Effect of Substrate Temperature on Microstructural Characteristics of Thermal Sprayed Superalloys

2011 ◽  
Vol 495 ◽  
pp. 13-17
Author(s):  
Fardad Azarmi ◽  
Ghodrat Karami
Keyword(s):  
Substrate Temperature ◽  
Plasma Spraying ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Thermal Spraying ◽  
Air Plasma ◽  
Microstructural Characteristics ◽  
Splat Formation ◽  
Vacuum Plasma Spraying ◽  
Porosity Level

Recently, there has been a huge interest in application of thermal spraying processes to apply a protective layer on the surface of engineering components. Thermal spraying as a near net shape forming technique has also found applications in manufacturing of advanced engineering components. Spraying methods such as High Velocity Oxygen Fuel (HVOF), Vacuum Plasma Spraying (VPS), and Air Plasma Spraying (APS) are among the most commonly used deposition techniques. Coatings are built up from impact of molten particles on the substrate surface and their flattening and solidification (splat formation). Deposition of millions of individual splats connected to each other at different layers will result in a lamellae type structure. This is a typical example of an anisotropic microstructure. The microstructural features such as porosity, oxide layers define the physical and mechanical properties of coating material. This study investigates the influence of substrate temperature on microstructural characteristics of APS deposited superalloy 625 on steel substrate. The coatings were deposited on substrates at different temperatures. The porosity level was measured using prosimetry. Both image analysis technique and Electron Probe Microanalysis (EPMA) was used to measure the amount of oxide phase. The results indicated that lower substrate temperature results in lower oxide in microstructure. There has been no significant change in porosity level due to substrate temperature.

The Effect of Substrate Preheating and Surface Organic Covering on Splat Formation

1998 ◽  
Author(s):  
C.J. Li ◽  
J.-L. Li ◽  
W.-B. Wang
Keyword(s):  
Stainless Steel ◽  
Stainless Steel Substrate ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Thermal Spraying ◽  
Splat Morphology ◽  
Organic Substances ◽  
Splat Formation ◽  
Molten Droplet ◽  
Preheating Temperature

Abstract The splashing usually occurs when a droplet impact on a substrate surface during thermal spraying, which results in the formation of splat with irregularly complicated morphology. In present study splats are formed on polished stainless steel substrate surface covered with different organic substances with different boiling points by plasma spraying under different preheating temperature of substrate in order to clarify the factors which control the splashing during droplet flattening in thermal spray process. The droplet materials used are aluminum, nickel, copper, Ah03 and molybdenum. Three kinds of organic substances used are xylene, glycol and glycerol which are brushed on the surface of substrate before spraying. It is found that when the preheating temperature exceeds 50°C over the boiling point of organic substance brushed on substrate surface the regular disk type splats are formed in the case that no substrate melting occurs by molten droplet. When the flattening of droplet causes the melting of substrate such as the combination of Mo droplet with stainless steel substrate, the preheating of substrate has no influence on splat morphology. The evaporated gas induced splashing and substrate surface melting induced splashing models are proposed to interpret the formation of the annulus-ringed splat

Microstructure Characterization and Modeling of Splat Formation during Air Plasma Spraying for Inconel 625 Superalloy

2007 ◽  
Vol 539-543 ◽  
pp. 1218-1223 ◽  
Author(s):  
F. Azarmi ◽  
A. Moradian ◽  
J. Mostaghimi ◽  
Tom W. Coyle ◽  
L. Pershin
Keyword(s):  
Plasma Spraying ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Thermal Spraying ◽  
Inconel 625 ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Three Dimensional Model ◽  
Splat Formation ◽  
Molten Droplets

There is a growing interest in use of the nickel-based alloy Inconel 625 coatings due to its ability to improve base materials high temperature properties. Thermal spraying methods such as Air Plasma Spraying (APS) can be considered as a convenient method to deposit this material. The present work deals with APS deposited Inconel 625 structures consisting of huge number of individual splats formed by impacting molten droplets on substrates during spraying process. It is clear that the splat formation mechanism which dominates its size, cohesion, and boundaries highly influences the microstructure of the coating. This paper presents a developed numerical technique performed to simulate splat formation using a three dimensional model. In this method flow field is solved by Finite Volume Method (FVM) and free surfaces are determined from Youngs’ Volume of Fraction method (VOF). Finally, the model prediction is correlated with the actual splat geometries.

