What type of material is typically used in slow-burning fire-resistant applications?

In slow-burning fire-resistant applications, ablative materials are particularly effective due to their unique properties. Ablative materials are designed to absorb and dissipate heat through a process of chemical and physical degradation. When exposed to high temperatures, these materials undergo a series of changes, including charring and the release of gases, which help to insulate and protect underlying structures from fire. This makes them ideal for applications where prolonged exposure to heat and flames is expected, as they can effectively slow down the transfer of heat and provide safety in critical situations.

The other options do not offer the same level of fire-resistant performance. Fast-burning composites would ignite and burn quickly rather than resist fire. Heavy metals, while having high melting points, are not typically used in applications requiring temperature regulation in a fire event and can conduct heat rather than insulate against it. Low-density plastics generally do not have sufficient fire-resistant properties, as many can be highly combustible and contribute to the spread of flames. Hence, ablative materials stand out as the most suitable choice for slow-burning fire-resistant applications.