Warm Spray Forming of Ti-6Al-4V

Warm spray (WS) is a modification of high-velocity oxy-fuel spraying, in which the temperature of the supersonic gas flow generated by the combustion of kerosene and oxygen is controlled by diluting the combustion flame with an inert gas such as nitrogen. The inert gas is injected into the mixing ch...

Full description

Saved in:
Bibliographic Details
Published inJournal of thermal spray technology Vol. 23; no. 1-2; pp. 197 - 212
Main Authors Molak, R. M., Araki, H., Watanabe, M., Katanoda, H., Ohno, N., Kuroda, S.
Format Journal Article
LanguageEnglish
Published Boston Springer US 2014
Subjects
Analytical Chemistry
Characterization and Evaluation of Materials
Chemistry and Materials Science
Corrosion and Coatings
Machines
Manufacturing
Materials Science
Peer Reviewed
Processes
Surfaces and Interfaces
Thin Films
Tribology
microstructure
warm spraying
porosity
oxygen content
Online AccessGet full text

Cover

More Information
Summary:Warm spray (WS) is a modification of high-velocity oxy-fuel spraying, in which the temperature of the supersonic gas flow generated by the combustion of kerosene and oxygen is controlled by diluting the combustion flame with an inert gas such as nitrogen. The inert gas is injected into the mixing chamber placed between the combustion chamber and the powder feed ports, thus the temperature of the propellant gas can be controlled from ~700 to 2,000 K. Since WS allows for higher particle temperatures in comparison to cold spray, warm sprayed particles are more softened upon impact, thus resulting in greater deformation facilitating the formation of shear instability for bonding. Recently, the combustion pressure of WS has been increased from 1 (low-pressure warm spray) to 4 MPa (high-pressure warm spray) in order to increase the velocity of sprayed particles. Effects of spray parameters on microstructure, mechanical properties, and splats formation of Ti-6Al-4V were systematically studied. Obtained coatings were examined by analyzing the coating cross-section images, microhardness as well as oxygen content. In addition, flattening ratio of splats was calculated as a function of nitrogen flow rate. It was found that the increased particle velocity caused by the increased combustion pressure had significant beneficial effects in terms of improving density and controlling the oxygen level in the sprayed Ti-6Al-4V coatings.
ISSN:1059-9630
1544-1016
DOI:10.1007/s11666-013-0024-7