Why do metals turn red or orange when exposed to high temperatures?
When a metal is exposed to high temperatures, the atoms within the metal start to vibrate and then emit electromagnetic radiation [1]. The atoms in the metal are vibrating so much that they emit a high electromagnetic frequency, which we see as different colors [1]. In essence, the color of the metal is a result of the thermal energy added to the metal. When we heat a piece of metal, we are adding thermal energy to the atoms within the metal [1]. Moreover, the passivation process makes steel rust resistant. It does so by producing magnetite, which is a Fe3O4 black iron oxide compound, not the Fe2O3 red oxide that’s commonly known as “Rust” [2]. The black oxide variant holds firm, so it acts as a protective barrier, plus it delivers big in terms of a visually alluring metal finish [2].
When metal is exposed to high temperatures, the atoms within the metal start vibrating due to the addition of thermal energy, which causes them to start emitting electromagnetic radiation [1, 2]. All objects, including metals, at a certain temperature can emit radiation, known as thermal radiation [2]. The color of the radiation is dependent on the temperature of the object and the properties of the object [2]. As the temperature of the metal increases, the object begins to emit light [2]. The charged particles near the surface of the object emit radiation [2]. As the temperature increases, the distribution of the emitted radiation moves towards short wavelengths [2]. Elements placed in a flame will change color [3]. The color depends on the electron orbitals and the energy required to move an electron from one orbital to another [3].