Engineering Department ENEN R&D on Advanced Materials: Status and Future Outlook N. Mariani, A....

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N. Mariani – CERN 1

R&D on Advanced Materials: Status and Future Outlook

N. Mariani, A. Bertarelli, F. Carra, A. Dallocchio, E. Krzyzak

1st Meeting AdColMat Working Group19.08.2013

19 August 2013

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Outline

19 August 2013

Review of materials adopted in LHC collimators

Metal-matrix composites under development

Figures of merit

Materials ranking

Conclusions

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Materials for LHC collimators


CFC (AC-150-K)

Graphite

Copper OFE

Inermet180

Molybdenum

Glidcop Al-15

Copper-Diamond

Molybdenum-Copper-Diamond

Silver-Diamond

Molybdenum-Graphite

19 August 2013

Already used in collimators active jaw

Already used for collimators, but not in the active jaw

Under R&D: never used for collimators

TCP/TCS

TCDI

TCLP

TCT

-

-

TCP/TCS

TCP/TCS

TCP/TCS

TCP/TCS

Type Material

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N. Mariani – CERN 419 August 2013

CFC and Graphite stand out as to thermo-mechanical performances. Adversely outweighed by poor electrical conductivity, expected degradation under irradiation.

High-Z metals and alloys (Cu, Mo, Glidcop, Inermet) possess very good electrical properties. High density adversely affects their thermal stability and accident robustness.

R&D focused on Metal Matrix Composites (MMC) with Diamond or Graphite reinforcements: goal is to combine the properties of Diamond and Graphite (high k, low r and low CTE) with those of Metals (strength, g , …).

Powder Metallurgy production techniques including: Rapid Hot Pressing (RHP), Spark Plasma Sintering (SPS) and Liquid Infiltration.

Graphite Punch

Powders

Graphite Die

Vacuum Chamber

Pressure

Pressure

DC Current(continuous or pulsed)

Materials for LHC collimators

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• Materials investigated are Copper-Diamond (Cu-CD), Molybdenum-Diamond (Mo-CD), Silver-Diamond (Ag-CD), Molybdenum-Graphite (Mo-Gr)

• Most promising materials are Cu-CD and Mo-Gr.

• Ag-CD and Mo-CD are, by now, sidelined as they are limited by (relatively) low melting temperature (Ag-CD) and insufficient toughness (Mo-CD).

• Mo-Gr is particularly appealing as it can be cladded with a Mo layer dramatically increasing electrical conductivity …

Cu-CD

Mo-CD

Ag-CD

Mo-Gr

19 August 2013 N. Mariani – CERN 5

Metal-matrix composites

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BC “bridge” stuck on CD surface.No CD graphitization

• Good thermal (~490 W/mK) and electrical conductivity (~12.6 MS/m).

• No diamond degradation (in reducing atmosphere graphitisation starts at ~ 1300 °C)

• No direct interface between Cu and CD (lack of affinity). Partial bonding bridging assured by Boron Carbides limits mechanical strength (~120 MPa).

• Cu low melting point (1083 °C) may limit Cu-CD applications for highly energetic accidents.

• CTE increases significantly with T due to high Cu content (from ~6 ppmK-1 at RT up to ~12 ppmK-1 at 900 °C)

150 x 150 x 4mm3

Developed by RHP-Technology (Austria) inside EuCard WP8.2 activities.


Copper-Diamond

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Low CTE Low Density High Thermal Conductivity (grade-dependent) Very High Service Temperatures High Shockwave Damping

• Very high melting point (2500+C)

• Low Density

• Outstanding Thermal Conductivity (700+ W/mK). 180% Cu, 170% Ag !!!

• No reinforcement degradation

• Possibility to reach excellent electrical conductivity by Mo cladding.

• Mechanical strength to be improved …

Co-developed by CERN EN/MME and Brevetti Bizz (Italy).

• R&D program still going on to further improve physical properties, particularly mechanical strength


Molybdenum-Graphite

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Molybdenum – Graphite core with pure Mo cladding having tailored thickness.

