Measurement of Densification of Zinc Oxide Compacts Using an Optical, Noncontact, Noninvasive Extensometer

An optical noninvasive, noncontact extensometer was used to measure the shrinkage of zinc oxide powder compacts during sintering. Powder compacts were uniaxially and isostatically pressed from micrometer, submicrometer, and nano powders and sintered in a thermal oven at temperatures up to 1100°C. The nanometer‐size sample started to densify at ∼400°C, about 200°C below the densification threshold of the micrometer‐size sample. The results are in good agreement with those obtained using a contact dilatometer.