MoS2/Al薄膜涂层磨损性能研究

采用磁控溅射法在304不锈钢表面制备双元复合涂层MoS₂/Al。采用EDS、扫描电子显微镜(SEM)、三维表面轮廓仪、摩擦磨损试验机等设备对涂层的摩擦学行为进行研究。结果表明，涂层的平均摩擦系数随着载荷的升高呈现下降趋势。载荷为2N时涂层的摩擦系数最高，达到0.34左右，载荷为20N时涂层的摩擦系数最低，约为0.21。对比单元MoS₂涂层可以发现，铝元素的加入提高了涂层的韧性与涂层的摩擦性能，MoS₂/Al复合涂层的破坏机制主要为裂纹的萌生和涂层的片状剥落。     

纳米压痕技术表征Al2O3/3%TiO2爆炸喷涂涂层的各向异性

利用纳米压痕技术研究了爆炸喷涂涂层的微观结构特征和力学性能的关系。结果表明:相对于涂层表面,涂层横截面存在着尺度分布较宽的孔洞和微裂纹等缺陷;涂层微观结构的各向异性使得涂层的弹性、塑性、硬度和弹性模量等出现各向异性;与涂层横截面相比,涂层表面具有较好的抵抗外加载荷的能力和卸栽后良好的弹性恢复能力;涂层表面的硬度和弹性模量分别为10．3 GPa和170．7 GPa,而涂层横截面的分别为2．9 GPa和234．5 GPa。     

“反向设计”法研制ZrB_2-Ni涂层及其性能研究

利用磁控溅射技术向ZrB_2涂层中掺杂金属Ni来改善涂层韧性,采用"反向设计"法研制ZrB_2-Ni涂层,即通过改变ZrB_2靶溅射功率调控ZrB_2-Ni涂层中Ni含量,系统研究涂层力学性能和摩擦磨损性能的变化规律,优化涂层制备工艺。结果表明:随着ZrB_2靶溅射功率增加,涂层沉积速率呈线性增加;纳米硬度、弹性模量和平均摩擦系数逐渐升高;涂层临界载荷和磨损率均先增加后下降,但变化不大。适量掺杂金属Ni在一定程度上改善了涂层韧性,当ZrB_2靶溅射功率为2.4kW时,制备的涂层临界载荷较高,约20.9N;涂层耐磨性最好,磨损率为4.3×10~(-1)μm~3/(N·μm),特征值H/E与H~3/E~(*2)最高,分别为0.066和0.075GPa。     

热障涂层平头压痕蠕变研究

研究典型热障涂层(thermal barrier coating,TBC)系统在圆柱形平头压痕下的蠕变响应。考虑刚性压头、弹性压头和弹性磨损压头作用下,压头压痕深度随时间的变化规律和压头前方的Mises应力分布,分析压头尺寸和外载荷变化对压痕深度和Mises应力分布的影响．可以得出结论,平头压痕下TBC系统的蠕变在较短时间内即达到稳态,压痕深度随外载荷和压头半径的增大而增大;在相同载荷和压头半径下,压痕深度的影响表现为弹性磨损心头大于弹性压头,弹性压头大于刚性压头;对于弹性磨损压头,在相同载荷和压头半径下,压痕深度随磨损圆角半径的增大而增大。     

等离子弧功率对Al2O3-13wt％TiO2涂层组织与磨损性能的影响

采用大气等离子喷涂方法在Q235钢基体上制备了不同等离子弧功率的Al2O3-13wt％TiO2涂层,粒度为(20～40)μm.采用扫描电镜、X射线衍射仪和能谱仪等对涂层微观形貌、相组织结构进行表征,测定了涂层截面孔隙率、沉积厚度、显微硬度以及干摩擦磨损性能.等离子弧功率为29640W时涂层质量较好,截面显微硬度达1145 HV0.2、沉积厚度为338μm,孔隙率为3.9％,干摩擦磨性能最佳.在较大载荷下犁沟效应明显,涂层失效形式表现为颗粒剥落、磨粒磨损.载荷减小时,涂层微观脆性断裂显著,磨损失效形式为疲劳剥落和显微犁削.     

