Particle Behavior During the Arc Spraying Process with Cored Wires

To use the manifold possibilities that arc spraying offers to deposit wear resistance layers, knowledge of the particle formation and their behavior is necessary. This work is focused on studying the particle properties during arc spraying with cored wires. Different cored wires under various spraying parameters are investigated by means of a high speed camera. Particle properties in-flight, such as velocity and temperature, are determined. Correlation between particle behavior and particle characteristics at different spraying conditions is established. At the same time, the particle-laden gas flow is simulated numerically and the computed solutions are used to illustrate the utility of the proposed CFD model and compared with experimental results. The employed mathematical model represents a system of macroscopic conservation laws for the continuous gas phase and for the gas-solid mixture. This approach formulation makes it possible to circumvent the numerical difficulties associated with the implementation of a (potentially ill-posed) two-fluid model. The discretization in space is performed using a high-resolution finite element scheme based on algebraic flux correction in terms of local characteristic variables. The artificial diffusion operator is constructed on the discrete level and fitted to the local solution behavior using a multidimensional flux limiter of TVD type.     

电弧喷涂粉芯丝材的研究与应用

简述了电弧喷涂技术的特点和发展。将电弧喷涂与其他热喷涂技术在涂层性能等方面做了对比。概述了电弧喷涂用粉芯丝材的研究和发展现状。展望了这种粉芯丝材在制备金属/陶瓷复合涂层、纳米结构涂层和非晶涂层等方面的应用前景。     

新型电弧喷涂粉芯丝材的现状与发展前景

粉芯丝材在电弧喷涂中的引入,拓展了电弧喷涂材料的应用范围,促进了电弧喷涂技术在耐磨抗蚀领域的进一步的发展和应用.对高速电弧喷涂粉芯丝材的特点及制备工艺进行了概述,并介绍了粉芯丝材的国内外发展现状.分析并提出金属陶瓷型粉芯丝材、金属间化合物型及Zn-Al复合型粉芯丝材具有广阔的工程应用前景.     

含碳化物陶瓷粉芯丝材电弧喷涂层的结构和性能

分别将WC、TiC、Cr3C2等碳化物陶瓷粉末与304不锈钢带轧制成3种粉芯丝材,采用电弧喷涂技术在Q235钢基体上制备铁基复合涂层.利用光学显微镜、SEM、XRD对3种涂层的形貌、相组成和磨损表面进行分析,并用湿砂橡胶轮磨损试验机(MLS-225)测试了涂层的抗磨粒磨损性能.结果表明,碳化物陶瓷粉末的加入使涂层的硬度和耐磨性显著提高,涂层的平均显微硬度值高达1100～1200 HV0.1.在本试验条件下,铁基复合涂层的耐磨性比Q235钢高6～18倍.塑性微切削和脆性剥落为涂层的主要磨粒磨损形式.     

AIMg/AI2O3粉芯丝材电弧喷涂的粒子和涂层特征

目的 研究AlMg/Al2O3粉芯丝材电弧喷涂的飞行粒子、扁平粒子、涂层结构及涂层抗冲击性能.方法 研制了2种含微米级Al2O3粉料的铝基粉芯丝材,利用扫描电镜对收集到的电弧喷涂过程中形成的飞行粒子、扁平粒子以及喷涂层的微观结构进行表征.采用自制的循环冲击设备测试了涂层的抗冲击性能.结果 AlMg/Al2O3粉芯丝材电弧喷涂过程中形成了含有铝镁、铝镁包覆氧化铝、氧化铝3种不同类型的飞行粒子,添加的Al2O3粒径越小,铝镁包覆氧化铝飞行粒子中的铝镁膜增厚,所包覆的Al2O3颗粒越多.喷涂形成的扁平粒子形状复杂多样,表面不平坦,有溅射现象.制备的涂层结构致密、缺陷少,Al2O3粉料粒径范围为400～500μm和30～50μm制备的AlMg/Al2O3涂层表面的Al2O3颗粒平均面积含量分别为5.52％、13.54％,说明添加小粒径Al2O3颗粒的涂层中残留的Al2O3颗粒增多.在500次循环冲击试验下,AlMg涂层和AlMg/Al2O3涂层没有明显的径向、环形裂纹和大面积剥落现象,但存在明显的塑性变形.结论 随着添加的微米级Al2O3颗粒粒径的减小,涂层中Al2O3颗粒的含量增加.制备的AlMg/Al2O3涂层以塑性变形吸收了大部分冲击功,降低了冲击疲劳裂纹产生的可能性,涂层与基体保持良好的结合状态.     

