The use of electric potential drop techniques to detect delamination in a melt-infiltrated SiC-based composite

For composite systems where the matrix is electrically conductive, the possibility that the nature of electrical current flow in the composite can be used to detect defects such as out-of-plane delamination. Melt-infiltrated SiC-based composites are an ideal candidate material for such to verify this since the Si content of the matrix is the primary current carrier in the system. Two different potential drop techniques utilizing the four-point probe method were developed on a composite panel that had a large preexisting delamination defect that occurred during processing. The first technique incorporated current leads to supply current in a through-thickness manner and determine the nature of current spreading (voltage drop) some distance away from the current source to assess the location of the delamination. The other technique incorporated current leads in a more conventional manner to produce axial current flow and assessed the nature of current flow in between the current leads on both surfaces of the composite. In this way, in the presence of a delamination, current flow was forced to primarily flow on the side of the current leads. Both techniques were quite effective at locating the preexisting delamination in a panel of 2D woven Tyranno ZMI slurry-derived melt-infiltrated SiC composite.

Automated summary

Two different potential drop techniques utilizing the four-point probe method were developed to detect the location of delamination defects in composite materials.