Change of the Substrate Surface After Removal Multiple Plasma Spraying Layers

2018 ◽  
pp. 351-361
Author(s):  
Jozef Kužma ◽  
Michal Krescanko ◽  
Sergej Hloch
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface

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.

Plasma Spray Deposition Processes

MRS Bulletin ◽  
1988 ◽  
Vol 13 (12) ◽  
pp. 60-67 ◽  
Author(s):  
Herbert Herman
Keyword(s):  
High Temperature ◽  
Plasma Spraying ◽  
Protective Coatings ◽  
Spray Deposition ◽  
Substrate Surface ◽  
Extractive Metallurgy ◽  
Thermal Plasmas ◽  
Corrosive Media ◽  
Wide Range ◽  
Deposition Processes

The concept of plasma is central to many scientific and engineering disciplines—from the design of neon advertisement lights to fusion physics. Plasmas vary from low density, slight states of ionization (outer space) to dense, thermal plasmas (for extractive metallurgy). And plasmas are prominent in a wide range of deposition processes — from nonthermal plasma-activated processes to thermal plasmas, which have features of flames and which can spray-deposit an enormous variety of materials. The latter technique, arc plasma spraying (or simply, plasma spraying) is evolving rapidly as a way to deposit thick films (>30 μm) and also freestanding forms.This article will review the technology of plasma spraying and how various scientific disciplines are contributing to both an understanding and improvement of this complex process.The plasma gun dates back to the 1950s, when it was introduced for the deposition of alloys and ceramics. Due to its high temperature flame it was quickly discovered that plasmas could be used for depositing refractory oxides as rocket nozzle liners or to fabricate missile nose cones. In the latter technique, the oxide (e.g., zirconia-based ceramics, spinel) was sprayed onto a mandrel and the deposited material was later removed as a free-standing form.The technique's versatility has attracted considerable industrial attention. Modern high performance machinery is commonly subjected to extremes of temperature and mechanical stress, to levels beyond the capabilities of present-day materials. It is becoming increasingly common to form coatings on such material surfaces to protect against high temperature corrosive media and to enhance mechanical wear and erosion resistance. Several thousand parts within an aircraft gas turbine engine have protective coatings, many of them plasma sprayed. In fact, plasma spraying has emerged as a major means to apply a wide range of materials on diverse substrates. The process can be readily carried out in air or in environmental chambers and requires very little substrate surface preparation. The rate of deposit buildup is rapid and the costs are sufficiently low to enable widening applications for an ever increasing variety of industries.

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

scholarly journals Effect of Transferred Arc Treatment on Substrate Surface for Low Pressure Plasma Spraying.

1993 ◽  
Vol 42 (478) ◽  
pp. 874-880 ◽  
Author(s):  
Yoshiyasu ITOH ◽  
Masahiro SAITOH ◽  
Keizo HONDA ◽  
Matuo MIYAZAKI
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Low Pressure ◽  
Pressure Plasma ◽  
Low Pressure Plasma ◽  
Transferred Arc ◽  
Low Pressure Plasma Spraying

A model of the interface between plasma jet simulation and the simulation of coating formation during atmospheric plasma spraying (APS)

2004 ◽  
Vol 120 ◽  
pp. 373-380
Author(s):  
E. Lugscheider ◽  
R. Nickel ◽  
N. Papenfuß-Janzen
Keyword(s):  
Heat Transfer ◽  
Plasma Spraying ◽  
Substrate Surface ◽  
Fem Analysis ◽  
Software Tool ◽  
Plasma Jet ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Barrier Coating ◽  
Coating Formation

The atmospheric plasma spraying (APS) process can be divided into sub-processes, which are simulated by different numerical methods. The balance equations of momentum, mass and energy of the plasma jet are solved numerically by applying the finite volume method (FVM) using a CFD (Computational Fluid Dynamics) software tool. On the other hand the solution of the thermo-mechanical problem of the coating formation on the substrate is estimated using the finite element method (FEM). The movement of the plasma jet above the surface of the substrate during the spraying process causes a time dependent boundary condition for the FEM-analysis. The heat transfer from the plasma jet to the substrate has to be taken into account. There is also a mass and heat transfer of heated particles to the substrate surface, which is responsible for the formation of the coating. Not only the plasma jet influences the boundary conditions of the coating formation, but the substrate is also a boundary for the plasma jet. This has to be considered during the plasma jet simulation, as well. This article describes the physical and mathematical background of the plasma jet/substrate heat transfer interface model, the implementation in the overall simulation process and its use in the simulation of the formation of a thermal barrier coating (TBC) made of partially yttria stabilized zirconia on a turbine blade during atmospheric plasma spraying.

Influence of Interfacial Temperature on the Adhesion Properties of Plasma-Sprayed Metal-Ceramic Coatings

1998 ◽  
Author(s):  
C.R.C. Lima ◽  
R.D.E. Trevisan
Keyword(s):  
Plasma Spraying ◽  
Substrate Surface ◽  
Ceramic Coatings ◽  
Industrial Applications ◽  
Thermal Barrier ◽  
Adhesion Properties ◽  
Barrier Coating ◽  
Metal Ceramic ◽  
Interfacial Temperature ◽  
Plasma Sprayed

Abstract Metal-ceramic coatings have been widely used for industrial applications, mainly in the thermal barrier coating technology (TBC). Plasma spraying is the common manufacturing process of TBC's. Conventional thermal barrier coatings consist of a metallic bond coat layer and an insulating ceramic overlay. Graded coatings or functionally gradient coatings have also been applied in order to solve the problems associated with the early spallation of plasma-sprayed conventional TBCs. Temperatures and gradients during plasma spraying have and important influence on the coating quality, specially the temperature of the particles just hitting the substrate surface. When applying so distinct materials like metals and ceramics this fact has an increased importance. In this work metal-ceramic coatings have been applied on metallic substrates. The interfacial temperature measurements were performed by optical pyrometry. The substrate temperature was measured by thermocouples. The adhesion of the coatings was determined by standard ASTM tests and correlated with the measured temperatures. In a general way, results show that the coatings with lower adhesion values were that with lower interfacial measured temperatures.

Transient Droplet/Substrate Contact Pressure During Droplet Flattening on Flat Substrate in Plasma Spraying

2000 ◽  
Author(s):  
C.-J. Li ◽  
J.-L. Li
Keyword(s):  
Contact Pressure ◽  
Plasma Spraying ◽  
Early Stage ◽  
Substrate Surface ◽  
Maximum Pressure ◽  
Coordinate Systems ◽  
Flat Substrate ◽  
Cylindrical Coordinate ◽  
Transient Contact ◽  
Contact Pressures

Abstract The spreading process of an isothermal droplet impinging on flat substrate surface in plasma spraying is studied numerically in 2D cylindrical coordinate systems by using 'Marker-And-cell (MAC) Technique. The changes and distributions of the transient contact pressures upon substrate surface at flattening are calculated under different droplet conditions with different impacting velocities and densities. The simulated results show that the transient contact pressure is initially high and concentrates at a small contacting area, it then spreads and drops quickly while droplet flattens. The maximum pressure is located at the front of the droplet at early stage of deformation, which pushes the fluid moving quickly along substrate surface and results in lateral flow. The contact pressure is mainly related to the droplet density and impact velocity. The peak pressure reduces consistently along the substrate surface so that the splashing at the periphery of flattening droplet may occur to form a reduced disk like splat because of the falling of contact pressure in this region and the escaping of the evaporated gas from the droplet / substrate interface.

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.

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