Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
ALUMINA COATINGS ON STAINLESS STEEL AND GRAPHITE SUBSTRATES OBTAINED BY PLASMA SPRAY PROCESS
Submission Author:
Roberson Silva , SP
Co-Authors:
Roberson Silva, Tiago Campos, FELIPE MIRANDA, Homero Maciel, GILBERTO PETRACONI
Presenter: Roberson Silva
doi://10.26678/ABCM.COBEM2021.COB2021-1176
Abstract
Aeronautical and aerospace applications for devices such as turbines and rocket engines require resistance to extreme environmental conditions for some materials, which are used. Metallic materials resistant to oxidation, when used in extreme environments such as turbine combustion chambers, at high temperatures, may be more susceptible to ablation and chemical attacks. Graphite, which is commonly used in rocket engine throats and nozzles, has thermal and mechanical properties that remain at high temperatures, but oxidation can limit its applicability. Refractory ceramics are known for their resistance to chemical and thermal attack environments. A ceramic coating can be used as a way to complement the properties of these materials, protecting them from oxidative and ablative processes at high temperature. Thus, the objective of this work is to study the ceramic coating on stainless steel and graphite substrates by using a thermal spray plasma process with ceramic powder. This work presents the experimental studies performed by using a tornado-type thermal plasma torch, working at a power of 30 kW, at 105 A. In this condition, the hot gas plasma generated at 5200 ºC melt the alumina powder of 70-200 mesh, which is sprayed on the substrate. The spraying of the powder in the plasma jet was performed by a vibrating powder feeder with powder flow rate at 5-10 g/min and flow rate of carrying gas at 5 SLPM. The powder melted in the thermal spray was deposited on substrates of AISI 304 stainless steel and on graphite. The application of the coating on the substrates was performed in two ways, i.e., fixed and dynamic. The fixed application was performed with the substrate positioned at an optimized distance on the axis of the spray jet. The dynamic application was performed by means of an automatic device, developed to apply rotation and horizontal movement to the substrates, performing an area sweep with the jet on its surface to obtain a homogeneous coating. The formation of a uniform alumina coating on both stainless steel and graphite was observe by SEM and EDS, showing that this technique can be used to obtain refractory coatings on these materials.
Keywords
thermal spray, plasma spray, alumina coating, Powder, aerospace
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