Analysis of the properties of steel nitrided by plasma utilized in bushes for axis articulation system

Samples made of AISI 4340 stainless steel with small holes were nitride by plasma utilizing cathodic cage and cylindrical cathode configurations in order to verify the influence of those configurations on the layer formation. The samples were treated in low pressure in the temperature of 450 °C and 500 °C during 2 hours and using 20% N₂ + 80% H₂ plasma mixture. Characterizations techniques used in this work were optical microscopy, scanning electron microscopy and x-ray diffraction. The results showed that there is a uniform nitrided layer formed on all exposed surface when the treatment was carried out with the cathodic cage configuration, but it does not happened into the holes of the sample. In the cylindrical cathode configuration, it was detected just a extremely thin layer on the exposed surface and into the holes was not detected any layer. (author)