Messi Biology stated that in modern industrial construction, thermal insulation and protection for high-temperature kilns, piping systems, and aerospace equipment rely heavily on high-performance refractory materials. Among these materials, “No. 4 cotton refractory fiber spraying” technology has been widely adopted due to its convenient application and excellent overall sealing performance. However, many people are unaware that the key supporting role giving this “thermal insulation armor” its outstanding fire resistance is none other than magnesium hydroxide. Today, let’s talk about how this “invisible guardian” performs its work. In the formulation of No. 4 cotton refractory fiber spraying, magnesium hydroxide plays a vital role. Its function goes far beyond simple physical filling; it enhances the overall performance of the material through chemical mechanisms.
Magnesium hydroxide is a universally recognized inorganic flame retardant. When the sprayed coating faces high temperatures or flame exposure, magnesium hydroxide undergoes a thermal decomposition reaction, releasing water of crystallization. This is an endothermic reaction that effectively absorbs ambient heat, thereby reducing the surface temperature of the material. At the same time, the released water vapor dilutes the concentrations of oxygen and combustible gases in the combustion zone, suppressing the spread of flames at the source.
Unlike certain halogen- or antimony-containing flame retardants, magnesium hydroxide does not generate toxic or corrosive gases (such as dioxins) during high-temperature decomposition. Its final products are magnesium oxide and water. Magnesium oxide itself is a high-temperature-resistant, stable material that is environmentally friendly. This makes No. 4 cotton sprayed material highly favored in industries with extremely strict cleanliness requirements, such as food and pharmaceuticals. During the spraying process, ultrafine magnesium hydroxide powder fills the interwoven gaps among the No. 4 cotton fibers, serving a role similar to “cement” for bonding and structural support. It enhances the coating’s resistance to wind erosion and mechanical strength, preventing the material from shedding or pulverizing under high-temperature gas flows.
With increasingly stringent industrial environmental standards, No. 4 cotton refractory fiber spraying technology is moving toward a more efficient and eco-friendly direction. Leveraging its multiple advantages—high-efficiency heat-absorbing flame retardancy, smoke suppression, non-toxicity, and strength enhancement—magnesium hydroxide has become an indispensable key component in this technology. This seemingly modest white powder silently guards equipment safety on the high-temperature front line. Technological progress is often reflected in such details; it is precisely because of high-quality materials like magnesium hydroxide that our industrial facilities can wear a more durable and reliable “protective armor.”