13422 Solgel Oxide Oxide

The test sample used in this study was a 20.3-cm diameter cylinder, 20.3 cm long with approximate a 3-mm-thick wall. The fiber was 3M Corporation N720 cloth and was laid up layer by layer and infiltrated by the sol-gel process with an aluminosilicate matrix. Figure 13.32 shows the results of using both

Tlieranal (iiffusivity image data

Tlieranal (iiffusivity image data

FIGURE 13.32 Delamination detection in 20-cm-diameter, 20-cm-long oxide/oxide com-bustor liner: (a) photograph of cylinder, (b) thermal diffusivity image map of surface, and (c) air-coupled through-transmission C scan.

Cut^jmfBiEiice

FIGURE 13.32 Delamination detection in 20-cm-diameter, 20-cm-long oxide/oxide com-bustor liner: (a) photograph of cylinder, (b) thermal diffusivity image map of surface, and (c) air-coupled through-transmission C scan.

through-transmission air-coupled ultrasound and through-thickness thermal dif-fusivity for detection of delams. The delamination was verified by destructive sectioning as shown in Fig. 13.32. One special feature about oxides is to be noted when conducting NDE using the thermal method. That is, in order to quantify the thermal diffusivity data, care must be exercised in the spectral output of the flash lamp. Recall that Parker's theory [55] requires that a step input in heat be applied at the surface of the sample under study. Oxide materials have a high optical translucency, and thus, if the optical band pass of the flash lamp is not correct, some heat of the flash lamp will penetrate into the volume of the test sample, thereby giving erroneous times for the back surface temperature to rise.

0 0

Post a comment