Splashing of Nickel Droplets During Plasma Spraying

2000 ◽  
Author(s):  
V. Pershin ◽  
I. Thomson ◽  
S. Chandra ◽  
J. Mostaghimi
Keyword(s):  
Substrate Temperature ◽  
Nickel Powder ◽  
Steel Substrate ◽  
Spray Coating ◽  
Building Blocks ◽  
Thermal Spray Coating ◽  
Substrate Heating ◽  
Polished Stainless Steel ◽  
Plasma Sprayed ◽  
Droplet Impacts

Abstract Individual splats are the building blocks of any thermal spray coating. Near the coating-substrate interface, they affect coating properties like adhesion strength. This article examines the effect of substrate heating on droplet splashing. Nickel powder was plasma-sprayed onto a polished stainless steel substrate at various temperatures and the resulting splats were analyzed. Droplet splashing was observed experimentally for three different cases: low substrate temperature, high substrate temperature, and droplet-splat interaction. Mechanisms for splashing were explained with the help of computer-generated nickel droplet impacts. The article proposes that the jetting of molten metal is not triggered by the formation of a central splat but rather a solidified ring on the periphery of the splat. It was observed that, on substrates below 350 deg C, splashing is triggered by solidification at the edge of the spreading droplet. Interactions with previously deposited splats also cause droplets to splash.

THE EFFECT OF COATING THICKNESS ON FATIGUE PROPERTIES OF STEEL THERMALLY SPRAYED WITH Ni-BASED SELF-FLUXING ALLOY

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3599-3604 ◽  
Author(s):  
HIROYUKI AKEBONO ◽  
JUN KOMOTORI ◽  
HIDETO SUZUKI
Keyword(s):  
Fatigue Strength ◽  
Thermal Spray ◽  
Coating Thickness ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Fatigue Cracks ◽  
Spray Coating ◽  
Maximum Size ◽  
Thermal Spray Coating ◽  
Fatigue Properties

The Thermal spraying is one of the most popular surface coating techniques. To achieve the most efficient use of this technique in practice, it is very important to clarify the fatigue properties of steel coated with a thermal spray coating. In this study, to clarify the effects of coating thickness on the fatigue properties of the steel substrate, three types of sprayed specimens with different coating thickness (0.2, 0.5 and 1.0mm) were prepared and fatigue tests were carried out. Coating thickness strongly affected the fatigue properties; the thinner the coating thickness, the higher the fatigue strength. Fatigue crack propagation behaviors were observed. Accordingly the fatigue cracks propagated through many defects on the coated surface. The sizes and number of the coating defects were determined by coating thickness; the thicker the coating thickness, the larger the defect and number. Therefore, the sprayed specimens with thinner coatings indicated higher fatigue strength. Furthermore, estimations of the fatigue strength were performed by using Murakami's equation. The fatigue strengths of thermal spray coated specimens were estimated by three parameters; (i) maximum size of coating defects estimated by statistics of extreme value, (ii) hardness of the matrix and (iii) volume fraction of coating defects.

Effect of Contact Resistance and Substrate Melting on Thermal Spray Coating

2000 ◽  
Author(s):  
D.W. Sun ◽  
J. Xu ◽  
H. Zhang ◽  
Y.P. Wan ◽  
V. Prasad ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Steel Substrate ◽  
Solidification Rate ◽  
Interface Velocity ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Interface Shape ◽  
Droplet Temperature ◽  
Solidification Interface ◽  
The Impact

Abstract A numerical model is developed to study the effects of the contact resistance, droplet impacting droplet temperature, and substrate temperature on the droplet solidification rate and temperature of the droplet under the condition when the substrate can melt and re-solidify. Two-dimensional simulations show that the interface velocity is small in the area of poor contact with an irregular solidification interface shape. During the impact of Molybdenum on a steel substrate, Mo solidifies while the steel substrate melts.

Study on Microstructure of Nano-Zirconia Coating by Atmospheric Plasma Spraying

2014 ◽  
Vol 618 ◽  
pp. 43-49
Author(s):  
Ying Chang ◽  
Qin Biao Zhu ◽  
Shi Jie Dong ◽  
Hui Hu Wang ◽  
Kuan He Du
Keyword(s):  
Electron Microscopy ◽  
Layer Structure ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Ceramic Particle ◽  
Atmospheric Plasma ◽  
Zirconia Coating ◽  
Technical Parameters ◽  
Columnar Grains ◽  
Plasma Sprayed

On the basis of successfully preparing nanozirconia coating via reasonable spraying technical parameters, the cross section and surface morphology of coating were determined by scan electron microscopy (SEM), and the ceramic particle sizes of coating were determined by transmission electron microscopy (TEM). Experimental results indicate that plasma sprayed zirconia coating possesses typical layer structure of thermal spray coating, in which columnar grains pile up together. Meanwhile, the non-molten nanopowders coexist with the layer structure. In addition, the equiaxial grains exist in the zirconia coating according to TEM, but the grain size is not uniform.

