Novel components by magnetron sputtering

Brookes, MG

Abstract

The advent of the closed field unbalanced magnetron sputtering (CFUBMS)
technique has provided a novel method for the production of ultra thick (above
50(jm) multilayer coatings, which form free standing foils when removed from the
substrate. Applications for this method range from the production of complex
metal/ceramic probe tips, to an alternative route for the production of
axisymmetric high precision-machined components, such as a bellows component
used in the production of uranium enrichment by the sponsors of this project,
Urenco (Capenhurst) Ltd. In this study the CFUBMS system was developed to
grow 50 Jim metallic and reactive compound multilayer foils. These foils were
tested for compatibility with uranium hexafluoride, UFe , a corrosive gas used in
the production of enriched uranium that is also in contact with the bellows
component. Secondly the CFUBMS system was developed to grow 50umaluminium/
aluminium oxide, Al/A^Os, aluminium-magnesium/ magnesium (Al-
Mg/Mg) and titanium/ titanium nitride (Ti/TiN) multilayer combinations. The
Al/A^Os and Ti/TiN foils were deposited using vertically opposed magnetrons,
with the A^Os and TiN layers produced by reactive sputtering. The Al-Mg/Mg
foils were deposited from commercial purity Al and Mg targets in a co-planar
configuration; conditions having been initially found that produced high hardness/
high strength amorphous Al-Mg alloy foils. All three multilayer systems benefit
mechanically from the combination of a high strength component (ALzOs, TiN and
Al-Mg) and a ductile component (Al, Ti, and Mg). Global conditions were found
that limited the stresses induced in these ultra thick coatings. Experimental arrays
were then constructed to investigate the effect of relative percentage volume fraction, substrate power and interlayer wavelength against the hardness, Young's
modulus, tensile strength, UTS and other mechanical properties of the foils. These
properties were determined using a modified Hounsfield tensometer. The study
found that when in tension, the interlayer wavelength has no effect upon the
tensile strength of the foil. However, as expected, tensile strength was strongly
dependent upon the relative percentage volume fraction of the high strength
component of the foil. The substrate power was found to have a limited influence
upon mechanical properties. Conditions were found that produced a tensile
strength-to-film density ratio of 238 MPa/ g cm" 3 , approaching that of tool steel.

Citation

Brookes, M. Novel components by magnetron sputtering. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Jul 30, 2021
• Award Date: Jan 1, 2005