IN-SITU MEASUREMENT OF SINTERING SHRINKAGE IN POWDER COMPACTS BY DIGITAL IMAGE CORRELATION METHOD

An in situ system for monitoring sintering shrinkage of powder compact s using digital image correlation has been developed. This system will provide completely automated non-contact measurement of two-dimension al deformation, and thus enables in situ quantification of non-uniform and anisotropic shrinkage, if any, of a powder compact during sinteri ng. A brief description is given of the procedure for identifying micr o-areas on a specimen surface before and after deformation by the digi tal image correlation method. A new digital image processing algorithm has been developed to determine the two-dimensional distribution of s hrinkage rate in powder compacts during sintering. A measurement of th e shrinkage non-uniformity in a die pressed carbonyl nickel powder com pact during sintering from room temperature to 1573 K is presented. Th e results showed successful identification of non-uniform and anisotro pic shrinkage arising from powder filling inhomogeneities and the neut ral zone effect of die wall friction on green density. (C) 1995 The In stitute of Materials.