Thermal Shock Resistance of Far-infrared Honeycomb Ceramic Combustion Plates
Briefly introduces the thermal shock resistance of far-infrared honeycomb ceramic combustion plates.
Thermal Shock Resistance of Far-infrared Honeycomb Ceramic Combustion Plates
Thermal shock resistance is the ability of a combustion plate to withstand sudden temperature changes (room temperature ↔ 800-1000℃) without cracking, and is a key indicator determining its service life.
Causes of Thermal Shock
Sudden temperature changes cause uneven thermal expansion and contraction, generating thermal stress. During heating, the surface is under pressure and the interior is under tension; during cooling, the surface is under tension. When the thermal stress exceeds the material's strength, cracks appear.
Comparison of Thermal Shock Resistance of Various Materials
Material | Coefficient of Thermal Expansion | Thermal Conductivity | Thermal Shock Resistance |
Cordierite | 1.5-2.5 | 1.5-2.5 | Optimal |
Silicon Carbide | 4.0-5.0 | 15-30 | Good |
Corundum-Mullite | 5.0-7.0 | 2.0-3.0 | Good |
Alumina (95% Ceramic) | 7.0-8.0 | 2.0-3.0 | Average |
Cordierite has the lowest thermal expansion and the best thermal shock resistance; silicon carbide has extremely high thermal conductivity, allowing for rapid equilibrium of internal and external temperature differences.
Measures to improve thermal shock resistance
Measures | Effects |
Using cordierite (for frequent start-stop cycles) | Lowest thermal expansion, high tolerance |
Using silicon carbide (for continuous high temperatures) | Fast thermal conductivity, small temperature difference |
Reducing wall thickness (≤0.6mm) | Reduces internal and external temperature difference |
Rounded transition design | Eliminates stress concentration |
Controlling the heating rate ≤20℃/min | Reduces temperature gradient |
Selection Recommendations
Operating Conditions | Recommended Materials |
Frequent Start-Stop (>10 times/day) | Cordierite |
Continuous Operation, Occasional Start-Stop | Silicon Carbide |
Temperature Difference >500℃ | Cordierite |
Ultra-High Temperature (>1400℃) | Silicon Carbide (Recrystallization) |
Summary
Thermal shock resistance summary: Cordierite (expansion 1.5-2.5) best for frequent start/stop; SiC (conductivity 15-30) best for continuous high heat. Choose by cycles & temperature swings, control ramp rate (≤20°C/min), use thin walls & radiused edges. Essential for long combustion plate life.