scholarly journals Role of Coating Processes on the Corrosion Kinetics and Mechanism of Zinc in Artificial Seawater

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7464
Author(s):  
Jitendra Kumar Singh ◽  
Soumen Mandal ◽  
Raihana Jannat Adnin ◽  
Han-Seung Lee ◽  
Hyun-Min Yang
Keyword(s):  
Corrosion Resistance ◽  
Thermal Spray ◽  
Steel Substrate ◽  
Spray Coating ◽  
Steel Structures ◽  
Thermal Spray Coating ◽  
Artificial Seawater ◽  
Arc Spraying ◽  
Plasma Arc ◽  
Resistance Performance

Zinc (Zn) coating is being used to protect steel structures from corrosion. There are different processes to deposit the coating onto a steel substrate. Therefore, in the present study, a 100 µm thick Zn coating was deposited by arc and plasma arc thermal spray coating processes, and the corrosion resistance performance was evaluated in artificial seawater. Scanning electron microscopy (SEM) results showed that the arc thermal spray coating exhibited splats and inflight particles, whereas plasma arc spraying showed a uniform and dense morphology. When the exposure periods were extended up to 23 d, the corrosion resistance of the arc as well as the plasma arc thermal spray coating increased considerably. This is attributed to the blocking characteristics of the defects by the stable hydrozincite (Zn5(OH)6(CO3)2).

Impurity Effects on Shear Adhesive Strength of Tungsten Carbide Thermal Spray Coatings on Steel

2001 ◽  
Vol 7 (S2) ◽  
pp. 328-329
Author(s):  
Seetala V. Naidu ◽  
James D. Garber ◽  
Gary A. Glassc
Keyword(s):  
Surface Roughness ◽  
Tungsten Carbide ◽  
Thermal Spray ◽  
Adhesive Strength ◽  
Steel Substrate ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Test Method ◽  
Coating Process ◽  
Ring Shear

We have used High Velocity Oxy-Fuel (HVOF) thermal spray coating process to obtain tungsten carbide coatings on steel. It is important to control the powder quality and surface roughness of the substrate in the thermal spray coating process to obtain good adherence. The adhesive strength is greatly effected by the interfacial impurities. Most commonly used in the thermal spray industry is Al2O3 grit abrasive for good surface roughness of steel substrate to produce anchor patterns for the coating. The previous studies indicated that some fine Al2O3 particles are trapped in the rough surface grooves during this process. The ring shear test method, described previously, appears to give the most accurate results on shear adhesive strength. The ring shear strength test was comprised of a 0.02” thick and 0.25” wide ring coating on a 1” diameter cylindrical substrate rod. This rod is placed in a disk with a cylindrical hole of the rod size and an incremental pressure is applied on the rod.

The Splat Morphology of Plasma Sprayed Particle and the Relation to Coating Property

2000 ◽  
Author(s):  
N. Sakakibara ◽  
H. Tsukuda ◽  
A. Notomi
Keyword(s):  
Young’S Modulus ◽  
Adhesive Strength ◽  
Young's Modulus ◽  
Steel Substrate ◽  
Splat Morphology ◽  
Coating Properties ◽  
Spherical Powder ◽  
Spraying Parameters ◽  
Polished Stainless Steel ◽  
Plasma Sprayed

Abstract Yttria stabilized zirconia particles are plasma sprayed on polished stainless steel substrate. Starting powders are fused and crushed powder, and hollow spherical powder. Four types of the splat morphology, which are splash, rugged, gravel mounted, and disk splats, are observed. Splash and disk splats are fully melted particles, but rugged and gravel mounted like splats are partially melted particles Gravel mounted like splat is observed from only hollow spherical powder, and disk splat is observed in the case of high substrate temperature. It is found that the ratio of splat morphology changes with spraying parameters. Porosity of the coating from fused and crushed powder is higher and Young's modulus of that is lower than that from hollow spherical powder. The ratio of rugged and gravel mounted splats affect porosity and Young's modulus. Adhesive strength increases with the increase in the ratio of disk splat. So, the coating properties are improved by controlling splat morphology. KEYWORDS: Splat Morphology, Partially Melted Particle, Disk Splat, Porosity, Young's Modulus, Adhesive Strength

A Preliminary Study on Hybrid Use of Thermal Spray Coating and Ultrasonic Nanocrystalline Surface Modification Technique on the Tribological Properties of Yttria-Stabilized Zirconia Coating

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Auezhan Amanov ◽  
Young-Sik Pyun
Keyword(s):  
Surface Modification ◽  
Thermal Spray ◽  
Tribological Properties ◽  
Steel Substrate ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Mechanical And Tribological Properties ◽  
Sprayed Coating

An ultrasonic nanocrystal surface modification (UNSM) technique was applied to a thermally sprayed yttria-stabilized zirconia (YSZ) ceramic coating deposited onto a hot tool steel substrate to improve the mechanical and tribological properties. The friction test results showed that the UNSM-treated coating had a smoother surface, a lower friction, and a higher resistance to wear compared to that of the as-sprayed coating. It was also demonstrated that the UNSM technique improved the adhesion behavior of the coating by about 24%. Hence, it was found that a hybrid use of thermal spray coating (TSC) and UNSM technique is a meaningful way to bring together synergy effect of two emerging surface technologies in terms of tribology.

