Plasma-assisted process of ceramization of polymer precursor on surface, surface comprising ceramic polymer
The present invention lies in the fields of chemistry and materials engineering. More specifically, the present invention describes a process of heat treatment of polymeric precursors including as active phases particle charge or a mixture of active phases with inert phases called “fillers”. It is also described a surface including ceramic polymer obtained by said process. The volumetric positive variation resulting from the formation of new phases, which for their formation, incorporate atoms from the gaseous phase, contributes to a minor shrinkage of the composition during the heat treatment process. The process of the present invention allows obtaining the desired phases in smaller treatment times and lower temperatures, when compared to a thermal treatment process as conventional pyrolysis (PC) due to the presence of highly reactive species, as for example atomic nitrogen produced by the dissociation of nitrogen molecules in the plasma environment.
1. A ceramization process of a polymer precursor suspension containing at least one polymer precursor and at least one active filler or a mixture of the at least one active filler with at least one inert filler on at least one component surface, wherein the at least one inert filler is an agent added to stabilize distribution of the at least one active filler in the suspension, reducing sedimentation effects during the process, the process comprising the steps of:
(a) preparation of the suspension comprising:
said at least one polymer precursor;
the at least one active filler;
at least one solvent; and
at least one dispersant;
(b) application of said suspension on the at least one component surface, forming at least one suspension coated component surface; and
(c) plasma-assisted pyrolysis heat treatment of the at least one suspension coated component surface in a medium that contains at least one reactive species from dissociation of molecules of at least one molecular species selected from the group consisting of hydrogen, nitrogen, hydrocarbons or combinations thereof, wherein the plasma-assisted pyrolysis heat treatment is DC plasma-assisted pyrolysis, and wherein the plasma-assisted pyrolysis heat treatment is performed at a pressure of about 1.33×10 1 Pascal (0.1 Torr) to 1.33×10 4 Pascal (100 Torr) and is carried out for 30 minutes to 300 minutes at a temperature of 800 to 1200° C.; and
with the heat treatment by DC plasma-assisted pyrolysis, obtaining, from the at least one suspension coated component surface, a polymer derived crystalline ceramic from the at least one polymer precursor, wherein the polymer derived crystalline ceramic comprises a phase formed by reaction of the at least one active filler with the at least one reactive species.
2. The process according to claim 1 , characterized by said at least one polymer precursor being an organometallic polymer.
3. The process according to claim 2 , characterized by the organometallic polymer being selected from the group consisting of polyorganosilanes, polyorganocarbosilanes, polyorganosilylcarbodiimides, polyorganosilazanes, and combinations thereof.
4. The process according to claim 1 , characterized by said active filler being selected from the group consisting of: Ti, Cr, V, Mo, B, MoSi 2 , Fe, Al, Nb, Hf, TiSi 2 , CrSi 2 , TiB 2 , Si, and B 4 C and/or said inert filler being selected from the group consisting of: Al 2 O 3 , SiC, BN, Si 3 N 4 , ZrO 2 , as well as combinations of the active fillers and the inert fillers in the same suspension.
5. The process according to claim 1 , characterized by said at least one component surface being a metallic surface.
6. The process according to claim 1 , characterized by the step (b) of applying said suspension on the at least one component surface being carried out by a technique selected from the group consisting of immersion, spray, spin coating, and casting tape.
7. The process according to claim 1 , characterized by the plasma-assisted pyrolysis being carried out in a plasma reactor at a cathode or an anode.
8. The process according to claim 7 , characterized by the plasma-assisted pyrolysis being carried out in a plasma reactor at the cathode.
9. The process according to claim 2 , characterized by the organometallic polymer being selected from the group consisting of polycarbosilanes, polysilazanes, doped polysilazanes, polysilylcarbodiimides, polyborosilanes, and combinations thereof.