On the nature, properties and wear response of s-phase (nitrogen-alloyed stainless steel) coatings on AISI 316L

Abstract

Nitrogen-alloyed AISI 316L coatings with nitrogen contents, [N], between 1.2 and 80 nitrogen atoms per 100 metal atoms (N/100 Me) were obtained by reactive sputter deposition. Coatings comprising only a nitrogen supersaturated metastable face-centred cubic (fcc) phase (s-phase) were obtained for 8.6 4 [N] 4 48 N/100 Me. For [N] 4 5.8 N/100 Me body-centred cubic (bcc) phases were present in the coatings while at [N] 5 65 N/100 Me the coatings comprised unidentified high nitrogen phases in addition to s-phase. The lattice parameter of the fully s-phase coatings increased linearly with increasing [N] according to a 0:3585 0:00075 [N] nmThe hardness of the s-phase coatings attained a maximum value of %20 GPa at [N] % 30-40 N/100 Me. The nitrogen in the s-phase coatings reduced the wear of the coatings by 1-2 orders of magnitude compared to the wrought material by promoting an oxidational wear mechanism.

A Microstructural and Wear Resistance Study of Stainless Steel-Ag Coatings Produced through Magnetron Sputtering

“…Tribooxidation was a general phenomenon in the wear test at room temperature. The coatings deposited in the reactive atmosphere ( Figure 10) exhibited greater evidence of oxidative wear, according to the results of the EDS analysis (Table 4), where high percentages of oxygen can be seen in the evaluation of the chemical composition carried out on the wear tracks [25]. The plastic deformation and oxidative wear in these films can generally be attributed to the high concentration of pressure on the surface, causing a local increase in temperature, thus generating oxidation processes during wear [17].…”

“…The coatings deposited in a nitrogen atmosphere have a smaller crystallite size and higher values of deformation and lattice parameters. This could be attributed to the inclusion of nitrogen in the octahedral sites of the austenite lattice, generating a lattice distortion as well as expansion of the FCC lattice [9,10,25,26]. Figure 3 shows the surface morphology and cross section of the stainless steel coating with the highest Ag content (sample Ar4Ag) deposited in an inert atmosphere, where a homogeneous surface, without the presence of defects and a columnar structure that is in accordance with zone I of the Thornton model [27] can be seen.…”

Crystallographic Orientation Dependence of Nitrogen Mass Transport in Austenitic Stainless Steel

“…The low-temperature plasma nitriding (performed at temperatures up to 450 • C) of ASS results in improved properties, such as a greatly increased surface hardness, wear resistance, fatigue resistance, and corrosion resistance [1][2][3][4][5][6][7][8][9][10][11][12][13]. Such a hardening process is related to the lattice distortion of the fcc austenitic phase (γ phase), leading to the formation of nitrogen-rich expanded austenite (γ N phase), with a hardness close to 1500 HV and no loss of corrosion resistance [6,14].…”

Development and characterisation of novel anti-bacterial S-phase based coatings

“…a) remains unconfirmed. Other S-phase coating studies did produce nitrogen concentrations up to 44.44at%; however additional phases were detected through XRD such as γ'-(Fe, Cr, Ni) 4 N[30]. Through this study it is possible to conclude that the addition of silver to the S-phase layer allowed such ultra-saturation of nitrogen within the S-phase coating as opposed to super-saturation normally reported for S-phase structures.…”