锭坯双喷嘴扫描喷射成形雾化锥沉积轨迹及其耦合研究

双喷嘴扫描喷射成形是提高生产效率和制备大直径锭坯的主要工艺方式.研究了双喷嘴扫描喷射成形工艺雾化锥扫描沉积轨迹及其耦合产生条件.建立了雾化锥沉积轨迹坐标及扫描沉积区域数学模型,分析了工艺参数对沉积轨迹的影响规律,从理论上推导了沉积轨迹耦合条件.对沉积轨迹模型和耦合特性进行了图形仿真.研究表明:沉积轨迹呈"花瓣"形状,由喷嘴偏心距、初始倾斜角、扫描范围角、喷射高度、扫描频率、沉积盘旋转速度确定.通过喷射成形试验对建立的理论模型和研究结论进行了验证,表明了其正确性.     

开放式雾化器的雾化特性研究

讨论了在雾化压力、雾化器喷射顶角一定的条件下,中心孔直径的大小、气流的牵引等雾化参数对喷粉过程的影响。通过实验对开放式环孔雾化器在雾化过程中的堵塞现象进行了实验研究,解决了雾化器的堵塞问题。     

基于凸轮驱动喷嘴分阶段变速扫描的锭坯喷射均匀沉积研究

喷射成形技术可以制备出高性能、高质量的工业锭坯,对工业的发展具有重要影响。雾化喷嘴系统是喷射成形装置的核心,喷嘴扫描运动方式对锭坯的均匀沉积有着重要的作用。本文以锭坯均匀沉积为目标,提出了基于凸轮驱动的参数可调的喷嘴扫描方式,建立了喷嘴分阶段变速扫描过程,确定了凸轮形状,对锭坯沉积轨迹进行了仿真并做了分析。最后用喷射成形实验对喷嘴分阶段变速扫描进行了验证,表明了其正确性。     

喷射成型锭坯形状的数值模拟研究

建立了描述喷射成型过程中沉积坯外轮廓动态生长的三维数学模型,该模型考虑了喷射成型过程中各种工艺参数的影响,这些工艺参数包括喷嘴的雾化特性值、偏心距离、沉积盘的旋转速度和下拉速度,在计算后进行数据处理得出了锭坯生长的三维外形轮廓,通过与实际喷射成型设备成形的锭坯对比,两种结果符合较好,并可用此模型来预测不同工艺条件下锭坯的外形生长轮廓。     

Al10Zn2.9Mg1.7Cu超高强铝合金的喷射成形制备研究

采用喷射成形技术制备了Al10Zn2.9Mg1.7Cu高强高韧铝合金沉积坯件，研究了喷射成形制备过程中各工艺参数对沉积坯件的成形性、显微组织、致密度的影响，确定了适当的工艺参数，研究了沉积坯件的热挤压及热处理工艺，对材料的组织进行了分析并对不同状态的材料性能进行了比较。研究结果表明：当喷射成形工艺参数合理时，沉积坯件具有良好的成形性与致密度，在随后的热挤压过程中，通过较低的挤压比即可使材料达到全致密；通过对合金进行适当的热处理，材料的极限抗拉强度达到810MPa，同时延伸率保持在8％-11％，该材料是一种理想的轻质高强结构材料。     

