The Effect of Substrate Temperature on the Adhesion of Plasma-Sprayed Borosilicate Glass Coatings

1997 ◽  
Author(s):  
D.T. Gawne ◽  
Y. Bao ◽  
T. Zhang
Keyword(s):  
Substrate Temperature ◽  
Borosilicate Glass ◽  
Retention Rate ◽  
Theoretical Calculations ◽  
Substrate Surface ◽  
Large Temperature ◽  
Stress Distributions ◽  
Coating Adhesion ◽  
Major Increase ◽  
Plasma Sprayed

Abstract Experimental work has been undertaken to investigate the importance of the temperature of the substrate during deposition on the coating-adhesion of plasma sprayed borosilicate glass coatings. The work shows that the measured adhesion increases markedly with substrate temperature up to 400°C above which no further major increase takes place. Heat transfer and fluid mechanics calculations predict that the effect of substrate temperature is due to its influence through the cooling rate on the viscosity and flow of the molten glass particles as they impact on the substrate surface. The theoretical calculations also predict large temperature gradients through the thickness of the splats and glass coatings, and the consequent non-uniform thermal stress distributions are expected to contribute to the reduced splat retention rate and coating-adhesion at low substrate temperatures. The predictions were confirmed by an electron microscopy examination of the morphology of isolated splats, the deposits and the coating-substrate interface.

Numerical Study on Rapid Solidification of a Plasma-Sprayed Cast Iron Splat on a High-Temperature Substrate

2009 ◽  
Vol 79-82 ◽  
pp. 1129-1132 ◽  
Author(s):  
Ya Zhe Xing ◽  
Qiu Lan Wei ◽  
Jian Min Hao ◽  
Can Shang
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Rapid Solidification ◽  
Numerical Study ◽  
Substrate Surface ◽  
Melt Temperature ◽  
Metallurgical Bonding ◽  
Initial Substrate ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, an experiment was performed to demonstrate the possibility of the metallurgical bonding in plasma-sprayed cast iron coatings at high substrate temperature. A quantitative analysis of splat cooling and rapid solidification of cast iron splat is then presented. The effect of the substrate temperature on the development of melt undercooling within the splat is investigated in detail. The results indicated that the initial substrate temperature has a profound effect on the development of melt undercooling in a splat, the splat bottom melt temperature, and the substrate surface temperature. A high initial temperature of the substrate restrains the cooling of the splat and leads to a high melt temperature that may promote the grain growth directly on cast iron substrate surface to form the metallurgical bonding.

Analysis on Rapid Cooling and Epitaxial Solidification of a Plasma-Sprayed Yttria Stabilized Zirconia Splat on a High-Temperature Substrate

2007 ◽  
Author(s):  
Ya-Zhe Xing ◽  
Chang-Jiu Li ◽  
Jiang-Hao Qiao ◽  
Guo-Xiang Wang
Keyword(s):  
Substrate Temperature ◽  
Epitaxial Growth ◽  
Initial Temperature ◽  
Substrate Surface ◽  
Yttria Stabilized Zirconia ◽  
Transfer Model ◽  
Stabilized Zirconia ◽  
Model Calculations ◽  
Equilibrium Solidification ◽  
Plasma Sprayed

In many applications, it will be beneficial if the plasma-sprayed Yttria stabilized zirconia (YSZ) coatings exhibit epitaxial growth. Early experiments in plasma spray have shown that a high initial substrate temperature may help develop epitaxial growth from the previous deposited splats. This paper has performed an experiment to demonstrate the possibility of epitaxial growth in plasma-sprayed YSZ coatings at high substrate temperatures. A quantitative analysis of splat cooling and rapid solidification of the YSZ splat is then presented. The analysis is based on a one-dimension heat transfer model of a thin liquid YSZ layer in contact with an YSZ substrate at fairly high initial temperature. The model calculations indicate that equilibrium solidification may take place on the YSZ substrate but with a solidification temperature that is much higher than the YSZ substrate temperature. Such equilibrium solidification requires nucleation of new crystalline YSZ and therefore only leads to non-epitaxial growth. Epitaxial growth, on the other hand, requires a large melt undercooling so the YSZ crystalline can grow directly from the substrate surface, which is at a much lower temperature than the equilibrium melting point. The effect of the substrate initial temperature on the development of melt undercooling within the splat is investigated in detail. Some interesting observations have been made which may explain the physics of epitaxial growth in YSZ coatings.

