APPLICATION OF A NEW LASER SPECKLE EXTENSOMETER FOR DETERMINATION OF MECHANICAL PROPERTIES OF REFRACTORIES

摘要

Determination of e.g. Young's modulus or fracture mechanical investigations necessitates displacement measurements at high temperatures. Suitable methods have to be applicable for rather small specimen sizes with an accuracy of some 0,1μm. For this purpose, a laser speckle extensometer is used. The measurement is based on the shift of a speckle pattern which is created on the specimen surface itself by laser light. Therefore neither any mechanical contact to the specimen nor a special specimen preparation is needed. A testing furnace has been designed and equipped with two extensometers. It has been applied for the determination of Young's modulus and for fracture mechanical investigations. The determination of load-displacement diagrams, the evaluation and the results for typical ordinary ceramic refractory materials are presented.