Under high-temperature cycling conditions, will the soluble components of alkaline earth silicate fiber blanket accelerate structural degradation and affect its long-term thermal insulation performanc
Publish Time: 2026-02-19
Alkaline earth silicate fiber blanket, as a new type of environmentally friendly high-temperature insulation material, is widely used in industrial kilns, heat treatment equipment, aerospace, and new energy fields due to its advantages such as low thermal conductivity, low heat storage, high tensile strength, and absence of organic matter. Its "soluble" design aims to reduce the potential harm to the environment and human health from traditional ceramic fibers after disposal, and to improve biodegradability.1. The Dual Nature of Soluble Components: Environmental Advantages and High-Temperature Stability ChallengesAlkaline earth silicate fiber blanket typically replaces aluminum or zirconium in traditional ceramic fibers with alkaline earth metal oxides such as calcium and magnesium, forming a silicate network structure that dissolves slowly under physiological conditions. This characteristic significantly reduces the risk of long-term retention in the lungs after inhalation, meeting modern green material standards. However, in high-temperature cycling environments of 800℃–1200℃, water vapor, oxygen, and even trace amounts of acidic gases may diffuse into the fiber interior through micropores, reacting with soluble alkaline earth components, leading to localized softening of the glassy phase, weakening of grain boundaries, or rearrangement of the amorphous structure. Repeated thermal expansion and contraction further exacerbate microcrack propagation, causing fiber embrittlement and fracture, macroscopically manifested as volume shrinkage, density decrease, and pore structure collapse.2. Cumulative Damage to Microstructure from High-Temperature CyclingIn a single high-temperature exposure, alkaline earth silicate fiber blankets typically maintain good stability; however, the thermal fatigue effect under cyclic conditions is cumulative. During each heating process, the fiber generates internal stress due to thermal expansion; during cooling, if the cooling rate is too fast, residual stress cannot be completely released, easily forming microcracks at fiber intersections or defects. Furthermore, soluble components may form low-melting-point eutectics at high temperatures, lowering the local softening point and making the fiber more susceptible to plastic deformation or adhesion under stress. After multiple cycles, the originally loose and porous needle-punched three-dimensional network gradually densifies, and the porosity decreases, leading to an increase in thermal conductivity—contradicting its initial advantages of "low heat storage and low thermal conductivity."3. Synergistic Degradation Effect of Environmental MediaIn actual industrial environments, high temperatures are often accompanied by corrosive atmospheres. For example, in metallurgical or waste incinerators, flue gas contains SO₂, Cl⁻, or alkali metal vapors. These substances can react with alkaline earth ions to generate volatile or expansive products such as sulfates and chlorides, further damaging the fiber skeleton. Even in seemingly "clean" air environments, atmospheric moisture promotes the hydrolysis of silicon-oxygen bonds at high temperatures, especially in the presence of soluble cations, where the hydrolysis rate is significantly accelerated. This "humid heat aging" effect is particularly prominent in cyclic operating conditions because each cooling phase provides a window for moisture adsorption, while heating accelerates chemical reactions, creating a vicious cycle.The solubility of alkaline earth silicate fiber blankets is a double-edged sword: while it endows materials with environmentally friendly properties, it can also become a cause of structural degradation under harsh high-temperature cycling conditions. The future direction is not to abandon solubility in design, but rather to improve high-temperature durability while maintaining biocompatibility through component fine-tuning, surface modification, or composite reinforcement. Only in this way can we truly achieve a balance between "green" and "reliable," propelling high-temperature insulation materials towards high performance, long lifespan, and sustainability.
