AN/Crl-xAlxN/Cr30 (Al, Y) 70N hard gradient coating and preparation method thereof

The invention discloses an AN/Crl-xAlxN/Cr30 (Al, Y) 70N hard gradient coating and a preparation method of the AN/Crl-xAlxN/Cr30 (Al, Y) 70N hard gradient coating. The coating is prepared on hard alloy or a steel base body, and the structure of the coating consists of three parts, wherein the first part is a CrN or TiN film layer which is taken as a bonding layer and a transition layer; the second part is a Crl-xAlxN gradient film layer, the aluminum content X in a structural formula from the inside to the outside of the gradient film layer linearly transits to 0.7 from 0.1; and the outer layer of the third part of the coating is a Cr30 (Al, Y) 70N film layer containing yttrium. The preparation method of the AN/Crl-xAlxN/Cr30 (Al, Y) 70N hard gradient coating comprises the steps of preprocessing the surface of a workpiece, preheating, cleaning and etching the surface, preparing a transition layer, preparing the gradient film layer and preparing the Cr30 (Al, Y) 70N film layer. According ...