用冲击刮削法测量封严涂层的力学性能

利用自制的电子冲击刮削试验机，测试封严涂层的冲击刮削载荷－位移曲线。曲线上的屈服点和最大点综合表征了封严涂层的可磨耗性和涂层与基体的结合强度。曲线所包围的面积为冲击刮削韧性，用它可表征涂层的抗冲蚀性，通过一次测量即可获得涂层的上述力学性能指标     

盐雾腐蚀对铜铝/镍石墨封严涂层可磨耗行为的影响

本文通过中性盐雾试验以及电化学分析技术研究了铜铝/镍石墨封严涂层的腐蚀行为和腐蚀机制,中性盐雾腐蚀后铜铝/镍石墨显示出明显的腐蚀迹象,表面形成大量的腐蚀产物。通过对涂层的宏观形貌、显微组织、结合强度等性能进行测试分析,掌握了铜铝/镍石墨封严涂层盐雾腐蚀后的性能衰变特征。利用高速刮擦试验机模拟高压压气机叶片与封严涂层的刮擦行为,研究了喷涂态以及腐蚀态的铜铝/镍石墨封严涂层与高温合金模拟叶片试件的磨损行为。结果表明:在高速刮削条件下,喷涂态以及腐蚀态的铜铝/镍石墨封严涂层与高温合金叶片的磨损机制为涂层剥落和叶片氧化磨损机制。高温合金叶片与腐蚀态的铜铝/镍石墨封严涂层对磨后,涂层表面状态恶化,涂层更容易剥落,叶片磨损情况变化不大。     

封严涂层性能评定的新方法

利用研制成功的新型电子冲击刮削试验发现，可测试航空发动机封严涂层的冲击载荷－位移曲线，由此得出的屈服载荷点、最大载荷点、冲击刮削韧性等参数可用于定量综合评估封严涂层的可磨耗性、抗冲蚀性以及涂层与基体结合强度。     

模拟服役条件下镍-石墨涂层的可磨耗性研究

火焰喷涂镍石墨封严涂层广泛应用于高压压气机前对开机匣和其他航空发动机零件上,其目的 是通过与叶尖或蓖齿之间的磨削控制转子与机匣壳体之间的间隙,从而提高发动机的效率,降低燃油消耗率,可磨耗性是评价封严涂层性能的重要指标之一.根据航空发动机设计的迫切要求,开展了模拟工况下镍-石墨涂层的摩擦磨损试验,并对涂层的可磨耗性进行了深入研究,分析了切削深度、切削速率等因素对涂层可磨耗性能的影响机制.结果 表明:在相同叶尖线速度下,切削深度对涂层磨损的影响比切削速率的影响更为显著;镍-石墨涂层在高线速度下的主要摩擦磨损机制是塑性变形和摩擦氧化;环境温度对涂层的摩擦磨损有一定的影响.     

封严涂层材料及应用

介绍了封严涂层的特点、测试方法、分类以及国内外可磨耗和耐磨封严涂层的应用情况,对部分封严涂层材料的发展过程及涂层的特殊制备工艺进行了阐述。评述了封严涂层的研究现状及在航空工业的发展前景。     

等离子喷涂铝硅聚苯酯封严涂层的组织及抗冲蚀性能

抗冲蚀磨损性能是封严涂层最重要的性能指标之一.采用铝硅聚苯酯(Alsi-ployester)粉末和PARXAIR-3710等离子喷涂系统制备了可磨耗封严涂层.采用磨粒冲蚀试验研究了不同冲蚀角度、冲蚀时间、冲蚀颗粒尺寸和冲蚀速度对涂层抗冲蚀性能的影响,并用SEM观察冲蚀表面形貌.结果表明:在相同冲蚀条件下,Alsi-ployester涂层冲蚀率随冲蚀颗粒速度的增加而增加;涂层的冲蚀率受冲蚀角的影响,90°时的冲蚀率大于30°的;30°时涂层损失主要以刮削为主,90°时以凿削为主;涂层失重与冲蚀时间存在良好的线性关系;涂层冲蚀率随着冲蚀颗粒尺寸增加成波动变化,当颗粒尺寸为250μm时,冲蚀率达到最大.在实际工程应用中,Alsi-ployester涂层展示了良好的抗冲蚀性能.     