Electron microscopy studies of plasma-sprayed materials

1983 ◽  
Vol 41 ◽  
pp. 70-71
Author(s):  
K.R. Subramanian ◽  
A.H. King ◽  
H. Herman
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Flame Temperature ◽  
Ceramic Coatings ◽  
Metallic Substrates ◽  
Hot Plasma ◽  
Almost All ◽  
Plasma Sprayed ◽  
Hostile Environments ◽  
Plasma Spraying Process

Plasma spraying is a technique which is used to apply coatings to metallic substrates for a variety of purposes, including hardfacing, corrosion resistance and thermal barrier applications. Almost all of the applications of this somewhat esoteric fabrication technique involve materials in hostile environments and the integrity of the coatings is of paramount importance: the effects of process variables on such properties as adhesive strength, cohesive strength and hardness of the substrate/coating system, however, are poorly understood.Briefly, the plasma spraying process involves forming a hot plasma jet with a maximum flame temperature of approximately 20,000K and a gas velocity of about 40m/s. Into this jet the coating material is injected, in powder form, so it is heated and projected at the substrate surface. Relatively thick metallic or ceramic coatings may be speedily built up using this technique.

scholarly journals Growth of GaN from elemental Gallium and Ammonia via Modified Sandwich Growth Technique

2004 ◽  
Vol 831 ◽  
Author(s):  
E. Berkman ◽  
R. Collazo ◽  
R. Schlesser ◽  
Z. Sitar
Keyword(s):  
Growth Rate ◽  
Gas Flow ◽  
Transport Model ◽  
Theoretical Calculations ◽  
Substrate Surface ◽  
Maximum Growth ◽  
Direct Reaction ◽  
Pure Nitrogen ◽  
Flow Rates ◽  
Reactor Pressure

ABSTRACTGallium nitride (GaN) films were grown on (0001) sapphire substrates at 1050°C by controlled evaporation of gallium (Ga) metal and reaction with ammonia (NH3) at a total reactor pressure of 800 Torr. Pure nitrogen (N2) was flowed directly above the molten Ga source to prevented direct reaction between the molten Ga and ammonia, which causes Ga spattering and GaN crust formation. At the same time, this substantially enhanced the Ga transport to the substrate. A simple mass-transport model based on total reactor pressure, gas flow rates and source temperature was developed and verified. The theoretical calculations and growth rate measurements at different ammonia flow rates and reactor pressures showed that the maximum growth rate was controlled by transport of both Ga species and reactive ammonia to the substrate surface.

Formation of the Cast Iron Coatings Plasma-Sprayed at Different Substrate Temperatures

2010 ◽  
Vol 44-47 ◽  
pp. 2144-2147
Author(s):  
Ya Zhe Xing ◽  
Chao Ping Jiang ◽  
Hong Chen ◽  
Jian Min Hao
Keyword(s):  
Cast Iron ◽  
Substrate Temperature ◽  
Phase Structure ◽  
Processing Parameters ◽  
Optical Microscope ◽  
Atmospheric Plasma ◽  
Cross Sectional ◽  
The Cross ◽  
Plasma Sprayed ◽  
Iron Coatings

In this work, three cast iron coatings were produced by atmospheric plasma spraying. During spraying, the surface temperature of three coatings (substrate temperature) was controlled to be averagely 50oC, 180oC and 240oC by changing the processing parameters. X-ray diffraction (XRD) was employed to analyze the phase structure of the starting powder and the coatings. The results showed that the powder was mainly composed of (Fe,Cr)7C3 and martensite and both the spraying processing and the substrate temperature exerted no influence on coating phase structure. An optical microscope (OM) was used to characterize the microstructure of the cross-section and surface of the coatings. It was found that the cross sectional hardness increased with the increase of the substrate temperature due to the improvement in interlamellar bonding.

