Microstructure, mechanical and thermal properties of TiAlN/CrAlN multilayer coatings

The wide application range of multilayer Ti–Al–N and Cr–Al–N coatings for wear protection leads to sustaining development in their performance. Here, we prepare TiAlN/CrAlN nano-multilayer coatings with different bilayer periods in order to improve the properties of Ti–Al–N and Cr–Al–N single layer coatings. Multilayer structure results in an increased hardness with a maximum value of ~ 38.2 GPa for TiAlN/CrAlN coating (TiAlN/CrAlN_2) with bilayer period of ~ 18 nm, and also an increase in adhesive strength to a maximum value of 98 N for TiAlN/CrAlN coating (TiAlN/CrAlN_1) with bilayer period of ~ 18 nm. Additionally, TiAlN/CrAlN nano-multilayer coatings combine the thermal stability of Ti–Al–N and oxidation resistance of Cr–Al–N, and thus their application temperature range is broadened. Consequently, an improved machining performance regardless of continuous cutting or milling is obtained by TiAlN/CrAlN nano-multilayer coated inserts.

► We have prepared TiAlN/CrAlN multilayer coatings to improve the properties of Ti–Al–N and Cr–Al–N single layer coatings.
► An increase in hardness to ~ 38.2 GPa and adhesion to 98 N is obtained by TiAlN/CrAlN multilayer coatings.
► TiAlN/CrAlN multilayer coatings improve the thermal properties of single layer coatings.
► Machining performance of coated inserts is improved by multilayer structure.