Methods of producing low-halogen-containing polysilazane resins, which are used to make silicon carbide fibers and ceramic coatings, provide processes for removing halogens, including chlorine, from precursor polysilazane resins.

A method for creating polycrystalline silicon nitride fibers is discussed. The method includes dispersing silicon nitride powder to create dispersed silicon nitride powder. The dispersed silicon nitride powder is classified to create classified fine silicon nitride powder. Likewise, a sintering aid is dispersed to create a dispersed sintering aid and then classified to create a classified sintering aid. A plasticizer, a binder, and the classified sintering aid are added to the classified fine silicon nitride powder to define a compound. The compound is mixed to create a mixed slurry, which is then dried to create a material. The material is extruded through a nozzle that is less than 40 micrometers in diameter to create a preform, which is then sintered to create the polycrystalline silicon nitride fibers.

A process for creating polycrystalline silicon nitride fibers includes dispersing silicon nitride (Si3N4) powder to create dispersed silicon nitride powder. The dispersed silicon nitride powder is then classified to create classified fine silicon nitride powder. Likewise, a sintering aid is dispersed to create a dispersed sintering aid and then classified to create a classified sintering aid. A plasticizer, a binder, and the classified sintering aid are added to the classified fine silicon nitride powder to define a compound. The compound is mixed to create a mixed slurry, which is then dried to create a material. The material is extruded through a nozzle that is less than 40 m (microns) in diameter to create a preform, which is then sintered to create the polycrystalline silicon nitride fibers