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Properties of Polysilazanes (PSN)
Polysilazanes feature a backbone of Si-N bonds and are primarily categorized into two types: perhydropolysilazane (PHPS) and organopolysilazane (OPSZ). Their core advantages lie in their processability at room temperature and their ability to transform into ceramics at high temperatures.
1. Ceramic Precursor Characteristics
They exist as liquids or low-viscosity resins at room temperature and are suitable for spray coating, spin coating, dip coating, and 3D printing.
Upon high-temperature pyrolysis, they convert into ceramic phases such as SiO₂, Si₃N₄, SiCN, and SiON, achieving ceramic yields of up to 85%. Cross-linking and ceramicization begin at approximately 300°C, with the ceramic phase transition completed above 800°C. The resulting pyrolysis products are dense and have low porosity, enabling the fabrication of ultra-thin ceramic coatings and complex ceramic components.
2. Heat Resistance
The cured ceramic materials exhibit excellent high-temperature resistance; SiCN ceramics can withstand temperatures exceeding 1200°C for long periods and up to 1500–1800°C for short durations.
They possess low thermal conductivity, flame retardancy, thermal shock resistance, and high-temperature oxidation resistance, making them ideal materials for thermal protection and environmental barrier coatings.
3. Film-Forming and Mechanical Properties
They exhibit excellent film-forming capabilities at room temperature, allowing for the creation of ultra-thin, dense inorganic films.
Containing active Si-N and N-H groups, the molecules form chemical bonds with substrates such as metal, glass, and ceramics, resulting in superior adhesion. The cured coatings are hard and resistant to friction and scratching; hydrolysis by moisture creates a dense Si-O network structure, resulting in coatings with minimal defects and high structural integrity.
4. Corrosion Resistance and Surface Properties
They offer resistance to acids, alkalis, organic solvents, and salt spray corrosion, providing long-term anti-corrosion performance that far surpasses conventional organic coatings.
The coatings feature low surface energy and excellent hydrophobicity—with water contact angles reaching 95°–105°—offering self-cleaning, anti-fouling, and anti-graffiti properties.
5. Electrical Properties
The cured ceramic layer exhibits excellent insulation, a low dielectric constant, and high dielectric strength, making it suitable for use as passivation layers in microelectronic devices and insulation packaging layers for precision electronics.
6. Processing and Curing Characteristics
The raw material is liquid, can be diluted with solvents, and supports various application methods.
It allows for multiple curing modes—including moisture curing, heat curing, and photocuring—facilitating convenient processing. Notably, perhydropolysilazane is sensitive to water vapor and requires strict moisture-free storage; while organopolysilazane offers better storage stability, the resulting ceramic has relatively lower purity.
7. Material Limitations
Perhydropolysilazane is prone to hydrolysis and requires stringent storage conditions. Pyrolysis of thick layers releases small-molecule gases, making thick green bodies prone to cracking; thus, the material is better suited for preparing thin coatings. Overall material costs are relatively high.
Key Application Areas: High-temperature thermal protection in aerospace, long-term anti-corrosion for industrial metals, electronic insulation and passivation coatings, anti-fouling coatings for automotive and architectural applications, ceramic matrix composites, protective coatings for new energy batteries, etc.
Organopolysilazanes/ Polysilazane chinese manufacturer/producer/factory/ nanjing sanfan chemical co.,ltd.
