In the application of high-performance protective coatings on substrates such as metals, glass, plastics, and composite materials, a single curing method often has to make a trade-off between "construction convenience" and "final performance" - UV curing has high efficiency but presents challenges with shadow curing for dark or complex workpieces; thermal curing has wide applicability but the heating process may damage thermally sensitive substrates. The organic polysilazane 9108 simultaneously supports UV curing and thermal curing (without initiator 200°C+/peroxide 120°C+/platinum catalysis 80°C+), with a hardness of 6H after curing, the recommended curing temperature for clear coat coatings is <600°C, the formulation coatings can be ceramicized up to 1600°C, the metal adhesion scratch test grade is 0, the visible light transmittance is >95%, and it can be used as a candidate base material for high-hardness and high-temperature-resistant transparent coatings.


Why do polysilazane coatings often fail to meet expected performance during curing, high-temperature service, or ceramic conversion?


The selection of curing method does not match the substrate and process window - UV curing has high efficiency but the photoinitiator has limited temperature resistance (yellowing above 300°C); thermal curing has wide applicability but the substrate's tolerance needs to be evaluated.


Insufficient curing conditions - if the thermal curing does not reach the initiation temperature (without initiator requires 200°C+, peroxide 120°C+, platinum catalysis 80°C+), the coating cannot complete cross-linking.


The use of the coating at 300°C or above with UV curing process leads to yellowing due to residual photoinitiator.


The film thickness exceeds the resin cracking threshold (100μm+), causing cracking during high-temperature environments or ceramic conversion.


The choice of diluent solvent is inappropriate - the product is miscible with most non-polar solvents (alkanes, ethers, ketones, esters), but alcohol ether solvents (such as diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol butyl ether) should not be used.


The cracking atmosphere does not match the target ceramic phase - nitrogen/argon → SiC/Si₃N₄, ammonia → Si₃N₄, air → SiOCN.


First, determine at which stage the coating problem occurs.


Failure stage Possible causes Priority inspection direction
Insufficient curing after curing (<6H) Insufficient curing conditions or catalyst/initiator issues Inspection of curing temperature/time, UV light dose, photoinitiator addition
Yellowing of UV curing coating at >300°C Residual photoinitiator thermal decomposition Assessment of whether to use thermal curing process
Coating cracking Membrane thickness exceeds 100μm cracking threshold Thickness control, verification of high-temperature usage temperature
Poor adhesion Insufficient substrate surface treatment or solvent residue Surface cleanliness, drying conditions, type of diluent
Ceramic yield lower than expected Cracking atmosphere or heating program mismatch Cracking atmosphere (N₂/Ar/NH₃/Air), filler influence assessment
Shortened storage period or resin deterioration Entry of moisture into container Container sealing, inert gas replacement operation
Comparison of curing paths and performance of 9108


Curing method Conditions Applicable scenarios Performance characteristics Important boundaries
UV curing Photoinitiator + UV irradiation High-efficiency curing, thermally sensitive substrates Excellent coating performance Yellowing due to photoinitiator residue at 300°C or above
Thermal curing (without initiator) 200°C+ baking High-temperature resistant substrates No need for additional initiator Higher curing temperature
Thermal curing (peroxide) 120°C+ medium-temperature baking Medium-temperature resistant substrates Shorten curing time Minimal addition, does not affect coating properties
Thermal curing (platinum catalysis) 80°C+ medium-temperature baking Thermally sensitive substrates, low-temperature curing Minimum curing temperature Ensure no catalyst poison in the system
Comparison of 9108 and 9120


Comparison item 9108 9120 (polyborosilazane)
Functional group 乙烯基 + Si-H Repeated Si-N/Si-N-B units
Curing method UV curing + thermal curing Thermal curing (120-180℃) / platinum catalysis (80-100℃)
Hardness after curing 6H Thermal curing (hardness not separately indicated)
Clear coat usage temperature <600℃ <300℃ (9283)
Ceramicization temperature 1400℃ crystallization 1600℃ crystallization
Ceramic yield (800℃) 60-70% >50% (curing material ceramic yield)
What conditions need to be confirmed before selection and construction?


