Ni-WC复合镀层的制备与研究

采用复合电沉积工艺制备了Ni-WC复合镀层,通过SEM、EDS、XRD和金相显微镜等手段对其结构与表面和断面形貌进行了观察表征,并通过试验研究了Ni-WC复合镀层的耐磨损性能,借助matlab软件拟合了镀液中WC浓度与镀层中WC含量的关系曲线。结果表明:WC微粒随着电沉积过程逐步嵌入复合镀层并均匀分布,镀层与基体间结合良好,随着镀层中WC含量的增加,镀层的耐磨性也随之增加,拟合的曲线出现一定偏离,经修正之后能较好的预测试验结果。     

Process Parameter Optimization of AISI 316L(N) Weld Joints Produced using Flux-Cored Arc Welding Process

Bead on plate welds were carried out on AISI 316L(N) austenitic stainless steel using flux cored arc welding process. The bead on plates weld was conducted as per L₂₅ orthogonal array with statistical design of experiment technique. In this paper, the welding parameters will be optimized based on the weld bead geometry such as depth of penetration, bead width and weld reinforcement. Grey relational analysis and desirability approach are used to optimize the input parameters like wire feed rate, voltage, travel speed and torch angle while considering the multiple output variables simultaneously. Confirmation experiment has also been conducted to validate the optimized parameters.     

Microstructural and Mechanical Characterization of as Weld and Aged Conditions of AA2219 Aluminium Alloy by Gas Tungsten Arc Welding Process

In this article, Welding of AA2219 aluminium alloy using Gas tungsten arc welding process (GTAW) and evaluation of metallurgical, mechanical and corrosion properties of the joints are discussed. The weld samples were subjected to ageing process at the temperature range of 195°C for a period of 5 h to improve the properties. AA2219 aluminium plates of thickness of 25 mm were welded using gas tungsten arc welding (GTAW) process in double V butt joint configuration. The input parameters considered in this work are welding current, voltage and welding speed. Tensile strength and hardness were measured as performance characteristics. The variation in the properties were justified with the help of microstructures. The same procedures were repeated for post weld heat treated samples and a comparison was made between as weld condition and age treated conditions. The post weld heat samples had better tensile strength and hardness values on comparing with the as weld samples. Fracture surface obtained from the tensile tested specimen revealed ductile mode of failure.     

Performance Evaluation of Arc Welding Process Using Weld Data Analysis

Shielded metal arc welding (SMAW) and metal inert gas (GMAW) welding process are the two most widely used welding processes. These processes are widely used for the construction and fabrication purpose in almost all type of industries. Some of the important factors which govern the weld quality in these welding processes are welding power sources, role of shielding gas (for GMAW process), welding consumables and skill of the welders. Currently, effects of these factors are evaluated by examining the quality of the weld produced and not by monitoring how welding process is affected by change in these factors. This is an indirect method because actual contribution made by individual parameter in physical process is effectively ignored. Further, this is expensive and time-consuming as the assessment can be carried out only after the weld is completed. Hence, a procedure to assess the quality of welding process using the data acquired while welding is in progress is preferred to testing of the weld for this purpose. In both SMAW and GMAW processes, welding speed, voltage and current are important parameters that affect the quality of the welds. Among these, monitoring of welding speed is relatively easy; but monitoring voltage and current is not. This is because, welding is a stochastic process in which wide variation in voltage and current occurs and duration of these variations is so short that they are not observed in the voltage and current displayed in the power source. However, with the help of a high-speed data acquisition system, voltage and current variations during actual welding process can be recorded and subsequently analysed to reveal very useful information on the welding process, and subsequently quality analysis of individual welding parameters can also be done. In the present study, the voltage and current signals acquired using a digital storage oscilloscope have been used to study SMAW and GMAW processes. Data was acquired for duration of 20 s at a sampling rate of 100,000 samples/s while welding is in progress. In the case of SMAW process, welding data was acquired for welds made using different welding power sources, but with same welder and same type of electrode. In the case of GMAW process, welds were made using same wire and same welder but with different gases for shielding and at different set currents. Dynamic variation in the voltage and current signals were carefully studied using time domain and statistical analyses. Results showed that differences in the characteristics of the different power sources used for SMAW process and effect of shielding gases and arc current on GMAW process could be easily revealed by such analysis. For SMAW process, results obtained could also be correlated with the appearance of the weld beads. Hence, a procedure involving high-speed data acquisition of voltage and current signal while welding is in progress and the statistical analysis of the acquired data have been proposed for monitoring of these two arc welding processes.     

