Imo classes
Class 4.1
Flammable Solids or SubstancesSelf-reactive materials,which are thermally unstable and that can undergo a strongly exothermic decomposition even without participation of air.
Readily combustible solids that can cause a fire through friction and show a burning rate faster than 2.2 mm (0.087 inches) per second, or metal powders that can be ignited and react over the whole length of a sample in 10 minutes or less.