真空退火对磁控溅射CuS-MoS2涂层润滑性能的影响

为提高MoS2润滑涂层承载力和抗湿性能,使用磁控溅射技术制备CuS掺杂MoS2复合涂层,并对制备涂层进行220、320和420℃真空退火处理,以发挥CuS与MoS2协同润滑作用。采用场发射扫描电子显微镜、激光拉曼光谱分析涂层结构,通过洛氏硬度压痕试验、摩擦磨损试验和纳米压痕试验对涂层性能进行分析。实验结果表明:随CuS靶溅射功率提高,涂层中出现颗粒长大和CuS结晶化趋势,且CuS掺杂抑制了MoS 2形核长大,涂层膜-基结合力有所下降;真空退火处理后CuS-MoS2复合涂层表面发生分解,厚度明显降低,MoS2(002)相形核长大,摩擦学性能得到提升;320℃退火处理后涂层在常温和RH70%大气环境下获得最低平均摩擦因数0.08,纳米硬度达到5.64 GPa,并具有较好的耐磨损性能。研究认为由于CuS受热分解导致复合涂层结构和成分变化,生成了有利于发挥CuS与MoS2协同润滑效应的微晶相,使得涂层润滑性能得到明显提升。     

MoS2/石墨溅射涂层在真空中不同载荷下的摩擦磨损行为研究

为改进纯MoS2涂层的耐磨损性能,采用溅射技术合成了添加石墨的MoS2涂层。在球-盘摩擦试验机上,考察了法向载荷对MoS2/石墨溅射涂层真空中的摩擦因数和磨损率的影响,并利用扫描电子显微镜对其磨损形貌进行了分析。结果表明:在真空条件下,涂层的摩擦因数随着法向载荷的增大而减小;磨损率随载荷的增加而增加。涂层在真空中较低载荷下的磨损机制为疲劳磨损;在较高载荷下的磨损主要由塑性变形引起的小板片磨损控制。     

MoS2/Ti复合固体润滑膜的力学性能与摩擦特性

采用非平衡磁控溅射法在9Cr18轴承钢基底上制备了厚度约3μm的MoS2/Ti复合固体润滑膜,基于球形压头纳米压痕试验,采用连续刚度法对MoS2/Ti复合固体润滑膜的力学性能进行研究,探究MoS2/Ti复合固体润滑膜力学性能随压痕深度的变化规律;根据压痕试验载荷-位移曲线,采用Hertz接触理论计算MoS2/Ti复合固体润滑膜的弹性模量并与试验结果进行对比;利用CSM摩擦试验机对低速、低载下MoS2/Ti复合固体润滑膜的摩擦特性进行研究;基于压痕试验提出了一种能够更准确计算钢球加载时MoS2/Ti复合固体润滑膜接触应力的方法,并计算了摩擦试验不同载荷下的接触应力。结果表明:MoS2/Ti复合固体润滑膜的力学性能和摩擦特性都会受到表面形貌的影响;除表面初始压入阶段外,MoS2/Ti复合固体润滑膜的弹性模量和接触刚度都随着压痕深度的增大而增大;滑动速度和载荷共同影响MoS2/Ti复合固体润滑膜的摩擦特性。     

等离子喷涂纳米Al_2O_3-13%TiO_2陶瓷涂层的组织结构与抗冲蚀性能

采用等离子喷涂方法分别制备了常规和纳米Al2O3-13%TiO2陶瓷涂层,用扫描电子显微镜分析了涂层的显微结构,并对涂层进行了抗冲蚀试验。结果表明:常规陶瓷涂层具有典型的片层状结构,但纳米陶瓷涂层片层状结构并不十分明显,且涂层裂纹数量明显减少;纳米陶瓷涂层中的显微结构的变化改善了涂层的韧性和结合性能;在冲蚀过程中,常规陶瓷涂层表面剥落严重,而纳米陶瓷涂层的冲蚀质量损失较小,抗冲蚀性能比常规陶瓷涂层提高了30%左右。     

