Effects of Angular Injection, and Effervescent Atomization on High-Velocity Suspension Flame Spray Process
Effects of Angular Injection, and Effervescent Atomization on High-Velocity Suspension Flame Spray Process
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DOI：
10.1016/j.surfcoat.2016.06.028
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发表时间：
2016-09
影响因子：
5.4
通讯作者：
M. Mahrukh;Arvind Kumar;S. Gu
中科院分区：
文献类型：
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作者：
M. Mahrukh;Arvind Kumar;S. Gu
本文介绍了利用超音速火焰喷涂技术制备纳米涂层的方法。纳米结构涂层的形成需要使用液体原料将纳米尺寸的粉末颗粒注入热喷枪内。液体原料在喷入高速氧燃料（HVOF）火炬时需要雾化。本文研究了在高速悬浮火焰喷涂（HVSFS）过程中，液体原料的斜喷和斜喷雾化对气体和液滴动力学、汽化速率和二次破碎的影响。对不同的喷射角度进行了试验，得到了最佳的喷射角度。此外，还研究了基于双流体喷射的超音速火焰雾化技术，以提高超音速火焰雾化的效率。考虑了悬浮液滴中不同的固体纳米颗粒浓度。在角喷射中，液滴被喷射到燃烧区的核心;这立即蒸发液滴，并且蒸发在火炬内完成。选择10°-15°作为最佳喷射角度，以改善炬内气体和液滴的动力学，并避免与炬壁的碰撞。采用较高的气液质量流量比，增大喷雾锥角，将悬浮液直接喷入燃烧火焰，可以提高雾化效率。研究还发现，纳米颗粒浓度的增加对液滴的崩解过程没有显著的影响。然而，蒸发的位置是显着不同的均匀和非均匀的液滴。
This work presents the nanostructured coating formation using suspension thermal spraying through the HVOF torch. The nanostructured coating formation requires nanosize powder particles to be injected inside a thermal spray torch using liquid feedstock. The liquid feedstock needs to be atomized when injected into the high-velocity oxygen fuel (HVOF) torch. This paper presents the effects of angular injection and effervescent atomization of the liquid feedstock on gas and droplet dynamics, vaporization rate, and secondary breakup in the high-velocity suspension flame spray (HVSFS) process. Different angular injections are tested to obtain the optimum value of the angle of injection. Moreover, effervescent atomization technique based on twin-fluid injection has been studied to increase the efficiency of the HVSFS process. Different solid nanoparticle concentrations in suspension droplets are considered. In angular injection the droplets are injected into the core of the combustion zone; this immediately evaporates the droplets, and evaporation is completed within the torch. The value of 10°–15° is selected as the optimal angle of injection to improve the gas and droplet dynamics inside the torch, and to avoid the collision with the torch's wall. The efficiency of the effervescent atomization can be enhanced by using high gas-to-liquid mass flow rate ratio, to increase the spray cone angle for injecting the suspension liquid directly into the combustion flame. It is also found that the increment in the nanoparticle concentration has no considerable effects on the droplet disintegration process. However, the location of evaporation is significantly different for homogeneous and non-homogeneous droplets.