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1.
介绍基底往复式喷射成形制备大壁厚管坯的工艺原理。研究单层沉积轨迹特性及其数学模型,针对沉积轨迹螺旋特性,分析基底运动参数(ω,v)对单层沉积特性的影响。建立多旋转周期沉积轮廓叠加的单层沉积厚度模型,利用该模型在不同沉积轨迹螺距下,对沉积厚度进行计算仿真,获得保证均匀沉积面的运动参数优化条件。在此基础上,提出单层沉积厚度的简易计算方法,并通过实验进行了验证,测量结果与预测值一致性较好。将研究结果用于实际喷射成形管坯生产中,制备得到表面形貌良好、性能稳定的管坯。 相似文献
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介绍了基底往复式喷射成形制备大壁厚管坯的工艺原理,并对雾化锥流率的空间分布和单层沉积轨迹进行了研究,在此基础上建立了单层沉积的数学模型.针对此模型和沉积轨迹的螺旋特性,分析了模型参数(mmax,a,d)和基底运动参数(w,v)对单层沉积特性的影响以及基底半径对单层沉积厚度的影响.通过对多旋转周期沉积轮廓叠加的单层沉积厚度的仿真,优化了管坯制备的运动参数(w,v). 相似文献
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为了解决陶瓷颗粒增强铝基复合材料大直径厚壁管坯、圆柱锭坯和环件的制备技术问题,作者发明了坩埚移动式自动化控制喷射共沉积技术和一系列装置,研究了喷射共沉积过程原理及基本规律,制备出了尺寸为dout650 mm/din 300 mm×1 200 mm的6066Al/SiCp管坯,d700mm×600 mm的7075Al/SiCp圆柱锭坯和dout1 200mm/din600 mm×250 mm的7075Al/SiCp环件.沉积层的冷速达104K/s.在沉积过程中雾化颗粒的沉积轨迹是一种有规律的扭合曲线.实验结果表明,该技术是适合于制备大尺寸快速凝固铝基复合材料坯件的理想技术. 相似文献
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喷射成形过程模拟研究 总被引:7,自引:5,他引:7
喷射成形将快速凝固技术与金属材料的直接成形技术有机地结合起来,是一种先进的材料制备技术,可用于制备晶粒细小、成分均匀、合金元素过饱和度高的管坯、板坯或圆柱坯等。为了认识喷射成形过程,优化设计喷射成形工艺,近年来人们对喷射成形过程开展了大量的模拟研究工作。介绍了雾化液滴冷却凝固过程模型和喷射成形沉积坯形状演变过程模型。 相似文献
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以喷射沉积技术制备出Mg-Al-Zn系合金沉积坯,对其尺寸不均匀的挤压坯在高度、厚度方向上进行性能与微观组织的不均匀性研究。结果表明,挤压坯高度方向硬度值几乎没有变化,而壁厚方向硬度值则表现出"中间层小、内外层大"的规律,挤压过程中沉积坯塑性变形的不均匀是影响镁合金挤压坯组织及性能不均匀性的主要原因。 相似文献
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分别使用传统喷射电沉积和摩擦辅助喷射电沉积技术制备一组不同沉积时间的镍沉积层,并采用非接触式表面三维形貌仪对其表面形貌进行观察,采用XRD分析沉积层的晶粒大小和织构随沉积时间的变化,用TEM观察沉积层组织机构的不同,通过沉积层的厚度分析对两种方法的沉积效率和稳定性进行比较。结果表明:传统喷射电沉积镍层随着沉积时间的增加表面逐渐变得粗糙,沉积时间由20 min增加至120 min时,粗糙度Ra值由212 nm增加至282 nm,而摩擦辅助喷射电沉积镍层可以始终保持光亮平整,Ra值由最初的228 nm逐渐减小,并最终稳定在171 nm左右;摩擦辅助装置的加入对喷射电沉积效率影响很小,但使沉积的均匀性和稳定性得以提高;同时,该装置细化晶粒,使平均晶粒大小由15.6 nm减少至10.9 nm。 相似文献
7.