中碳钢表面Fe-Al-Nb涂层显微结构与力学性能研究

为了提高机床零件用中碳钢的耐磨及耐腐蚀性能,采用热浸镀技术与双辉等离子渗技术在中碳钢表面制备出Fe-Al-Nb涂层。采用扫描电子显微镜、能谱仪及X射线衍射仪表征了涂层的形貌、元素组成及物相结构,采用维氏硬度计和纳米压痕仪测量力学性能。试验结果显示,涂层表面呈胞状结构,与基体之间呈冶金结合,主要由Nb、Fe_2Al_5、Fe_3Al、AlNb_2相与Fe_7Nb_6相组成。显微硬度及纳米压痕测试结果显示,Fe-Al-Nb涂层比基体具有更高的表面硬度及韧性。划痕法测试结果表明,涂层与基体之间结合力强,并表现出优异的耐磨损性。     

Indentation of Polytetrafluoroethylene (PTFE) Thin Film: Simulations by Using Continuum Damage Mechanics

Thin compliant films on relatively hard substrates have a wide range of applications. In this work, continuum damage mechanics is used to simulate indentation of a 10-μm-thick polytetrafluoroethylene (PTFE) film deposited on glass for different load levels by finite element analysis. The results, compared to experiments, are useful in investigating the mechanics of wear and friction of soft thin films. The material model is elastic–plastic before damage initiation and includes linear damage progression thereafter. The effects of ductile and shear damage criteria and two parameters pertinent to the damage model, the equivalent plastic strain for damage initiation and the bulk fracture toughness, on the indentation are investigated. It is shown that the shear damage model is more suitable to characterize the indentation of the PTFE thin film. The bulk fracture toughness has greater significance with regard to damage compared to equivalent plastic strain at the onset of damage initiation. Comparison of simulation and experimental results shows that bulk fracture toughness of the thin PTFE film is approximately 20 J/m². This value is lower than that for the bulk PTFE, and the difference is attributed to the thin-film nature of the case considered here.     

光学玻璃亚表面损伤深度预测及实验研究

为了进一步揭示超声振动辅助磨削加工机理,建立了超声振动辅助磨削亚表面损伤深度与断裂韧性的预测模型,设计几何形状随机的单颗磨粒超声振动压痕实验和超声振动辅助磨削实验,调查两种情况下K9光学玻璃压痕变形区域形貌特征,提出一种适用于超声振动和非超声振动两种加载条件的等效断裂韧性计算方法,并通过超声振动辅助磨削实验来验证预测模型的可靠性。实验结果表明,超声振动可以有效增加K9光学玻璃抵抗断裂的能力,降低亚表面损伤程度,且预测模型与实验结果具有良好的一致性。     

涂层硬质合金铣刀组织性能研究

针对3种涂层硬质合金铣刀铣削性能差异,通过表面轮廓仪、接触角测量仪,表征涂层的表面状态和基体的硬度,洛氏硬度压痕法和Zeiss超景深三维显微镜表征涂层与基体的结合强度,扫描电镜(SEM)、能量分散光谱法(EDS)分析涂层表面-界面形貌、化学元素分布,铣削420模具钢实验表征切削性能,研究涂层刀具组织差异对切削性能的影响,为涂层选用提供实际和理论依据。结果表明:涂层铣刀铣削性能不仅与涂层种类和结合力相关,还与铣刀基体材料有关。涂层铣刀涂层种类较好,涂层结合力优异,基体脆性小,切削性能优异;涂层刀具涂层种类优异,涂层结合力一般,基体脆性小,切削性能良好;涂层刀具涂层种类优异,涂层结合力良好,基体脆性大,切削性能一般。     