IN-SITU PREPARATION OF YBa2Cu3O7 SUPERCONDUCTING THIN FILMS BY PULSED Nd:YAG LASER DEPOSITION

1992 ◽  
Vol 06 (08) ◽  
pp. 477-483 ◽  
Author(s):  
QINGXIN SU ◽  
SHIFA XU ◽  
DAFU CUI ◽  
HUIBIN LU ◽  
YONGJUN TIAN ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Nd:Yag Laser ◽  
Ac Susceptibility ◽  
Substrate Surface ◽  
Zero Magnetic Field ◽  
Superconducting Thin Films ◽  
In Situ Preparation ◽  
Zero Resistance

High-T c superconducting thin films of YBa 2 Cu 3 O 7 were grown in-situ on (100) SrTiO 3 substrates by Nedymium:yttrium aluminum garnet [Nd:YAG] laser ablation. The effects of the substrate temperature on the transition temperature, microcrystalline structure and surface morphology of the films were discussed. Best results were obtained in the 730°–770°C range. X-ray diffraction analysis showed that these films were highly c-oriented with the c-axis perpendicular to the substrate surface. At the optimum substrate temperature, a very smooth morphology with only a few small particles were observed by scanning electron microscopy. The zero resistance temperature of these films were ≥ 90 K with a narrow transition width and the ac susceptibility measurement also gave the same result. The highest critical current density obtained at 77 K and zero magnetic field was 3.8 × 106 A/cm 2.

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.

Influence of Substrate Temperature and Hydrothermal Treatment on the Phase Composition of Plasma-Sprayed Phosphate Coatings

2021 ◽  
Vol 57 (6) ◽  
pp. 598-602
Author(s):  
V. I. Kalita ◽  
D. I. Komlev ◽  
A. A. Radyuk ◽  
V. S. Komlev ◽  
V. F. Shamrai ◽  
...  
Keyword(s):  
Phase Composition ◽  
Substrate Temperature ◽  
Hydrothermal Treatment ◽  
Phosphate Coatings ◽  
Influence Of Substrate ◽  
Plasma Sprayed

On-Line Control of Particle Spray Jet and Residual Stresses in Plasma Sprays

2000 ◽  
Author(s):  
T. Renault ◽  
M. Vardelle ◽  
A. Grimaud ◽  
P. Fauchais ◽  
H. Hoffman
Keyword(s):  
Residual Stresses ◽  
Substrate Temperature ◽  
Particle Velocity ◽  
Low Cost ◽  
Substrate Surface ◽  
Surface Preparation ◽  
Ccd Camera ◽  
Powder Injection ◽  
Input Parameters ◽  
On Line

Abstract The quality of plasma sprayed coatings depends strongly on substrate surface preparation, especially roughness, grit residue, and oxidation stage; particle spray jet position and size relative to the plasma jet; impacting particle distribution; particle velocity, temperature, and size prior to impact; substrate temperature; and pass thickness. A simple and low-cost spray and deposit control system developed in our laboratory allows to monitor on-line the position, shape, and centroid of the hot particle spray jet. Such a tool has proved to be very sensitive to any drift in powder injection conditions and torch input parameters. Although it gives no direct information on particle velocity and temperature, this system can be easily implemented in an industrial environment and help to maintain constant the particle parameters during spraying. A CCD camera is used in conjunction with a pyrometer making it possible to measure simultaneously substrate temperature. The system can monitor coating parameters such as deposition efficiency and residual stresses. This paper describes how the system can be used to set the tolerance range of process input parameters to obtain coating parameters within given specifications.

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