叶片转速对铝硅聚苯酯涂层刮磨性能的影响

目的研究铝硅聚苯酯涂层的刮磨性能,并明确刮磨转速对涂层可磨耗性能的影响规律。方法采用等离子喷涂技术(APS)制备了铝硅聚苯酯涂层,并利用自制的刮磨试验机进行三种不同叶片转速条件下的刮磨试验。采用激光共聚焦显微镜(CLSM)、扫描电镜(SEM)及能谱仪(EDS)等测试分析设备,研究了叶片转速对铝硅聚苯酯涂层刮磨性能的影响。结果叶片转速分别为4000、4500、5000 r/min时,铝硅聚苯酯涂层的刮磨深度分别为100、200、360μm,面粗糙度分别为47.3、53.712、57.778?m,后两者与前者相比,刮磨深度分别增加了100%和260%,面粗糙度分别增加了13.6%和22.2%。随着刮磨转速的增加,铝硅聚苯酯涂层分别呈现出"光滑带+粗糙线"、"光滑带+粗糙条"和"光滑带+粗糙带"的刮磨形貌。结论转速不同时,造成铝硅聚苯酯涂层表现出不同刮磨性能。主要原因是,叶尖的微切削作用和三体磨粒磨损(脱落铝硅相、叶尖和涂层之间)的程度均随着刮磨转速的增加而逐渐加剧。     

Scraping Morphology and Adhesion Morphology Analysis of Sealing Coating Based on Scraping TemperatureEI北大核心CSCD

为了探究航空发动机可磨耗封严涂层与叶片在高速刮磨过程中磨损和黏附情况,使用大气等离子喷涂方法制备 AlSi-PHB 中低温封严涂层,对其进行高速刮磨试验,并对涂层和叶尖形貌和黏附形态进行研究。通过高速转子试验台测得刮磨过程中径向力和切向力并拟合刮磨温度曲线。采用共聚焦显微镜和扫描电镜设备获取涂层和叶尖表截面形貌、EDS 面扫描能谱以及涂层表面粗糙度,采用高精度电子秤测得涂层和叶尖失重量并计算失重速率,进一步佐证刮磨温度变化趋势。结果表明：高速刮磨时的单次切削量影响涂层失重速率,且产生不同的刮磨温度,刮磨温度影响叶尖黏附物状态;叶尖黏附物形态进一步影响刮磨后的涂层表面形貌,最终影响涂层封严性能。对高速刮磨过程中涂层刮磨形貌和叶尖黏附形态进行定性和定量分析,可为判断不同刮磨形态对涂层使用性能影响提供参考。     

基于多重分形的可磨耗涂层相结构表征及高速刮磨行为分析

目的研究不同结构铝硅聚苯酯(AlSi-PHB)低温封严涂层中聚苯酯相的分布在高速刮磨条件下与涂层刮削力的关系。方法利用大气等离子喷涂方法制备三种不同结构的AlSi-PHB封严涂层,采用扫描电镜和激光共聚焦设备获得涂层截面形貌的金相照片,通过Matlab软件得出表征聚苯酯相分布的多重分形谱。采用UMT-2微摩擦磨损实验机得到摩擦系数。通过高速转子试验台测得涂层在给定高速刮磨条件下的刮削力,并分析涂层的摩擦磨损机制。结果多重分形谱可以定量表征聚苯酯相的分布及大小颗粒数目比例。三种摩擦副得到的摩擦系数分别为0.64、0.56、0.55,高速刮磨过程中的刮削力分别为104、154、90 N。三种涂层都发生了微观切削和粘着磨损的摩擦磨损机制。结论在聚苯酯相含量相差不多的情况下,平均摩擦系数与聚苯酯相含量、分布均匀程度及颗粒大小数目比例有关:聚苯酯含量越多,平均摩擦系数越小;在聚苯酯相含量相差不多的情况下,聚苯酯相分布越均匀,颗粒越细小,摩擦系数越小。同时,聚苯酯相的分布均匀程度会影响高速刮磨过程中的刮削力,聚苯酯相分布越均匀,涂层结合强度越高,刮削力越大,涂层越不容易发生脱落。     

利用TiO_2包覆聚苯酯粉末制备高温封严涂层的研究

可磨耗性能是评价封严涂层好坏的重要性能指标,可以通过增加涂层的孔隙数量和添加润滑相来调节高温封严涂层中陶瓷层的孔隙率及硬度,最终改善高温封严涂层的可磨耗性能。所制备的高温封严涂层以氧化钇稳定的氧化锆(YSZ)为耐高温基相涂层材料,聚苯酯为造孔剂,二氧化钛为包覆层和润滑相。主要介绍了二氧化钛包覆型聚苯酯粉末的制备方法和大气等离子弧喷涂制备涂层工艺,通过扫描电镜和激光显微镜对包覆型粉末和涂层截面进行观察,采用摩擦磨损试验机对涂层进行摩擦磨损试验。结果显示,聚苯酯颗粒表面被二氧化钛稳定包覆,制备的氧化锆基高温封严涂层中的孔隙大小均匀,孔隙率增加,摩擦因数降低,涂层摩擦磨损失重增加。     

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...     

