Novel components by magnetron sputtering

The advent of the closed field unbalanced magnetron sputtering (CFUBMS)technique has provided a novel method for the production of ultra thick (above50(jm) multilayer coatings, which form free standing foils when removed from thesubstrate. Applications for this method range from the production of complexmetal/ceramic probe tips, to an alternative route for the production ofaxisymmetric high precision-machined components, such as a bellows componentused in the production of uranium enrichment by the sponsors of this project,Urenco (Capenhurst) Ltd. In this study the CFUBMS system was developed togrow 50 Jim metallic and reactive compound multilayer foils. These foils weretested for compatibility with uranium hexafluoride, UFe , a corrosive gas used inthe production of enriched uranium that is also in contact with the bellowscomponent. 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. TheAl/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/Mgfoils were deposited from commercial purity Al and Mg targets in a co-planarconfiguration; conditions having been initially found that produced high hardness/high strength amorphous Al-Mg alloy foils. All three multilayer systems benefitmechanically from the combination of a high strength component (ALzOs, TiN andAl-Mg) and a ductile component (Al, Ti, and Mg). Global conditions were foundthat limited the stresses induced in these ultra thick coatings. Experimental arrayswere then constructed to investigate the effect of relative percentage volume fraction, substrate power and interlayer wavelength against the hardness, Young'smodulus, tensile strength, UTS and other mechanical properties of the foils. Theseproperties were determined using a modified Hounsfield tensometer. The studyfound that when in tension, the interlayer wavelength has no effect upon thetensile strength of the foil. However, as expected, tensile strength was stronglydependent upon the relative percentage volume fraction of the high strengthcomponent of the foil. The substrate power was found to have a limited influenceupon mechanical properties. Conditions were found that produced a tensilestrength-to-film density ratio of 238 MPa/ g cm" 3 , approaching that of tool steel.

Level dc:type.qualificationlevel

Doctoral (Level 8)

Year dc:date.issued

2005

Author dc:creator

• Brookes, MG

Language dc:language

en

Identifier

oai:salford-repository.worktribe.com:1338062

OAI identifier oai:identifier

oai:salford-repository.worktribe.com:1338062