Patent ID: 8828562

Claim:
A hard coating film for use in dyes for cold plastic working, the hard coating film comprising (Nb x M 1-x ) y (B a C b N 1−a−b ) 1−y , where 0.2≦ x≦ 1.0 Equation (1) 0 ≦a≦ 0.3 Equation (2) 0≦1 −a−b≦ 0.5 Equation (3) 0.5 ≦b ≦1 Equation (4) 0.4≦1 −y≦ 0.9 Equation (5) wherein M denotes (a) Ti or V, or (b) V and at least one specie of element other than V selected from the group consisting of Si, Al, an element from Group 4 of the periodic table, an element from Group 5 of the period table, and an element from group 6 of the periodic table; x, 1−x, a, b, 1−a, and 1−a−b represent respectively the atomic ratio of Nb, M, B, C and N; and y and 1−y represent respectively the ratio of (Nb x M 1−x ) and (B a C b N 1−a−b ); with the provisos that: when x=1 and b=1, then 0.5<1−y≦0.7; when M=Ti and b=1, then 0.4≦1−y≦0.6; and when x<1, then 1−a−b=0.