Composite structures, heater apparatus, fast light-off exhaust aftertreatment systems, and methods of manufacturing and using same

A composite structure, exhaust aftertreatment system, and method of manufacture. The composite structure includes a body that includes an array of intersecting walls that form a plurality of channels extending in an axial direction through the body such that adjacent channels are located on opposite sides of each wall. A composite material of the body includes a first phase of a porous glass or ceramic containing material. The first phase includes an internal interconnected porosity. A second phase of an electrically conductive material is included that is a continuous, three-dimensional, interconnected, electrically conductive phase at least partially filling the internal interconnected porosity of the first phase, which creates an electrical path through at least some of the walls in a lateral direction perpendicular to the axial direction between the opposite sides of the walls.