Effect of abrasive grinding on the strength and reliability of alumina

Abstract

In the present study, the effect of depth of cut during abrasive grinding on the strength and reliability of alumina is investigated. The reliability is expressed in terms of Weibull modulus. The alumina specimens were prepared by die-pressing and sintering. Large flaws are formed in the surface region during die-pressing. The strength and reliability of the as-sintered alumina specimens are improved after abrasive grinding. The improvement is contributed by the change of flaw size distribution and the introduction of residual stresses during grinding. As the depth of cut is less than 10 μm pass-1, large surface flaws are either removed or reduced in size. The grinding process can induce residual stresses near surface. The presence of the residual stresses enhances the average strength of alumina by roughly 30 MPa. As the depth of cut is increased to 20 μm pass-1, many machining flaws are formed in the surface region. The average strength and Weibull modulus are then decreased. Due to the formation of many surface cracks, residual stresses are released. Therefore, there is no contribution from residual stresses to the strength of the specimens ground with large depth of cut. © 1998 Elsevier Science Limited. All rights reserved.