsurface dama ge to the material. These defects can significantly reduce the strength and reliability of the finished component and are sensitive to grinding parame ters. In this investigation, the effect of finish electrolytic in-process d ressing (ELID) grinding on the flexural strength of silicon nitride specime ns were studied. Kyocera's silicon nitride SN 235, in the form of Modulus o f Rupture (MOR) specimens, were ground using the application of ELID grindi ng with a # 6000 grit sized cast iron bonded diamond (CIB-D) grinding wheel . A significant improvement in the strength of the Si3N4 specimens was note d when finish ELID grinding was performed. This was the result of ductile r egime grinding using the application of finish ELID grinding. Another metho d to improve the flexural strength of silicon nitride specimens will also b e addressed in this paper. (C) 1999 Elsevier Science Ltd. All rights reserv ed.