Magnesium WorkingGroup

November 9, 2006

Mr. Wm Troy TackChairman, Difficult Group

TAGNITE Protects the MD 500/600 and H-6 Little Bird

Little Bird has Approximately 9 WE43 Castings Which After 9 Years in Service are Showing No Signs of Corrosion (450-0 Record)

H-6 Little Bird Tail Rotor Gearbox Coated with Tagnite in Approximately 1997

HH--6 Little Bird Tail Rotor Gearbox 6 Little Bird Tail Rotor Gearbox Coated with Tagnite in Approximately Coated with Tagnite in Approximately 1997 1997

Magnesium GOTChA Chart• Goal

– Highly corrosion resistant magnesium alloys for Enhanced Readiness, Improved Performance and Lower Life Cycle Costs

• Objectives– A cast magnesium transmission gearbox with a 50% decease in

life-cycle cost compared to baseline ZE41A or AZ91C alloys – A magnesium casting alloy/attach point system that provides

galvanic performance superior to aluminum/steel– A magnesium alloy designed from first principles that mimics the

oxide structure of aluminum oxide (stainless magnesium)

• Technical Challenges

• Approaches

Technical Challenges: MagnesiumObjective 1

1. Support Fleet Readiness Center initiativesa) Implementation of existing technology (Tagnite, Rockhard, EV31)b) Cold spray technology “supersonic particle deposition” (field repair)c) Weight savings of total system must be considered with Mg (effect

on total vehicle)d) Better methods of NDI that do not require the coatings to be

removed2. Expand and transition current and future technology to DoD and DHS

a) Optimization integration of passive sacrificial systemsb) The lack of heat treatment knowledgec) Technological neural infusiond) Non metallic options around steel hardware

3. Data fusion to enable NAE forward positioning

A cast magnesium transmission gearbox with a 50% decrease in life-cycle cost compared to baseline ZE41A or AZ91C alloys

Technical Challenges: MagnesiumObjective 1 Condensed Approaches

1. Expand and transition current technology to DoD and DHS 2. Support Fleet Readiness Center cost wise readiness initiatives3. Data fusion to enable NAE forward positioning

Approaches

1. Navy roadmap platform implementation of existing technologies (Tagnite, Rockhard, EV31) to reduce corrosion issues near term

1. Forward positioning of new technologies2. Leveraging off of MANTECH project3. Corrosion based business case with ROI

A cast magnesium transmission gearbox with a 50% decrease in life-cycle cost compared to baseline ZE41A or AZ91C alloys

Technical Challenges: MagnesiumObjective 2

1. Innovative Protective Materials and Processesa) Mimic or better produce better galvanic isolation coatings on attaching

hardware (better than Cd)b) Steel alloy development for hardwarec) Sacrificial interface (non conductive gaskets for magnesium)d) Explosive forming

2. Implementation of Innovative Joint Designsa) Modeling of joints / fastening b) Improved joint designc) Dissimilar metal joints

3. Field Repaira) Sensor based health monitor

A magnesium casting alloy/attach point system that provides galvanic performance superior to aluminum/steel

Mount foot corrosionMount foot corrosionFretting not the sourceFretting not the source

for corrosion in this areafor corrosion in this area.

Technical Challenges: MagnesiumObjective 2 Condensed Approaches

1. Innovative Protective Materials and Processes2. Innovative Joint Design3. Field Repair

Approaches

1. Develop new coating/assembly approach1. Al plating2. Sn/Zn3. Sacrificial to Mg coating (e.g. paste for bolt)

2. Analytical joint design1. Inert or non conducting fasteners/bushing2. Impressed current systems3. Transition joint design

3. Health status monitoring

A magnesium casting alloy/attach point system that provides galvanic performance superior to aluminum/steel

Technical Challenges: MagnesiumObjective 3

1. Empirical characterization of Mg Alloysa) Microstructure, corrosion / mechanical propertiesb) Establish what is knownc) Processes – wrought, cast, heat treated, joints, surface modifications2. Introduce new alloy combinations / compositions and characterize3. Develop multi-scale models combining mechanical, corrosion and process

evolution models4. Produce pseudo-phase diagrams from models as basis for alloy design5. Alternative compounds as barrier layer i.e., nitrides, fluorides via alternate

processing such as heat treat

A magnesium alloy designed from first principles that mimics theoxidation behavior and mechanical properties of aluminum (stainless magnesium)

Technical Challenges: MagnesiumObjective 3 Condensed Approaches

1. Empirical characterization of Mg Alloysa) Microstructure, corrosion / mechanical propertiesb) Processes – wrought, cast, heat treated, joints, surface modifications2. Introduce new alloy combinations / compositions and characterize

Approaches

1. Novel alloy compositions1. Develop multi-scale models combining mechanical, corrosion and process

evolution models2. Produce pseudo-phase diagrams from models as basis for alloy design3. Thermodynamic modeling of alloying elements solubility and stable oxide

formation of binary, ternary, quaternary, and quintenary systems4. Extend solubility with RS and other techniques5. Statistical data pertaining to the microstructure6. Alternative compounds as barrier layer i.e., nitrides, fluorides via alternate

processing such as heat treat7. Nano-encapsulation of corrosion inhibitors8. Surface modification by ion implantation

2. Solidification modeling and mold metal interface behavior

A magnesium alloy designed from first principles that mimics theoxidation behavior and mechanical properties of aluminum (stainless magnesium)