高温封严涂层材料的基本性能研究与评价

为了提高飞机发动机用封严涂层的使用温度,适应发动机的迅猛发展,对能够在高温条件下使用的封严涂层材料进行了研究,自行设计制备了可磨耗封严涂层团聚粉末材料,使用等离子喷涂工艺成功制备了P7268涂层,随后对研制的在1 000℃以上环境使用的高温封严涂层P7268的基本性能进行探讨,并对涂层在1 000℃的高温稳定性和1 000℃～室温抗热震性能进行了试验.测试发现,P7268涂层在所测试温度具有良好的高温稳定性,具有较小的硬度变化,并且涂层的抗热震性能可以达到耐冷热循环50次.     

温度和厚度对纳米金刚石涂层残余应力的影响

目的通过改善液相等离子喷涂制备纳米金刚石涂层的工艺参数,提高纳米金刚石涂层的显微硬度与结合强度。方法利用Ansys有限元软件对纳米金刚石涂层中的残余应力进行数值模拟。建立纳米金刚石涂层的有限元分析模型与热传导方程,探讨了涂层的厚度与降温速度对纳米金刚石涂层残余应力的影响。通过扫描电子显微镜对制备的纳米金刚石涂层表面进行分析,并且利用显微硬度计和表面划痕仪测定纳米金刚石涂层的显微硬度和结合强度。结果纳米金刚石涂层的主应力为拉应力,涂层的最大主应力随着厚度的增大而具有先增大、后减小、再增加的特点。随着涂层厚度的增加,涂层的最大剪应力由涂层表面转移到涂层界面,其值先减少,后保持稳定。涂层整体、涂层界面和涂层表面的最大主应力与最大剪应力,随涂层温度的升高而呈线性递减的趋势。纳米金刚石涂层的主应力集中在涂层的四周,而涂层的剪应力分布在涂层表面。纳米金刚石涂层表面较光滑,由大量纳米级的细小扁平颗粒紧密排布而形成。结论采用适当的工艺参数制备出厚度为0.1 mm的纳米金刚石涂层,其显微硬度和结合强度分别约为150HV和9 N。     

hBN含量对CuAl/hBN封严涂层高温磨损性能的影响

目的 研究hBN含量对CuAl/hBN可磨耗封严涂层在450℃下磨耗性能的影响。方法 利用大气等离子喷涂工艺制备原始粉末中hBN质量分数分别为10%、15%、20%、25%的Cu Al/hBN涂层。采用QUALITEST表面洛式硬度仪表征喷涂态涂层表面洛氏硬度。采用高温摩擦磨损试验机及场发射扫描电镜等方法,表征450℃下涂层及摩擦副的磨损形貌和质量磨损比,探讨涂层的磨损机理。结果 随着原始粉末中hBN质量分数由10%增加至25%,所制备喷涂态涂层的表面洛式硬度逐渐降低,分别为69HR15Y、56HR15Y、46HR15Y、36HR15Y。涂层与摩擦副之间的质量磨损比分别为-0.88%、-0.25%、-0.13%、-1.40%,在原始粉末中hBN质量分数为20%时质量磨损比更接近0,涂层磨耗性能更优异。涂层与摩擦副在相对摩擦过程中,主要以涂层的磨损剥落为主。在摩擦销接触面上同时观察到混合转移层,且随着涂层hBN含量的增高,接触面转移层质量先减小后增大,表面涂抹程度更加平缓,形貌起伏更加均匀。结论 低线速度条件下,摩擦热效应对涂层及摩擦副形貌及二者间的磨损行为的影响起关键作用。hBN组分理...     

Corrosion Behavior of an Abradable Seal Coating System

A novel NiTi/BN composite abradable coating and two traditional Ni/C and Ni/BN coatings were manufactured with NiAl as the bond layer using thermal spray technology and their corrosion behaviors were investigated. In salt spray corrosion testing of the Ni/BN coating, defective sites of the metal matrix were corroded preferentially. Simulated occlusion experiments and electrochemical tests indicated that migration of ions resulted in pH decrease and Cl^? enrichment in defects, and a more aggressive electrolyte led to a decrease of the corrosion potential of the metal inside defects but an increase of the corrosion current density, representing an autocatalytic corrosion process. Moreover, galvanic corrosion between the top and bond coatings of the abradable system was studied via the electrochemical technique. The results showed that, for the NiTi/BN, Ni/BN, and Ni/graphite coatings with a NiAl bond coating, current flow was generated between the anode and cathode. The NiTi/BN coating acted as the cathode due to its passivation, while the Ni/BN and Ni/graphite coatings acted as the anode because of their lower corrosion potential compared with the NiAl coating. The anode suffered serious corrosion damage due to galvanic corrosion, while the cathode corroded only slightly.     

