How does intumescent fire retardant coating achieve dual protection against fire and corrosion?
Publish Time: 2025-11-19
In modern large-scale public buildings and industrial facilities, steel structures are widely used due to their high strength and rapid construction. However, their fatal weakness lies in their rapid softening and instability at high temperatures—ordinary steel loses more than 50% of its strength at 600℃, leading to structural collapse within 15 minutes. Simultaneously, steel components exposed to moisture, salt spray, or industrial atmospheres face the risk of corrosion, which weakens their load-bearing capacity over the long term. Traditional methods often employ a layered application of "anti-corrosion primer + fire retardant coating," a cumbersome process with difficulty in ensuring interlayer compatibility. Intumescent fire retardant coating, through innovative material formulation and functional integration, successfully combines excellent fire resistance with long-term corrosion protection, achieving "dual protection with one coating," providing efficient, economical, and reliable comprehensive protection for critical steel structures such as stations, bridges, and factories.1. Dense Expanded Carbon Layer: The Core of Fire Protection, Also Acting as a Physical BarrierThe core mechanism of intumescent fire retardant coating lies in its fire response. When the ambient temperature rises to 200–300℃, the acid, carbon, and gas sources in the coating undergo a synergistic reaction, rapidly releasing non-combustible gases. This causes the coating to expand 10–30 times, forming a porous yet dense honeycomb-like carbonaceous insulation layer. This carbon layer has extremely low thermal conductivity, effectively isolating the heat from the flames from the steel substrate and significantly slowing down the heating rate. This meets the fire resistance limit requirements of 0.5 to 2.5 hours, ensuring that load-bearing components such as beams, columns, and floor slabs maintain structural integrity during a fire, buying valuable time for evacuation and fire rescue.2. High-Performance Base Material System: Constructing a Long-Lasting Corrosion Protection FoundationBeyond fire protection, the coating itself possesses excellent corrosion resistance. Its film-forming material uses modified epoxy or acrylic resin, which has a high cross-linking density and low water vapor permeability, effectively blocking oxygen, moisture, and corrosive ions from penetrating to the steel surface. Combined with the corrosion-inhibiting effect of rust-inhibiting pigments, even without the application of an additional anti-corrosion primer, the coating can provide basic cathodic protection and passivation protection for the steel. Actual testing shows that in C3-C4 grade industrial or coastal atmospheric environments, a single coat of intumescent fire retardant coating can maintain its rust-free condition for over two years, significantly outperforming traditional pure fire-retardant coatings.3. Strong Adhesion and Mechanical Properties: Ensuring Interlayer Stability and DurabilityThe prerequisite for achieving integrated "fireproofing + corrosion protection" is the coating's own superior performance. NSP-BD-C coating boasts three key characteristics: fast drying, high hardness, and strong adhesion: surface dry ≤ 2 hours, complete dry ≤ 24 hours, facilitating rapid recoating; after curing, its pencil hardness reaches H grade or higher, exhibiting excellent impact resistance and abrasion resistance; adhesion to sandblasted steel ≥ 1 MPa, far exceeding national standards. This high mechanical strength not only resists daily wind loads, vibrations, and minor impacts but also prevents fireproofing failure or corrosion exposure due to coating cracking and peeling, ensuring continuous and effective protection throughout its entire lifespan.4. Highly Compatible with Substrate, Simplifying Construction ProcessThis coating is specifically designed for steel structures, with a thermal expansion coefficient similar to steel, avoiding delamination caused by thermal stress. Its construction adaptability is strong, allowing for spraying, brushing, or roller coating without complex pretreatment, significantly shortening the construction period and reducing labor costs. It is particularly suitable for renovation projects or large venue construction with tight schedules, avoiding the quality control difficulties and interface risks associated with the traditional multi-step process of "primer-intermediate paint-fireproof layer."Intumescent fire retardant coating, through the ingenious integration of materials science, breaks through the traditional limitations of "fireproof but not corrosion-resistant, corrosion-resistant but not fireproof." With a single coating, it simultaneously constructs a heat shield against intense flames and a protective wall against corrosion, not only improving the safety redundancy of steel structures but also optimizing project efficiency and life-cycle maintenance costs. In today's increasingly stringent building safety standards, this intensive, high-performance dual-protection solution is becoming the preferred path for the protection of steel structures in large public infrastructure projects.
