1. The Composition Difference
The two grades differ in the silicon carbide content: 90% silicon carbide contains about 90% SiC, while 88% contains about 88%. The difference is made up of free silicon, silica and other impurities, which are higher in the 88% grade. Although two percentage points sound small, they change the active material delivered per ton and the impurity load of the addition.
2. Effect on Metallurgical Performance
In steelmaking and foundry use, the higher SiC content of the 90% grade delivers more carbon and silicon per ton, giving higher and more consistent carbon recovery and less slag. The 88% grade requires a larger addition weight for the same pickup and produces more slag per unit of active material. For tight chemistry control, the 90% grade is the safer choice.
3. Impurity and Quality Differences
The 88% grade carries more free silicon, silica and mineral impurities, which can introduce oxygen and increase the slag burden. For ductile iron and clean steel production, where residual elements and cleanliness matter, the higher impurity load must be managed. The 90% grade has a tighter impurity profile and more predictable behavior.
4. Price and Cost per Unit
The 90% grade costs more per ton, but the comparison must be made on the delivered cost per unit of active silicon carbide. Depending on the market, the two grades can be close on this basis, and the 90% grade often wins when the value of consistent chemistry and lower slag is included. Buyers should request offers on the same basis and calculate the unit cost.
5. Selection Guidance
| Factor | 88% SiC | 90% SiC |
|---|---|---|
| Active SiC per ton | Lower | Higher |
| Carbon recovery | Good | Better, more consistent |
| Impurity load | Higher | Lower |
| Price per ton | Lower | Higher |
| Best for | Cost-sensitive additions | Tight chemistry and clean steel |
6. FAQ
Q1: What is the difference between 88% and 90% SiC? The silicon carbide content: 90% has more active SiC and fewer impurities than 88%.
Q2: Which gives better carbon recovery? The 90% grade gives higher and more consistent carbon recovery.
Q3: Does the 88% grade produce more slag? Yes, the higher impurity content increases the slag volume per unit of active material.
Q4: Is the 90% grade worth the price? Compare the delivered cost per unit of active SiC; the consistency and lower slag often justify it.
Q5: Which should I choose for ductile iron? The 90% grade, because the lower impurity load protects the residual-element control of the iron.
Q6: How are the grades verified? By the certificate of analysis reporting the SiC content and impurities per batch.