FeCrAl合金基陶瓷涂层残余应力场的有限元分析

利用有限元方法,采用弹塑性理论对FeCrAl合金基陶瓷涂层中的应力场进行了数值模拟,得出了陶瓷涂层中应力σx(在x方向)、σy(在y方向)和τxy(x-y平面)的分布特征。研究表明在试样近边缘处涂层界面的残余拉应力σx和σy出现极大值,对于上部涂层分别为40和43.04MPa,对于侧面涂层分别为40.40和43.38MPa。涂层开裂或剥落最有可能从此处开启,然后在残余压应力σx(上部涂层)、σy(侧面涂层)和剪切应力τxy的作用下向试样中部涂层中扩展,从而导致涂层的保护功能失效。模拟结果与试样的抗热冲击试验获得较好吻合。     

Corrosion Resistance of Ti_3Al/BN Abradable Seal Coating

Ti–Al mixed powder(Ti:Al = 3:1 in atomic ratio) and Ti3 Al intermetallic alloy powder mechanically clad hexagonal BN to fabricate Ti Al/BN and Ti3Al/BN composite powders. The corresponding porous abradable seal coatings(named as TAC-1 and TAC-2, respectively) were deposited using vacuum plasma spray(VPS) technology, and their corrosion behavior was studied via salt spray corrosion and electrochemical tests. Phase compositions and microstructures of these coatings before and after corrosion were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM) facilitated with energy dispersive X-ray spectrometer(EDS). The results showed that spontaneous passivation of TAC-1 and TAC-2 granted the coatings excellent corrosion resistance than that of commercial Al/BN coating. Additionally, TAC-2 exhibited higher corrosion potential(Ecorr) and breakdown potential(Ebp) but a lower corrosion current density(icorr) than TAC-1. A small quantity of the corrosion product(Al(OH)3and Al O) could be detected on the surface of TAC-1, while no corrosion product appeared in TAC-2. The non-uniform elements distribution in the metal matrix of TAC-1 resulted in localized corrosion and relatively poor corrosion resistance compared to TAC-2.     

高强度钢冲压回弹量对板料力学性能参数的灵敏度分析

回弹是板料冲压成形中影响冲压件质量的关键因素之一。本文采用正交试验方法,以典型高强钢DP钢U形件弯曲为例,对影响回弹的板料力学性能参数进行了灵敏度分析。考虑各参数按照相同百分比波动时的灵敏度分析结果表明：弹性模量对板料回弹量的影响最大,其次分别为硬化系数、初始屈服应力、硬化指数以及各向异性参数r0,而各向异性参数r45及r90对回弹量的影响可忽略。考虑各参数按照不同百兮比波动时的灵敏度分析结果表明：弹性模量对回弹量的影响最大,其次分别为硬化系数、硬化指数、初始屈服应力以及备向异性参数r0,而r45及r90对回弹量的影响则可忽略。所以,板料的力学性能参数中弹性模量对回弹的影响最明显,其次为硬化系数、硬化指数、初始屈服应力及各向异性参数r0,而r45及r90对回弹量几乎没有影响。     

等离子喷涂Al/hBN可磨耗封严涂层的制备与性能(英文)

通过等离子喷涂技术制备了可用于航空发动机的Al/hBN可磨耗封严涂层材料。Al/hBN复合粉体通过喷涂造粒——108胶为粘结剂(ZLPC);水玻璃为粘结剂(ZLSC)和水玻璃包覆(BFSC)等3种方法制备。系统分析了涂层的显微结构、物相组成和力学性能。结果表明:在ZLPC型涂层中AlN和AlB2的含量最高;在ZLSC型涂层中AlN和AlB2的含量较少;在BFSC型涂层中未发现AlN和AlB2的存在。涂层的洛氏硬度和结合强度由小到大的顺序为:ZLPC、ZLSC和BFSC;涂层的冲蚀量由多到少的顺序为:ZLPC、ZLSC和BFSC。这可能是由于Al/hBN涂层洛氏硬度增加的原因。     

