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

Abstract

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-μm-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 ∼8 μm up to ∼37 μm. 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-μm-thick TiN coating deposition did not exceed the initial value.