Core-shell structure in situ reinforced aluminum matrix composites: microstructure, mechanical and tribological properties

我们系统地学习了微观结构和 Ni-5wt%Al 和成双电线的弧在不同试验性的条件下面喷洒在 6061-T6 铝合金表上制作的 Ni-20wt%Al 合成涂层的机械性质。磨料穿合成涂层的行为和接口散开行为被干燥 / 湿的橡胶车轮磨料评估分别地穿测试和热处理。试验性的结果显示粘合剂的合成涂层展览特征穿。而且， NiAl 和 Ni3Al 的 Vickers microhardness 金属间化合的混合物比底层的相对大，它为提高 wear 抵抗是有益的。随温度和时间，在 Ni-Al 涂层之间的接口散开区域和底层逐渐地与 NiAl3 和 Ni2Al3 阶段的形成扩展的退火的增加，并且被铝原子的散开控制。Ni-Al 涂层的散开动力学的谷物生长代表 n，经由在 400， 480，和 550 掳 C 的一个高温度的散开模型计算，在 028 和 038 之间。这满足立方的法律，它与高温度的散开的一般理论关系一致。

Microstructure and mechanical properties of twin-wire arc sprayed Ni-Al composite coatings on 6061-T6 aluminum alloy sheet

Droplets deformation and solidification characteristics in twin-wire arc sprayed Ni-Al were explored in depth. Both theoretical method and numerical model were established for calculating the deformation process of the droplets impacting on the substrate and their solidification behavior in airflow, which based on two models of the volume of fluid (VOF) dual-phase flow and the standard k-e. The morphology and the microstructure of the composite coatings were analyzed by XRD, SEM and TEM. The results of the experiment indicate the droplets cooling rate ranges from 3.0×107 to 7.5×107 K/s. The main components of Ni-5wt.% Al coating were Ni solid solution, and a small number of Ni3Al4, Al2O3 and NiO. The main phases of Ni-20wt.% Al coating are Ni3Al and NiAl. EDS and TEM analysis shows that there are a few amorphous and equiaxed crystals in the Ni-Al coating. The surface roughness increases with the decrease of spraying pressure and spraying distance.

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Deformation and Solidification Characteristics and Microstructure of Arc Sprayed Ni-Al Composition Coatings

The invention discloses an atomizer for spray forming of high-melting-point alloy deposit billets, and relates to an atomizer. The invention solves the problem that deposit billets prepared by the atomizer have large grains and low compactness, and cannot be subjected to spray forming to form the high-melting-point alloy deposit billets. A thermal insulating crucible and an atomizing cone are fixedly connected through an atomization plant; the upper part of an upper atomizer is provided with a 35-degree inner taper hole, while the lower part is provided with a step hole communicated with the inner taper hole; the outer wall of the upper atomizer is provided with first external threads; the center of a lower atomizer is provided with first internal threads, a first cylindrical hole and a second cylindrical hole in turn from top to bottom; the side wall of the first cylindrical hole is provided with a second internal threaded hole; the first external threads are screwed in the first internal threads; a cavity is formed between the first cylindrical hole and the outer wall of the step hole; a gap is reserved between the second cylindrical hole and the outer wall of the step hole; andboth the upper atomizer and the lower atomizer are made of graphite. The atomizer is suitable for preparing the high-melting-point alloy deposit billets through spray forming.

Atomizer for spray forming of high-melting-point alloy deposit billets

The invention provides an assisted densification ultrasonic vibration and deposition device for a spray-formed deposition billet, and relates to an ultrasonic vibration and deposition device, which is used for solving the problem that the deposition billet with excellent properties can be obtained after densification treatment due to the wide freezing range, high viscosity, difficulty in spreading and high possibility of gap formation during the existing fogdrop deposition process. The assisted densification ultrasonic vibration and deposition device comprises a deposition disk (1) and a rotary motor (2), wherein, the deposition disk (1) is arranged on an output shaft of the rotary motor (2); and the device further comprises a flange (3), a piezoelectric ceramic (4) and a support disk (5) which are sequentially and fixedly connected together and sheathed on the rotary motor (2) from the top to bottom. The assisted densification ultrasonic vibration and deposition device is suitable for preparing the deposition billet during the spray forming process; and the prepared deposition billet has the advantages of high quality and good uniformity, thus being applicable to finished billets and industrial production.

Assisted densification ultrasonic vibration and deposition device for spray-formed deposition billet

The well-known Spectral Element Method (SEM) has a broad application in vibration analysis for various configurations, such as flat plates, beams and straight pipes. Considering the fluid–structure coupling effects in variable cross-section, it has one limitation in dealing with the nonuniform pipes conveying fluid. In the present work, an improved frequency-domain SEM (IFSEM) is proposed for the analysis of the nonuniform fluid-conveying pipes by introducing structural wave propagation. In the IFSEM, the wave propagation coefficient plays a critical role to construct the equivalent dynamic stiffness, improving the analysis accuracy and efficiency. And there is a rule that the propagation coefficients are mainly related to the pipe diameter, flow rate and hydrodynamic pressure. A Simplification is put forward to obtain these coefficients in advance, which can significantly facilitate the vibration analysis. Finally, the IFSEM is validated through several numerical examples and the results show that it can analyze the vibration of the liquid-conveying nonuniform pipes efficiently and accurately. • An improved frequency-domain SEM (IFSEM) is used to analyze nonuniform fluid-conveying pipes by structural wave propagation. • The IFSEM proves to be effective in dealing with various types of pipes under different fluid–structure interaction loads. • The propagation coefficients can be obtained in advance which further improve the accuracy and efficiency. 

Jixiao Wang

Papers

Deformation and Solidification Characteristics and Microstructure of Arc Sprayed Ni-Al Composition Coatings

Atomizer for spray forming of high-melting-point alloy deposit billets

Assisted densification ultrasonic vibration and deposition device for spray-formed deposition billet

Improved frequency-domain Spectral Element Method for vibration analysis of nonuniform pipe conveying fluid