Piston Ring Multilayer Nitride Coating for Crack Resistance

The patent applies composite materials by creating a multilayer coating system where each layer consists of different metal nitrides (e.g., CrN, TiN, AlN, SiN) with distinct properties. This composite structure combines the wear resistance of hard nitrides like CrN and TiN with the crack resistance and ductility of softer nitrides like AlN and SiN, achieving both improved wear protection and enhanced crack resistance under high stress conditions.

The patent implements local quality by assigning different material compositions to different layers of the coating. Each layer is locally optimized with specific metal nitride combinations and thicknesses to provide targeted functionality—harder layers at the surface for wear resistance, softer intermediate layers for crack resistance, and gradient transitions to prevent stress concentration. This local differentiation resolves the contradiction between wear resistance and crack resistance.

The patent applies parameter changes by systematically varying the composition parameters (metal type, nitrogen content, layer thickness) of each coating layer to optimize wear resistance. By controlling these parameters during the PVD coating process, the patent achieves superior wear protection while managing process complexity through structured parameter selection rather than random variation.

The patent segments the coating into multiple distinct layers, each with specific metal nitride compositions and thicknesses. This segmentation allows the complex coating process to be broken down into manageable deposition steps, where each layer can be independently optimized and controlled. The periodic repetition of these segmented layers simplifies the overall process while achieving the desired wear resistance through cumulative effect.

The patent uses composite materials to achieve high protective capability with reduced material consumption. By combining multiple metal nitrides with different properties in a multilayer structure, the coating provides enhanced wear and crack resistance without requiring excessive thickness. The synergistic effect of the composite layers delivers superior protection more efficiently than a single thick layer of any individual material.

The patent applies local quality by concentrating material resources where they are most needed—creating harder, more durable layers at the wear surface while using softer, more ductile materials in intermediate layers for crack resistance. This localized optimization of material properties throughout the coating thickness achieves maximum protective capability with minimum total material usage, avoiding the need for uniformly thick coatings throughout.