Development of Plasma Spray Ceramic Coating for Industrial Application (original) (raw)
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Development & characterization of alumina coating by atmospheric plasma spraying
IOP conference series, 2018
Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi's L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results.
Plasma Sprayed Ceramic Coatings on Metallic Substrates
2002
Plasma spraying stands out as one of the most versatile and technologically sophisticated thermal technique in the field of surface engineering. Plasma sprayed ceramic coated components are used as wear resistant and as thermal barrier materials. The objective of the present work is to study the tribo/ogica/and thermal behaviour of different types of ceramic coatings. Zircon and aluminazircon coatings are tried out on mild steel substrates with (W-Al and high carbon iron) bond coat and also without bond coat. The coatings have been characterized by XRD, SEM, Wear, Grindability and Thermal Fatigue successfully. The presence of mullite in the top coat has been found to be reponsible for the superior high temperature properties of the coating.
Metallurgical and Materials Transactions A, 2003
Various ceramics and metals are being deposited as functional, protective, and near-homogenous coatings on engineering components by exploiting the characteristic properties of plasma medium. Such coatings are known to exhibit improved wear, thermal, and corrosion resistance. Although a lot of studies have been reported on coatings made up of a large number of metals and ceramic particles, hardly any effort is made to coat glass microspheres on metals despite their high hardness. In view of this, the present work was undertaken to study the preparation and characterization of a new class of coatings made up of borosilicate glass microspheres (BGM) premixed with micro-sized aluminum oxide (Al 2 O 3) in different proportions. Deposition of these BGM and BGM=Al 2 O 3 coatings is carried out at five different levels of torch input power. Coatings are characterized in terms of their thickness, hardness, adhesion strength, and porosity. The coatability of BGM and the BGM=Al 2 O 3 mixture on metallic substrates is assessed by evaluating the coating deposition efficiency. This work reveals that the torch input power and the Al 2 O 3 content in the feedstock affect the major coating characteristics, and premixing of Al 2 O 3 with BGM results in better coating properties.
Plasma transferred arc surface modification of atmospheric plasma sprayed ceramic coatings
Journal of Mechanical Science and Technology, 2016
In this study, a 90MnCrV8 steel surface was coated with aluminum oxide and chromium oxide powders through the Atmospheric plasma spray (APS) and Plasma transferred arc (PTA) methods. The effects of PTA surface melting on the microstructure, hardness, and wear behavior were investigated. The microstructures of plasma-sprayed and modified layers were characterized by Optical microscopy (OM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The dry-sliding wear properties of the samples were determined through the ball-on-disk wear test method. Voids, cracks, and nonhomogeneous regions were observed in the microstructure of the APS ceramic-coated surface. These microstructure defects were eliminated by the PTA welding process. The microhardness of the samples was increased. Significant reductions in wear rate were observed after the PTA surface modification. The wear resistance of ceramic coatings increased 7 to 12 times compared to that of the substrate material.
Development and implementation of plasma sprayed nanostructured ceramic coatings
Surface and Coatings Technology, 2001
A broad overview of the science and technology leading to the development and implementation of the first plasma sprayed nanostructured coating is described in this paper. Nanostructured alumina and titania powders were blended and reconstituted to a sprayable size. Thermal spray process diagnostics, modeling and Taguchi design of experiments were used to define the optimum plasma spray conditions to produce nanostructured alumina-titania coatings. It was found that the microstructure and properties of these coatings could be related to a critical process spray parameter (CPSP), defined as the gun power divided by the primary gas flow rate. Optimum properties were determined at intermediate values of CPSP. These conditions produce limited melting of the powder and retained nanostructure in the coatings. A broad range of mechanical properties of the nanostructured alumina-titania coatings was evaluated and compared to the Metco 130 commercial baseline. It was found that the nanostructured alumina-titania coatings exhibited superior wear resistance, adhesion, toughness and spallation resistance. The technology for plasma spraying these nanostructured coatings was transferred to the US Navy and one of their approved coating suppliers. They confirmed the superior properties of the nanostructured alumina-titania coatings and qualified them for use in a number of shipboard and submarine applications. ᮊ number of applications in the US Navy, this program provided a 'market pull' for this new technology.
Ceramics International, 2010
Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. Critical plasma spraying parameter (CPSP) is a key factor to control the quality of coatings. In this study, Alumina-Titania composite coatings in different compositions (Alumina-3 wt.% Titania, Alumina-13 wt.% Titania and Alumina-40 wt.% Titania) were prepared by 40 kW atmospheric plasma spray torch at three different CPSP conditions (833.33, 1000 and 1166.66) and their influence on coatings and plasma jet temperature were studied. The phase, microstructure, sliding and erosive wear rates, microhardness and porosity of the different Alumina-Titania composite coatings was investigated and correlated to CPSP conditions. The result shows that increasing CPSP increases the hardness and anti wear behavior of Alumina-Titania composite coatings except Alumina-40 wt% Titania coating.
Post-treatment of Plasma-Sprayed Amorphous Ceramic Coatings by Spark Plasma Sintering
Journal of Thermal Spray Technology, 2015
Alumina-zirconia ceramic material has been plasma sprayed using a water-stabilized plasma torch to produce free standing coatings. The as-sprayed coatings have very low porosity and are mostly amorphous. The amorphous material crystallizes at temperatures above 900°C. A spark plasma sintering apparatus has been used to heat the as-sprayed samples to temperatures above 900°C to induce crystallization, while at the same time, a uniaxial pressure of 80 MPa has been applied to their surface. After such post-treatment, the ceramic samples are crystalline and have very low open porosity. The posttreated material exhibits high hardness and significantly increased flexural strength. The post-treated samples have a microstructure that is best described as nanocomposite with the very small crystallites embedded in an amorphous matrix.
Research on engineering structures & materials, 2019
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Process-microstructure-property relationships in controlled atmosphere plasma spraying of ceramics
2004
Thermal plasma spray processes with their various operating parameters can be considered a flexible technique to carry out appropriate manufacturing of advanced ceramics coatings. This paper reports on investigations dealing with plasma spraying of several ceramics powders (hydroxyapatite, Al O -TiO , Al O , ZrO -Y O (YSZ) and Cr O ) with suitable parameters using a 2 3 2 2 3 2 2 3 2 3 'controlled atmosphere plasma spraying' (CAPS) system. High-pressure plasma spraying, air plasma spraying and inert plasma spraying modes were applied in order to obtain suitable microstructures in the coatings. The investigation of microstructures and phase compositions showed that high-pressure in the CAPS chamber leads to sufficient heating of the powder and have a promising coating quality. ᮊ