SHS／PHIP法制备铁基平面TiC陶瓷涂层研究

用燃烧合成结合准热等静压技术（简称SHS／PHIP）在钢板表面制备金属陶瓷复合涂层。采用X射线衍射、扫描电镜、能谱、硬度测定及抗热震性等实验对合成的涂层进行了研究。结果表明：涂层主要是由α-Fe相、TiC相组成多相金属陶瓷组成的复合体系，其显微组织均匀致密，与基体间为冶金结合，硬度是基体的4倍，抗热震实验显示涂层具有良好的结合力。     

SHS/PHIP法制备铁基平面TiC陶瓷涂层研究

用燃烧合成结合准热等静压技术(简称SHS/PHIP)在钢板表面制备金属陶瓷复合涂层.采用X射线衍射、扫描电镜、能谱、硬度测定及抗热震性等实验对合成的涂层进行了研究.结果表明:涂层主要是由α-Fe相、TiC相组成多相金属陶瓷组成的复合体系,其显微组织均匀致密,与基体间为冶金结合,硬度是基体的4倍,抗热震实验显示涂层具有良好的结合力.     

平面铁基Al2O3陶瓷涂层的SHS/PHIP法制备

利用燃烧合成结合准热等静压(简称SHS/PHIP)技术在钢板表面制备金属陶瓷复合涂层.采用X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)、硬度仪及抗热震性测试仪等测试手段对合成的涂层进行了研究.结果表明:涂层主要是由α-Al2O3相、FeAl2O4(FeO·Al2O3)相组成的金属陶瓷复合体系,其显微组织均匀致密,涂层与基体间为冶金结合,硬度是基体的2.5倍,抗热震试验显示涂层具有良好的结合力.     

热喷涂NiCr/Cr3C2、NiCrCoAlY、涂层的微观组织结构及抗震性能

研究分析了等离子喷涂NiCr／Cr3C2、NiCrCoAlY涂层的微观组织结构，并对2种涂层进行了显微硬度及抗热震性能实验。结果表明：NiCr／Cr3C2涂层的硬度高于NiCrCoAlY涂层．而NiCrCoAlY涂层的抗热震性能优于NiCr／Cr3C2涂层。     

燃烧合成Cr3C2-AIN-FeCr复相陶瓷涂层的研究

采用燃烧合成技术在碳钢表面制备了复相金属陶瓷涂层。为改善涂层与基体之间的润湿性，采用了σ-FeCr金属间化合物作为润湿组分。涂层试样的微观组织形貌及相组成分析表明，涂层主要是由Cr3C2、AIN以及σ-FeCr所组成的复相体系。涂层界面形貌观察分析表明涂层与基体之间为冶金结合，热震实验结果表明涂层具有良好的结合力。     

等离子喷涂Al_2O_3(13%TiO_2)涂层和NiCr-Cr_3C_2涂层的组织性能研究

通过等离子喷涂方法在穿孔顶头尾部材料42CrMo钢表面分别制备NiCr-Cr3C2涂层和Al2O3(13%TiO2)涂层,运用OM,XRD,SEM等分析测试手段对涂层的组织、形貌和物相成分进行表征,并对两种涂层进行了显微硬度及抗热震性能实验.结果表明:喷涂涂层为典型的层状结构,涂层与基体为机械结合.Al2O3(13%TiO2)涂层以亚稳相γ-Al2O3相为主要相,同时存在α-Al2O3相.喷涂形成NiCr-Cr3C2涂层后物相成分为Cr23C6、Cr7C3、Cr3C2等Cr的碳化物.NiCr-Cr3C2涂层和Al2O3(13%TiO2)涂层的表面平均显微硬度分别为586.4HV,和557.7HV.其平均热震循环次数分别为25次和18次.     

40Cr钢表面等离子喷涂Al_2O_3-TiO_2及Mo/Al_2O_3-TiO_2复合涂层的性能

采用等离子喷涂法在40Cr钢表面制备了Al_2O_3-Ti O_2涂层和Mo/Al_2O_3-Ti O_2复合涂层。利用扫描电镜(SEM)对涂层的微观形貌进行观察,并对涂层的结合强度、抗热震性能以及涂层的耐腐蚀性进行研究。结果表明:涂层与基体、涂层与涂层之间结合良好;复合涂层抗热震性能优于Al_2O_3-Ti O_2涂层;在40Cr钢喷涂Mo/Al_2O_3-Ti O_2复合涂层后可显著提高耐腐蚀性。对涂层进行封孔处理后,可进一步提高耐腐蚀性。     

燃烧合成Cr3C2-AlN-FeCr复相陶瓷涂层的研究

采用燃烧合成技术在碳钢表面制备了复相金属陶瓷涂层。为改善涂层与基体之间的润湿性,采用了σ-FeCr金属间化合物作为润湿组分。涂层试样的微观组织形貌及相组成分析表明,涂层主要是由Cr3C2、AlN以及σ-FeCr所组成的复相体系。涂层界面形貌观察分析表明涂层与基体之间为冶金结合,热震实验结果表明涂层具有良好的结合力。     

汽轮机动叶片水蚀防护技术研究及应用

采用超音速火焰喷涂(HVOF)、超音速电弧喷涂(SWAS)制备两种抗水蚀涂层,对比分析了两种NiCr金属陶瓷涂层的组织结构、力学性能、热震性能、磨粒磨损及冲蚀磨损性能.结果表明,超音速火焰喷涂制备的NiCr金属陶瓷涂层结合强度为70 MPa,孔隙率为0.5％,涂层致密,抗热疲劳性能良好,耐磨粒磨损性能以及抗冲蚀性能优异,与2Cr13基体材料相比其抗磨损和冲蚀性能均得到显著提高.     

hBN含量对NiCr/Cr_3C_2-hBN复合涂层抗热震性能和氧化性能的影响

为了提高NiCr/Cr3C2复合涂层的摩擦性能,在涂层中加入了hBN作为固体润滑剂,研究了hBN含量对涂层抗热震性能和氧化性能的影响。采用大气等离子喷涂技术制备了hBN含量分别为0%、2.5%、5%、10%和20%的NiCr/Cr3C2-hBN复合涂层,并研究了复合涂层在700、800和850℃的抗热震性能和在850℃的恒温氧化性能。结果表明:NiCr/Cr3C2-hBN复合涂层呈层状结构,各层之间结合良好;所有涂层在700、800和850℃水淬10次均未出现明显的裂纹和脱落现象,涂层抗热震性能均良好。涂层的氧化增重随着hBN含量的增加逐渐增大,96h后NiCr/Cr3C2-20%hBN涂层氧化非常严重。在850℃时,所有涂层的氧化动力学曲线均遵循抛物线规律。     

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。