scholarly journals Splat morphology and microstructure of chelate flame sprayed Er2O3 films

2020 ◽  
Vol 128 (11) ◽  
pp. 945-953
Author(s):  
Yan Xin DAN ◽  
Xiao Long ZHOU ◽  
Atsushi NAKAMURA ◽  
Keiji KOMATSU ◽  
Hidetoshi SAITOH
Keyword(s):  
2012 ◽  
Vol 510-511 ◽  
pp. 547-553 ◽  
Author(s):  
M. Khalid ◽  
M. Mujahid ◽  
Aamer Nusair Khan ◽  
R.S. Rawat ◽  
I. Salam ◽  
...  

Alumina was coated on Ti6Al4V alloy by atmospheric plasma spraying. Surface and cross sectional analysis of the coating by SEM showed that diameter and thickness of splat was greatly influenced by arc current and stand-off distance. In turn, this variation in splat morphology had effect on evolution of α-Al2O3 and γ-Al2O3 phases as revealed by XRD. Higher proportion of required γ-Al2O3 phase was achieved at stand-off distance of 130 mm and arc current of 500A.


2013 ◽  
Vol 738-739 ◽  
pp. 357-361
Author(s):  
Nuria Cinca ◽  
Antonio Isalgué ◽  
Javier Fernández ◽  
S. Sampath

Vacuum Plasma Spraying has been used to produce coatings onto steel substrates. This work deals with the study of splat morphology of the NiTi alloy sprayed by VPS onto different substrates (aluminium, copper, stainless steel, glass and alumina). All the previous characteristics are discussed in terms of wettability and thermal conductivities regarding the rapid cooling involved in the process. Although identical conditions were used during thermal spraying, a wide variety of splat formations were observed; commonly, slushy or splash/disc splats are formed depending on whether the particles have partially or fully melted. The thermal effusivity of the substrate material, which is a measure of its ability to exchange thermal energy with its surroundings, seems to play an important role promoting more or less spreading. The higher the thermal effusivity is, the more rapidly the splats are cooled, thus starting the solidification before they come to rest and, changing their morphology.


2004 ◽  
Vol 449-452 ◽  
pp. 925-928 ◽  
Author(s):  
Sachio Oki

New method for characterization of coating microstructures and for evaluation of coating property by means of surface morphology has been proposed. In this paper, the distribution of shape and dimensions of splat was examined using quantitative analysis of scanning electron microscope images from the surface of spray pattern as well as the surface of coating. Results obtained in this study indicate that it is necessary to analyze the spray pattern as well as the surface morphology in order to estimate the coating property by means of the distribution of splat which composes the coating. Moreover, the splats, which are in the interface between the substrate and the coating, should have the same morphology as those of the coating surface. The relationship between splat morphology and the property of coatings was discussed.


Author(s):  
X.Y. Jiang ◽  
S. Sampath ◽  
A. Vardelle ◽  
M. Vardelle ◽  
P. Fauchais

Abstract This is part II of the two part paper based on international collaboration between the University of Limoges, France and the State University of New York, Stony Brook, USA, aimed at fundamental understanding the relationship between processing condition and microstructure development and properties of thermally sprayed materials. In this study, the effects of deposition temperature on the microstructure and properties development of molybdenum coating was investigated. It is found that with the increase of steel substrate temperature, the molybdenum splat morphology changes from fragmented to more contiguous disk-like shape. The splats on molybdenum substrate show predominantly disk shape. With the increase in deposition temperature, the coating exhibits better lamellar structure with less interlayer pores and debris. The fracture characteristics changes gradually from interlamellar to trans-lamellar and, thermal conductivity is enhanced. Higher deposition temperature improves dramatically the adhesion and bonding of the splats, therefore the physical and mechanical properties of coatings.


Author(s):  
M. Fukumoto ◽  
E. Nishioka ◽  
T. Matsubara

Abstract A free falling experiment was conducted as a simulation of a thermal spray process. A flattening behavior of the freely fallen metal droplet impinged onto a flat substrate surface was fundamentally investigated. The substrates were kept at various designated temperatures, and the substrates coated with gold by PVD were also prepared in order to investigate the effect of a wetting at the splat/substrate interface on the flattening behavior of the droplet. A falling atmosphere was atmospheric pressure nitrogen to prevent the oxidation of the melted droplet, and the experiments under low-pressure condition were also conducted. A transition of the splat morphology was recognized in atmospheric pressure nitrogen experiments, that is, the splat morphology on a room temperature substrate was a splash type, whereas that on a high temperature substrate was a disk type. The cross-section microstructure of the splat obtained on the room temperature substrate was an isotropic coarse grain, whereas that on the high temperature substrate was a fine columnar. The grain size changed transitionally with increasing the substrate temperature. Transition temperature on the gold-coated substrate was higher than that on the substrate without coating. The cross-section microstructure of the splat obtained under low-pressure was a fine columnar even on the room temperature substrate. The results indicate that the metal droplet wets better under low-pressure condition than in atmospheric pressure nitrogen condition, and the wetting has a significant role in the flattening of the droplet.


2007 ◽  
Vol 534-536 ◽  
pp. 409-412
Author(s):  
Pisit Apichayakul ◽  
Sittichai Wirojanupatump ◽  
Sukanda Jiansirisomboon

Correlations between in-flight particle, splat and coating microstructure of thermally sprayed Ni20Cr were investigated. Flame spray and arc spray systems were employed for spraying Ni20Cr powder and Ni20Cr wire, respectively. The results showed that the arc spray process produced a broader size distribution for both in-flight particles and splats compared to flame process. Flower-like splat morphology was obtained from the arc spray whereas a pancake-like splat was obtained by flame spray. Ni20Cr coating sprayed by arc process had a denser microstructure, lower porosity and better adhesion at the interface. This could be due to the higher temperature and velocity from the arc spray process enhancing the melting and adhering for coating formation.


Author(s):  
H. Zhang ◽  
H. B. Xiong ◽  
L. L. Zheng ◽  
A. Vaidya ◽  
L. Li ◽  
...  

Effects of particle size, velocity, and temperature on the splat morphology have been well studied in the open literature. Effects of melt fraction on deposition efficiency and splat morphology are, however, not well understood. In this paper, we will focus on the melting behavior of in-flight particles and their impact on splat morphologies. A group parameter, “melting index”, has been derived to correlate the melting status of in-flight particles with particle size, velocity, and temperature which can be measured experimentally. Numerical simulations have been used to determine the unknown parameters in the melting index. The effects of initial particle diameter on the melting behavior have also been investigated.


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