Application
Composites and ceramization
The resin is the precursor, not the coating
The situation
A porous or cracked ceramic body that has to be densified, a thermal-spray coating that has to be sealed, or two ceramic parts that have to be joined and then used hot. The polysilazane is not the finish here: it is the source of the ceramic.
What fails today
- A liquid precursor that shrinks on pyrolysis leaves a cracked, porous residue after the first cycle.
- Sizing or binder left in the preform burns out at the wrong moment and blows the infiltration out of the part.
- Joining two ceramics with an organic adhesive works until the joint reaches the service temperature, then the adhesive disappears.
- Sealing a thermal spray with a resin that cannot wet the pores simply sits on the surface.
How to apply it
Vacuum or vacuum-pressure infiltration: a low-viscosity liquid enters an open pore, a thick one does not.
Repeat infiltration and pyrolysis cycles: one cycle rarely closes the porosity, and the second is usually where the gain is.
Ramp slowly to the pyrolysis temperature. The rate matters more than the hold.
Fillers change the final composition; the resin alone gives an amorphous residue that crystallises later.
How to qualify it
- Ceramic yield by TGA in the atmosphere the part will see, with heating rate and end temperature recorded: a yield quoted in nitrogen does not describe an air furnace.
- Weight change and open porosity before and after infiltration, on the actual preform.
- A bend or shear test on the joined pair after the full cure schedule, not on a bulk sample of the resin.
- Where the film is a barrier, a leak rate rather than a visual check.
Bring your substrate and your target; we quote a grade and a cure schedule against it.
Next step