Knowledge of slag balls in ceramic fibers

1. What are slag balls? Why are they important?

Slag balls are composed of spherical glass particles that did not transform into fibers during the manufacturing process. Fibers are produced through a melting process, during which the formation of slag balls is inevitable. This is because the fibers initially start as molten glass droplets that are drawn into filaments through a high-energy spinning process, and typically, these droplets have already cooled and solidified into spherical shapes before being drawn into fibers. Therefore, the presence of slag balls indicates the existence of a significant amount of non-fibrous material, providing a shortcut for heat conduction. They have a smaller surface area, thus cannot effectively block thermal radiation.

2.What impact does slag balls have on thermal insulation?

A slag ball with a diameter of 250μm can be converted into a fiber with a length of 1,500,000μm (1.5m) and a diameter of 3μm. The specific surface area of the slag ball particles with a diameter of 250μm is 0.01 m²/g, while the specific surface area of the fibers with a diameter of 3μm is 0.5 m²/g. Due to its low specific surface area, slag balls have poor thermal radiation blocking efficiency. The energy passing through the slag ball particles is higher, thus affecting the thermal insulation effectiveness of the fibers.