Evaluation of Nitriding, Nitrocarburizing, Organosilicon Interlayer, Diamond-Like Carbon Film and Duplex Plasma Treatment in the Wear and Corrosion Resistance of AISI 4340 Steel

Study of the Effect of Nitrogen on Corrosion, Wear resistance and Adhesion Properties of DLC Films Deposited on AISI 321H

“…The analysis of representative corrosion region is showed in Figure 7. It can be observed that the predominant mechanism of corrosion is by the pitting formation (Figure 7a), that induces the dissolution of metal substrate that can promote the unleash of the film from the surface (Figure 7b), as discussed by Campos et al 11 . Also, the TiN precipitates with rectangular shape, as detached in Figure 7c, presented in this kind of metal can support the corrosion process 40 .…”

“…This indicates that, even though improving the response in relation to the uncoated sample, the presence of N in the DLC films diminishes the resistance to stable pits nucleation and growth. As discussed before, the DLC and DLC(N) films presented defects produced due to the precipitates present in the substrate or gases blow hole causing the lack of film 11,19 . These defects can influence the corrosion behavior of the material, but the results did not show a correlation with the Table 3.…”

“…It is already known that adhesion to the substrate has a direct influence on the wear resistance of DLC films 11,19,21 . Figure 4 shows the wear volume of DLC and DLC(N) films from 0 to 50% N 2 .…”

“…Considering the results reported by Almeida et al 19 , these films presented a higher percentage of sp 3 C-N bonds, corroborating with the suggestion that this kind of structure presents an important influence in corrosion, adhesion, and wear behavior of the DLC(N) films. Also, the DLC films have defects that allow the corrosive solution to reach the surface of the base material, initiating localized corrosion 11,41 . In the case of the treated stainless steel, the defect can allow the formation of micro-galvanic cells, which can be the driving force for the onset of localized corrosion impairing the corrosion resistance compared with the untreated material, mainly when the defect is produced in a location with the presence of inclusion in the substrates 11 .…”

“…Hence, DLC films deposited on 321H stainless steels are expected to improve surface properties, such as high hardness, high wear resistance, and low friction coefficient to this material [5][6][7][8] . It is possible, however, that the inherent defects of this film could impair the corrosion resistance of the treated material 10,11 .…”