1、 【关键词】磁控溅射 硬质涂层 高温磨损 热疲劳【英文关键词】magnetron sputter hard coating high temperature wear thermal fatigue磁控溅射论文：非平衡磁控溅射离子镀沉积 Cr-Me-N涂层高温承载能力研究【中文摘要】采用物理气相沉积(PVD)技术在基体表面涂覆抗高温、耐磨的硬质涂层,可以提高材料表面性能。CrN 硬质涂层具有硬度高,耐磨、耐腐蚀性等特点,在铸造、机械加工及成型等领域得到较广泛的应用。但是,由于 CrN薄膜抗氧化温度较低,高温使用性能差,限制了其在高温领域的应用。添加其他合金元素形成多元合金硬质涂层可有效提高薄膜
2、的高温使用性能,尤其对提高模具的使用寿命有重要意义。本研究在 CrN薄膜中加入 A1和 Nb元素并对其合金化,应用闭合场非平衡磁控溅射离子镀沉积技术,在 M42高速钢和 H13热作模具钢基体上制备具有优异结合强度的 CrAlN和 CrAlNbN两种多组元硬质梯度薄膜。利用 XRD、GDS、EDX、SEM、光学显微镜等检测方法,分析研究薄膜的相组成、成分分布、表面及截面形貌。通过高温球盘磨损实验机、显微硬度计、洛氏硬度计及球坑仪等仪器考察了镀膜试样的摩擦系数、比磨损率、膜基结合强度等力学性能,深入研究 CrAlNbN和 CrAlN薄膜的高温摩擦学行为,阐述了不同阶段摩擦系数变化规律及薄膜的高温磨
3、损机理。并通过观察镀膜试样在模拟真实压铸模具工作条件下表面裂纹形貌,分析了不同循热环次数后镀膜的热疲劳性能以及 Nb元素对薄膜抗热疲劳性能的影响。得出主要结论如下：1.选取 Al及 Nb作为添加合金元素,利用磁控溅射制备CrAlNbN和 CrAlN薄膜并进行工艺参数优化。在 Al、Nb 靶电流为 2A工艺下制备的薄膜成分梯度分布,膜基结合强度最好,表面光滑,致密性好,缺陷较少。薄膜呈柱状晶生长,晶柱间间距很小。CrAlN 薄膜相组成主要包括 CrN和 AlN；加入 Nb元素后,生成了 NbN化合物相。2.高温磨损时摩擦系数在摩擦开始阶段较大,随后逐渐降低。与CrAlN薄膜相比,CrAlNbN
4、薄膜的摩擦系数相对较高,但磨损量较少,比磨损率降低。CrAlNbN 薄膜中 NbN化合物的弥散析出和固溶强化,不仅改善基体断裂韧性,降低摩擦过程中镀层的断裂或剥落倾向,是提高其耐磨性的主要原因。CrAlN 和 CrAlNbN薄膜的磨损机理分别以磨粒磨损和黏着及氧化磨损为主。3. CrN、CrAlN 和 CrAlNbN镀膜试样的抗热疲劳性能相对基体均有所提高。其中,镀 CrAlNbN薄膜的试样表面出现的裂纹长度短、数量少,其抗热疲劳性能优于 CrN和 CrAlN薄膜。CrAlNbN 薄膜中高硬 NbN化合物可提高薄膜的表面强度,抑制热疲劳裂纹的萌生。此外,高温形成的 Nb2O5氧化物高温稳定性好
5、,可改善模具表面的抗腐蚀性能,有助于提高薄膜的热疲劳抗力。【英文摘要】Hard coatings deposited by PVD have been used to enhance the ability of high temperature wear-resistant. Chromium nitride is one of the most commonly used coating materials for casting, machining and forming applications because of its high hardness, excellent wear
6、 and corrosion resistances. To improve its poor oxidation resistance and tribological performance in high temperature, ternary compounds including other metals such as Al, V, Nb have been explored to prolong the life of die casting tools. In this paper, Al and Nb are added to CrN coatings to form al
7、loy coatings. The different tribological properties of CrAlNbN and CrAIN coatings at high temperature, the details of friction character and mechanism of wear resistant of coatings at various sliding friction stages have been studied. Thermal fatigue property of H13specimens deposited different coat
8、ings was tested using the thermal fatigue test machine and crack morphology was observed by optical microscope. The influence of Nb in promoting the thermal bearing capacity has been studied. With the technology of closed field unbalanced magnetron sputter system (CFUBMS), CrAlN and CrAlNbN hard coa
9、ting were deposited on the surface of the M42HSS and H13steel. The surface and cross-section morphology, the adhesion between the substrate and the coating, phase structure as well as the morphologies for coatings and the worn surfaces was evaluated using the Rockwell indentation, EDX, SEM, GDS and
10、XRD, respectively. A series of pin-on-disc experiments sliding against a WC/Co counterpart ball, were carried out at high temperature(550). Effect of alloy elements Nb adding to the CrAlN film showed that:1. Chosen aluminum and niobium as the target materials, CrAlN and CrAlNbN films are prepared us