Condition category Required information
Base material type Metal, alloy, glass, paint film, PP/PC/PVC/PMMA and other plastics
Curing method UV curing, thermal curing (without initiator/peroxide/platinum catalysis)
Curing equipment UV lamp (wavelength/intensity), oven temperature capacity
Film thickness control Suggest single layer < 100μm (cracking threshold)
Usage temperature Clear coat < 600℃ / formulation coating < 1600℃ (after ceramicization)
Target ceramic phase N₂/Ar → SiC/Si₃N₄, NH₃ → Si₃N₄, Air → SiOCN
Saturated solvent Alkanes, ethers, ketones, esters (strictly prohibit alcohol-ether)
Storage conditions 0-20℃, dry and cool, sealed, inert gas protection
Which key indicators should be verified?


Verification items Primary function Content that cannot be replaced
Hardness after curing (6H) Verify curing degree and scratch resistance Need to be verified separately for different curing methods
High-temperature stability (<600℃ clear coat) Verify upper usage temperature limit Membrane thickness affects cracking temperature
Transmittance (%) (>95%) Verify optical transparency Transmittance may be different between light curing and thermal curing
Adhesion (grid method 0 grade) Verify bonding force with substrate Need to be verified on different substrates
Ceramic yield (60-70% at 800℃) Evaluate precursor conversion efficiency Affected by decomposition atmosphere and fillers
Hydrophobic angle (100-105°) Evaluate surface hydrophobic effect Need to be tested after curing
Recommended construction scheme


Ensure the base material surface is thoroughly cleaned and dried to ensure the presence of active sites for Si-NH-Si bond reaction.


Choose the appropriate curing method based on the base material type and process conditions: UV curing (requires photoinitiator), thermal curing (without initiator 200℃+/peroxide 120℃+/platinum catalysis 80℃+).


Adjust the construction viscosity with a dry non-polar solvent (strictly prohibit alcohol-ether type).


Control the coating film thickness (<100μm), and reduce or use multiple thin coatings in high-temperature environments.


For high-temperature ceramicization applications, select the decomposition atmosphere according to the target ceramic phase (N₂/Ar → SiC/Si₃N₄, NH₃ → Si₃N₄, Air → SiOCN).


Intermix with various resins (epoxy silicone resin, organic silicone resin), and use them together to shorten curing time and increase hardness.


After use, quickly clean tools with acetone or solvent oil. Once cured, do not use solvents to remove it.


Common misunderstandings


The high-temperature performance of UV curing and thermal curing coatings is the same: UV curing will yellow at 300℃+ due to photoinitiator residue; thermal curing (especially without initiator system) has better high-temperature stability and the selection should be based on the actual usage temperature.


The higher the thermal curing temperature, the better: Selecting the thermal curing method should match the substrate's tolerance temperature - without initiator 200℃+, peroxide 120℃+, platinum catalysis 80℃+, and choose the low-temperature path to protect the substrate as much as possible under the condition of meeting the curing requirements.


The thicker the film, the better the protection: The cracking threshold of 9108 resin is 100μm. A single-layer film thickness exceeding this value is prone to cracking in high-temperature or ceramicization processes, and multi-layer thin coating is better than single-layer thick coating.


The choice of pyrolysis atmosphere does not affect the final performance: The pyrolysis atmosphere directly determines the composition of the ceramic phase, and has a decisive influence on the thermal stability and oxidation resistance of the ceramicized material. 


All solvents can be used for dilution: 9108 is insoluble in alcohol-ether solvents (such as diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, tetraethylene glycol butyl ether).


FAQ


What curing methods are available for IOTA9108?
There are two main curing methods: 1) UV curing (requires the addition of a photoinitiator); 2) Thermal curing, which is divided into three paths: without initiator (baking at 200°C or above), peroxide initiator (baking at 120°C or above), and platinum catalysis (baking at 80°C or above).


What hardness can be achieved after curing?
Pencil hardness 6H.


What is the transmittance?
Visible light transmittance > 95%.


What is the recommended curing temperature for the clear coat?
< 600°C (related to film thickness, the higher the film thickness, the easier it cracks at high temperatures).


What ceramic products can be obtained after pyrolysis?
Nitrogen or argon → SiC and Si₃N₄; ammonia → Si₃N₄; air → SiOCN. Amorphous below 1400°C, crystallizes above this temperature.


Which substrates is this product suitable for?
Suitable for metals, alloys, glass, paint films, and various plastic substrates such as PP, PC, PVC, PMMA, etc. Adhesion scratch test grade 0, it is recommended to verify separately on different substrates.