The Difference between TiAlN Based and AlTiN Based PVD Coatings
Both TiAlN (Titanium Aluminum Nitride) and AlTiN (Aluminum Titanium Nitride) coatings are formed by the combination of Aluminum, Titanium and Nitrogen, which form a hard-ceramic thin film structure as a result of reactions happening in the plasma phase. The difference between them is the atomic ratio of aluminum and titanium metals.
In general, the coating, which is obtained when the aluminum / titanium atomic ratio is equal to 50% or less than 50%, that is, when the film structure is rich in titanium, is called as TiAlN. Similarly, the coating, which is obtained, when the aluminum / titanium ratio is more than 50%; that is, when the film structure is rich in aluminum, is called as AlTiN.
In general, the metallic ratio in TiAlN coatings is in the form of 65-75% Titanium, and of 25-35% Aluminum. As to AlTiN coatings, it is generally in the form of 60-70% Aluminum, and of 30-40% Titanium. When the atomic ratio of aluminum exceeds 70%, the lattice structure deteriorates and, since the cubic lattice structure disappears from the media, the mechanical properties of the film deteriorate. For this reason, AlTiN films, with an atomic aluminum content of more than 70%, are not produced in commercial applications.
In general, high temperature resistance, high temperature oxidation resistance and wear resistance of AlTiN coatings which are rich in aluminum are higher.
In TiAlN coatings which are rich in titanium, mechanical properties such as film toughness, impact resistance and strength are better. When choosing coating, these parameters should be taken into consideration, and AlTiN coatings should be preferred in cases where high hardness and temperature resistance are required while TiAlN coatings should be preferred in cases where high toughness, better surface properties and impact resistance are desired.