基体结构对Al/BN涂层性能的影响

Al/BN涂层是一种适用于450℃以下的可磨耗封严涂层,常应用于燃气轮机压气机部位的气路封严。等离子喷涂Al/BN涂层在机械加工后常出现涂层表面疏松及涂层表面粗糙度不均匀的现象,在服役过程中会出现不可预料的涂层脱落以及粘附叶片等现象,影响发动机性能和可靠性。本文针对等离子喷涂Al/BN可磨耗封严涂层开展热喷涂工艺研究,对涂层显微组织、拉伸结合强度、硬度等性能检测及评价,并着重研究基体材料结构对涂层性能的影响,结果表明相对于平板试片,带有螺纹结构试片的涂层结合强度稍高,但其Al/BN涂层与底层厚度不均匀,造成结合强度值波动较大。     

含磨粒润滑条件下3Cr13涂层加速磨损机理研究

提出3Cr13涂层加速磨损失效新的实验方法.采用该方法在MM200摩擦磨损试验机上,对高速电弧喷涂3Cr13涂层在含SiO_2磨粒的润滑条件下磨损失效开展了加速磨损试验,通过对比分析扫描电镜照片筛选合适的磨粒颗粒,并分析SiO_2磨粒加速涂层磨损可能的机理.结果表明:适合3Cr13涂层的加速磨损试验的磨粒粒度为微米级,通过磨损表面照片得出了磨粒在润滑条件下对涂层加速磨损作用主要表现为:微观切削、挤压和磨粒的聚集.     

航空发动机常用封严涂层的金相制备与显微组织检测技术

目前对航空发动机封严涂层的检测技术研究十分欠缺,尤其是对封严涂层金相制样及显微检测评定技术的研究处于空白。通过对航空发动机常用的几种可磨耗封严涂层金相样品制备技术及截面显微组织评价技术的研究,确定了可磨耗封严涂层金相样品合适的制备技术及工艺参数以及可磨耗涂层组织中的各相形貌及相含量。试验结果表明:采用自动化制样系统和最佳制样参数才能够得到反映涂层真实显微组织结构的金相试样,研究的封严涂层相分析技术及典型图片,可以达到准确分析和评定热喷涂涂层质量的目的。     

干摩擦条件下3Cr13涂层的磨损寿命研究

在MM200摩擦磨损试验机上对高速电弧喷涂3Cr13涂层进行了干摩擦条件下的磨损寿命试验,通过恒定应力加速模型分别建立了载荷、涂层厚度、摩擦副转速与3Cr13涂层磨损寿命的关系图,并采用多元回归分析建立了预测3Cr13涂层磨损寿命的模型,对影响因素进行了相关度分析.结果表明:载荷的增大引起涂层内分层失效,涂层厚度的减小则引起涂层整层剥落,摩擦副的转速主要影响摩擦副间的犁沟和微切削程度.影响磨损寿命大小的因素依次顺序为:涂层厚度、载荷和摩擦副转速.     

The wear,deterioration and transformation phenomena of abradable coating BN–SiAl–bounding organic element,caused by the friction between the blades and the turbine casing

In modern design of gas turbines, the use of abradable materials for the coating seal of engines is widespread. Indeed, in order to increase efficiency of gas turbines, clearances between rotating blades and the casing should be as small as possible. Therefore, the blades scrape this BN–SiAl seal to form a minimum gap. The aim of this work is to investigate the behaviour of a particular abradable material, the BN–SiAl–bounding organic element, during interreaction with the blades under experimental conditions of operating the rotor blade. For this purpose, we use a Sulzer Metco abradability test. Tests are made with different incursion speeds of blade within the coating seal as well as linear blade velocities. The obtained results are shown in the form of graphs describing how the transfer of coating wear occurs and the different effects are observed on the coating surface.     

