Cutting instrument, coating and method

A cutting instrument comprising:

• a cutting blade comprising steel;
• and
• a sputtered coating having only a single layer disposed directly on the cutting blade, the coating having a thickness of 0.1 to 0.6 microns and comprising an amorphous material including titanium, chromium, carbon and nitrogen, the titanium and chromium being present in a weight ratio in the range of 3:1 to 1:3,
• wherein at least some of the chromium is in the form chromium carbonitride and titanium chromium carbonitride and at least some of the titanium is in the form of titanium carbonitride.

A method comprising:

• obtaining a cutting instrument having a cutting blade comprising steel;
• placing the cutting instrument in a position suitable for coating the cutting blade;
• cleaning the cutting blade;
• depositing a first coating layer comprising an amorphous material including chromium, titanium, carbon and nitrogen directly on the cutting blade using physical vapor deposition, and
• depositing a second coating layer comprising an amorphous material including chromium, titanium, carbon and nitrogen on the first coating layer using physical vapor deposition, the second coating layer having an inner surface in direct contact with the first coating layer and an opposite outer surface,
• wherein
• at least some of the chromium in each layer is in the form chromium carbonitride and titanium chromium carbonitride and at least some of the titanium is in the form of titanium carbonitride,
• the first and second coating layers each comprise chromium and titanium in a weight ratio in the range of 3:1 to 1:3,
• the second coating layer has a higher ratio of chromium to titanium than the first layer, and
• the overall thickness of the first and second coating layers is in the range of 0.1 microns to 0.6 microns.