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6267 |
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Development of a novel long laminar plasma jet on atmospheric plasma spray process: Microstructure of a quasi-columnar YSZ coating |
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Sen-Hui Liu* / Beihang University, P.R. China Hong-Bo Guo / School of Materials Science and Engineering, Beihang University,, China Juan. Pablo Trelles/ Department of Mechanical Engineering, University of Massachusetts Lowell, Massachusetts 01854, USA, USA Anthony Murphy/ CSIRO Manufacturing, Lindfield NSW 2070, Australia, Australia Chang-Jiu Li/ School of Materials Science and Engineering, Xi'an Jiaotong University, , China Cheng-Xin Li/ School of Materials Science and Engineering, Xi'an Jiaotong University, , China |
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We propose a novel atmospheric plasma spray method, which by using a newly development plasma torch that can generate a long, stable and silent plasma jet in atmospheric environment without any other auxiliary equipment. The lengths of these plasma jets vary from 100 mm to 1000 mm in an atmospheric environment. The fluid characteristics of plasma jets present a laminar or quasi-laminar with a low-level noise (< 80 dB) through numerical simulation and experimental analysises. Moreover, the lengths of the plasma jets are increased by the increasing of the output power at every constant gas flow rate in the ranging of 8 ~ 15 SLPM and decreased as the increasing of total gas flow rate at every constant output power in the ranging of 8 ~ 100 kW. In this work, we obtain a vapor and droplet co-deposited YSZ coating by using a novel long laminar plasma spray method at a long spraying distance of 250 mm in an atmospheric environment. The microstructures of this coating present a quasi - columnar structure that distributed along the cross - section within a certain interval and a large number of cluster-liked structures on the top surface of coatings. Comparing with other current atmospheric plasma spray methods, a super long particle flight time under a lower particle velocity are obtained in this work and contributed to generate a mass of vapor YSZ materials. The self - shadowing effect of impinging particles at the boundary layer of the substrate is demonstrated by the numerical simulation and the experimental observation. This method can provide a new selection for the atmospheric plasma spray technology. |