The Magical Metal That Changes Color - Titanium

Titanium metal is very stable in air at room temperature. Only when it is heated to high temperature for a period of time will it produce "colorful" changes. This is mainly because when titanium metal is heated in the air, it will undergo an oxidation reaction with oxygen to form a dense oxide film. This oxide film not only protects the surface of titanium metal, but is also the fundamental source of the color change of titanium.

The reaction equation of 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 titanium surface is almost transparent and is difficult for people to detect with the naked eye. However, when the temperature rises, the oxide film inside the pot will slowly thicken and interfere with light. Different colors will also appear in human eyes. Therefore, the thickness of the oxide film determines the color of the titanium surface.

According to relevant research, after heating in the air for half an hour, the surface of titanium heated at 200°C is silvery white, 300°C is light yellow, 400°C is golden yellow, 500°C is blue, 600°C is purple, and 700°C is purple. ℃ (to) - 800 ℃ is gray-red, 900 ℃ is gray, the entire color change can be described as colorful. [1] The ignition temperature of natural gas is 270-540℃, the ignition temperature of liquefied petroleum gas is 365-460℃, and the ignition temperature of city gas is 270-605℃. They can all reach the temperature where titanium oxidizes and changes color. If it is your titanium pot If it can change color, it means that you are buying a pure high-quality titanium pot.

The oxide film of titanium not only changes the color of titanium, but also greatly improves the corrosion resistance of titanium. However, the thicker the titanium oxide film is, the better the corrosion resistance is. When the heating temperature is below 500°C, 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 reaches 600°C-700°C, the oxide film on the titanium surface will become thicker ; After exceeding 700°C, although the thickness of the oxide film increases, it becomes loose, easy to break, and loses its protective effect. Therefore, titanium generally has good corrosion resistance at room temperature.