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.

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.

scholarly journals Wear Behavior Analysis of Al2O3 Coatings Manufactured by APS and HVOF Spraying Processes Using Powder and Suspension Feedstocks

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 879
Author(s):  
Monika Michalak ◽  
Paweł Sokołowski ◽  
Mirosław Szala ◽  
Mariusz Walczak ◽  
Leszek Łatka ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Wear Behavior ◽  
Ceramic Coatings ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Hvof Spraying ◽  
The Coefficient Of Friction ◽  
Wear Mode ◽  
Α Al2o3 ◽  
Plasma Sprayed

Thermally sprayed ceramic coatings are applied for the protection of surfaces that are exposed mainly to wear, high temperatures, and corrosion. In recent years, great interest has been garnered by spray processes with submicrometric and nanometric feedstock materials, due to the refinement of the structure and improved coating properties. This paper compares the microstructure and tribological properties of alumina coatings sprayed using conventional atmospheric plasma spraying (APS), and various methods that use finely grained suspension feedstocks, namely, suspension plasma spraying (SPS) and suspension high-velocity oxy-fuel spraying (S-HVOF). Furthermore, the suspension plasma-sprayed Al2O3 coatings have been deposited with radial (SPS) and axial (A-SPS) feedstock injection. The results showed that all suspension-based coatings demonstrated much better wear resistance than the powder-sprayed ones. S-HVOF and axial suspension plasma spraying (A-SPS) allowed for the deposition of the most dense and homogeneous coatings. Dense-structured coatings with low porosity (4 vol.%) and good cohesion to the metallic substrate, containing a high content of α–Al2O3 phase (56 vol.%) and a very low wear rate (0.2 ± 0.04 mm3 × 10−6/(N∙m)), were produced with the S-HVOF method. The wear mechanism of ceramic coatings included the adhesive wear mode supported by the fatigue-induced material delamination. Moreover, the presence of wear debris and tribofilm was confirmed. Finally, the coefficient of friction for the coatings was in the range between 0.44 and 0.68, with the highest values being recorded for APS sprayed coatings.

Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings

2007 ◽  
Author(s):  
Lida Shen ◽  
Yinhui Huang ◽  
Zongjun Tian ◽  
Guoran Hua
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Bond Coat ◽  
Continuous Wave ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Al2o3 Ceramic ◽  
Plasma Sprayed ◽  
Steel Substrates

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.

Study of the Adhesion Strength of Plasma-Sprayed Coatings Using Statistical Methods

2020 ◽  
Vol 897 ◽  
pp. 56-60
Author(s):  
Nikolay Kuleshov ◽  
Nikolay Dolgov ◽  
Igor Smirnov ◽  
Leonid Vinogradov ◽  
Vladimir Shestakov
Keyword(s):  
Plasma Spraying ◽  
Adhesion Strength ◽  
Ceramic Coatings ◽  
Optimization Criterion ◽  
Alumina Powder ◽  
Nano Powder ◽  
Plasma Sprayed Coatings ◽  
Tensile Adhesion ◽  
Plasma Sprayed ◽  
Sprayed Coatings

The adhesion strength of plasma-sprayed ceramic coatings was studied. Alumina powder was used for plasma spraying. A titanium oxide Nano powder with a particle size of 40-50 [nm] was used as a modifier. The optimal conditions of plasma spraying of coatings are established. The adhesion strength was used as an optimization criterion. Coating adhesion was determined by tensile adhesion testing. A mathematical model is obtained that allows one to determine the effect of spraying conditions (lens current, arc current, and the position of the solenoid relative to the nozzle) on the adhesion strength.

Wear Resistance of Al2O3, Al2O3-40wt.%TiO2 Coatings Prepared by Plasma Spraying on H13 Hot-Worked Die Steel

2012 ◽  
Vol 538-541 ◽  
pp. 235-238 ◽  
Author(s):  
Ren Guo Song ◽  
Pu Hong Tang ◽  
Chao Wang ◽  
Guo Lu
Keyword(s):  
Wear Resistance ◽  
Plasma Spraying ◽  
Ceramic Coatings ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Die Steel ◽  
X Ray ◽  
Hardness Tester ◽  
Plasma Sprayed ◽  
Scanning Electron

Al2O3 and Al2O3-40wt.%TiO2 ceramic coatings on H13 hot-worked die steel have been prepared by plasma spraying, and then the microstructure, micro-hardness as well as wear resistance of the prepared coatings have been investigated by means of x-ray diffraction (XRD), scanning electron microscope (SEM), Vickers hardness tester and ball-on-disk high temperature tribometer. The results showed that the plasma sprayed ceramic coatings are of higher hardness and wear resistance than H13 hot-worked die steel.

Microstructure of Al2O3-13TiO2 Coatings Deposited from Nanoparticles by Plasma Spraying

2013 ◽  
Vol 58 (2) ◽  
pp. 335-339 ◽  
Author(s):  
A. Góral ◽  
L. Litynska-Dobrzynska ◽  
W. Zórawski ◽  
K. Berent ◽  
J. Wojewoda-Budka
Keyword(s):  
Plasma Spraying ◽  
Steel Substrate ◽  
Nanosized Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lamellar Morphology ◽  
Transmission Electron ◽  
Plasma Sprayed ◽  
Plasma Spraying Process ◽  
Spraying Process

The aim of the study was to characterize nanostructured Al2O3-13TiO2 coatings deposited by plasma spraying on a grit blasted steel substrate. The Al2O3-13TiO2 coatings were characterized using scanning and transmission electron microscopy and X-ray diffraction techniques. Obtained coatings possessed a unique microstructure consisting of fully melted regions with the microstructure similar to a typical plasma sprayed lamellar morphology as the conventional coatings and areas comprising unmelted or partially melted nanosized particles. The analysis showed that most of the α-Al2O3 phase from the nanostructured powders transformed into γ-Al2O3 phase after plasma spraying process. Moreover, the presence of amorphous phase was also observed.

