Can I lock up CO2 into silicon carbide?
Yes, but not practically.

The reduction of silica and carbon dioxide to silicon carbide is a conducted at high temperatures (commonly higher than 1500 °C, reaching 2500 °C). The energy required to reach these temperatures is immense. Furthermore, this is done in a nearly pure carbon dioxide atmosphere. I remind you that our atmosphere has about 400 ppm of carbon dioxide.

Silica is not abundant as you think. The main source for silica, sand, is actually quite rare and many countries are experiencing environmental damage due to illegal or legal mining of sand. Sand is commonly host to fragile and unique ecosystems. You can mine sandstone, but you will need to crush it to sand. Pulverising is the most energy intensive phase of any mining operation. For silicon carbide to form efficiently, it has to be crushed to a fine powder. Sand size is not enough. This is extremely energy intensive.

This is going to be an extremely expensive undertaking, and since the source of most of our energy is still fossil fuels, then this would be counter productive.