Requirements for green carborundum GC in the production of Teflon coatings
The core requirements for green carborundum GC in the production of Teflon coatings (especially food contact applications such as non-stick pans) are as follows:
1. Chemical composition requirements
High purity: SiC ≥98% to ensure hardness and wear resistance.
Low heavy metal residue: Hexavalent chromium and other heavy metal residues must be <0.01 ppm to avoid food contact contamination.
Impurity control: Fe₂O₃≤0.40%, free carbon (C)≤0.2%, to reduce the impact on coating performance.
2. Physical performance requirements
High hardness: Mohs hardness ≥9.4, to ensure coating wear resistance (such as passing ≥5000 wear resistance tests).
High temperature resistance: It needs to withstand high temperatures of 1900-2250℃ to match the sintering process of Teflon coatings.
Chemical stability: It has acid resistance, salt resistance, and antioxidant properties to prevent corrosion in cooking environments.
3. Particle size and uniformity
Sizes: Normal sizes are 800 mesh, 1000 mesh, and 1200 mesh
Particle size distribution: Green carborundum GC micropowder produced by acid washing and overflow grading must be used. It has high cleanliness and concentrated particle size distribution to avoid coarse particles scratching the coating.
4. Special process requirements
Surface treatment: It must be treated with acid washing and water washing to reduce the content of magnetic materials and improve chemical purity.
Low magnetic materials: Avoid magnetic impurities (such as ferroalloys) interfering with coating performance.
5. Differences from other materials
Black carborundum cannot be used as a substitute: Black carborundum (Mohs hardness of about 9.2) has lower wear resistance than green carborundum GC, and impurity control is more stringent, so it is limited to low-requirement fields.
White corundum has low applicability: Although both are wear-resistant fillers, green silicon carbide is better in high temperature resistance and chemical stability.
VI. Functions and effects
Adding green carborundum GC can fill the pores of Teflon coating, enhance the anti-scratching property, and extend the life of the coating. At the same time, it needs to be coordinated with other processes (such as substrate cleaning and curing parameters) to optimize wear resistance.