Strengthening of cutting tools using beams of fast neutral atoms in a low-pressure gas discharge plasma

The surface of a 26-mm-diameter reamer made of AISI M2 high-speed steel has been nitrided in a low-pressure glow discharge plasma. Then a 3-mu m-thick wear-resistant TiN coating has been magnetron sputtered on the hardened surface. After the combined processing the reamer`s cutting edges radii grew from the initial value of similar to 8 mu m up to similar to 37 mu m. The reason for the strengthened tool blunting is selective sputtering of the edges by heating ions accelerated from the plasma. Another reamer under nitriding was heated by a beam of fast atoms arriving at the tool surface from an immersed in the plasma concave grid negatively biased to 6 kV. Due to the uniform sputtering of the tool surface by the beam, the edges radii after nitriding and 3-mu m-thick TiN coating deposition did not exceed the initial value.