Why does titanium turn blue when heated

Complete black is the complete absence of light. The thickness of this layer is what controls which light waves are blocked. The thickness of the oxide layer is dependent on the temperature that the steel hits while in contact with oxygen.

In other words, heat will initiate a chemical reaction between the iron in the steel and the oxygen in the air. This forms an oxide layer, which is a thin film that will filter out some wavelengths while enhancing others, depending on its thickness.

This is how the color changes. Another example of a metal that turns blue and other colors with heat is titanium. The titanium oxide can have the same result, although it will take different temperatures to achieve it.

According to some, steel coloring was the first useful application of the thin film effect. The hotter the steel gets, the thicker this oxide layer becomes. This means that different wavelengths of light are either muted or amplified, thereby changing the color of the steel. It will also become slightly less hard. Machinists will also use this color indication of heat to determine when cutting conditions are ideal for machining steel. Blue chips mean that the heat is being absorbed and removed by the chips, instead of the workpiece or cutting tool.

Now, different grades of steel will have different oxide layer thicknesses at different temperatures. That list is based on tool steels, which have a medium carbon content. This is mainly because when titanium is heated in the air, it oxidizes with oxygen to form a dense oxide film.

This oxide film not only protects the surface of titanium, but also is the fundamental source of titanium color change. When the heating temperature is low, the oxide film on the surface of the titanium is almost transparent, which is difficult to detect with the naked eye, but when the temperature rises, the oxide film in the pot will gradually thicken and interfere with the light.

In the eyes of people, they will also show different colors. Therefore, the thickness of the oxide film determines the color of the titanium surface.

I read some articles that in this kind of electrolyte you don't have the color change. But, the color change is related with the thickness of titanium dioxide layer. Corrosion resistance is related with thickness layer too. When the thickness layers increase, the corrosion resistance increases too. Thanks Ghisana. Yes, the oxides are actually essentially colorless. The perceived colors are because of an interference pattern whereby light bounces off both the surface of the oxide and the surface of the component under the oxide and "interferes".

It's the same concept as the rainbow sheen which a drop of oil imparts to a puddle of water. Once the oxide coating is sufficiently thick, those partial wavelength interference patterns go away. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. If you are seeking a product or service related to metal finishing, please check these Directories:.

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