Comparison of The Effect of N2 Gas Content and Annealing Temperature of Chromium Nitride Thin Films on the Surface Hardness of CK35 Steel.

Abstract

In this paper, a comparison was made between the effect of nitrogen gas content and annealing temperature of chromium nitride films on the surface hardness of samples of medium carbon steel (CK35), where thin films of chromium were deposited on samples of medium carbon steel by electron beam method. At different parameters of power and voltage and the introduction of secondary gas is N2 gas with variable flow values ​​to obtain a layer of hard chromium nitride. Some samples were also subjected to an annealing process at temperatures ((25o.200o.400o.700o.900oC) to stimulate carbon diffusion to the surface of the sample, and then spectral analysis of the elements of the crystal structure was done before and after the deposition process using scanning electron microscopy (SEM), which showed The surface structure is dense and homogeneous for both experiments, and then the hardness of the samples was tested by Vickers method.

The results showed that the hardness increases significantly at the temperature of 700 ° C due to the dense layer and the small granular structure and the formation of some carbides and oxides, then the hardness values ​​decrease at the temperature 900 ° C due to the large grain growth. Nitrogen gas content, the hardness values ​​ranged between 250 HV and 363 HV.