Hello, I used a tube furnace for carbonization of polyacrylonitrile nanofiber mat at 1000C under the flow of Nitrogen with a heating rate of 5 degrees per minute, and dwell time was 1h at 1000 C. Samples are kept without any substrate. samples are cooled under nitrogen flow, but I don't find a single carbonized mat piece in the ceramic Boat after the carbonization process. what could be the reason behind this ??