6 Common Methods to Eliminate Carbon in Silicon Carbide Powder--Chemical Methods

- Jan 08, 2019 -

1.1 Heating Method for Oxidation

By calcining Silicon Carbide Powder, we could have free C and graphite oxidized by oxygen in the air and turn into CO2 or CO.

Here are 2 experiments:

Experiment 1 : Calcining temperature :900℃

Calcining period: 3 hours

Result: Carbon could be eliminated totally

Experiment 2: Calcining temperature : 450~560℃

Calcining period : 4 hours

Oxidation media: air

Result: ratio of elimination : 98. 6%~99. 2%

Conclusion: With certain temperatures and calcining-periods, the ratio could be 98%.

Because of the high BET of Silicon Carbide Powder, when grits are put through too much heat, there will be a thin oxidation film covering grits and prohibiting the elimination of carbon.

1.2Chemical Method for Oxidation

To eliminate free C in Silicon Carbide Powder, we would use acids or add inorganic oxidants into the acids.

Kinds of acid: 1. Nitric acid,

2. Sulfuric acid,

3. Perchloric acid

4. Mixed acid of those three acids

Inorganic oxidants :KMnO4 and K2Cr2O7

This chemical method could eliminate free C by oxidizing and turning them into gas. However, these strong oxidability acids would have serious corrosion on workers and machines. This method can’t be wildly applied in large-scale industrial silicon carbide manufacture.