Accession Number : AD0714491

Title :   An Assessment of Surface and Sub-Surface Damage Introduced in Ceramics by Semi-Finish Grinding Operations.

Descriptive Note : Technical rept. no. 2,

Corporate Author : HONEYWELL INC HOPKINS MINN CORPORATE RESEARCH CENTER

Personal Author(s) : Koepke,B. G.

Report Date : OCT 1970

Pagination or Media Count : 53

Abstract : The nature and extend of grinding damage introduced by surface grinding a number of ceramics having widely varying mechanical properties was studied. Surface damage was characterized by optical and electron microscopy and subsurface damage was observed using etch pit techniques. Grinding damage was found to depend strongly on wheel type and rate of material removal as well as on the mechanical behavior and microstructure of the workpiece. The results indicate that grinding damage is mainly composed of mixtures of three types depending on the mechanism of material removal. When material is removed efficiently from low impact resistance ceramics (e.g., magnesium oxide and ferrite) the surfaces are generated by brittle fracture and are composed of regions of transgranular and intergranular fracture. When grinding is inefficient; i.e., when the grinding wheel loads up, material is removed by plastic flow. The resultant surfaces on deformable ceramics (e.g., magnesium oxide, ferrite, and silicon) are smooth and burnished but may contain thermal cracks due to the heat generated. In this instance subsurface damage consists of a discrete, highly deformed layer containing cracks in most cases. (Author)

Descriptors :   (*CERAMIC MATERIALS, DAMAGE), (*GRINDING, CERAMIC MATERIALS), SURFACE PROPERTIES, DEFORMATION, FRACTURE(MECHANICS)

Subject Categories : Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE