The Research On Grinding Damage In Nanostructured Ceramic Coating

Nanostructured ceramic coatings, a kind of new engineering materials, are developed in recent years. This kind of materials will be extensively used in industrial applications. But machining difficulties have been associated with the uses. Under current state-of-the-art, no detailed and thorough study on the precision grinding nanostructured ceramic coating have been reported. So the research work in this respect has a very realistic and great meaning.The present paper deals with the grinding damage in n-WC/12Co coating ground with diamond wheels. The formation and propagation of median/radial and lateral cracks are analyzed using "indentation fracture mechanics" approach. Finally critical grinding condition models, which are fit for nanostructured ceramic coatings, are proposed and also verified by the experiments. Based on the critical load model the material removal mechanism can be quantitatively analyzed. The other important aspect of this paper is to announce the effects of grinding conditions on the depth of subsurface damage to reveal the inherent relation among the subsurface damage and relevant factors in grinding, such as wheel depth of cut, table federate, wheel grit size, wheel bond type and so on.Investigations had been conducted by comparing the subsurface damage of material under different grinding conditions. Some meaningful conclusions had beenmade:l.Two major crack patterns are identified, namely median/radial cracks andlateral cracks.2.Based on the critical load for lateral cracking and the experimental results, we found that grinding mark is the most significant characteristic on the ground n-WC/12Co under all grinding conditions. At the higher the normal force per grit, brittle fracture is also observed.3.The depth of subsurface damage grows with the increase of wheel depth of cutor table federate.4.Larger grit size results in deeper damage. The depths of damage are larger in the coatings ground with the mental bond wheel than in those ground with the vitrified and resin bond wheels. There is no great difference among those coatings ground with the vitrified and resin bond wheels. The effects of wheel bond type on the depth of damage are insignificant when compared with those from wheel depth of cut and table federate.The present paper investigated the subsurface damage of nanostructured WC/12Co coating. Some laws, which can guide the precision grinding nanostructured ceramic coatings and predict the grinding process, are obtained. A model between subsurface damage depth of nanostructured ceramic coatings and the cut depth per grit is established.