中国科学院力学研究所机构知识库

一体化压铸模具在汽车产业轻量化和节能环保政策的背景下应时而生，其在服役过程中受到高温、高速铝液冷热交替作用，传统的表面处理技术不能满 足如此苛刻的服役条件，采用HiPIMS技术制备结构致密光滑，同时具有良好力学性能的 AlCrN 涂层是提升模具表面性能的重要手段之一。本文通过复合涂层体系设计、表面功能层的制备与性能研究，制备出具有抗铝黏着性能 AlCrN 涂层。 首先，开展涂层体系的数值模拟设计与优化，通过 ABAQUS 建立均布荷载 下三维 AlCrN / CrN / Cr 涂层模型，使用显示分析准静态加载过程，研究涂层表 界面处的应力演化规律，同时构建归一化的厚度配比云图，分析不同厚度配比对涂层体系应力响应的影响。实验发现，CrN 与 Cr 涂层厚度提升可以显著提升涂层的承载能力，同时 AlCrN 涂层对界面剪应力和表面拉应力有显著的影响， 同时可通过调整 AlCrN 的厚度控制最大剪应力出现位置。选取 0.8 / 0.1 / 0.1 厚度配比的涂层可以保证涂层体系拥有小表面拉应力和部分界面剪应力的同时， 具备较低的 Mises 应力和不处于界面处的最大剪应力。根据数值模拟实验结果 制备了处于不同厚度影响区的涂层体系，并通过纳米压痕检测涂层体系的力学 性能。发现 AlCrN 涂层厚度最大而 CrN 与 Cr 厚度较薄时，涂层体系内呈现最 优的应力分布状态。该厚度配比的涂层体系可以有效预防涂层裂纹和脱落的产 生，从而提升涂层的承载能力。 其次，根据优化后的厚度配比制备涂层。基于等离子体发射光谱(OES)，采 用高能脉冲磁控溅射(HiPIMS)技术在不同基底偏压和不同的 N₂ / Ar 流量比下制 备具有致密结构的高性能 AlCrN 涂层。结果表明，基底偏压对涂层的微观结构 有显著影响，随着基底偏压增大，涂层沉积速率降低，截面微观结构有明显细 化趋势。同时溅射过程中靶放电特征和等离子体参量演变并不明显，涂层成分也保持稳定。在 100 V 的基底偏压下制备的涂层具有致密微观结构的同时也可 保证了涂层与基体良好结合。通过对不同 N₂ / Ar 流量比下制备的涂层发现，N₂ / Ar 流量比的增加，HiPIMS 下的峰值电流随之升高，沉积速率先增大后降低； 成膜环境出现大量的离子态，Cr Ⅱ、Al Ⅱ、N Ⅱ的强度明显提升；涂层结构随着 N₂ / Ar 流量的变化主要呈现三种状态：非晶结构、hcp-AlN 与 fcc-AlCrN 混合相、 主要为单一 fcc-AlCrN 相，涂层中 N 含量整体呈上升趋势并最终接近化学计量 组成；在最高的 N₂ / Ar 流量下制备出择优取向为(220)的 fcc-AlCrN 相涂层，具 有最高的硬度和弹性模量。 最后，开展涂层抗铝黏着性能的研究，分别进行了室温下水和液态金属接触角的检测，以及模拟 700 ℃高温抗铝黏着测试。抗铝黏着测试结果表明，涂层的相结构是影响涂层高温下抗铝黏着性能的主要影响因素，由于 fcc-AlCrN 结 构在高温下具有良好的稳定性，在抗铝液黏着实验中，此结构的涂层表现出不粘铝的特性，且并未发生相分解，涂层表面完整，化学成分基本保持不变。 本文以高能脉冲磁控溅射技术为手段，以 AlCrN-CrN-Cr 涂层为研究对象， 进行了涂层体系的数值模拟研究，研究不同厚度配比下的涂层应力分布，选取最优的设计方案；通过研究HiPIMS的放电特性以及成膜粒子的发射光谱，建立等离子体特性与涂层形貌、元素配比、相组成以及力学性能的关联。使用 HiPIMS 技术制备出具有均一致密结构的抗铝黏着 AlCrN 涂层，这种良好性能的 涂层为提升一体化压铸模具表面抗铝黏着性能提供了一种解决方案。

The integrated die-casting die was born in the context of the lightweight, energy saving and environmental protection policies of the automobile industry. It is subjected to the alternating action of high temperature and high-speed aluminum liquid cooling and heating during the service process. The traditional surface treatment technology cannot meet such harsh service conditions. The preparation of AlCrN coating with dense and smooth structure and good mechanical properties by HiPIMS technology is one of the important means to improve the surface properties of the die. In this paper, AlCrN coating with aluminum adhesion resistance was prepared by composite coating system design, surface functional layer preparation and performance research. Firstly, the numerical simulation design and optimization of the coating system are carried out. The three-dimensional AlCrN / CrN / Cr coating model under uniform load is established by ABAQUS. The quasi-static loading process is analyzed by display analysis to study the stress evolution law at the surface interface of the coating. At the same time, a normalized thickness ratio cloud diagram is constructed to analyze the influence of stress response of different thickness ratio coating systems. It is found that the increase of CrN and Cr coating thickness can significantly improve the bearing capacity of the coating. At the same time, AlCrN coating has a significant effect on the interfacial shear stress and surface tensile stress. At the same time, the maximum shear stress can be controlled by adjusting the thickness of AlCrN. The coating with a thickness ratio of 0.8 / 0.1 / 0.1 can ensure that the coating system has a small surface tensile stress and partial interfacial shear stress, and has a low Mises stress and a maximum shear stress not at the interface. According to the results of numerical simulation experiments, the coating systems in different thickness influence zones were prepared, and the mechanical properties of the coating systems were tested by nanoindentation. It