Nanometer grain ternary Ti(C,N) coatings of excellent mechanical properties with continuously graded surface onto Si3N4 cutting tools were deposited at room temperature via a newly developed equipment, pulsed high energy density plasma coaxial gun. The maximum critical load by nanoscratch tests of the coatings onto Si3N4 substrates is approximately 100 mN. The maximum hardness of the coatings is more than 50 GPa by nanoindentation tests. Compared with the uncoated tools, the tribological properties of the coated tools, which were evaluated by the cutting performances in turning hardened CrWMn steel under industrial conditions, were improved dramatically with the flank wear reduced by a factor of 6-8. (C) 2004 Elsevier B.V. All rights reserved.