喷射铸造:一种崭新的成形工艺 总被引:3,自引:0,他引:3
喷射铸造是一种新的成形工艺。它可生产管材、坯料、板材及形状简单的异形件。在沉积过程中,液体金属被压缩惰性气体(如N_2、Ar等)雾化,形成雾化锥。雾化的金属液滴被高速气体冷却并被加速,打在衬板上,凝固成一层厚的沉积层。由于冷却速度快(如钢可达10~3~10~5℃/s),使得沉积层具有精细的显微结构、少偏析、加工性好等特点。喷射沉积是介于传统铸造和粉末冶金之间的一种工艺。 相似文献
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A mathematical model is formulated to predict the shape evolution and the final geometry of a tubular product prepared by spray forming. The effects of several important processing parameters on the shape evolution of the tube are investigated. The model is validated against experiments of spray formed large diameter tubes. The experimental and the modeling results show that there are three distinct regions in the preform, i.e., the left transition region, the middle uniform diameter region and the right transition region. The results show that the atomization parameters as and bs, traversing speed v of the substrate, the outer diameter D0 of the substrate, and the initial deposition distance d0 play important roles in the contour and the wall thickness of the spray formed tube. But the angular velocity ω of the substrate has little effect on the buildup of the deposit. After a certain time from the beginning of the process, the deposit will come into a steady growth state. In addition, an equation is provided to estimate the wall thickness of the deposit under the steady growth state based on the mass conservation. 相似文献
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Taeyoung Han Zhibo Zhao Bryan A. Gillispie John R. Smith 《Journal of Thermal Spray Technology》2005,14(3):373-383
The kinetic spray coating process involves impingement of a substrate by particles of various material types at high velocities.
In the process, particles are injected into a supersonic gas stream and accelerated to high velocities. A coating forms when
the particles become plastically deformed and bond to the substrate and to one another upon collision with the substrate.
Coating formation by the kinetic spray process can be affected by a number of process parameters. In the current study, several
spray variables were investigated through computational modeling and experiments. The examined variables include the temperature
and pressure of the primary gas, the cross-sectional area of the nozzle throat, the nozzle standoff distance from a substrate,
and the surface condition of nozzle interior and the powder gas flow. Experimental verification on the effects of these variables
was performed primarily using relatively large-size aluminum particles (63–90 μm) as the feedstock material. It was observed
that the coating formation is largely controlled by two fundamental variables of the sprayed particles: particle velocity
and particle temperature. The effects of different spray conditions on coating formation by the kinetic spray process can
be generally interpreted through their influences on particle velocity and/or particle temperature. Though it is limited to
accelerate large particles to high velocities using compressed air or nitrogen as carrier gas, increasing particle temperature
provides an additional means that can effectively enhance coating formation by the kinetic spray process. 相似文献
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Gas dynamic principles of cold spray 总被引:15,自引:0,他引:15
This paper presents an analytical model of the cold-spray process. By assuming a one-dimensional isentropic flow and constant
gas properties, analytical equations are solved to predict the spray particle velocities. The solutions demonstrate the interaction
between the numerous geometric and material properties. The analytical results allow determination of an optimal design for
a cold-spray nozzle. The spray particle velocity is determined to be a strong function of the gas properties, particle material
density, and size. It is also shown that the system performance is sensitive to the nozzle length, but not sensitive to the
nozzle shape. Thus, it is often possible to use one nozzle design for a variety of operational conditions. Many of the results
obtained in this article are also directly applicable to other thermal spray processes. 相似文献
16.
A. Nadeau L. Pouliot F. Nadeau J. Blain S. A. Berube C. Moreau M. Lamontagne 《Journal of Thermal Spray Technology》2006,15(4):744-749
In the past 10 years, significant progress has been made in the field of advanced sensors for particle and spray plume characterization.
However, there are very few commercially available technologies for the online characterization of the as-deposited coatings.
