Titanium: A Magical Metal That Will Change Colors
Titanium is very stable in the air at room temperature, and only when it is heated at high temperature for a period of time will it produce “colorful” changes. This is mainly because when the metal titanium is heated in the air, it oxidizes with oxygen to form a dense oxide film. This layer of oxide film can not only protect the surface of titanium, but also the fundamental source of titanium color changes.
The reaction equation for titanium oxidation is Ti+O2=TiO2, and the reaction condition is high temperature heating. When the heating temperature is low, the oxide film on the surface of titanium is almost transparent, which is more difficult for people to detect with the naked eye, but when the temperature rises, the oxide film in the pot will slowly thicken and interfere with the light, which will show different colors in people's eyes. Therefore, the thickness and depth of the oxide film determine the color of the titanium surface.
According to relevant studies, after heating in the air for half an hour, the surface of titanium heated at 200℃ is silver-white, 300℃ is light yellow, 400℃ is golden yellow, 500℃ is blue, 600℃ is purple, 700℃ (to) -800℃ is gray-red, 900℃ is gray, the entire color change can be described as colorful. The ignition temperature of natural gas is 270-540℃, the ignition temperature of liquefied petroleum gas is 365-460℃, and the ignition temperature of urban gas is 270-605℃, which can reach the temperature of titanium oxidation and discoloration. If your titanium pot can change color, it means that you are buying a pure high—quality titanium pot.
The oxide film of titanium can not only discolor titanium, but also greatly improve the corrosion resistance of titanium. However, the thicker the oxide film of titanium, the better the corrosion resistance. When the heating temperature is below 500℃, oxygen and titanium will form a dense oxide film of TiO2, which has a certain protective effect on the titanium surface; when the heating temperature is 600℃-700℃, the oxide film on the titanium surface will become thicker; after exceeding 700℃, although the thickness of the oxide film increases, it becomes loose, easy to break, and loses its protective effect.Therefore, generally at room temperature, titanium has good corrosion resistance.
