Drying and Sintering Process of Combined Heat Storage Plates
Briefly introduces the drying and sintering process of the combined heat storage plate.
Drying and Sintering Process of Combined Heat Storage Plates
Drying and sintering are key processes that determine the strength, thermal shock resistance, and dimensional accuracy of the sheet.
Drying Process
The moisture content of the formed green body is 15%-25%, and it needs to be dried to below 3% to prevent cracking during sintering.
Drying Method | Temperature | Time | Characteristics |
Hot Air Drying | 80-150℃ | 4-12 hours | Most commonly used, uniform and controllable |
Microwave Drying | — | Short | Fast, uniform, high equipment investment |
Infrared Drying | — | Short | High efficiency, difficult to control thickness |
Key control points:
Heating rate: 2-5℃/min; excessively rapid heating can easily cause surface cracking.
Ambient humidity: 40%-60% to slow down surface moisture evaporation.
Moisture content: below 3%.
Sintering process
Sintering consists of three stages:
Stage | Temperature Range | Heating Rate | Function |
Low Temperature Stage | Room Temperature - 600℃ | 2-3℃/min | Drainage of water and organic matter (holding required at 200-500℃) |
Medium Temperature Stage | 600-1200℃ | 3-5℃/min | Initial sintering of particles |
High Temperature Stage | 1200℃ - Maximum Temperature | — | Densification, holding for 1-3 hours |
Sintering temperatures: Cordierite 1350-1420℃, Corundum-Mullite 1500-1600℃, Silicon Carbide 1400-1500℃ (protective atmosphere required).
Too low a temperature → insufficient strength; too high a temperature → coarse grains, increased brittleness.
Common defects and countermeasures
Defects | Causes | Countermeasures |
Surface Cracks | Too rapid drying and heating | Control heating rate ≤3℃/min |
Warping/Deformation | Uneven temperature | Improve temperature field, increase weight |
Insufficient Strength | Low sintering temperature | Increase temperature or extend holding time |
Overheating/Deformation | Too high temperature | Decrease temperature, shorten holding time |
Summary
Drying and sintering can be summarized as follows: Drying requires controlling moisture content (<3%) and preventing cracking; sintering requires controlling temperature (1350-1600℃) and maintaining strength; a phased heating curve is crucial. Different materials have significantly different sintering temperature requirements and must be set separately. Proper drying and sintering are prerequisites for ensuring sheet quality.