Development of Bioactive Hydroxyapatite Coatings on Titanium Alloys

2012 ◽  
Vol 533 ◽  
pp. 183-193 ◽  
Author(s):  
Adele Carradò
Keyword(s):  
Plasma Spraying ◽  
Sol Gel ◽  
Coating Properties ◽  
Bioactive Coatings ◽  
Bone Implant ◽  
Advantages And Disadvantages ◽  
Hydroxyapatite Coatings ◽  
Coating Methods ◽  
Plasma Sprayed ◽  
Plasma Spraying Process

Bioactive coatings are currently manufacturing using plasma-sprayed technique on metal implant surfaces in order to optimize bone-implant interactions. Nevertheless, some problems exist with coating process, e.g. poor interfacial adhesion, modification of coating properties, and the lack of an existing coating standard. In order to overcome some of the problems with the plasma-spraying process, researchers are investigating other experimental coating methods to enhance the adhesion and to control the coating properties. This paper will discuss the advantages and disadvantages of plasma spraying and the experimental coating processes as pulsed laser deposition as well as spin-coated sol-gel.

scholarly journals Ceramic on Metal Substrates Produced by Plasma Spraying for Thick Film Technology

1983 ◽  
Vol 10 (2-3) ◽  
pp. 143-150 ◽  
Author(s):  
Leszek Gołonka ◽  
Lech Pawłowski
Keyword(s):  
Stainless Steel ◽  
Thick Film ◽  
Plasma Spraying ◽  
Ceramic Coatings ◽  
Pure Alumina ◽  
Film Conductor ◽  
Steel Substrates ◽  
Resistance Stability ◽  
Sprayed Coatings ◽  
Plasma Spraying Process

The arc plasma spraying process was applied to obtain ceramic coatings on stainless steel substrates. The outer coatings were formed from pure alumina or alumina + 2 wt. % titania mixture. The nichrome intermediate coating was applied to increase adhesion of ceramic coating to stainless steel. The X-ray analysis, metallographic and SEM investigations of the sprayed coatings were also carried out. The effect of interaction of thick film conductor and resistor compositions was studied. Conductor ink P 202 PdAg and resistor ink DP 1321 were evaluated. The TCR, resistance stability were measured as a function of firing cycles. These parameters and the resistivity of sprayed alumina were compared with standard 96% alumina substrate characteristics.

Densification of Plasma Sprayed SOFC Electrolyte Layer Through Infiltration With Aqueous Nitrate Solution

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
A. Mirahmadi ◽  
K. Valefi
Keyword(s):  
Plasma Spraying ◽  
Gas Permeability ◽  
Nitrate Solution ◽  
Atmospheric Plasma ◽  
Electrolyte Layer ◽  
Gas Leakage ◽  
Condition Optimization ◽  
Aqueous Nitrate Solution ◽  
Plasma Sprayed ◽  
Plasma Spraying Process

Electrolyte of the solid oxide fuel cells deposited by atmospheric plasma spraying of 8 mol.% yttria (8YSZ), is not applicable in as sprayed condition. Optimization of the plasma spraying process parameters or application of feedstock powder, consisting of 8YSZ and 5wt.% alumina improves the problem of gas leakage through electrolyte layer, whereas provides no solution to the problem of electrodes short-circuiting. Infiltration of deposited electrolyte layer with a thin aqueous solution of nitrate precursors of 8YSZ for one time is a solution to high gas permeability; however three infiltration cycles are required to omit the risk of electrodes short circuiting thoroughly.

scholarly journals Microstructure and Wear Behaviors of Plasma-Sprayed MoAlB Ceramic Coating

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 474
Author(s):  
Fuzhu Li ◽  
Shengnan Sun ◽  
Yong Xu ◽  
Lihui Tian ◽  
Yun Wang ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Plasma Spraying ◽  
Ceramic Coating ◽  
Adhesive Wear ◽  
Ceramic Coatings ◽  
Atmospheric Plasma ◽  
Wear Rates ◽  
Arc Power ◽  
Plasma Sprayed

MoAlB ceramic coatings were prepared on a 316 steel surface by atmospheric plasma spraying with different arc power levels. The phase composition, microstructure and wear resistance of coatings against GCr15 and Si3N4 counterparts were studied. The MoAlB ceramic decomposed and was oxidized to form MoB and Al2O3 during plasma spraying. With the increase of the arc power, MoAlB experienced more decomposition, but the coatings became denser. When the arc power increased from 30 to 36 kW, the wear rates of coatings against GCr15 and Si3N4 balls reduced by 91% and 78%, respectively. The characterization of wear tracks shows that when against GCr15 counterparts, the main wear mechanisms are abrasive and adhesive wear, and when against Si3N4 counterparts, fatigue and abrasive wear are dominant. The refinement of wear resistance by increasing arc power can be attributed to the improvement of density and adhesive strength among splats.

Sign in / Sign up

Export Citation Format

Share Document