电弧喷涂非晶纳米晶复合涂层材料研究

FeCrBSiNb非晶纳米晶复合涂层和FeAlNbB金属间化合物非晶纳米晶涂层均由非晶和纳米晶两相结构组成,涂层结合强度高,摩擦磨损性能等明显优于传统耐磨涂层,在机械金属零件的再制造修复领域应用前景广阔。     

钼对等离子堆焊钴基合金组织结构及性能的影响

采用光学显微镜，扫描电镜（SEM），X射线衍射（XRD），透射电镜（TEM）和磨粒磨损试验，研究了8％Mo对等离子堆焊钴基合金组织结构和性能的影响。结果表明，堆焊合金层主要是由面心立方的γ（Co）和六方结构的M7C3构成，并且在钴基固溶体中存在着许多堆垛层错。8％Mo的加入，没有改变合金层的相结构，但其亚结构却发生了变化，堆垛层错消失，在钴基固溶体中出现了大量的位错。8％Mo的加入，不但可以细化钴基固溶体和共晶体组织，还可以提高合金层中富Cr碳化物相的相对含量，有助于提高合金层的硬度和耐磨性能。     

炼钢电弧炉工艺过程的仿真,预测,诊断与优化

介绍了以计算机为工具，对炼钢电弧炉工艺过程进行仿真与优化的一些应用，包括：炼钢电弧炉工艺指标预测，诊断和优化，竖式电弧炉废钢预热过程仿真，钢液中磷，硫浓度的预测，直流电弧炉电磁偏弧和控制弧仿真以及电弧炉操作监控仿真等。     

电弧离子镀沉积Al-O-N高温扩散阻挡层的研究

采用电弧离子镀技术在DSM11合金与NiCoCeAlY涂层间沉积Al-O-N高温扩散阻挡层薄膜,研究了不同O2、N2流量对Al-O-N薄膜相结构的影响及高温下Al-O-N薄膜阻挡合金元素互扩散的行为.实验结果表明,电弧离子镀法沉积的Al-O-N薄膜为多晶膜,具有α-Al2O3+六方AlN的相结构,随着N2的增加,AlN相的含量增加.在1050℃下氧化100h后,Al-O-N层能有效阻挡DSM11合金中的Ti元素向外扩散,扩散阻挡层对涂层的氧化动力学影响不大.     

SiCP增强泡沫铝基复合材料制备工艺及润湿性研究

对采用熔体发泡法直接制备碳化硅颗粒增强泡沫铝基复合材料进行了探索，讨论了制备过程中SiCp与铝液间的润湿性、发泡工艺参数与温度控制等对制备工艺的影喻。表明该工艺简单，易于操作，不需任何增粘措施，处理后的SiCp浸润性好且分布均匀，孔洞分布均匀。     

Effect of Yttrium on Toughness of Weld Metal Deposited by TiO_2－CaO Type Electrode

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Compressive and Tensile Properties of STS304-Continuous-Fiber-Reinforced Zr-Based Amorphous Alloy Matrix Composite Fabricated by Liquid Pressing Process

An STS304-continuous-fiber-reinforced Zr-based amorphous alloy matrix composite with excellent fiber/matrix interfaces was fabricated without pores and misinfiltration by liquid pressing process. Approximately 60 vol pct of continuous fibers were homogeneously distributed in the matrix, in which considerable amounts of polygonal and dendritic crystalline phases were formed by the diffusion of metallic elements from the fibers. The ductility of the composite under compressive or tensile loading was drastically improved over that of the monolithic amorphous alloy. According to the compressive test results, a strength of 700 to 830 MPa was sustained until reaching a strain of 40 pct, because fibers interrupted the propagation of shear bands initiated in the matrix and took over a considerable amount of load. Under tensile loading, the deformation and fracture occurred by crack formation and opening at matrices, necking of fibers, fiber/matrix interfacial separation, and cup-and-cone–type fracture of fibers, thereby resulting in a high tensile elongation of 27 pct.     

