MEASUREMENT METHODS FOR DETERMINATION OF SPALLATION OF OXIDE SCALES

Several experimental techniques are being used to obtain numerical information concerning the spallation of protective oxide scales formed during high temperature corrosion. These data are required both for mechanistic modelling of the spallation process and for the construction of spall databases for engineering design purposes. By far the most universally employed experimental method is gravimetry, involving either continuous or discontinuous measurements. Thin layer activation can monitor spallation and has potential for further exploitation. Acoustic emission and, to a lesser extent, the resonant frequency technique are the principal methods used to detect or monitor cracking which precedes spallation. These experimental procedures are described and assessed, while further technique development requirements are detailed.