Al_2O_3-TiB_2陶瓷刀具材料的特性及其应用

Al_2O_3-TiB_2陶瓷刀具材料具有一系列优异性能,其硬度、韧性、导热性和耐磨性等均优于目前正在广泛使用的Al_2O_3-TiC、Al_2O_3-TiN陶瓷刀具材料。本文概述了这种陶瓷刀具材料的特性和应用情况;并对山东工业大学研制成功的牌号为LP1的Al_2O_3-TiB_2陶瓷刀具材料做了介绍。     

Investigation of mechanical and tribological properties of amorphous diamond-like carbon coatings

We investigated the mechanical and tribological properties of amorphous diamond-like carbon (DLC) coatings deposited on Si(100) by a pulsed bias deposition technique. Tribological studies were performed using a pin-on-disc (POD) apparatus under a normal load of 6.25 N and at 10% relative humidity, with a ruby pin as a slider. Hardness measurements were performed using a nanoindenter and apparent fracture toughness using indentation techniques. We studied the influence of residual stresses on apparent fracture toughness. The data revealed that the thickness, hardness and compressive stress of the coating play different roles in the apparent fracture toughness. Crack initiation is influenced by the thickness and hardness of the coating, whereas crack propagation is influenced by the compressive stress in the film. The apparent fracture toughness of DLC coatings increased with coating hardness.     

Defects formed within hardness indenter interaction zone in Al2O3–ZrO2 composite

The Al₂O₃?10 wt% ZrO₂ composites were subjected to hardness tests using a Vickers diamond indenter up to 98.1 N. The microstructure observation using a transmission electron microscopy technique helped to identify up to four zones differing in defect level and character. The densest dislocation tangles, twins accumulation and frequent presence of three slip systems were found in regions that were in contact with the sides of the diamond pyramid. The second zone, characterized by two, or at least one, active slip systems, started at the bottom of the indentation mark and extended up to a distance comparable with the depth of indentation. In the third zone, with a thickness comparable to that above, only some α‐Al₂O₃ crystallites showed the presence of dislocations, whereas other crystallites were defect free. In the last zone the alumina crystals were left unaffected but the ZrO₂ crystallites showed twinning characteristic of strain‐induced transformation.     

Mechanical characterization of micro/nanoscale structures for MEMS/NEMS applications using nanoindentation techniques

Mechanical properties of micro/nanoscale structures are needed to design reliable micro/nanoelectromechanical systems (MEMS/NEMS). Micro/nanomechanical characterization of bulk materials of undoped single-crystal silicon and thin films of undoped polysilicon, SiO(2), SiC, Ni-P, and Au have been carried out. Hardness, elastic modulus and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Fracture toughness was measured by indentation using a Vickers indenter. Bending tests were performed on the nanoscale silicon beams, microscale Ni-P and Au beams using a depth-sensing nanoindenter. It is found that the SiC film exhibits higher hardness, elastic modulus and scratch resistance as compared to other materials. In the bending tests, the nanoscale Si beams failed in a brittle manner with a flat fracture surface. The notched Ni-P beam showed linear deformation behavior followed by abrupt failure. The Au beam showed elastic-plastic deformation behavior. FEM simulation can well predict the stress distribution in the beams studied. The nanoindentation, scratch and bending tests used in this study can be satisfactorily used to evaluate the mechanical properties of micro/nanoscale structures for use in MEMS/NEMS.     

Effects of Proximity on Hardness and Elastic Modulus Measurements of SiO2 and Cu by Nanoindentation

The effects of distance between two indentation points in the measurements of hardness and elastic modulus by the nanoindentation technique were assessed. Silicon Oxide (SiO₂) and Cu were used to represent the nanoindentation behavior of brittle and ductile material, respectively. The distance between two indentation points was varied from being sufficiently far apart to being almost adjacent to the boundary of the neighboring indentation mark. Contrary to common understanding, it was discovered that proximity between indentation points had almost no effect on the hardness and elastic modulus measurements. Finite element method simulations were also performed to understand and verify the experimental results.