Titanium Contact MechanicsIncreasing use of titanium led to the need to specifically investigate wear mechanisms, establish test methods and provide solutions.Basic wear mechanism simulated by simple hammer wear test and like versus like solutions introduced in the 1960s onwards which offered low wear with intermediate friction. Continued developments to introduce low friction coatings appropriate to fan blade root fixings in the 1980s. With the increased complexity of modern designs, dedicated rigs are used to understand geometry and service loadings.

Fan Blade Low Friction Coatings

Fan Blade Low Friction CoatingsCombined HCF/LCF cycles Representative of engine conditions (Load, frequency etc) Fretting wear Representative edge of bedding contact pressures / stresses Representative friction conditions

Low loads, sliding conditions Point contact Unrepresentative of engine conditions Ranking testButton on Plate RigBi-axial Rig

Advanced Sub-Element Testing Typical blade + Disc FE sector modelFan Blade sub-element test: captures geometry, surface condition and loading. Computer control: combined load spectra as in engineLow friction coatings give low transmitted load

Composite Plating Disc Fin Seal CoatingsAbrasive coatings used to control the degree of frictional heating during contact on disc fin seals.Works by cutting a clean path in the abradable liner.Rig testing showed that the application of the abrasive system significantly reduced the degree of heat generated during rubs

Highly Instrumented Abradability FacilityComparison of un-tipped with c-BN tipped nickel fins

Increases in TET associated with progress in turbine materials and technology

Turbine Blade Cooling and Coating Technology

Alloying Additions into Turbine Blade AlloysSource: R C Reed, Superalloys: Fundamentals and Applications, Cambridge University Press, 2005

TBC Bondcoat Design

Ability to establish a pure alumina scale which exhibits a low growth rateImproved phase stability to reduce the influence of damaging substrate elementsBondcoat capable of replenishing the aluminium that is lost to alumina formation Bondcoat compatible with single crystal alloys and low parasitic weightNo impact on the thermal mechanical fatigue properties of the TBC system Strength at high temperature to limit creep deformationNo formation of SRZs on third and fourth generation alloys

Potential for a System Design Optimisation Approach for Turbine Hardware

ModellingCalculate process parameters and microstructureCalculate mechanical propertiesImprove and optimiseDefine the material and processRequirementsSolution

Manipulating Atoms to Make Materials Governments, corporations, and venture capitalists spent more than $8.6 billion worldwide on nanotechnology R&D in 2004. NanoMaterialsNanograined alloysStructural materialsNanoreinforced polymersCoatingsTribologyHard Low frictionThermalFire Retardant TBCAnticorrosion Low surface energy Smart Materials-AnticokingcoatingsThe United States has appropriated over $4 billion for nanotechnology R&D since 2000

Titanium metal matrix compositesConventionaldisk & bladesBlisk - up to 30% weight savingBling - Ti MMC - up to 70% weight saving

Systems Design - Making the DifferenceSummary

Requirement for highly engineered solutionsEffective integration of materials and manufacturing technology.Continuity of funding/teamsTaking time out of the material development processExtensive use of modelling/simulation to expedite material and process developmentDemonstrator opportunitiesMaintenance of key relationships with University network and throughput of skills

FromTo Evolving design requirements Defined design requirements Extensive development trials Controlled parameters Product performance assessed by build and test Product performance modelled and simulated Empirical understanding Data driven environment Performance and producibility problems fixed after product in use Designed for robust performance and producibility Quality tested in Quality designed in

Turbines have to survive in conditions hotter than the melting temperature of the metals. This is made possible by passing cooler air through them. However, this air is often over 600C so is still not exactly cold.The cooling air absorbs some of the heat as it passes through the blade and is then exhausted through holes in the surface to provide an additional protective blanket.

Makes the point that RR designed a new class of bondcosts to ensure performance characteristics needed to match component life.