Erosive damage of nitride coatings is predominantly attributed to coating delamination caused by crack initiation, propagation, and coalescence. For brittle nitride coating materials, inhibiting the crack initiation and propagation within the coating may enhance their erosion resistance. This paper focuses on TiAlN/TiAl multilayer coatings, and by increasing the thickness of the metallic sublayers, the initiation and propagation of cracks in ceramic/metal multilayer coatings are significantly suppressed. As the metallic sublayer thickness increases from 1 to 4 μm, the TiAlN/TiAl coating erosion rate decreases from 0.032 to 0.002 mg⋅g−1, resulting in an improvement in the erosion resistance of over ten times. Based on the failure mechanism of ceramic/metal multilayer coatings under sand erosion conditions and finite element analysis, there are two reasons for improving the erosion resistance of ceramic/metal multilayer coatings by increasing the toughness of the metal layer. On one hand, increasing the thickness of the ductile metal layer can effectively reduce the maximum tensile stress value on the coating surface and decrease the equivalent plastic deformation of the ductile metal layer, thereby improving the crack initiation suppression ability of the coating. On the other hand, increasing the TiAl layer thickness effectively suppresses the downward propagation of longitudinal cracks and the coalescence of transverse cracks in nitride coatings. This research proposes a new approach for enhancing the erosion resistance of nitride coatings.

In this study, TiN/Ti coatings with various modulation ratios (TiN/Ti-4:1, TiN/Ti-1:1, and TiN/Ti-1:4) were deposited on 2A70 aluminum to improve its sand erosion performance. The structural design of ion implantation + high thickness Ti transition layer + TiN/Ti coatings was applied to alleviate the differences in physical properties between hard nitride coatings and 2A70 aluminum. Surface roughness, XRD, elastic modulus, hardness, and the sand erosion failure mechanism of each coating were evaluated. The hardness of TiN/Ti-4:1, TiN/Ti-1:1, and TiN/Ti-1:4 on aluminum was 26.99 GPa, 21.70 GPa, and 10.99 GPa. Sand erosion test results showed that TiN/Ti-1:1 had the highest erosion rates due to its rougher surface. Under a 90° incident angle, TiN/Ti-4:1 and TiN/Ti-1:4 both exhibited vertical cracks parallel to the coating growth direction in the bottom TiN layer at the initial erosion stage. Also, a lateral crack caused by TiN layer crack deflection emerged due to a higher crack resistance in the thicker Ti layer of TiN/Ti-1:4. Furthermore, in comparison with the layer-by-layer spalling failure behavior of TiN/Ti-1:4, overall spallation induced by the crack coalescence of the TiN layer was exhibited in TiN/Ti-4:1. In addition, cracks formed and intersected in the inner TiN layer in TiN/Ti-1:1 and TiN/Ti-4:1, resulting in layer-by-layer spallation under a 45° incident angle.

This paper addresses the challenge of ranking the factors that affect the erosion resistance of lightweight alloys, with a specific focus on aluminum alloys. A three-factor, four-level orthogonal experimental design was employed to examine the influence of various sand particle sizes, erosion speeds, and sand concentrations on the abrasion qualities of these alloys. Parameters such as mass loss, depth, residual stresses, and failure mechanisms were assessed to determine erosion performance. Analysis of variance (ANOVA) and regression analysis of the three key factors were performed. Our findings resulted in an erosion rate formula: erosion rate = 0.679 sand particle size +0.067 sand concentration −0.002 erosion velocity +0.285. Our findings indicate that particle size is the most significant factor affecting erosion rate, with sand concentration and erosion velocity being secondary factors. The failure mechanism reveals that larger sand particles tend to produce deeper slides, and higher sand concentrations result in an increased number of slides. A lower concentration leads to the appearance of erosion pits. And the test conditions of high concentration and low velocity lead to more serious brittle fractures of the substrate, often accompanied by the appearance of cracks.

This study employed magnetic filtered cathodic vacuum arc deposition to fabricate TiN/Ti multilayer coatings, examining the impact of nitrogen flow rates—4, 8, 12, and 16 sccm—on their performance, with an emphasis on gradient flow rates from 4 to 12 sccm. The coatings’ phase composition shifted from TiN_0.26 to a Ti₂N and TiN composite, optimizing the microstructure and significantly increasing the hardness to 24.37 GPa and the elastic modulus to 219.84 GPa at the 16 sccm rate. The surface roughness reduction further improved erosion resistance. Coatings made under gradient flow exhibited reduced mass loss and an erosion rate of 0.07 mg·g⁻¹, outperforming single flow rates. Erosion failure analysis highlighted that while 12 sccm coatings failed due to extensive crack interconnection, 16 sccm coatings showed spalling from crack expansion. Gradient flow coatings, despite the presence of a crack, demonstrated a more confined damage area and enhanced erosion resistance, indicating the benefits of varied nitrogen flow rates in coating optimization.