is found that when the thickness of AlCrN coating is the largest and the thickness of CrN and Cr is thin, the optimal stress distribution state is presented in the coating system. The coating system with this thickness ratio can effectively prevent the generation of coating cracks and shedding, thereby improving the bearing capacity of the coating. Secondly, the coating was prepared according to the optimized thickness ratio. Based on plasma emission spectroscopy (OES), high-energy pulsed magnetron sputtering (HiPIMS) technology was used to prepare high-performance AlCrN coatings with dense structure under different substrate bias voltages and different N₂ / Ar flow ratios. The results show that the substrate bias has a significant effect on the microstructure of the coating. As the substrate bias increases, the deposition rate of the coating decreases, and the cross-section microstructure has a significant refinement trend. At the same time, the evolution of target discharge characteristics and plasma parameters during sputtering is not obvious, and the coating composition remains stable. The coating prepared at a substrate bias of 100 V has a dense microstructure and ensures good bonding between the coating and the substrate. Through the coatings prepared under different N₂ / Ar flow ratios, it was found that the peak current under HiPIMS increased with the increase of N₂ / Ar flow ratio, and the deposition rate increased first and then decreased. A large number of ionic states appeared in the film-forming environment, and the strength of Cr II, Al II and N II increased significantly. With the change of N₂ / Ar flow rate, the coating structure mainly presents three states : amorphous structure, hcp-AlN and fcc-AlCrN mixed phase, and single fcc-AlCrN phase. The N content in the coating showed an overall upward trend and eventually approached the stoichiometric composition. The fcc-AlCrN phase coating with a preferred orientation of (220) was prepared at the highest N₂ / Ar flow rate, with the highest hardness and elastic modulus. Finally, the anti-aluminum adhesion performance of the coating was studied. The contact angle of water and liquid metal at room temperature was tested, and the antialuminum adhesion test at 700 °C was carried out. The results of anti-aluminum adhesion test show that the phase structure of the coating is the main factor affecting the anti-aluminum adhesion performance of the coating at high temperature. Because the fcc-AlCrN structure has good stability at high temperature, in the anti-aluminum liquid adhesion experiment, the coating of this structure shows the characteristics of non-adhesive aluminum, and no phase decomposition occurs. The surface of the coating is intact, and the chemical composition remains basically unchanged. In this paper, the numerical simulation of AlCrN-CrN-Cr coating system was carried out by means of high-energy pulsed magnetron sputtering technology. The stress distribution of the coating under different thickness ratios was studied, and the optimal design scheme was selected. By studying the discharge characteristics of HiPIMS and the emission spectra of film-forming particles, the relationship between plasma characteristics and coating morphology, element ratio, phase composition and mechanical properties was established. The anti-aluminum adhesion AlCrN coating with uniform and dense structure was prepared by HiPIMS technology. This good performance coating provides a solution for improving the anti-aluminum adhesion performance of the surface of the integrated die casting die.