Modified zirconia abradable seal coating for high temperature gas turbine applications

The results and development of a new full ceramic abradable turbine seal coating material prepared by thermal spraying are presented. The main objective was to achieve high temperature abradability and low mating part wear using an erosion-resistant coating with high temperature stability and thermal shock resistance. The new coating was successfully laboratory tested at temperatures of at least 1100°C (2012°F). Commercial metal-based abradable coatings which are currently available are limited to lower operating temperatures. Typical plasma- sprayed ceramic coatings, because of inherent high particle velocities, are normally to dense to permit abrading without experiencing high turbine blade tip wear damage. In contrast, lower velocity combustion-sprayed ceramic coatings frequently have lower toughness and cohesive particle strength for resistance to abrasive erosion. The new coating material is designed to react exothermically, during combustion spraying, to produce a coating both with high interparticle cohesive strength for resistance to abrasive particle erosion and with controlled porosity for low turbine blade tip wear and effective abradability. Adjustment of spraying conditions gives flexibility to alter the coating hardness and porosity and permits the tailoring of abradability and erosion resistance properties for specific operating requirements.Based on specially developed test methods for high temperature abradability, high temperature particle erosion and thermal cycling, the modified zirconia coating showed superior performance to high performance baseline materials tested in the program. Industrial evaluation of this coating is presently being conducted.     

Blade protection and efficiency preservation of a turbine by a sacrificial material coating

In order to preserve the efficiency and power of a gas turbine, the clearances between rotating blades and the interior casing should be as small as possible. To obtain that, one sprays a sacrificial material by an atmospheric plasma spraying torch and obtains a coating layer. During their rotation, the blades scrape the coating and tear off fine layers, creating a functional gap between the blades and the casing seal. The combustion gases do not escape through the clearance and contribute to the power production. The aim of this work is to investigate the behavior of a particular sacrificial material and its effect on turbine blade wear under operating conditions. For this purpose, we use the abradability test rig in which three functional parameters are varied. Blade wear or material displacement is shown on various graphs and on the wear map, which indicates the other observed phenomena.     

影响涂料耐磨性能的主要因素

研究了影响涂料耐磨性能的主要因素，试验表明，填料的种类，粒径，含量，涂料基料的种类，配比对涂层的耐磨性能影响较大，利用扫描电镜图对涂料的耐磨过程及机理进行了探讨，证明在涂层磨损过程中，有选择性磨损现象出现，这在一定程度上，减轻了涂层的磨损过程。     

耐磨高熵合金制备工艺研究进展

耐磨高熵合金具有主元多、强度高、硬度大、磨损率低和耐高温等特征,应用前景广阔,是近几十年发展起来的一种新型耐磨材料。围绕耐磨高熵合金的主要制备工艺与耐磨性能的影响因素两方面,对近年来耐磨高熵合金的主要研究进展进行了综述。重点阐述了固、液、气态成型的耐磨高熵合金制备技术,总结了影响高熵合金耐磨性的因素,包括金属元素与非金属元素在内的多种元素对高熵合金耐磨性能的影响,说明了高熵合金及其碳氮化物涂层耐磨性能的研究进展。耐磨高熵合金的制备工艺较多,应根据合金形态成分的不同选择合适的制备方法;通过添加金属或非金属元素诱导硬质相析出仍是提高合金耐磨性能的主要手段;有些高熵合金或高熵合金涂层在高温、润滑等条件下也能够表现出优异的耐磨性能。     

溶胶-凝胶FeS涂层的表征与减摩行为研究

通过溶胶-凝胶法在45^#钢基体上制备了厚约500μm的FeS固体润滑涂层.摩擦 磨损试验结果表明,FeS固体润滑涂层具有良好的减摩效果和耐磨性能.由于涂层较厚,摩擦 行为只发生在涂层内部,很好地保护了基体不被磨损.利用XRD检验了涂层的相结构,通过 SEM+EDX观察分析了涂层在表面的磨痕形貌及能谱分布.     