高速电弧喷涂FeCrNi/WC粉芯丝材的研制与性能研究

介绍了FeCrNi/WC粉芯丝材的研制过程,采用高速电弧喷涂技术将研制的FeCrNi/WC粉芯丝材成功地制备出FeCrNi/WC复合涂层.对涂层的结合强度、硬度、抗热震性和耐磨损性能等进行了测试,利用扫描电子显微镜(SEM),能谱仪(EDS)等手段对涂层进行分析.结果表明:涂层的组织呈现出典型的层状结构特征;综合力学性能优异,具有较高的结合强度、高致密度、较好的耐热震性能和耐磨损性能.     

药芯焊丝和金属粉芯焊丝电弧焊的新发展（一）

本文概述了药芯焊丝和金属粉芯焊丝电弧焊的发展历程,全面分析了这两种焊接工艺方法的优点,详细论述了药芯焊丝、金属粉芯焊丝制造技术、品种、性能、质量和相关标准的新发展,列举了药芯焊丝和金属粉芯焊丝电弧焊典型应用实例。     

Microstructure and Corrosion Resistance of Fe-Based Coatings Prepared by Twin Wires Arc Spraying Process

FeB, FeBSi, and FeNiCrBSiNbW coatings were prepared by twin wires arc spraying process on AISI 1045 steel substrate, and the microstructure and phases were characterized by scanning electron microscope, transmission electron microscope, and x-ray diffraction. The corrosion resistance was investigated by means of electrochemical tests. It was found that FeB coating and FeBSi coating were composed of α-Fe, FeO, and Fe₂O₃ phases. FeNiCrBSiNbW coating consisted of amorphous phase and α-(Fe, Cr) nanocrystalline phase, with porosity of 1.8%, hardness of 807 Hv_0.1 and tensile bonding strength of 52.1 MPa. Three kinds of electrochemical tests were employed to identify the corrosion resistance of the coatings. The results indicated that the FeNiCrBSiNbW coating had a superior corrosion resistance, much better than FeB and FeBSi coatings. It was attributed to the amorphous/nanocrystalline structure and the presence of corrosion-resistant element Cr.     

高速电弧喷涂FeCrNi/CBN粉芯丝材的研制与性能研究

介绍了FeCrNi/CBN粉芯丝材的研制过程,采用高速电弧喷涂技术将所研制的FeCrNi/CBN粉芯丝材成功地在45钢基体上制备出FeCrNi/CBN复合涂层。对涂层的结合强度、硬度、抗热震性和耐磨损性能等进行了测试,利用扫描电镜,能谱仪等手段对涂层进行分析。研究表明,涂层的组织呈现出典型的层状结构特征;综合力学性能优异,具有较高的结合强度、高致密度、较好的耐热震性能和耐磨损性能。     

高速电弧喷涂FeCrNi/CBN粉芯丝材的研制与性能研究

介绍了FeCrNi／CBN粉芯丝材的研制过程，采用高速电弧喷涂技术将所研制的FeCrNi／CBN粉芯丝材成功地在45钢基体上制备出FeCrNi／CBN复合涂层。对涂层的结合强度、硬度、抗热震性和耐磨损性能等进行了测试，利用扫描电镜，能谱仪等手段对涂层进行分析。研究表明，涂层的组织呈现出典型的层状结构特征；综合力学性能优异．具有较高的结合强度、高致密度、较好的耐热震性能和耐磨损性能。     

电弧喷涂Zn-22Al-Mg-RE合金涂层的耐蚀性能

采用电弧喷涂技术和自主研发的合金丝材在Q345基体上制备出Zn-22Al-Mg-RE合金涂层。通过SEM、铜加速乙酸盐雾试验、XRD和极化曲线来比较纯锌涂层和Zn-22Al-Mg-RE合金涂层的微观结构及耐蚀性能。结果表明,Zn-22Al-Mg-RE合金涂层相比于纯锌涂层结合强度提高了40%,在铜加速乙酸盐雾试验中出现第一锈点的时间延长1倍以上。电化学实验结果也表明合金涂层具备更优异的耐蚀性能。研究认为,Zn-22Al-Mg-RE合金涂层腐蚀产物中出现大量稳定致密的Zn6Al2(OH)16CO3·4H2O物相,是耐蚀性能提高的主要原因之一。     

Microstructure and Mechanical Properties of FeBSiNb Metallic Glass Coatings by Twin Wire Arc Spraying

In this study, FeBSiNb coatings were prepared by twin wire arc spraying process. The microstructure and mechanical properties of as-sprayed coatings were characterized. The results show that the coating is adhering well and very compact with porosity of 1.2% (the value range is 0.9-1.7%). The microstructure of the coating consists of full glassy structure. The crystallization temperature, microhardness, elastic modulus, and average adhesive strength of the coating are 819 K, 16.42 GPa (the value range is 14.38-18.46 GPa), 219 GPa (the value range is 201-237 GPa), and 57.4 MPa (the value range is 55-64 MPa), respectively. The relatively wear resistance of the coating is about three times than that of 3Cr13 martensite stainless steel coating. The reasons for excellent wear resistance of FeBSiNb metallic glass coating are attributed to a uniform amorphous structure, the high ratio of hardness to elastic modulus (H/E) and the ratio of the elastic deformation energy to the total deformation energy (η value). The main failure mechanism of the coating is brittle failure and fracture.     

