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Microstructure characterization of spray forming of Fe-based Amorfizable alloy

Grant number: 12/22787-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): March 01, 2013
Effective date (End): February 28, 2014
Field of knowledge:Engineering - Materials and Metallurgical Engineering
Principal Investigator:Conrado Ramos Moreira Afonso
Grantee:Maurício Junior da Silva Ananias
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The use of amorphous Fe-based alloys has been explored in order to enlarge the size of the amorphous products obtained, also expanding the range of technological applications. The microstructure condition of these alloys to display these exceptional characteristics of high hardness, wear and corrosion resistance is partially amorphous, this means that the cooling rate to achieve the nanocrystalline state is not as high as that for achieving the condition of 100% amorphous. One posible route to obtain Fe-based amorphous and glassy alloys is the spray forming (SF) process where the cooling rate (102 - 105 K / s) is not as high as the process of "melt-spinning" (106 K / s) used to produce ribbons of micrometric thickness. An alternative to these two routes would be the realization of a surface coating (hundreds of microns to millimeters thick) of the part (substrate) subjected to wear with a material which promotes a significant increase in wear resistance of base material (mild steel). The amorphous Fe-based alloys is presented as an alternative with good perspectives for obtaining coatings with high wear resistance and good adhesion to steel substrates for common structural applications in oil and gas industry. The objective of this research project is to contribute to the development of coatings technology using amorphous Fe-based alloys, specifically based in high Cr white cast irons with B and Nb additions [Fe65Cr17Mo2C14Si1Cu1]100-xBx (x= 5, 10 e 15%at) e [Fe65Cr10Mo1C14Si1]100-x-yNbyBx (y = 4% e x= 5, 10 e 15%) (%at) alloys, to obtain steel coatings in order to increase wear resistance. In this way, the proposed methodology includes the processing of the alloy by spray forming (SF) with two objectives: i) to obtain coatings (mm to mm thick) with amorphous structure deposited on steel substrates and ii) the production micrometric powders for the subsequent obtaining of micrometric coatings through the thermal spraying process. The main focus of this research project is the characterization and evaluation of the wear resistance of deposits and coatings produced by SF, the atomized powders ("overspray") and the interface of coating with base metal (mild steel) in the samples obtained from the thermal spraying of overspray powder, as a byproduct from the spray forming.