残余应力的测量与模拟分析方法

残余应力分析在失效分析中具有重要作用和地位,有时甚至可能是唯一可用的获取零件服役条件下应力状态的手段。残余应力的大小需要测量和/或模拟分析方可获得,阐述了残余应力的作用范围、测试分析方法,并分析了计算机模拟分析对于获得残余应力场形成与演化过程的重要性,指出加强残余应力研究对于失效分析的重要性,并提出建议。     

Optimization of the Mechanical Properties and Residual Stresses in 2024 Aluminum Alloy Through Heat Treatment

Residual stresses induced during quenching of aluminum alloys cause dimensional instability and distortion. In this study, the effects of different concentrations of polyalkylene glycol (PAG) quenchants on residual stresses and mechanical properties of 2024 aluminum alloy were investigated. Surface residual stresses were measured by using hole-drilling strain-gauge method. Also, mechanical properties and microstructure of the heat-treated samples were analyzed using hardness measurements, tensile tests, and transmission electron microscopy. Results showed that quenching into a 15% polymeric solution and aging at 190 °C for 12 h cause 50% reduction in residual stress as compared with quenching in water at 20 °C and naturally aging. Moreover, tensile strength decreased by 104 MPa (~?20%) in compared with the T6 sample.     

Effect of Residual Stresses and Prediction of Possible Failure Mechanisms on Thermal Barrier Coating System by Finite Element Method

This work is focused on the effect of the residual stresses resulting from the coating process and thermal cycling on the failure mechanisms within the thermal barrier coating (TBC) system. To reach this objective, we studied the effect of the substrate preheating and cooling rate on the coating process conditions. A new thermomechanical finite element model (FEM) considering a nonhomogeneous temperature distribution has been developed. In the results, we observed a critical stress corresponding to a low substrate temperature and high cooling rate during spraying of the top-coat material. Moreover, the analysis of the stress distribution after service shows that more critical stresses are obtained in the case where residual stresses are taken into account.     

耐磨涂料成分对钢基摩擦材料摩擦性能的影响

采用正交试验法优化了耐磨涂料配方,确定最佳耐磨涂料配方方案为:碳化硅粒度为80μm,碳化硅含量为40%(体积百分比),铬粉含量为1.5%(体积百分比),EPS颗粒余量。磨损试验表明,利用该耐磨涂料配方得到的表面复合材料耐磨性能较高,并分析了耐磨涂料各成分对钢基摩擦材料摩擦性能的影响。     

Strain Rate Dependency of Simulated Welding Residual Stresses

In the present work, the influence of taking into consideration the strain rate-dependent nature of steel S355 during a calculation of the welding residual stresses through a finite element simulation is investigated. The Perzyna material model is calibrated using experimental values found in the literature and is introduced to a validated weld simulation model, where the strain rate dependency had not been taken into consideration before this study. The calculated profiles of the welding residual stresses, for strain rate-dependent and independent behavior, are then compared with experimentally measured profiles. The results of this first-step analysis show that taking into consideration strain rate dependency during a welding simulation of the investigated S355 has non-negligible influence on the calculated welding residual stresses.     

Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young’s moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.     

基于不同基体材质的Sm2Zr2O7/YSZ热障复合涂层残余热应力的数值仿真

采用有限元分析软件ANSYS对1Cr13Ni9Ti、Ni、45钢和2Cr13基体等离子喷涂Sm2Zr2O7/YSZ热障双层涂层系统的残余热应力分布进行了数值仿真.结果表明:复合涂层系统表面层及界面存在较大的径向残余热应力,且径向、轴向及剪切应力梯度随金属基体的热膨胀系数增加而增大;涂层系统的轴向应力及剪切应力在径向距离距中心处约2/3的范围内基本不变,呈现出与基体材质的无关性.     