Experimental Approach to Adhesion between an Alumina Plasma-Sprayed Coating and Polymeric Substrate

1996 ◽  
Author(s):  
P. Lucchese ◽  
R. Jeandin ◽  
G. Surdon ◽  
A. Delavernme
Keyword(s):  
Bond Coat ◽  
Surface Preparation ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Fiber Layer ◽  
Bond Coats ◽  
Reinforced Polymer ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Thermally Sprayed

Abstract Thermal spray coating of fiber reinforced polymer (FRP) components has a high development potential to improve their wear, erosion and corrosion resistance. This paper deals with the optimization of plasma spraying conditions of alumina onto a FRP substrate, including the study of surface preparation. The so-called "Atmosphere and Temperature Controlled Process (ATC, patented by CEA)" was used to maintain the substrate temperature at a rather low level, i.e. near room temperature. Various surface preparation processes such as grit blasting, cleaning using the plasma torch and pre-coating with an intermediate bond coat were tested. The latter was shown to improve adhesion between the coating and the substrate significantly, when using 2 types of bond coats. One consisted of an additionnal fiber layer directly stuck to the substrate, the other of an intermediate thermally-sprayed PEEK layer. Results of adhesion tests were discussed in the light of interface characterization. Using a PEEK bond coat led to an adhesion strength between alumina and the substrate 3 times better than that for the material without any bond coat.

Effect of Substrate Temperature on Properties of Silicon Nitride Films Deposited by RF Magnetron Sputtering

2011 ◽  
Vol 254 ◽  
pp. 187-190 ◽  
Author(s):  
Ruchi Tiwari ◽  
Sudhir Chandra
Keyword(s):  
Refractive Index ◽  
Silicon Nitride ◽  
Magnetron Sputtering ◽  
Substrate Temperature ◽  
Rf Magnetron Sputtering ◽  
Building Blocks ◽  
Film Deposition ◽  
X Ray ◽  
Substrate Heating ◽  
Silicon Nitride Films

In the present work, we report the preparation, characterization and application of silicon nitride thin films deposited by RF magnetron sputtering on oxidized silicon substrates. The properties of the films were investigated with respect to the substrate temperature during film deposition. X-ray energy dispersive spectroscopy confirms the presence of silicon and nitrogen in the films. The X-ray diffraction results indicate that the films were amorphous when deposited without external substrate heating. On the other hand, the deposition on heated substrate (300 °C) results in weakly crystalline structure. Spectral reflectance technique was used for thickness and refractive index measurements. With substrate heating, the refractive index was observed to increase. Atomic force microscope images revealed that the films were smooth and had uniform texture. The etching characteristics of the films in buffered hydrofluoric acid at room temperature and 40 wt % potassium hydroxide at 80 °C were also investigated. Significant reduction in etch rates was observed when the films were deposited on heated substrates. Using the sputter deposited silicon nitride films, microstructures such as cantilevers and diaphragms, which are basic building blocks in micro-electro-mechanical system (MEMS) based sensors, were fabricated using micromachining techniques.

scholarly journals Microstructure and Sliding Wear Resistance of Plasma Sprayed Al2O3-Cr2O3-TiO2 Ternary Coatings from Blends of Single Oxides

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 42 ◽  
Author(s):  
Maximilian Grimm ◽  
Susan Conze ◽  
Lutz-Michael Berger ◽  
Gerd Paczkowski ◽  
Thomas Lindner ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Sliding Wear ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Corrosion And Wear ◽  
Atmospheric Plasma ◽  
Spray Parameters ◽  
Oxide Materials ◽  
Spray Process ◽  
Plasma Sprayed

Al2O3, Cr2O3, and TiO2 are most commonly used oxide materials for thermal spray coating solutions. Each oxide shows unique properties comprising behavior in the spray process, hardness, corrosion, and wear resistance. In order to exploit the different advantages, binary compositions are often used, while ternary compositions are not studied yet. Atmospheric plasma spraying (APS) of ternary compositions in the Al2O3-Cr2O3-TiO2 system was studied using blends of plain powders with different ratios and identical spray parameters. Coatings from the plain oxides were studied for comparison. For these powder blends, different deposition rates were observed. The microstructure, roughness, porosity, hardness, and wear resistance were investigated. The formation of the splats from particles of each oxide occurs separately, without interaction between the particles. The exception are the chromium oxide splats, which contained some amounts of titanium. The predominant oxide present in each blend has a decisive influence on the properties of the coatings. While TiOx causes a low coating porosity, the wear resistance can be increased by adding Cr2O3.

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