Microstructure and Tribological Properties of Plasma-sprayed Nanostructured Sulfide Coating

The friction and wear properties of plasma-sprayed nanostructured FeS coating were investigated on an MHK- 500 friction and wear tester under both oil lubrication and dry friction condition. The microstructure, worn surface morphology and phase composition of the coating were characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. It was found that the coating was mainly composed of FeS. a small quantity of Fe1-xS and oxide were also found. The coating was formed by small particles of 50～100 nm in size The thickness of the coating is approximately 150 μm. The friction-reduction and wear-resistance properties of plasma-sprayed nanostructured FeS coating were superior to that of GCr15 steel substrate. Especially under oil lubrication condition, the friction coefficient of nanostructured FeS coating was 50% of that of GCr15 steel, the wear scar widths of the coating were also reduced to nearly 50% of that of GCr15 steel under high load. The failure of the coating was mainly attributed to plastic deformation under both oil lubrication and dry friction condition.     

Nanocrystalline diamond coatings for mechanical seals applications

A mechanical seal is a type of seal used in rotating equipment, such as pumps and compressors. It consists of a mechanism that assists the connection of the rotating shaft to the housings of the equipments, preventing leakage or avoiding contamination. A common cause of failure of these devices is end face wear out, thus the use of a hard, smooth and wear resistant coating such as nanocrystalline diamond would be of great importance to improve their working performance and increase their lifetime. In this paper, different diamond coatings were deposited by the HFCVD process, using different deposition conditions. Additionally, the as-grown films were characterized for, quality, morphology and microstructure using scanning electron microscopy (SEM) and Raman spectroscopy. The topography and the roughness of the films were characterized by atomic force microscopy (AFM).     

Sliding wear performance of metallic laser coatings against composite PTFE seals

Laser coatings are frequently used in applications where they slide against various elastomeric and polymeric seals or guide bands in different environments. Examples of such applications include hydraulics, maritime propulsion systems and components in pulp & paper industry. In this study highly corrosion resistant Inconel 625 (DIN Mat. No. 2.4856) and Thermanit 2509 super duplex stainless steel (～1.4501) coatings manufactured by novel coaxial hot‐wire laser cladding technique are tested in dry conditions at room temperature against various composite polytetrafluoroethylene (PTFE) seals. Despite only small difference in coating surface hardness, ～1.4501 and 2.4856 show significant differences in wear and friction performance against various seals. For instance, ～1.4501 is superior to 2.4856 against glass fiber and MoS₂ reinforced PTFE in terms of wear resistance and friction characteristics, whereas 2.4856 performs better against bronze reinforced PTFE seal. The reference Stellite laser coating, which is the hardest counter surface in this study, exhibits the best wear behavior against all the seal materials tested. The differences in wear performances are explained by cohesive and adhesive wear mechanisms.     

Effect of coating defects on oxidation behavior of three dimensional C/SiCcomposites from room temperature to 1500°C

Oxidation tests of a three-dimensional C/SiC composites with different coatings were conducted in dry air and the effect of defects in the coatings on the oxidation behavior were investigated. There existed two kinds of preparation defects in the CVD SiC coating, including the supporting defects and the machining defects. The former were produced by supporting of the specimens and the later were produced from the matrix pores formed between the fiber bundles after machining. There existed two kinds of deposition defects in the multi-layer CVD SiC coating, including the plane-defects and the net-defects. The former were formed between the layers and the later were produced at the boundaries between the particles. Increasing the coating thickness can seal the machining defects, but it can not seal the supporting defects. Multi-deposition can not completely seal the preparation defects although it decreased remarkably the weight loss. The Si-Zr outer layer can seal completely defects in the multi-layer, but it increases the weight loss at low temperature, and furthermore has a low resistance to oxygen diffusion. The borosilicate glass can seal the coating cracks, but it nearly loses all ability of sealing defects at high temperature. The preparation defects can be completely sealed if there exist no plane-defects in the multi-layer coating. Increasing the deposition temperature and decreasing the deposition pressure will be favorable to removing the plane-defects.