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.

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.

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.

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.

Interfacial Elemental Distribution In Tungsten Carbide Coated Steel

1999 ◽  
Vol 5 (S2) ◽  
pp. 838-839
Author(s):  
S.V. Naidu ◽  
Carlos Green ◽  
Christopher Maxie ◽  
James D. Garber ◽  
Gary A. Glass
Keyword(s):  
Thermal Spray ◽  
Steel Substrate ◽  
Spray Coating ◽  
High Hardness ◽  
Thermal Spray Coating ◽  
Elemental Distribution ◽  
Coated Steel ◽  
X Ray ◽  
Carbide Coatings ◽  
Steel Substrates

Thermal spray of carbide coatings with high hardness and corrosion resistance onto steel substrates has technological importance. The adhesive strength is greatly effected by the interfacial impurities. Low porous and good quality 200 μm thick 86WC10Co4Cr coatings on 4140 steel are obtained by thermal spray methods using SC-HVOF gun at Cooper Oil Tools, Houston, TX. A Carl Zeiss DSM942 SEM with 3.5 nm resolution at 30 keV and Kevex LPX1 Super Dry Quantum Si(Li) Detector with < 145 eV resolution for Energy Dispersive X-ray Spectroscopy (EDXS) were used to study the elemental distribution across the interface. Fig. 1 shows the SEM micrographs of the interface between 86WC10Co4Cr thermal spray coating and 4140 steel substrate. The anchor patterns seen at the interface are believed to improve the adhesive qualities between the coating and the substrate.

Resistance of Thermal Sprayed Duplex Coating Composed of Ai And Ni-Cr Alloy Against Aqueous Corrosion

1998 ◽  
Author(s):  
K. Ishikawa ◽  
T. Suzuki ◽  
S. Tobe ◽  
Y. Kitamura
Keyword(s):  
Steel Substrate ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Aqueous Environment ◽  
Aqueous Corrosion ◽  
Duplex Coating ◽  
Coating Method ◽  
Polarization Characteristics ◽  
Sprayed Coating ◽  
Al Coating

Abstract The development of corrosion resistant sprayed coating without sealing is required to increase reliability of the thermal spray coating method and to expand the field of application for the wet corrosion environments. The conventional wire flame sprayed Al coating on the steel substrate without sealing has poor resistance against aqueous corrosion, so as to be restricted in use in practical fields. A duplex coating composed of sprayed Al on a 80Ni-20Cr alloy undercoat was proven to have sufficient resistance in a hot, near neutral aqueous environment through a trial use in a vegetable oil process. In this paper, mechanism of the corrosion resistance of the duplex coating is clarified by electrochemical measurements of the corrosion potential and the anodic polarization characteristics.

Finite Element Analysis of Particle Impact on Substrates Using HVOF Thermal Spray Coating

2016 ◽  
Vol 852 ◽  
pp. 446-451
Author(s):  
Vaibhav Shelar ◽  
D. Davidson Jebaseelan ◽  
C.P. Karthikeyan ◽  
Joseph Stokes
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Flame Spray ◽  
Element Analysis ◽  
Hvof Thermal Spray ◽  
The Impact

Lower flame temperature characteristics of high velocity oxygen fuel (HVOF) flame spray process favor several surface coating applications. Simulation of HVOF coating is extremely complex to analyze, since its properties and microstructure depend on numerous processing parameters. Finite element analysis (FEA) is used in this paper to analyze the influence of particle heat input and impact velocity on HVOF coating on various substrates. HVOF thermal spray coating conditions, Tungsten Carbide Cobalt (WC-Co) particles and steel substrate were modeled using ANSYS 14.5. Droplets of different size were considered as particles in the numerical analysis to study their impact on the substrate. Thermal and residual stress analysis was done on both the particle and substrate during different stages of the high velocity impact process. Both rigid and soft conditions of the particle and substrate were simulated. Thermal stress of both the particle and substrate were found to increase rapidly very close to the impact process. Smaller sized particles had higher plastic strain when compared to larger sized particles. However, the residual stress and plastic strain of the substrate increased when impacted by larger sized particles. Residual stress of both particle and substrate were found to be influenced by the impact and thermal stress of each other. Higher velocity of the flame spray showed improved plastic strain and stress on individual particles, which is a major reason for the dense pattern of coating.

Assessing the effect of night ventilation on PCM performance in high-rise residential buildings

2019 ◽  
Vol 43 (3) ◽  
pp. 229-249 ◽  
Author(s):  
Shahrzad Soudian ◽  
Umberto Berardi
Keyword(s):  
Thermal Energy ◽  
Phase Change Materials ◽  
Positive Impact ◽  
Residential Buildings ◽  
Solidification Rate ◽  
Operative Temperature ◽  
High Rise ◽  
Ventilation Strategies ◽  
Night Ventilation ◽  
The Impact

This article investigates the possibility to enhance the use of latent heat thermal energy storage (LHTES) as an energy retrofit measure by night ventilation strategies. For this scope, phase change materials (PCMs) are integrated into wall and ceiling surfaces of high-rise residential buildings with highly glazed facades that experience high indoor diurnal temperatures. In particular, this article investigates the effect of night ventilation on the performance of the PCMs, namely, the daily discharge of the thermal energy stored by PCMs. Following previous experimental tests that have shown the efficacy of LHTES in temperate climates, a system comprising two PCM layers with melting temperatures selected for a year-around LHTES was considered. To quantify the effectiveness of different night ventilation strategies to enhance the potential of this composite PCM system, simulations in EnergyPlusTM were performed. The ventilation flow rate, set point temperature, and operation period were the main tested parameters. The performance of the PCMs in relation to the variables was evaluated based on indoor operative temperature and cooling energy use variations in Toronto and New York in the summer. The solidification of the PCMs was analyzed based on the amount of night ventilation needed in each climate condition. The results quantify the positive impact of combining PCMs with night ventilation on cooling energy reductions and operative temperature regulation of the following days. In particular, the results indicate higher benefits obtainable with PCMs coupled with night ventilation in the context of Toronto, since this city experiences higher daily temperature fluctuations. The impact of night ventilation design variables on the solidification rate of the PCMs varied based on each parameter leading to different compromises based on the PCM and climate characteristics.

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