Effect of Nb–Zr–N Alloying Layer on Surface Mechanical Properties and Biocompatibility of Medical 316L Matrix

The aim of this study is to further improve the mechanical properties, corrosion resistance, and biocompatibility of the material. We propose a novel method via double-glow plasma alloying–nitriding processing to obtain a Nb–Zr–N alloying layer on medical 316L (316LVM). The surface phase composition and microstructure were observed via X-ray diffraction and scanning electron microscope, respectively. The three-dimensional confocal map of the samples was measured via laser profilometer, the static water contact angle was measured via optical contact angle measuring instrument, and the surface reflectivity was measured via spectrophotometer. Results revealed that the obvious Nb2N and Zr3N4 phase and uniform nanoscale cytosolic organization are obtained at the argon–nitrogen ratio of 1:1 and of gradient distribution of nitride composition forms in the alloying layer. The addition of nitrogen element significantly improved the hardness, friction, and wear properties of the samples. The nano-scale structure of Nb–Zr–N layer plays a better protective role for the substrate with high corrosion resistance, and the corrosion resistance rate is approximately one order of magnitude higher than that of the matrix. In addition, the nontoxic Nb–Zr–N alloying layer exhibits excellent biocompatibility for improving the adsorption, proliferation, and differentiation of cells. Therefore, our work provides a feasible method by which to modify the surface of the Nb–Zr alloying layer via ion nitriding and shows the prospect of its application in medical and biological fields.