Influence of Surface Composition of Silicon-Based Material on their Bioactivity

2012 ◽  
Vol 512-515 ◽  
pp. 1826-1829
Author(s):  
Ya Ran Niu ◽  
Xue Bin Zheng ◽  
You Tao Xie
Keyword(s):  
Silicon Wafer ◽  
Plasma Spraying ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Surface Composition ◽  
Control Sample ◽  
Atomic Ratio ◽  
Air Plasma ◽  
Vacuum Plasma Spraying ◽  
Silicon Based

Silicon coatings were prepared by vacuum plasma spraying (VPS) and air plasma spraying (APS) technologies. The samples were hydrothermally treated and then incubated in simulated body fluid (SBF) to evaluate their bioactivity and silicon wafer was used as control sample at the same time. The SBF test showed that a Ca-P layer was formed on the surface of silicon wafer and VPS-Si coating after immersion in SBF for certain time, indicating their improved bioactivity. Whereas no Ca-P layer was found on the surface of APS-Si coating. The results of X-ray photoelectron spectroscopy showed that the Si/O atomic ratio and chemical depth profiles of the silicon oxide films on the surface of silicon wafer, VPS-Si and APS-Si coatings were different. The results indicated that the bioactivity difference of silicon-based material resulted from the different composition of their surface. Hydrothermal treatment maybe a favorable method to improve the bioactivity of silicon-based material having silicon oxide of non-stoichiometric Si/O atomic ratio.

scholarly journals Microstructural Characteristics in Babbitt Coatings Deposited by LPCS

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 689
Author(s):  
Wolfgang Tillmann ◽  
Leif Hagen ◽  
Mohamed Abdulgader ◽  
Mark Dennis Kensy ◽  
Michael Paulus
Keyword(s):  
Solid Solution ◽  
Substrate Temperature ◽  
Thermal Spraying ◽  
Cold Spraying ◽  
Maximum Load ◽  
Gas Temperature ◽  
Microstructural Characteristics ◽  
Mesoscopic Structure ◽  
Solid Solution Matrix ◽  
Solution Matrix

Studies have already established that the mechanical properties of Babbitt coatings significantly depend on the microstructural characteristics, such as the amount and distribution of intermetallic compounds dispersed in a soft solid solution matrix. For Sn–Sb–Cu-based Babbitt coatings, the formation of SbSn- and CuSn-based precipitates has a substantial influence on the resulting microhardness and thus determines the maximum load carrying capacity. Thermal spraying of Sn-based Babbitt coatings results in a relatively more refined structure of these precipitates than in common manufacturing processes, such as casting, due to the thermal processing conditions. This study aims to evaluate the effect of the temperature of the propellant gas and substrate temperature on the microstructural characteristics of Sn–Sb–Cu-based Babbitt coatings deposited by low pressure cold spraying (LPCS). The deposits were examined for their phase composition, microhardness and mesoscopic structure. It was found that the coatings were mainly composed of Sb2Sn23, Sb0.49Sn0.51 and Sorosite (CuSn or CuSb0.115Sn0.835), regardless of the substrate temperature or temperature of the propellant gas to be investigated. For a gas temperature above 300 °C, an increased microhardness was observed, which correlates with the appearance of a more homogenous distribution of Sb0.49Sn0.51 dispersed in a soft Sn-rich solid solution matrix.