非稳定流动对喷射成型制备圆锭成型性的影响

利用计算机数值模拟技术与实验相结合的方法,着重研究了喷射成型过程中、中间包坩埚中金属熔体液高度对雾化锥的雾密度函 影响,以及对喷射成型制备圆锭的成型性的影响。     

多层喷射沉积制备双金属板材的机理初探

通过数学模拟和实际测试的结果对照，分析了多层喷射沉积制备双金属过程中一些沉积过程的规律问题，在此基础上提出了多层喷射沉积优化工艺参数的主要依据。     

非规则管坯喷射沉积成形工艺优化及试验验证

提出了基于往复式喷射成形工艺制备大璧厚非规则管坯的近终形成形工艺及其工艺参数优化方法,以实现坯件从CAD设计到喷射成形的快速制备过程。该工艺方法包括三个阶段:非规则管坯的三维CAD设计、分层处理和单层沉积厚度计算;基于沉积厚度与往复速度和质量流率的对应关系,计算满足各层沉积厚度所对应的控制参数;利用控制系统和执行机构对控制参数进行实时控制和调节,采用往复式多层喷射成形工艺制备满足设计轮廓的管坯。通过试验进行了验证,喷射成形制备的管坯形状和轮廓与CAD设计模型较好地一致,表明了该工艺方法的可行和正确性。     

Al_(10)Zn_(2.9)Mg_(1.7)Cu超高强铝合金的喷射成形制备研究

采用喷射成形技术制备了Al1 0 Zn2 .9Mg1 .7Cu高强高韧铝合金沉积坯件 ,研究了喷射成形制备过程中各工艺参数对沉积坯件的成形性、显微组织、致密度的影响 ,确定了适当的工艺参数 ,研究了沉积坯件的热挤压及热处理工艺 ,对材料的组织进行了分析并对不同状态的材料性能进行了比较。研究结果表明 :当喷射成形工艺参数合理时 ,沉积坯件具有良好的成形性与致密度 ,在随后的热挤压过程中 ,通过较低的挤压比即可使材料达到全致密 ;通过对合金进行适当的热处理 ,材料的极限抗拉强度达到 810MPa ,同时延伸率保持在 8%～ 11% ,该材料是一种理想的轻质高强结构材料。     

喷射成形工艺参数及热挤压制度对8009耐热铝合金的组织及性能的影响

采用喷射成形方法制备了A1-8．5Fe-1．4v-1．7Si(8009)耐热铝合金，研究了喷射成形工艺参数及沉积坯件的热挤压工艺对材料的微观组织及性能的影响。结果表明：喷射成形工艺能够有效地抑制8009合金中粗大的富铁相的析出，获得均匀细小的组织；当喷射成形工艺参数选择适当时，沉积坯件具有良好的成形性与致密度，在随后的热挤压过程中，通过较低的挤压比即可使材料达到全致密。合金经过热挤压后，在室温及高温下均具有良好的力学性能。     

Modeling of spray deposition: Measurements of particle size,gas velocity,particle velocity,and spray temperature in Gas-Atomized sprays

Spray deposition is a novel manufacturing process which is currently being developed for producing near-net-shape preforms. Spray deposition involves the creation of a spray of droplets by a gas atomizer and the consolidation of these droplets on a substrate to create a preform. In order to maximize the metallurgical benefits of spray deposition, a thorough characterization of momentum and heat transfer in the gas-atomized spray is required. The present paper describes measurements of particle size, gas velocity, particle velocity, and spray temperature in gasatomized Sn-Pb sprays. Measurements were performed on steady-state axisymmetric sprays which were generated using a close-coupled gas atomizer with Sn-5 wt p t Pb and Sn-38 wt p t Pb alloys, atomizer gas flow rates of 2.5 g/s (0.56 MPa) and 3.4 g/s (1.04 MPa), melt flow rates of 35 and 61 g/s, and atomizer-substrate distances of 180 and 360 mm. Gas velocities in the range to 4 m/s were measured using Pitot tube and laser Doppler anemometry (LDA). Droplet velocities in the range 3 to 32 m/s were determined from photographic streak-length measurements and LDA. Oil calorimetry of the spray enthalpy indicated that the spray temperature decreased with increasing axial distance from the gas atomizer, increasing gas flow rate, and decreasing melt flow rate. Formerly Doctoral Student, Department of Metallurgy and Science of Materials, Oxford University     

Spray Deposition Behavior and Numerical Simulation of Growth of Tubular Preform in Spray Forming Process

