Mechanism of high-temperature plasma nitriding of titanium

Abstract

The paper presents the results of studies on plasma nitriding of titanium in nitrogen at 1030°C. For the nitriding process, flat specimens were placed on the cathode and, after the treatment had been carried out, they were analyzed for differences between the layers produced on their upper and lower surfaces. The nitrided layers have the same thickness on both sides of the specimens. Microhardness and corrosion resistance in 15% H₂SO₄ of the layers produced on the upper surfaces are higher than those of the layers formed on the lower surfaces of the specimens.

The reason for these differences is the contamination of the lower layer by carbon. Carbon also causes an increase in the value of the lattice parameter of the TiN nitride.

The action of nitrogen ions on the upper surface of the specimens entails sputtering of the surface and removes the contamination by carbon.

For this reason, the nitrided layer produced on the upper surface contains less impurities and has better properties.