Deformation behavior of materials under sub-mum (nano) interference

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It is considered that the mechanism of such mechanical processing as fine grinding, lapping and diamond turning, which realize the super precision accuracy, is based on the nano-size chip removal. Namely, a cutting edge is supposed to interfere with the material in sub-mum (nm), form chips and remove them. In such micro-interference between the cutting edge and the work, the deformation and removal behavior of the materials have not been cleared, because their observations are quite difficult due to its microscopic phenomena. I believe it is not resonable to consider that the removal mechanism of nano-size micro chips is similar to the common cutting phenomenon. For example, it would be necessary to examine the properties of the materials under the nano-size deformation in order to discuss whether ceramics materials could form ductile mode chips or not.In this study, based on the assumption that cutting edges would be spheres, micro-contact deformation of some metals and ceramics by a spherical diamond indenter is analyzed theoretically and it is also investigated experimentally by the micro-indentation tests in order to evaluate mechanical properties of the materials under the micro-interference with cutting edges. As a result, the following conclusions are obtained : (1) In the sub-mum indentation tests by a diamond indenter, it is experimentally observed that even such brittle materials like the ceramics exhibit elasto-plastic behaviors in appearance. (2) The experimental results ((1)) can be sufficiently analyzed by the sphere-plane contact model proposed here. (3) It could be expected for the sub-mum indentation test to be applied for estimating the defect or the affected zone of the work surface induced by nano-machining.