WC/17Co含量对Ni基喷焊涂层性能的影响

将不同比例的WC/17Co与Ni60粉末进行混合,并采用氧乙炔火焰喷焊工艺制备了相应的涂层。分别用洛式硬度计和X衍射仪测试了各涂层的硬度和相结构;采用湿砂橡胶轮式磨粒磨损实验机对各涂层的抗磨粒磨损性能进行了测试,采用扫描电镜观察了喷焊粉末形貌和喷焊层的磨损形貌,并进行了能谱分析。结果表明,喷焊层的组织为在γ-Ni固溶体基体上弥散分布着细小的Cr7C3、Cr23C6、Cr2B、CrB2和WC等硬质相。喷焊层的硬度随WC/17Co添加量的增加先增加后减小,当WC的含量为25wt%时,喷焊涂层的硬度最高,相应的抗磨粒磨损性能最好。     

纳米WC增强Ni基合金喷熔层组织结构与抗磨粒磨损特性

目的研究纳米WC对Ni基合金喷熔层抗磨粒磨损性能的影响。方法采用扫描电镜、X射线衍射分析了氧乙炔火焰喷熔Ni基合金层和两种不同结构WC增强Ni基合金喷熔层的微观组织和相结构,并通过磨粒磨损试验平台对三种涂层进行磨损性能测试。结果纳米WC粉末的加入,能有效提高喷熔层的宏观硬度。通过组织分析得出纳米WC增强Ni基喷熔层中除含有γ-(Ni,Cr)固溶体、Cr的碳化物、硼化物以及微米级WC颗粒之外,还含有一定量的纳米WC团聚体和少量高硬度的W_2C相。磨粒磨损实验结果显示,纳米WC增强Ni基喷熔层的磨损失重分别为Ni60和NiWC35涂层失重的56%和73%。对比磨损后涂层的表面微观形貌可知,纳米WC颗粒在涂层中能有效降低磨粒压入喷熔层的深度,从而控制磨粒对喷熔层的犁削量。结论纳米WC增强Ni基合金喷熔层中含有的γ-(Cr,Ni)固溶体、Cr_(23)C_6、Cr_7C_3、Cr_3Ni_2及未熔化的WC颗粒和WC脱碳形成的W_2C等硬质相,使镍基自熔合金涂层的硬度有较大提高,同时也大大提高了涂层的抗磨粒磨损性能。     

铬锆铜表面等离子喷涂Cr3C2p/NiCr涂层的组织与性能

采用等离子喷涂技术在铬锆铜(CrZrCu)基体表面制备了Cr3C2 p/NiCr涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)等仪器研究了涂层的显微组织及结构,采用磨粒磨损试验机对Cr3C2 p/NiCr涂层与电镀NiCo层的磨损性能进行了测试比较。结果表明:涂层组织呈片层状结构,在NiCr合金片层上分布着未熔的Cr3C2和Cr7C3、Cr2Ni3、CrNi析出相。与电镀Ni-Co镀层相比,Cr3C2 p/NiCr涂层具有较高的硬度和耐磨粒磨损性能,其磨损量仅为电镀层的35%。     

铸造碳化钨添加量对镍基复合喷熔涂层性能的影响

在镍基合金粉末NiCrBSi中添加不同比例的铸造碳化钨(WC),并采用氧乙炔火焰喷熔工艺在低碳钢表面制备了相应的Ni基WC复合涂层.采用金相显微镜观察了涂层的显微组织,采用湿砂橡胶轮式磨粒磨损试验机测试了涂层的抗磨粒磨损性能,并采用扫描电镜观察了喷熔粉末和喷熔层磨损后的形貌.结果表明:喷熔层的组织为在NiCr合金基体上弥散分布着不同粒度的碳(硼)化物硬质相;涂层的显微组织和WC的含量对Ni基WC喷熔层的硬度和抗磨损性能影响很大,涂层的硬度和抗磨损性能随WC添加量的增加先增加后减小;当WC的含量为35％时,Ni基体WC喷熔涂层的硬度最高,相应的抗磨粒磨损性能最好.     