Excellent adhesion of Mo cladding thanks to carbide interface. Sandwich structure drastically increases electrical conductivity:

Simulations foresee a factor 10 Collimator impedance reduction!

Core: 1 MS/m

Mo Coating: 18 MS/m

Carbide layer: 1.5 MS/m

N. Mounet et al., Impedance @ 2013 Collimation Review, May 2013

Wish to install a full collimator with Mo-coated jaw in LHC …

New challenge: turn material R&D into a suitably industrialized product in short time…

… and each new material should be validated by accident simulations and tests (HiRadMat)19 August 2013 N. Mariani – CERN 8

Molybdenum-Graphite with Mo cladding

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Objectives have been turned into a set of Figures of Merit to assess relevant materials

• Reduce RF impedanceMaximize Electrical Conductivity

• Maintain/improve jaw geometrical stability in nominal conditionsMaximize the stability indicator Steady-state Stability Normalized Index (SSNI)

• Maintain Phase I robustness in accidental scenariiMaximize the robustness indicator Transient Thermal Shock Normalized Index

(TSNI)

• Improve cleaning efficiency (absorption rate)Increase Radiation and nuclear Interaction Lengths, i.e. Atomic Number

• Improve maximum operational temperatureIncrease Melting Temperature.

19 August 2013

kra

R(1-n)cpvEa

Z

Tm

g

Additional “standard” requirements include ...• Radiation Hardness, UHV Compatibility, Industrial producibility of large components, Possibility

to machine, braze, join, coat ..., Toughness, Cost …

Objectives for material R&D

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Material C-C Graphite Inermet MoCopper

(annealed)Glidcop ® Cu-CD Mo-Gr

Density [g/cm3] 1.65 1.85 18 10.22 8.9 8.9 ~5.4 2.8

Atomic Number (Z) 6 6 74 42 29 29 ~11.4 8.3

Tm [°C] 3650 3650 1083 2623 1083 1083 ~1083 ~2520

SSNI [kWm2/kg] 24 15.7 1.2 2.7 2.6 2.5

13.1 ÷ 15.3

85*

TSNI [kJ/kg] 793 608 30.8 40 7.9 37 44 ÷ 51 195*

Electrical Conductivity

[MS/m]0.14 0.05 8.4 19.2 96.2 53.8 ~12.6 1 ÷ 18 **


Materials Ranking & Discussion

* Estimated values** with Mo coatingworse better

Are figures of merit considered until now still valid or new requirements should be considered?

For actual figures of merit, Mo-Gr (eventually Mo-coated) seems the best solution for future LHC secondary collimators.

Other refractory metals like Molybdenum could be also of interest for tertiary collimators instead of Tungsten alloy. Need for Sixtrack/Fluka simulations to confirm effective cleaning efficiency of Mo instead of W alloy.

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N. Mariani – CERN 1119 August 2013

Conclusions Mo-Gr (eventually Mo-coated) looks like the best choice for future primary and

secondary collimators.

It is recommended to prosecute with the development, industrialization and characterization of MoGr.

Additional in-house testing equipment to be acquired (Laser Flash, Dilatometer, …)

Proposal for possible time-schedule: Oct-Nov ‘13: Sintering furnace optimization.

End of ‘13: Production of a representative “large” MoGr piece (~140x40x20 mm).

Dec ‘13: Additional samples for radiation hardness tests in BNL.

Early ‘14: Development and manufacturing of Mo-cladded MoGr.

Nov ‘13 – Jun ‘14: Detailed characterization, including:

Thermal properties up to high T (dilatometry, calorimetry and thermal diffusivity)

Electrical properties (electrical conductivity, dedicated RF tests, …)

Static and Dynamic mechanical properties,

Radiation damage resistance.

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Thank you for your attention!

Questions?

19 August 2013

Engineering Department ENEN R&D on Advanced Materials: Status and Future Outlook N. Mariani, A....

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