Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS
Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS
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DOI：
10.1007/s11666-009-9341-2
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发表时间：
2009-12-01
影响因子：
3.1
通讯作者：
Wenzelburger, Martin
中科院分区：
文献类型：
--
作者：
Dongmo, Esther;Gadow, Rainer;Wenzelburger, Martin
在热喷涂技术和涂层行业中，近年来，人们对不同材料和部件上的亚微米和纳米结构层进行了越来越多的研究和开发工作，这在功能和结构涂层性能方面具有巨大的潜力。这些潜力一直鼓励研究人员致力于加深对高速氧化物燃料 (HVOF) 系统的理解和优化，以便能够改进过程控制，从而控制涂层性能并实现亚微米和纳米结构涂层的更好应用。此外，在实验方面，已经开发了新的热喷涂技术来加工纳米粉末，即主要是基于悬浮液的技术，如悬浮液等离子喷涂或高速悬浮液火焰喷涂（HVSFS）。 HVSFS 是一种适合亚微米和纳米级颗粒的加工方法，可在超音速模式下获得致密的表面层并具有精细的最终结构，这是改善甚至优越的机械和物理性能的先决条件。然而，对 HVOF 和 HVSFS 反应流场中发生的化学和热力学现象的理论理解是过程建模所必需的，这是一个具有挑战性的多学科问题。在本研究中，分析了燃烧过程以及火焰、悬浮液滴（包括汽化）和固体喷雾颗粒之间的热、质量和动量相互作用，同时考虑了 HVOF 和 HVSFS 喷涂过程。对过程进行建模并描述数值模拟实验。因此，这些模型分别详细描述了描述燃烧室和膨胀喷嘴中完整喷涂过程的相关参数组。仿真结果可用于改进过程控制和火炬设计，例如，使燃烧室设计适应喷雾颗粒的轨迹和停留时间，以实现传热优化。
In thermal spray technologies and coating industries, increasing research and development efforts have been made in recent years toward submicron and nanostructured layers on different materials and components, promising large potentials in functional and structural coating properties. These potentials have been encouraging researchers to aim for an improved understanding and optimization of the high-velocity oxide fuel (HVOF) system to be able to improve process control, and thus, control coating properties and enable better applications for submicron and nanostructured coatings. Moreover, on the experimental side, new thermal spray technologies have been developed in order to process nanopowders, i.e., mainly suspension-based technologies like suspension plasma spraying or high-velocity suspension flame spraying (HVSFS). HVSFS is a suitable processing method for submicron and nanoscaled particles to achieve dense surface layers in supersonic mode with a refined final structure, which is the prerequisite for improved or even superior mechanical and physical properties. However, theoretical understanding of the chemical and thermodynamic phenomena occurring in the HVOF and HVSFS reacting flow field, which is necessary for process modeling, is a challenging, multidisciplinary issue. In this study, the combustion processes as well as the heat-, mass-, and momentum interactions between the flame, the suspension droplets (including vaporization), and the solid spray particles are analyzed, taking into account both the HVOF and HVSFS spray processes. The processes are modeled and numerical simulation experiments are described. Thereby, the models are giving a detailed description of the relevant set of parameters describing the complete spraying process in the combustion chamber and expansion nozzle, respectively. Simulation results can be applied for improved process control as well as torch design, e.g., adaptation of combustion chamber design to the trajectories and dwell time of spray particles for heat transfer optimization.