Study on Deposition Behavior of Less Than 5 μm YSZ Particles in VLPPS

Abstract

A particular YSZ feedstock for very low-pressure plasma spraying (VLPPS) has been designed which can be automatically divided into less than 5 μm YSZ molten particles in the long plasma jet. Fully molten particles were deposited on the substrate at different deposition distances of 250, 350 and 450 mm, respectively. The deposition behavior of less than 5 μm YSZ molten particles were studied aiming to obtain a thin gastight YSZ coating. The flattening ratio of particles at different deposition distances and the gas permeability of YSZ coating prepared by VLPPS were investigated. The results revealed that the thickness of flattened particles was about 0.10-0.35 μm and the flattening ratio of molten particles was about 4.7. The flattened particles were bonded well with substrates and the width of vertical cracks appeared in flattened particles was 0.01-0.02 μm. The gas permeability of coatings prepared at 350 mm was 1.5910 −7 cm 4 (gf) −1 s −1 .

Different Primary Gas Flow Rates in Determining the Flattening Behavior of In-Flight Particles in Plasma-Sprayed NiCrBSi Coatings and the Resultant Microstructure and Hardness

“…Wang et al [6] observed that the flattening level of droplets increases with increased substrate temperature. Similarly, Gao et al [10] found that the flattening level increases as the spray pressure decreases. Notably, existing methods cannot readily attend to the flattening behavior of an individual droplet, primarily due to the many restricting factors during actual plasma spraying processes.…”

Solid oxide cell electrolytes deposited by atmospheric suspension plasma spraying at high velocity and high temperature

“…To ensure good adhesion and minimize splashing of the incoming molten droplets on the underlying material [19,[35][36][37][38] and improved ionic conductivity [12], it is important that the substrate temperature is >600 • C, the critical bonding temperature for YSZ [15,16]. The thermal history of the 4 spray runs as measured by a thermocouple onboard the high-speed rotating substrate holder is illustrated in Figure 2.…”

“…Here, we expand upon prior work of APS YSZ deposition at high TSRVs (≥3.8 m/s) [5,6] by fabricating electrolytes at >800 • C, with the goal of reducing segmentation cracking and leak rates without the use of post-fabrication densification steps [17,18] or zirconium nitrate impregnations [11]. While it is well established that highly dense, low leak rate electrolytes can be fabricated using lowpressure environments [2,9,19], we continue to utilize APS due to its comparatively lower costs and reduced processing times [20,21]. APS NiO-YSZ coatings were prepared on substrates utilizing a recently developed CuO surface treatment in order to reduce fuel electrode roughness for subsequent YSZ deposition.…”