11、ing CFUBMS. The coatings deposited at the optimized parameter (target current of2A) is smooth, compact and less defects, exhibiting the gradient composition distribution and the strongly bonding to the substrate. The film grows as columnar crystal with a narrow spacing. The CrAlN coating is composed
12、 of CrN and AlN. The CrAlNbN coating contains NbN in addition to CrN and AlN.2. The friction coefficient for high temperature wear increases at initial stage and then decreases gradually. Compared to CrAlN coatings, the CrAlNbN coatings maintain a larger value of friction coefficient, but a lower va
13、lues for both wear volume and specific wear rate. The fracture toughness of substrates, spalling or fracture of coatings are improved by solution strengthening of NbN precipitate, resulting in a high wear resisitance. The wear mechanism is abrasive for CrAIN coatings and adhesive and oxidation wear
14、for CrAlNbN coatings3. The thermal fatigue properties of H13specimens deposited CrN, CrAIN, CrAlNbN coatings are improved obviously as compared to H13substrates. The thermal fatigue resistance of CrAlNbN coatings is the best because the density and length of cracks on the surface of CrAlNbN coatings
15、 is less than those of CrN and CrAIN coatings. It is attributed to the harder compound of NbN which can increase the surface strength of CrAlNbN coatings and restraine the initiation of thermal fatigue cracks. In addition, the oxide of Mb2O5with high temperature stability leads to the improvement of
16、 corrosion resistance and is also beneficial to increase thermal fatigue resistance.【目录】非平衡磁控溅射离子镀沉积 Cr-Me-N涂层高温承载能力研究 摘要 3-5 ABSTRACT 5-7 目录 8-11 第一章 绪论 11-23 1.1 引言 11 1.2 常用压铸模具钢及其性能 11-13 1.2.1 H13钢的性能 12 1.2.2 热作模具钢基本失效形式 12-13 1.3 提高模具寿命途径 13-15 1.3.1 氮化处理技术 14 1.3.2 表面涂覆技术 14-15 1.4 闭合场非平衡磁控溅
17、射离子镀技术 15-18 1.4.1 基本原理及发展 15-18 1.4.2 技术优缺点 18 1.5 研究课题的提出 18-20 1.5.1 研究目的和意义 18-19 1.5.2 研究内容 19-20 参考文献 20-23 第二章 实验设备及方法 23-31 2.1 实验材料 23 2.2 实验材料准备 23-24 2.3 实验设备 24 2.4 制备方法及工艺 24-26 2.5 检测方法 26-31 2.5.1 显微硬度的检测 26 2.5.2 涂层厚度的计算 26-27 2.5.3 膜基结合强度的测定 27 2.5.4 涂层形貌、微观结构及成分的检测 27-28 2.5.5 涂层磨损
18、性能的测试 28 2.5.6 热疲劳性能的测试 28-31 第三章 Nb 元素对Cr-N基薄膜的微观结构及基本力学性能的影响 31-43 3.1 前言 31-32 3.2 实验方法 32-33 3.3实验结果及分析 33-39 3.3.1 不同 Al或 Nb含量的薄膜厚度变化 33 3.3.2 薄膜厚度和结合强度变化 33-35 3.3.3 薄膜相结构 35-36 3.3.4 不同 Al或 Nb含量的薄膜形貌 36-39 3.4 结论 39-41 参考文献 41-43 第四章 添加 Nb元素对Cr-N系多元合金薄膜高温摩擦性能的影响研究 43-61 4.1 引言 43 4.2 磨损机理 43-
19、46 4.2.1 不同类型的磨损机理 43-45 4.2.1.1 磨粒磨损 43-44 4.2.1.2 黏着磨损 44 4.2.1.3 腐蚀磨损 44 4.2.1.4 疲劳磨损 44-45 4.2.2 耐磨性的影响因素 45 4.2.3 如何提高材料的耐磨性 45-46 4.3 实验方法 46 4.4 实验结果及分析 46-58 4.4.1 比磨损率 46-47 4.4.2 摩擦系数 47-49 4.4.3 显微硬度 49-50 4.4.4 成分变化 50-51 4.4.5 磨损区域形貌 51-58 4.4.5.1 对磨球形貌 51-53 4.4.5.2 轨道形貌 53-58 4.5 结论 5
20、8-59 参考文献 59-61 第五章 添加 Nb元素对多元合金薄膜热疲劳行为的影响研究 61-73 5.1 概述 61 5.2 实验方法 61-62 5.3 热疲劳相关机理 62-64 5.3.1 热疲劳定义 62 5.3.2 疲劳分类 62-63 5.3.3 热裂纹萌生机理 63 5.3.4 热裂纹扩展机理 63 5.3.5 影响因素 63-64 5.4 实验结果与分析 64-69 5.4.1 不同试样热疲劳裂纹形貌 64-68 5.4.2 表面缺陷的影响 68 5.4.3 热疲劳机理分析 68-69 5.5 结论 69-70 参考文献 70-73 第六章 结论 73-75 致谢 75-77 攻读硕士期间发表的论文 77
