Oxidation of Ti–6Al–4V titanium alloy in air plasma

Abstract The intensification of space activities has led to an increase in orbital debris, making it crucial to study its behavior during atmospheric re-entry. This study focuses on the oxidation of Ti–6Al–4V alloy, a material used in the manufacture of pressurized fuel tanks for the aerospace industry. This alloy was exposed to an inductively coupled air plasma in the SOUPLIN set-up at the CORIA laboratory. Two operating points were studied: (1400 Pa, 4.6 MJ $$\hbox {kg}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mtext>kg</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ) and (4500 Pa, 7.3 MJ $$\hbox {kg}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mtext>kg</mml:mtext> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> ), for oxidation times of up to 120 s. Surface analyses (XRD, Raman spectroscopy, and SEM-EDS) reveal a predominance of $$\hbox {TiO}_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>TiO</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> rutile throughout the oxide layer, as well as the localized presence of $$\hbox {Al}_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>Al</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> $$\hbox {O}_{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>3</mml:mn> </mml:msub> </mml:math> and $$\hbox {Al}_{2}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>Al</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> $$\hbox {TiO}_{5}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>TiO</mml:mtext> <mml:mn>5</mml:mn> </mml:msub> </mml:math> at temperatures above $$1150\,^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>1150</mml:mn> <mml:mmultiscripts> <mml:mspace/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:mrow> </mml:math> C.