热处理工艺对铝硅-聚苯酯涂层可磨耗性能的影响

利用等离子弧喷涂工艺制备铝硅-聚苯酯封严涂层,对涂层进行300℃条件下的保温处理,然后进行组织结构、表面硬度、可磨耗性能的分析,并利用激光共聚焦显微镜进行失效机理的分析。结果表明,喷涂态的涂层中铝硅连接成框架结构,聚苯酯呈团聚态;经过200 h以上的保温处理后,聚苯酯出现缺失,同时内部出现裂纹,涂层变得结构疏松多孔;经过300℃×300 h保温处理后涂层的表面硬度下降约50%,单位时间内的磨损失重显著上升。     

MCrAlYs高温封严涂层制备工艺的优化及其性能

采用真空等离子喷涂与大气等离子喷涂的复合方法在K77基体材料表面制备出具有三层结构的MCrAlYs高温封严涂层,分别测量了涂层的金相组织、结合强度、表面洛氏硬度(HR15Y)以及抗粒子冲刷能力等性能.研究结果表明:喷涂功率是影响高温封严涂层性能的关键因素,喷涂功率高,粒子熔化好、涂层结合好、抗粒子冲刷性能相对较高;但是喷涂功率过高,涂层表面洛氏硬度相对较高,使用过程中,涂层易对转子叶片造成磨损伤害.因此选择合适的喷涂功率以在涂层结合效果与表面硬度之间建立一个平衡是高温封严涂层应用的关键.研究发现:在试验范围内,31 kW为最合适的喷涂功率.     

NiCrAlYSi/h-BN高温可磨耗封严涂层摩擦磨损性能研究

目的加入h-BN和团聚聚苯酯分别作为固体润滑剂和造孔剂,以提高NiCrAlYSi基封严涂层的高温摩擦磨损性能。方法采用真空熔炼雾化造粒和料浆喷雾造粒技术制备NiCrAlYSi/h-BN聚苯酯复合粉体,再利用大气等离子喷涂技术制备高温可磨耗封严涂层,通过扫描电子显微镜(SEM)、能谱仪(EDS)、CSM摩擦磨损试验机和三维轮廓仪等手段,研究NiCrAlYSi/h-BN封严涂层显微结构、元素组成以及室温和800℃下的摩擦磨损性能,探究涂层在室温和800℃下的磨损机理。结果等离子喷涂NiCrAlYSi/h-BN封严涂层组织比较均匀,涂层结合强度可达15MPa,孔隙率约为32%。室温下封严涂层与DD6镍基单晶高温合金球间的平均摩擦因数为0.897,涂层磨损体积为2.09×10~8μm~3;800℃高温下平均摩擦因数为0.425,涂层磨损体积为3.22×10~8μm~3;封严涂层800℃下有良好的可磨耗性,相应对偶件的磨损较轻;高温下,封严涂层金属基相软化、h-BN的润滑作用和部分金属基相高温下生成自润滑性氧化物,是摩擦因数降低和对偶件磨损较轻的主要原因。NiCrAlYSi/h-BN封严涂层室温的主要磨损机理为涂抹、磨粒磨损和轻微氧化,高温下的主要磨损机理为切削、塑性变形、氧化和粘着磨损。结论等离子喷涂NiCrAlYSi/h-BN高温封严涂层在高温下的可磨耗性能较好。     

NiCrFeAl/h-BN.SiO2可磨耗封严涂层抗冲刷性能研究

利用METCO 6P-Ⅱ火焰喷涂制备NiCrFeAl/h-BN.SiO₂可磨耗封严涂层,采用SiO₂对NiCrFeAl/h-BN进行改性,改善涂层的可磨耗性。采用不同氧气/乙炔流量比(氧燃比)制备可磨耗封严涂层,并对涂层抗冲刷性能进行评价。结果显示：NiCrFeAl在喷涂过程中熔化并包覆h-BN和SiO₂粒子;随氧燃比的升高,金属相熔化更加充分,h-BN和SiO₂粒子在涂层中分布的均匀性提高,涂层表面洛氏硬度由50.8 HR15Y提高到70.3 HR15Y,结合强度升高;涂层冲刷后形貌表现出粘着磨损和磨粒磨损特征,冲刷表面粗糙度随氧燃比升高而降低,金属相对非金属相的充分包裹提高了涂层的内聚力,涂层质量损失降低,抗冲刷性能提高。     

含双氧水磨液对铝合金滚磨光整加工的影响

目的探索含双氧水磨液对铝合金试件滚磨光整加工后表面质量的影响及作用机理。方法在相同条件下,配制含不同浓度双氧水的磨液作为液体介质,对铝合金试件进行滚磨光整加工实验及摩擦磨损实验,测量铝合金试件滚磨光整加工前后的表面粗糙度值,并表征铝合金试件滚磨光整加工前后的表面形貌以及摩擦磨损实验后的磨痕形貌。分析摩擦磨损实验后,铝合金试件表面元素的变化情况,以及滚磨光整加工后,铝合金试件硬度随表面深度的变化情况。结果含双氧水磨液作用下的试件的表面粗糙度值下降率大于去离子水条件下的值,且其摩擦系数和磨损量明显小于去离子水及干式摩擦磨损作用下的值。试件表面初始粗糙度值较小时,含双氧水磨液对滚磨光整加工铝合金试件的作用明显,其中双氧水体积分数为0.3%的磨液作用下Ra从未加工时的0.220μm减小到0.055μm,表面粗糙度值下降率为74%。结论含双氧水的磨液对较低初始表面粗糙度值的铝合金试件经滚磨光整加工后的表面质量具有重要作用。由于磨液对铝合金的吸附、润湿作用,使得其在滚磨光整加工中具有一定的润滑性、清洗性,并且摩擦作用下会使铝合金表面发生一定的摩擦化学反应。磨液中的双氧水加快了铝合金表面的腐蚀氧化反应,并将氧化产物以颗粒的形式拔出表面。滚磨光整加工作用硬化了铝合金表面,提高了其机械性能。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。