Bi-layered coating: A breakthrough in fire-resistant materials

Fire safety is a critical concern across various industries, from construction and transportation to electronics and energy storage. Traditional flame-retardant coatings often fail to provide both immediate and prolonged protection, limiting their applicability. Now, researchers from the IMDEA Materials Institute, Beijing Technology and Business University, and Universidad Rey Juan Carlos, led by Professor Lijun Qian and Professor De-Yi Wang, have developed an innovative bi-layered coating that addresses these challenges. Their findings, published in Nano-Micro Letters, demonstrate superior fire resistance with a mere 320-micron thickness.

Why This Bi-Layered Coating Matters

• Fast Response and Extended Protection: The bi-layered coating combines an intumescent flame-retardant (IFR) outer layer and a ceramifiable inner layer, enabling both rapid response to fire and long-lasting protection.
• Superior Burn-Through Resistance: The coating withstands fire temperatures up to 1400°C for over 900 seconds, significantly outperforming traditional coatings. This level of protection is crucial for materials like aluminum and glass fabric-reinforced epoxy resin, which typically burn through in under 200 seconds.
• Enhanced Electrochemical Stability: When applied to lithium soft-package batteries, the bi-layered coating suppresses the formation and decomposition of solid interface layers, leading to prolonged electrochemical stability and fire safety.

Innovative Design and Mechanisms

• Relay Response Effect: The bi-layered structure functions like a relay, with the IFR layer providing immediate protection and the ceramifiable layer offering long-term stability. The IFR layer rapidly forms a char barrier at temperatures below 300°C, while the ceramifiable layer undergoes a phase transformation at around 550°C to create a durable ceramic barrier.
• Optimized Formulations: The researchers optimized the formulations of both the IFR and ceramifiable layers. The IFR layer, enhanced with alumina synergists, achieves a 31% residue yield at 800°C, while the ceramifiable layer, composed of low-melting glass powder and other fillers, maintains over 97% residue yield.
• Thermal Insulation and Barrier Effect: The bi-layered coating not only provides a rapid response but also excellent thermal insulation. The char layers formed during combustion effectively block heat transfer, protecting the underlying substrate from prolonged exposure to high temperatures.

Future Outlook

• Scalability and Commercialization: The thin and efficient nature of the bi-layered coating makes it highly scalable and suitable for large-area applications. Its ability to provide both rapid and long-lasting protection positions it well for commercial adoption in various industries.
• Versatility in Applications: The bi-layered coating has demonstrated effectiveness on multiple substrates, including polyurethane foam, aluminum, and glass fabric-reinforced epoxy resin. Its potential applications extend to fire-resistant coatings for buildings, flame-retardant materials for transportation, and fire-safe energy storage devices.
• Mechanistic Insights: This study provides valuable insights into the mechanisms of intumescent flame retardancy and ceramification, offering a blueprint for further development of high-performance flame-retardant coatings.

Stay tuned for more groundbreaking advancements from Professor Lijun Qian and Professor De-Yi Wang as they continue to push the boundaries of fire-resistant materials!