 Analysis on the deposition behavior of spray on deposition surface was made and an optimization method for the movement parameters (u, ω) of substrate was obtained. Simultaneously, a mathematical model of growth of tubular preform, specifically aimed at the kind of atomizer that is fixed and with a tilt angle was established. By integrating the optimization method and the mathematical model, the growth process and shape of preform were simulated. The results show that the tilt angle of atomizer plays an important role on the dimensions and shapes of tubular preforms and it can provide a guidance for the development of spray forming equipment.     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

喷射沉积铝合金管坯工业化生产中的控制系统研究

对多层喷射沉积制备大规格管坯工业化生产特点进行了分析，表明Osprey多程技术更适宜于喷射沉积工业化生产。构建了由系统管理层／控制层／设备层组成的三层递阶控制结构。对关键工艺参数的闭环控制技术进行了研究，提出了漏包连续移液和基于积分分离PID的液位精确控制结构和方法，研究了管坯沉积层厚度的在线检测及喷嘴喷射高度在线反馈控制方法，提出了基于沉积室微正压环境的氧含量控制技术。控制系统及相关控制技术已在国内首条自行研制的喷射沉积制备铝合金管坯工业化生产设备中得到应用，已生产出最大长度1500mm、最大壁厚300mm、不同内径的铝合金产品。     

雾化喷射沉积成形材料制备基本过程的分析

简要介绍目前为止喷射沉积过程所涉及的主要基本过程及其影响因素的主要研究结果及相应的理论,也给出实验处理方法的基本原理。     

喷射成形过程中圆锭坯外形生长的数值模拟

通过多次试验后得出雾化喷嘴的雾化特性公式,在此基础上建立了一种模拟喷射成形过程中圆锭坯外形生长的数学模型.该数学模型考虑了喷射成形过程中各种工艺参数,如喷嘴的雾化参数、偏心距离、沉积盘的旋转速度和下拉速度等参数的影响.经过模拟计算,得到了锭坯生长的三维外形尺寸,与实际喷射成形制备的锭坯外形对比,二者吻合很好;采用该模型分析了不同时间下锭坯的轮廓形状、偏心距离以及下拉速度变化后的锭坯轮廓形状.综合分析得出,此数学模型可以预测在不同工艺参数下喷射成形锭坯的外形生长过程.     

溶液前驱体等离子喷涂涂层微观结构影响因素研究

溶液前驱体等离子喷涂技术（SPPS）是以溶液前驱体替代常规等离子喷涂中的粉末,通过在等离子射流中形成细小陶瓷粒子,并沉积在基体上制备出具有独特结构涂层的新技术。溶液前驱体注入位置、溶液前驱体流量和喷涂距离显著影响涂层微观结构。分析表明：通过减小溶液前驱体注入位置、降低溶液前驱体流量可以保证更高比例溶液前驱体在等离子射流中发生充分反应,提高了涂层致密度。减小喷涂距离使更多在等离子射流中形成的陶瓷粒子以熔融态沉积在基体上,形成孔隙尺寸小及垂直裂纹密度高的YSZ涂层。     

A three-dimensional model of the spray forming method

A three-dimensional model has been formulated to calculate the shape of the general preform, using vector calculus. The shape of a rod, tube, plate, or irregular preform can be calculated at given spray forming conditions. The shape of a spray-formed rod was analyzed at various spray forming conditions using the three-dimensional model. The effects of spray forming parameters, such as spray distribution parameters, angular velocity of rotation, withdrawal velocity, spray angle, and eccentric distance on rod shape, were analyzed. The most important parameters affecting the shape of rods are the spray distribution parameters and the withdrawal velocity. The dynamic evolution of rod shape with a stepwise variation of the withdrawal velocity during spray forming was investigated. The effect of a stepwise change of the withdrawal velocity was the same as that of the scanning atomizer. The calculated surface profiles were compared with those of spray-formed 7075 aluminum alloy rods prepared on a pilot scale. The calculated results for the surface profiles were in agreement with those of the spray-formed rods.