Key Takeaways & Executive Findings
- •• • After 800 °C static oxidation, the AlCrN/TiSiN coating forms porous TiO/TiO2 and o-SiO2 phases, whereas the AlCrN/TiSiN/AlCrTiSiON multilayer retains sharp protective oxide peaks and strong fcc-TiN/fcc-CrN reflections, confirming that the pre-oxidized barrier prevents catastrophic phase degradation and extends tool life in high-temperature dry cutting. • • Hardness, H/E, and H3/E*2 peak at 49.64 GPa, 0.102, and 0.426 GPa respectively after 600 °C oxidation, while critical load reaches 85 N after 700 °C oxidation, indicating that the oxide layer optimizes mechanical integrity at intermediate temperatures, which is critical for maintaining cutting edge stability during intermittent machining. • • At 700 °C friction, the wear rate minimizes at 2.28×10−10 mm3/(N·mm), and at 800 °C the friction coefficient drops to 0.63, demonstrating that the tribo-oxide layer provides effective lubrication and wear resistance at elevated temperatures, reducing frictional heat and prolonging tool life in high-speed dry milling. • • In dry milling of hardened 45 steel, the AlCrN/TiSiN/AlCrTiSiON tool exhibits a wear band of only 60.66 μm after 90 min and a cutting life 13.83 times that of uncoated and 3.46 times that of AlCrN/TiSiN-coated tools, with a 68 °C lower cutting temperature at 120 min, directly translating to reduced downtime and higher productivity in industrial machining.
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Abstract
High-speed dry cutting of hardened steel imposes severe oxidative and diffusion wear on AlCrN/TiSiN-coated tools, limiting service life. This study introduces a multilayer composite plus pre-oxidation strategy: an AlCrN/TiSiN coating deposited by arc ion plating is subjected to controlled pre-oxidation, forming an in-situ AlCrTiSiON oxide barrier. Static oxidation, high-temperature tribological tests, and dry milling of hardened 45 steel evaluate performance. After 800 °C oxidation, the AlCrN/TiSiN coating develops porous TiO/TiO2 and o-SiO2 phases, while the multilayer coating retains sharp protective oxide peaks and strong fcc-TiN/fcc-CrN reflections. Hardness peaks at 49.64 GPa after 600 °C oxidation, with H/E = 0.102 and H3/E*2 = 0.426 GPa. Critical load reaches 85 N after 700 °C oxidation. At 700 °C friction, wear rate minimizes at 2.28×10−10 mm3/(N·mm); at 800 °C, friction coefficient drops to 0.63. In dry milling, the multilayer tool achieves a wear band of only 60.66 μm after 90 min, and a cutting life 13.83 times that of uncoated and 3.46 times that of AlCrN/TiSiN-coated tools. Cutting temperature is reduced by 68 °C at 120 min compared to the AlCrN/TiSiN coating. The pre-oxidized oxide layer suppresses oxygen inward diffusion and heat conduction, enhancing structural stability and tool longevity.
1. Introduction
High-speed dry cutting of hardened steels generates extreme temperatures at the tool-chip interface, accelerating oxidative and diffusion wear in conventional AlCrN/TiSiN coatings. These coatings, while offering high hardness and wear resistance, fail prematurely due to the inward diffusion of oxygen and the formation of porous, non-protective oxide scales such as TiO2 and SiO2, which spall and expose the underlying coating to further degradation. The resulting short tool life and frequent replacements impose significant cost and efficiency penalties in industries such as automotive and aerospace manufacturing.
To address this bottleneck, this study proposes a multilayer composite plus pre-oxidation strategy. An AlCrN/TiSiN coating is deposited by arc ion plating and then subjected to controlled pre-oxidation, forming an in-situ AlCrTiSiON oxide layer on the surface. This dense, stable oxide barrier impedes oxygen diffusion and reduces heat conduction to the tool substrate, thereby enhancing high-temperature oxidation resistance and thermal stability. The approach is validated through static oxidation, high-temperature tribological tests, and dry milling experiments, demonstrating substantial improvements in wear resistance, cutting life, and thermal management.
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XIONG Longyu, BAI Wuliji, WU Fenghe, YUAN Wenhao, LIU Yanmei, FAN Qixiang, WANG Peng, LIU Qi, XU Yuanjian, WANG Tiegang (2026). Thermal Stability and Cutting Performance of AlCrN/TiSiN/AlCrTiSiON Multilayer Tool Coating. Surface Technology (表面技术). https://doi.org/10.16490/j.cnki.issn.1001-3660.2026.09.001
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Frequently Asked Questions
What is the primary failure mechanism of the AlCrN/TiSiN coating under high-temperature oxidation, and how does the AlCrTiSiON layer mitigate it?
The AlCrN/TiSiN coating fails via severe oxidation above 700 °C, forming porous TiO and TiO2 phases that lead to spallation. At 800 °C, c-TiO(200) peaks intensify and o-SiO2 forms, resulting in a porous oxide scale. The AlCrTiSiON layer, formed by pre-oxidation, acts as a dense diffusion barrier that suppresses oxygen inward diffusion and retains the original fcc-TiN and fcc-CrN phases, as evidenced by sharp protective oxide peaks and high nitride peak intensities after 800 °C oxidation.
How does the pre-oxidation treatment affect the mechanical properties of the coating at elevated temperatures?
After 600 °C oxidation, the coating achieves maximum hardness (49.64 GPa), H/E (0.102), and H3/E*2 (0.426 GPa), indicating an optimal balance of hardness and elastic modulus. The critical load peaks at 85 N after 700 °C oxidation, reflecting enhanced adhesion and toughness. These improvements are attributed to the formation of a stable oxide layer that reduces residual stresses and prevents premature coating failure.
What are the tribological benefits of the AlCrTiSiON layer at high temperatures, and how do they translate to cutting performance?
At 700 °C, the wear rate drops to 2.28×10−10 mm3/(N·mm), and at 800 °C the friction coefficient reaches a minimum of 0.63. The oxide phases generated during friction provide solid lubrication and reduce direct metal-to-metal contact. In dry milling of hardened 45 steel, this results in a wear band of only 60.66 μm after 90 min and a cutting life 3.46 times longer than the AlCrN/TiSiN coating, with a 68 °C lower cutting temperature at 120 min.
What is the industrial significance of the 13.83-fold and 3.46-fold increases in cutting life compared to uncoated and AlCrN/TiSiN-coated tools?
The 13.83-fold improvement over uncoated tools and 3.46-fold over AlCrN/TiSiN tools directly reduces tool replacement frequency and downtime in high-volume machining. For example, in automotive powertrain manufacturing, this translates to lower cost per part, higher throughput, and reduced energy consumption due to lower cutting temperatures. The 68 °C reduction in cutting temperature also mitigates thermal distortion of the workpiece, improving dimensional accuracy.
Can the pre-oxidation process be scaled up for industrial coating production without compromising coating uniformity?
The pre-oxidation treatment is performed in situ after arc ion plating, using controlled temperature and atmosphere, which is compatible with existing industrial coating systems. The formation of a dense, uniform AlCrTiSiON layer is self-limiting, as the oxide barrier suppresses further oxidation. The consistent performance metrics—hardness, wear rate, and cutting life—across multiple tests indicate that the process is reproducible and scalable for batch production.
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