Metal Matrix Composites Deposition in Twin Wire Arc Spraying Utilizing an External Powder Injection Composition

The powder injection parameters, the location of the injection port, as well as the metal matrix composites are important features, which determine the deposition efficiency and embedding behavior of hard materials in the surrounding matrix of the twin wire arc-spraying process. This study investigates the applicability of external powder injection and aims to determine whether the powder injection parameters, the location, and the material combination (composition of the matrix as well as hard material) need to be specifically tailored. Therefore, the position of the injection port in relation to the arc zone was altered along the spraying axis and perpendicular to the arc. The axial position of the injection port determines the thermal activation of the injected powder. An injection behind the arc, close to the nozzle outlet, seems to enhance the thermal activation. The optimal injection positions of different hard materials in combination with zinc-, nickel- and iron-based matrices were found to be closer to the arc zone utilizing a high-speed camera system. The powder size, the mass of the particle, the carrier gas flow, and the electric insulation of the hard material affect the perpendicular position of the radial injection port. These findings show that the local powder injection, the wetting behavior of particles in the realm of the molten pool as well as the atomization behavior of the molten pool all affect the embedding behavior of the hard material in the surrounded metallic matrix. Hardness measurement by means of nanoindentation and EDX analysis along transition zones were utilized to estimate the bonding strength. The observation of a diffusion zone indicates a strong metallurgical bonding for boron carbides embedded in steel matrix.     

The Correlation Between the Coating Quality and the Moving Direction of the Twin Wire Arc Spraying Gun

Asymmetric melting behavior of the electrodes is a process-related feature of the twin wire arc spraying (TWAS) technique since the heating of the negative wire is different from that of the positive wire. The asymmetric melting behavior, particle crossover, irregular plume shape, and last but not least the arc voltage fluctuations affect the spraying jet on the whole and lead to an inhomogeneous plume. To investigate the effect of inhomogeneous spraying plume on coating characteristics, coatings were produced by moving the spraying gun in different directions, with respect to the electrodes. The porosity, micro-cracks, hardness, thickness, and adhesion strength of the sprayed coatings were measured and brought in correlation with the gun moving direction. In this study, two different wire types were investigated in order to find out the effect of the spraying gun moving direction on the coating quality.     

电弧喷涂线材的研究进展及应用

在简述电弧喷涂基本原理的基础上,分类介绍了各种电弧喷涂线材性能特点、发展现状和主要应用,指出了各电弧喷涂线材的发展方向.     

Particle Size Distribution of the Filling Powder in Cored Wires: Its Effect on Arc Behavior, In-Flight Particle Behavior, and Splat Formation

The filling powder, as a part of the feedstock in cored wires, directly influences the particle formation, in-flight particle behavior, the coating microstructure, and consequently the behavior of the desired coating, produced by twin wire arc spraying (TWAS). In this work, the effect of the particle size distribution of the filling powder in cored wires was studied. The process parameters were changed for different intervals of particle size distributions. Arc fluctuations were measured and found to be higher at smaller particle sizes. The in-flight particles showed a higher velocity when powders with smaller grain sizes were used and higher particle temperature when bigger grain sizes were used. The splats tended to form a regular disk shape in the case of smaller grain sizes. This investigation studied the important effect of using cored wires and the filling powders grain sizes on the TWAS process.     

双丝埋弧焊在风塔制造中应用

笔者通过参与企业技改就双丝埋弧焊在风塔制造中的应用情况,对双丝埋弧焊设备、焊接材料和焊接工艺等方面作了一些相关的论述,以供同行参考。     

药芯焊丝混合气体保护焊的熔敷特性研究

以Ar＋CO2作为保护气体，研究了药芯焊丝混合气体保护焊的混合气体配比、焊接电流、电弧电压和气体流量对熔敷速度、熔敷系数和熔敷效率的影响。试验结果表明，At＋CO2混合气体保护焊比CO2焊的熔敷效率高，Ar气比例达到60％以上，熔敷效率显著增加。焊接工艺参数选择合适时，可以获得较高的熔敷速度、熔敷系数和熔敷效率。     

药芯焊丝混合气体保护焊的熔敷特性研究

以Ar+CO2作为保护气体,研究了药芯焊丝混合气体保护焊的混合气体配比、焊接电流、电弧电压和气体流量对熔敷速度、熔敷系数和熔敷效率的影响。试验结果表明,Ar+CO2混合气体保护焊比CO2焊的熔敷效率高,Ar气比例达到60%以上,熔敷效率显著增加。焊接工艺参数选择合适时,可以获得较高的熔敷速度、熔敷系数和熔敷效率。