Silicon carbide ceramics' oxidation resistance is a key advantage in maintaining their long service life in high-temperature oxidizing environments. This property stems from their unique chemical composition and reaction mechanism. In high-temperature environments, most materials undergo an oxidation reaction with oxygen, leading to surface corrosion, structural porosity, and even performance failure. However, when exposed to oxygen, silicon carbide ceramics undergo a controlled oxidation reaction, forming a dense oxide film. This film effectively blocks further oxygen intrusion into the material, fundamentally slowing the rate of oxidative corrosion and providing long-term protection.
In high-temperature oxidizing environments, the oxide film formed on the surface of silicon carbide ceramics exhibits stable chemical properties and structural integrity. Primarily composed of silicon dioxide, this oxide film is chemically stable and resistant to reaction with other substances, maintaining its morphology even under sustained high temperatures. This film acts as a solid barrier, isolating the silicon carbide substrate from external oxygen and corrosive gases, preventing continued oxidation and consumption of the substrate material, thereby maintaining the material's structural integrity and extending its useful life.
The self-healing ability of the oxide film further enhances the oxidation resistance and durability of silicon carbide ceramics. In a high-temperature oxidizing environment, if the oxide film is locally damaged by minor friction or impact, the surrounding silicon carbide will continue to react with oxygen, regenerating silicon dioxide at the damaged site to fill the gap and restore the film's integrity. This self-healing mechanism ensures that the protective barrier persists despite minor damage, maintaining its protective effect and ensuring that silicon carbide ceramics maintain excellent oxidation resistance over long-term use.
The oxidation resistance of silicon carbide ceramics enables them to maintain stable mechanical properties at high temperatures. High-temperature oxidation can cause a decrease in mechanical properties such as strength and hardness in many materials. However, thanks to the protective oxide film, the base material of silicon carbide ceramics does not experience structural porosity or strength loss due to oxidation. Even in long-term high-temperature oxidizing environments, their compressive and wear resistance properties remain at a high level, ensuring that the resulting components continue to function stably and avoid premature failure due to material degradation.
This oxidation resistance reduces the rate of material loss in high-temperature oxidizing environments. Conventional materials in high-temperature oxidizing environments will undergo continuous oxidation and corrosion over time, gradually thinning and ultimately becoming unusable. Silicon carbide ceramics, on the other hand, oxidize slowly, and their oxide film effectively inhibits further oxidation, resulting in minimal material loss. This slow loss significantly prolongs the time it takes for the material to reach its critical thickness, significantly extending component lifespan and reducing replacement frequency.
Silicon carbide ceramics' oxidation resistance makes them suitable for high-temperature oxidizing environments with large temperature fluctuations. In real-world industrial scenarios, high-temperature environments are often accompanied by frequent temperature fluctuations, which can accelerate the material's oxidation process. The oxide film on silicon carbide ceramics offers excellent thermal compatibility with the substrate material, making it less susceptible to peeling or cracking due to thermal expansion and contraction during temperature fluctuations, maintaining complete protection. Even after repeated temperature cycles, its oxidation resistance does not significantly degrade, ensuring long-term, stable operation under complex operating conditions.
This oxidation resistance reduces maintenance requirements in high-temperature oxidizing environments, indirectly extending component lifespan. Because silicon carbide ceramics exhibit minimal oxidation corrosion in high-temperature oxidizing environments, component surfaces do not accumulate large amounts of oxide debris or corrosion products, eliminating the need for frequent cleaning or repair. This low maintenance requirement reduces additional damage to components caused by improper maintenance or frequent disassembly and assembly, while also avoiding interruptions in use due to maintenance stoppages, allowing components to continue working normally over a longer period, thereby comprehensively improving their actual service life.
