Why is silica powder called 'white carbon black' and how does it compete with carbon black in rubber reinforcement?

Why is silica powder called 'white carbon black' and how does it compete with carbon black in rubber reinforcement?
The name 'white carbon black' is a historical artifact from the early rubber industry, when workers needed a simple label for a white reinforcing filler that performed similarly to carbon black. Chemically it is precipitated or fumed silica (SiO2·nH2O), not carbon at all. Its commercial logic is straightforward: carbon black dominates tire and rubber reinforcement but is black, limiting product color options. Silica offers comparable or better reinforcement in white or colored compounds, plus superior tear strength, heat aging resistance, and adhesion. In tires, high-dispersion silica improves wet grip by 5-10% and cuts rolling resistance by about 25%, translating to roughly 5% fuel savings, without sacrificing wear. This has made silica a key enabler of green tire technology, especially as China's domestic tire makers push into premium and EV segments.