Hi,
The J-Head nozzle is made from brass. Carbon fibre is indeed abrasive and usage could enlarge the nozzle aperture.
E3D have recently introduced hardened steel nozzles designed for printing abrasive materials produced by the likes of Colorfabb. I think I would be inclined to use one of their hotends with a steel nozzle if I were to print significant quantities of the material.
Regards,
Neil Darlow
I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.