BN对镍基可磨耗密封材料烧结性能的影响

研究了BN含量对镍基可磨耗密封材料烧结性能的影响，分析了Ni-Cr和Ni-Cr／BN的烧结过程，并建立了烧结过程模型。结果表明：加入BN阻碍了粉末颗粒之间的烧结，引起材料烧结后体积膨胀和密度下降。     

基于Eulerian法计算多颗粒冷喷涂Ti-6Al-4V涂层的孔隙率和残余应力

冷喷涂涂层具有喷涂温度低、沉积效率高和结合强度高等特性,在航空航天等工业领域具有广阔的应用前景,但关于喷涂参数对涂层孔隙率和残余应力影响的研究较少。考虑送粉速度和涂层厚度的影响,建立不同颗粒密度和数量的随机分布颗粒冲击模型,采用Eulerian法模拟TC4(Ti-Al-4V)涂层的孔隙率和残余应力分布规律。结果表明,此方法能够很好地预测颗粒的沉积行为,揭示颗粒的原位夯实致密化效应,获得冷喷涂涂层的孔隙率和残余应力分布规律。颗粒密度减小,孔隙率略有降低;颗粒数量增加,孔隙率减小;当颗粒温度在一定范围（523～823K）时,孔隙率随温度上升呈线性降低。同时,不同颗粒密度和数量的模型获得的残余应力分布规律相似。计算结果可为冷喷涂涂层在航空航天等工业领域中的应用提供理论和数据支持。     

WC-17Co粉末密度对涂层力学性能及残余应力的影响

选取3种不同密度的WC-17Co粉末,采用超音速火焰喷涂法制备厚度为0.3 mm的涂层。通过扫描电镜观察分析了3种涂层的孔隙率,采用压痕法测量了涂层的努氏硬度与弹性模量,同时采用剥层法对不同密度粉末制备的WC-17Co涂层残余应力进行了测试与计算。结果表明,涂层孔隙率随WC-17Co粉末密度的增大而增大,涂层的努氏硬度、弹性模量均随WC-17Co粉末密度的增大而减小。WC-17Co涂层内部存在的残余应力表现为压应力,且应力值随涂层厚度的增大而增加,在临近涂层-基体界面处迅速减小。涂层残余压应力最大值随WC-17Co粉末密度的增大而增加：粉末密度为11.52、12.86、13.49 g·cm^-3所制备的涂层残余应力最大值分别为-798、 -986和-1120 MPa。     

γ—TiAl基金属间化合物合金的显微组织与内应力研究

通过采用不同的热处理工艺,对锻造后的TiAl基金属间化合物进行热处理,得到了含有不同等轴γ及片层（γ α）体积比的双态组织,并采用X射线衍射技术对试样进行内应力测定。实验结果表明,TiAl基金属间化合物合金中的内应力随显微组织及α2的体积分数的变化而变化,并对实验结果及产生内应力的原因进行了分析。     

盾构滚刀材料表面镍基碳化钨涂层摩擦学性能研究

目的 盾构滚刀磨损是盾构施工中最常见的问题之一,为减缓刀具的剧烈磨损、延长刀具的使用寿命,采用等离子堆焊工艺在盾构滚刀表面制备镍基碳化钨涂层以强化滚刀性能,基于盾构滚刀服役的真实工况,研究滚刀涂层的摩擦学性能及其合理的评价方式.方法 对镍基碳化钨涂层在往复滑动、冲滑复合(冲击+滑动)两种相对运动模式下进行摩擦磨损试验研究.结果 制备镍基碳化钨涂层后可提高滚刀的耐磨性.往复滑动磨损后,镍基碳化钨涂层的磨痕宽度为0.42 mm,而H13钢的磨痕宽度达到0.78 mm,镍基碳化钨涂层的抗冲滑性能也明显优于H13钢.两种相对运动模式下镍基碳化钨涂层均主要承受磨粒磨损,但往复滑动模式下涂层存在局部剥落,而冲滑复合模式下则伴随一定的粘着磨损.结论在两种相对运动模式下,镍基碳化钨涂层表面的高硬度碳化钨颗粒都可阻止磨粒对较软镍基合金区域的切削与碰撞.相较往复滑动模式,冲滑复合模式下镍基碳化钨涂层要承受冲击和滑动的耦合作用,涂层的磨痕特征以及损伤形式都有明显的不同.采用冲滑复合运动模式的摩擦磨损试验能对盾构滚刀刀圈的摩擦学性能进行更全面、合理的研究及评价.