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Silicon Carbide (SiC) Flame Spray Nozzles And Burners Are Widely Used In High-Temperature Combustion Systems In The Ceramic, Metallurgical, Chemical And Other Industries Due To Their Excellent High Temperature Resistance, Corrosion Resistance And Thermal Shock Resistance. The Performance Of Silicon Carbide Products Prepared By Different Processes Varies Greatly. This Article Will Focus On The Common Manufacturing Process Of Silicon Carbide Flame Spray Nozzles And The Key Preparation Process Of Reaction Sintered Silicon Carbide (RBSiC) Burners.
1. Manufacturing process of silicon carbide flamethrower
The manufacturing process of silicon carbide flame spray nozzle mainly includes the following:
Pressureless sintering process
High-purity silicon carbide micropowder is mixed with sintering aids (such as Al₂O₃, Y₂O₃, etc.), formed by dry pressing or isostatic pressing, and then sintered at a high temperature above 2000°C.
Advantages : The product has high density (＞98%), excellent mechanical strength, and is suitable for high-load conditions.
Disadvantages : high sintering temperature, high energy consumption and high cost.
Grouting molding process
Silicon carbide powder and a binder are mixed into a slurry, injected into a mold for forming, and then sintered after drying.
Advantages : Suitable for mass production of flamethrowers with complex shapes at low cost.
Disadvantages : The density and strength of the product are slightly lower than those of pressureless sintered products.
Hot Pressing Sintering Process
Silicon carbide powder is sintered at high temperature (1800~2000℃) and high pressure (20~50MPa) to obtain ultra-high density products.
Advantages : The product has almost no pores and excellent thermal shock resistance.
Disadvantages : high equipment requirements, low production efficiency, only suitable for high-end applications.
2. Preparation process of reaction sintered silicon carbide (RBSiC) burner
Reaction Bonded SiC is a high-performance material prepared by silicon infiltration reaction. The process flow is as follows:
Raw material mixing
Silicon carbide powder (α-SiC) is mixed with a carbon source (such as graphite or resin carbon) in proportion and a temporary binder is added.
forming
The porous green billet is formed by dry pressing, injection molding or extrusion, and pores are reserved in the green billet for subsequent silicon penetration.
Pre-sintering
Pre-sintering is carried out at 1000~1400℃ to give the green body a certain strength and form a partial carbon skeleton.
Silicon Infiltration Reaction
The green billet is placed in a vacuum or inert atmosphere furnace and heated to 1450~1600℃, so that molten silicon (Si) penetrates into the pores of the green billet and reacts with carbon to form β-SiC, eventually forming a dense Si-SiC composite material.
Post-processing
The burner dimensional accuracy is ensured by machining (such as CNC precision engraving), and the surface is polished or coated to improve corrosion resistance.
Process advantages :
The sintering temperature is lower (compared to pressureless sintering), and the energy consumption is low;
The product has good dimensional stability and is suitable for complex and special-shaped parts;
Residual silicon can improve thermal conductivity and is suitable for high-temperature combustion environments.
3. Process selection suggestions
High-precision, high-load scenarios : pressureless sintering or hot-pressed sintering silicon carbide flame spray nozzles are preferred;
Complex shapes and low-cost requirements : Slip casting or reaction sintering processes are more suitable;
Extreme thermal shock resistance : Reaction bonded silicon carbide (RBSiC) burners are the ideal choice.
The preparation process of silicon carbide flame spray nozzles and burners directly affects their performance and life. Enterprises need to choose the appropriate technical route based on actual application requirements.