In particular, coating thickness is one of the most important parameters to monitor and control. Current methods such as destructive
tests or direct mechanical measurements can cause significant production downtime. This article presents a novel approach
that enables online, real-time, and noncontact measurement of individual spray pass thickness during deposition. Micron-level
resolution was achieved on various coatings and substrate materials. The precision has been shown to be independent of surface
roughness or thermal expansion. Results obtained on typical high-velocity oxyfuel and plasma-sprayed coatings are presented.
Finally, current fields of application, technical limitations, and future developments are discussed.
This article was originally published inBuilding on 100 Years of Success: Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. 相似文献
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1 INTRODUCTIONSinceitwasdevelopedfromthelate 1 960s[1~ 3],thesprayformingtechnologyhasmaderapidprogresstheseyears.Inthe 1 990s,themanufactureoflargescalespray formedmaterialshasdevelopedinsomeenter prisesofEurope ,AmericaandJapanetc ,accordingtothe 3rdinternationa… 相似文献
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The plasma spray technique has been used by several researchers to deposit nanostructured ceramic coatings, but there is no
available literature discussing how to fabricate a bulk, freestanding nanostructured component by such a technique. In the
current study, net shape nanostructured Al2O3 structures have been fabricated using the plasma spray technique. A detailed characterization of the spray-formed Al2O3 structure has been performed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy
(TEM), and microhardness measurements. This study validates the feasibility of rapid fabrication of freestanding, near net
shape nanostructured Al2O3 components of larger size by plasma spray forming technique. Plasma spray parameters were controlled with a proprietary cooling
technique to retain a large fraction of nanosize Al2O3 powder particles in the spray deposit. Partially melted nanosize Al2O3 particles were trapped between the fully melted coarser, micrometer size Al2O3 grains. It was found that densification of the spray deposit has been dominated by both solidification and solid-state sintering.
This study proves that a variety of nanostructured materials and their combinations can be fabricated to near net shapes by
espousing a similar processing approach. 相似文献
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静电喷雾是一种高效且应用广泛的膜层制备技术,能够使微细粒子均匀分布,在微纳米材料加工制备领域表现出巨大的潜力.介绍了静电喷雾技术在制备功能化表面膜层的最新研究进展,总结了静电喷雾技术的优缺点.在静电喷雾机理与装置方面,详细阐述了泰勒锥液滴、微细射流及破碎雾化过程,分析了膜层在喷雾中的生长过程以及累积之后的内部变化,论述了膜层相组成和晶体结构的控制方式,介绍了液滴的带电方式和有无静电场的区别,对比了静电喷雾的多种装置及喷嘴类型;在氧化物膜层方面,介绍了金属氧化物膜层、非金属氧化物膜层、金属颗粒掺杂氧化物膜层,以及复合膜层的成膜条件、膜层相组成和晶体结构.归纳了多种功能的静电喷雾聚合物膜层,分析了静电喷雾在钠离子电池、锂离子电池以及钙钛矿太阳能电池中的应用.描述了含碳、硅等非金属无机物膜层的研究现状,探讨了静电喷雾参数对膜层结构的影响,以及膜层结构和性能的关系,并概括了多种膜层的厚度变化.最后,展望了静电喷雾技术的应用前景及发展趋势. 相似文献
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The formation of a thermal spray coating using an off-normal direction angle for the spray has been analyzed to identify the
causes of the large surface roughness of the coating. In the analysis, the string method was used for modeling the formation
of the coating. The method uses a string of equally spaced node points to define the shape of the coating surface and to track
the change in this shape as the thermal spray mass is deposited. The method allows for the calculation of arbitrary shapes
for the coating surface that may be very complex. The model simulates the stochastic deposition of a large number of thermal
spray droplets. Experiments were carried out to obtain the data used in the model for the mass flux distribution on the target
surface. The data show that when the thermal spray mass impinges on the target surface a large fraction of it, called overspray,
splashes off the target and is redeposited with a small direction angle. This component of the deposited mass results in a
large coating roughness. 相似文献