Effect of Bond Coat Diffusion on Adhesion Behaviour of Hard Alloy Powder NiCrBCSi (Fe) Coatings Thermally Sprayed on 60CrMn4 Steel

2008 ◽  
Vol 273-276 ◽  
pp. 8-13
Author(s):  
S. Abdi ◽  
B. Malki ◽  
S. Lebaili
Keyword(s):  
Bond Coat ◽  
Steel Substrate ◽  
Substrate Surface ◽  
Thermal Spraying ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chromium Plating ◽  
Previously Treated ◽  
Thermally Sprayed ◽  
Large Diffusion

The object of the present work is to study the spraying of poly-powders nickel bases containing Cr, Si, C and B elements addition with variable percentage of iron, deposited on a steel substrate by oxy fuel thermal spraying. The substrate surface was previously treated by Al–Ni bond coat and post–annealing at 650°C. The spraying powder and coating micro structure were investigated by combination of X-ray diffraction, electron microprobe and scanning electron microscope coupled to an analyzer energy dispersive x-ray. The adherence to substrate was determined by using shear test for adhesion. The result of this study was to investigate to compare potentials of HVOF sprayed NiCrBCSi and satellite 6 coating for a possible to replacement of hard chromium plating. A good adherence of coating NiCrBCSi (Fe) on steel substrate is explained by formation of large diffusion zone in interface after annealing and by the nature of the structure deposit duplexes.

Examination of Substrate Surface Melting-Induced Splashing During Splat Formation in Plasma Spraying

2006 ◽  
Vol 15 (4) ◽  
pp. 717-724 ◽  
Author(s):  
Chang-Jiu Li ◽  
Cheng-Xin Li ◽  
Guan-Jun Yang ◽  
Yu-Yue Wang
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Surface Melting ◽  
Splat Formation

Electrical Property Characterization of Plasma Sprayed Polycrystalline Silicon

2009 ◽  
Vol 620-622 ◽  
pp. 303-306 ◽  
Author(s):  
Ya Ran Niu ◽  
Xuan Yong Liu ◽  
Yi Zeng ◽  
Xue Bin Zheng ◽  
Heng Ji ◽  
...  
Keyword(s):  
Electrical Property ◽  
Plasma Spraying ◽  
Air Plasma ◽  
Free Standing ◽  
Vacuum Plasma Spraying ◽  
Significant Difference ◽  
Plasma Sprayed ◽  
Silicon Based ◽  
Property Characterization

Silicon-based materials have been widely applied in industrial fields, such as microelectronic and solar power, for the specific electronic properties. In the present work, free-standing thick silicon coatings were fabricated by air plasma spraying (APS) and vacuum plasma spraying (VPS) technologies. The microstructure and electrical property of the coatings were characterized. It was found that the electrical resistance of APS-Si coating was higher than that of VPS-Si coating. The impedance spectroscopy results showed there was significant difference in impedance curves of APS-Si and VPS-Si coatings. The grain boundary semicircle appeared in the plot of VPS-Si coating, while did not appeared in that of APS-Si coating. It was thought that the electrical property difference of the two kind coatings was related with the oxidation and microstructure difference of the coatings.

Building of Protective Coating Against Corrosion by Flame Spraying of Mechanofused Composite Particles

2015 ◽  
Vol 1765 ◽  
pp. 37-44
Author(s):  
A. Molina-Díaz ◽  
J. Delgado-Venegas ◽  
F. Juárez-López ◽  
G. Velázquez-García ◽  
R. Cuenca-Álvarez
Keyword(s):  
Protective Coating ◽  
Steel Substrate ◽  
Salt Spray ◽  
Thermal Spraying ◽  
Corrosion Damage ◽  
Flame Spraying ◽  
Composite Particles ◽  
Substrate Roughness ◽  
Alumina Layer ◽  
Splat Formation

ABSTRACTA protective coating was built and assessed in order to reduce the degradation of metallic substrates caused by corrosion damage. Hence, a set of coatings with different configurations, in terms of layer arrangement, was produced by flame-spraying of composite powder (AISI 316L stainless steel coated with an α-alumina layer) onto an AISI 1018 steel substrate. In order to ensure a homogeneous dispersion of phases, a correlation was established between the operating parameters of thermal spraying (roughness and surface temperature of substrate, spraying distance, passing speed) and the splat formation. Then, corrosion damage caused in the coated samples by exposure to a salt spray was monitored through weight measurements and observations with optical and scanning electron microscopy. The results show that corrosion still remains in all cases; however, it proceeds at lower rates for coatings made with composite particles plus an α-alumina layer. The weight loss due to corrosion damage was reduced in approximately 94% as compared with the substrate without protection. Coating adhesion was also improved by an increased substrate roughness, with no need for an intermediate layer.

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