氧乙炔火焰喷焊镍基复合涂层的显微组织和腐蚀性能研究

目的 研究Ni60和Ni60WC喷焊涂层的显微组织、防腐和耐磨性能及其腐蚀机理,为恶劣工况下服役的零件选择合适的喷焊涂层提供参考.方法 采用氧乙炔火焰喷焊工艺在16Mn钢基体上制备Ni60和Ni60WC涂层,用X射线衍射仪、金相显微镜和扫描电子显微镜分析了喷焊涂层的相结构和显微组织,并采用电化学工作站、盐雾腐蚀试验机、磨粒磨损试验机测试了两种喷焊涂层的防腐和耐磨性能.结果 喷焊层与基体间都存在冶金结合层和热影响区,Ni60涂层的显微组织为NiCr固溶体基体上弥散分布着大量细小粒状和杆状碳化物和硼化物.Ni60WC喷焊涂层组织中,除了具有与Ni60涂层类似的基体相和细颗粒硬质相外,还较均匀地分布着不同尺寸的WC颗粒.Ni60和Ni60WC涂层的磨损率分别为16Mn钢的8.3％和2.3％,自腐蚀电流密度分别为16Mn钢的1.0％和7.6％.另外,基体相和硬质相之间的电偶腐蚀是两种镍基喷焊涂层的主要腐蚀机理.结论 这两种镍基喷焊涂层均能显著提高16Mn钢的抗磨和防腐性能,其中,Ni60喷焊涂层耐腐蚀性更好,Ni60WC喷焊涂层耐磨损性能更好.     

等离子弧喷焊颗粒增强铁基合金涂层组织的分析

采用等离子弧喷焊技术,利用后送粉装置在45钢表面制作了WC颗粒增强铁基合金复合涂层,并采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)分别对涂层组织结构及成分进行了分析.结果表明,WC颗粒主要分布在涂层顶部,在中部和底部有少量的WC,分布比较均匀;从涂层与基体的熔合区到涂层顶部分别出现了平面晶、胞状晶、树枝晶和等轴晶;涂层表面组织中化合物主要由WC,Fe23B6,Cr23C6,Cr7C3,W2B5,FeW2B2等组成;在喷焊过程中,WC发生了溶解,涂层顶部WC的溶解量比较大;从基体到涂层表面,硬度值基本呈上升趋势,最高达2 218 HV.     

Ni基合金高速火焰喷焊层组织及耐磨性研究

使用QT-E-7/h型喷枪的高速火焰喷焊设备,在45圆钢表面喷焊添加了不同含量Ni包WC的Ni基合金粉末,并对喷焊层的微观组织、显微硬度及摩擦磨损性能进行研究。研究结果表明:喷焊层微观组织为奥氏体的基体上弥散分布着Fe Ni3,Cr2Ni3,Cr3Si,WC等相;Ni包WC含量在0%~30%范围内时,随着Ni包WC含量的增加,喷焊层显微硬度增加,耐磨性增强;当Ni基合金粉末中Ni包WC含量为27%时,喷焊层表层的显微硬度最高,耐磨性最好,耐磨性较不加Ni包WC提高了约1倍;喷焊层磨损机理以黏着磨损和磨粒磨损为主;当进一步增加Ni包WC含量达到30%时,喷焊层出现宏观裂纹,致使喷焊层无法成形。     

激光熔覆制备NiCr/Cr3C2-WS2-CaF2复合材料涂层

以NiCr/Cr3C2-WS2-CaF2复合合金粉末为原料,采用激光熔覆技术,在1Cr18Ni9Ti不锈钢表面制备了高温自润滑耐磨复合材料涂层。采用XRD、SEM和EDS等手段对所制备复合涂层的显微组织进行了分析,并分别测试了涂层在室温、300℃、600℃时的干滑动磨损性能。结果表明:该复合涂层由γ-(Ni,Fe)固溶体基体、Cr7 C3/WC增强相及CrS/WS2润滑颗粒组成;室温时,涂层的磨损率较大;随着温度的升高,由于润滑转移膜的形成,涂层拥有良好的减摩耐磨性能。     

高焓等离子喷涂WC-10Co4Cr涂层的耐磨性

为提高马氏体不锈钢（0Cr13Ni4Mo）的表面硬度及耐磨性能,对不锈钢表面进行高焓等离子喷涂WC10Co4Cr强化,对涂层进行组织观察和物相组成分析,并在不同温度下进行了摩擦磨损试验。研究表明：WC10Co4Cr涂层组织致密,主要由WC物相构成,另外还有少量的W2C和Co25Cr25W8C2。在室温和高温（400 ℃）时,WC10Co4Cr涂层均具有较低的摩擦因数。室温时,基体的磨损机制主要以粘着磨损和磨粒磨损为主。WC10Co4Cr涂层其磨损机制主要以微切削为主。400 ℃条件下,不锈钢基体的磨损机理主要以粘着磨损和剥层为主,磨痕边缘部位主要以磨粒磨损为主。WC10Co4Cr涂层试样的磨损机制主要以磨粒磨损为主,伴随有剥层现象出现。     

火焰喷涂Ni基WC复合涂层组织和性能的研究

研究了以T9铜为基体的Ni基WC火焰喷涂层的组织和性能特点。试验结果表明：自熔性合空粉末末喷焊后所形成的复合涂层除生成了γ-Ni固溶体外．还包含有WC、W2C、Ni，B、CrB、Cr7C3、Cr2B、Cr23C6、(Fe，Ni)23C6等化合物和硬质相，有效地提高了基体表面的硬度和耐磨性，其平均显微硬度达900HV。     

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。