Effect of Arc Welding Processes on the Weld Attributes of Type 316LN Stainless Steel Weld joint

The present study aims at understanding the effect of various arc welding processes on the evolution of microstructure, mechanical properties, residual stresses and distortion in 9 mm thick type 316LN austenitic stainless steel weld joints. Weld joints of type 316LN stainless steel were fabricated by three different arc welding processes which were commonly employed in the nuclear industry. All the weld joints passed radiographic examination. Microstructural characterization was done using optical and scanning electron microscope. Volume fraction of δ-ferrite was lowest in the A-TIG weld joint. The A-TIG welded joint exhibited adequate strength and maximum impact toughness values in comparison to that of weld joints made by SMAW and FCAW processes. The A-TIG weld joint was found to exhibit lowest residual stresses and distortion compared to that of other welding processes. This was attributed to lower weld metal volume and hence reduced shrinkage in the A-TIG weld joint compared to that of weld joints made by FCAW and SMAW processes which involved v-groove with filler metal addition. Therefore, type 316LN stainless steel A-TIG weld joint consisting of lower δ-ferrite, adequate strength, high impact toughness, lower residual stresses and distortion was suited better for elevated temperature service compared to that of SMAW and FCAW weld joints.     

TiC粒子增强钛基复合材料的显微组织与性能研究

探讨了添加粒子的形态对熔铸法制备的TiC粒子增强钛基复合材料力学性能与显微组织的影响。研究采用的TiC粒子增强的钛基复合材料是用预处理熔炼法 (PTMP)工艺制备的。将二次真空自耗电弧熔炼的铸锭用常规方法锻造成Φ13mm左右的棒材 ,在其上切取拉伸试样和蠕变试样 ,在 80 0～ 10 5 0℃温度范围内热处理 1h ,空冷。测试复合材料的室温和高温拉伸以及蠕变性能。研究结果表明 ,TiC粒子在基体分布均匀 ,添加尺寸为 5 μm以下的球形或近似球形TiC粒子时 ,粒子增强的钛基复合材料的综合性能优异 ,具有良好的热强性与室温塑性匹配 ,直至 65 0℃ ,复合材料仍具有良好的综合机械性能     

金属基复合材料的发展和未来

阐述了研究金属基复合材料的意义, 并着重论述了金属基复合材料的发展史、分类、研究技术的发展和现状, 指出了金属基复合材料理论研究的不足, 提出了有关界面结构模型和凝固过程的研究方向。     

表面活性剂辅助MoO_2亚微米球的水热合成与表征

以钼酸铵和盐酸为原料,CTAB作为结构导向剂,利用乙醇作溶剂和还原剂,通过水热法制备了MoO2亚微米球。采用XRD、SEM和TEM手段对产物进行了系统的表征。探究了产物从MoO3纳米棒向MoO2亚微米球转变的制备条件。初步探讨了MoO2亚微米粒子的形成机理。     

Characterization of Process Conditions in Industrial Stainless Steelmaking Electric Arc Furnace Using Optical Emission Spectrum Measurements

Emission spectroscopy is a potential method for gaining information on electric arc furnace (EAF) process conditions. Previous studies published in literature on industrial EAF emission spectra have focused on a smaller scales and DC arc furnaces. In this study emission spectrum measurements were conducted for 140t AC stainless steelmaking EAF at Outokumpu Stainless Oy, Tornio Works, Finland. Four basic types of emission spectra were obtained during the EAF process cycle. The first one is obscured by scrap steel, the second is dominated by thermal radiation of the slag, the third is dominated by alkali peaks and sodium D-lines and the fourth is characterized by multiple atomic emission peaks. The atomic emission peaks were identified by comparing them to the NIST database for atomic emission lines and previous laboratory measurements on EAF slag emission spectra. The comparison shows that the optic emission of an arc is dominated by slag components. Plasma conditions were analyzed by deriving plasma temperature from optical emissions of Ca I lines. The analysis suggests that accurate information on plasma conditions can be gained from outer plasma having a plasma temperature below 7000 K (6727 °C).