O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 1 Chamber Materials Progress Round Robin Materials Refractory Armored Ferritic Helium Management J. Blanchard 1, C. Blue, 5 A. Federov 2, N. Ghoniem 3, S. Gilliam 4, S. Gidcumb 4, J. D. Hunn 5, S. O’Dell 6, B. Patnaik 4, N. Parikh 4, G. R. Romanoski 5, S. Sharafat 3, L. Snead 5, T. Van Veen 2 Delft Institute 2, ORNL 5, PPI 6, UCLA 3, UW 1, UNC 4 Presented at the High Average Laser Program Workshop Georgia Institute of Technology February 5-6, 2004

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 2 I still think everyone is getting what they need Round Robin Materials

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 3 Facility Improvements : Implantation/Anneal Upper annealing temperature increased to 2500°C. System now fully automated. Moving towards round-the-clock operation (8 x 10 4 irr/anneal/day)

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 4 Facility Improvements : IR Thermal Fatigue Facility has been used for interfacial fatigue of W/LAF Previously 20 MW/m2 (time average), 20 msec pulse, 10 Hz, 10 cm 2

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 5 Facility Improvements : IR Thermal Fatigue Now capable of 100 MW/m2 (time average), 2 msec pulse, 10 Hz, 5 cm 2 Phase 1 goal 1000 MW/m2 (time average), 0.1 msec pulse, 10 cm 2

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 6 Development of Armor Fabrication process and repair He management Mech. & thermal fatigue testing “ Engineered Structures ” Ablation Underlying Structure bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness detailed structural analysiis thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer/coating Development of W/LAF : Phase 1 Effort and Milestones ! ! ! ! } ! scopingoptimizationscaling ! ! scoping & modelingoptimization !!

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 7 Phase I : Helium Management Objective: To understand parameters controlling helium diffusion in tungsten to develop armor with near zero helium retention. Approach: - Experimentally determine whether potential solutions exists. 04 Milestone. - Get diffusion coefficients of ideal materials for modeling. 04 Milestone - Define effect of microstructure, implantation, and anneal conditions, on retention of helium. - Carry out diffusion modeling and determine if “engineered” structures are required. 04 Milestone. -Phase I Goal : Perform long-term (>10 5 cycles, >10 21 He/m2) IFE relevant implantation on candidate W/LAF ! ! !

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 8 1x10 21 (He/m 2 ) 1.5 MeV He implanted polycrystalline W : 850  C,flash annealed to 2000  C. Spallation Problem 2x10 21 (He/m 2 ) 5x10 21 (He/m 2 )10x10 21 (He/m 2 )

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 9 Comparison of Polycrystalline, Single Crystal, and CVD W (a) 850°C implant, as-implanted  At 5 x He/m 2 single crystal, polycrystalline, and CVD tungsten exhibited comparable helium retention.  Before and after annealing the proton yields collected by NRA were the same within a few percent. (b) 850°C implant, 2000°C anneal

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 10 Step Implantations What happens when we approach IFE implant/anneal cycle? 1.3 MeV He implantation Poly-X tungsten target Resistive Heating A series of implantation to He/m 2 for 1, 10, 100 and 1000 cycles has been completed for both single X and powder processed W.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 11 Proton spectra for polycrystalline (a) and single crystal (b) tungsten implanted at 850  C and flash annealed at 2000  C in 1, 10, 100, and 1000 cycles to reach a total dose of He/m 2. The sample implanted with the total dose in one step was analyzed before and after the 2000  C anneal. (a) (b) Step Implantations What happens when we approach IFE implant/anneal cycle?  In both single and polycrystalline tungsten the helium dose per cycle affects retention significantly.  Single crystal releases helium more easily than polycrystalline.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 12 Effect of Annealing Temperature on Retention: Single-X W  Single crystal annealed at 2500°C shows significantly less helium retention than the 2000°C anneal.  Temperature plays a significant role when comparing the step sizes and the two different annealing temperatures.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY Milestone : Go/No Go on helium management. Is there the potential to defeat the spallation problem? Where are we ??? ! Even though we have an extremely high fluence of helium, due to the small implant “packets” and the extreme annealing associated with the fusion event, difficult to diffuse helium clusters are not formed in single crystal W and the helium is released. We’re good to Go? What is now needed: - Determine effective diffusivity needed for modeling. - Determine the annealing kinetics and carry out rapid implant/anneal experiments.(current experiments have long anneal) - Continue to define role of microstructure on retention. (as seen from the polyX W results, real structures may spall.) - Carry out high-cycle implantations (10 5 anneal/implantation) - Include effects of hydrogen.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 14 Phase I : Fabrication Process and Repair Tungsten Armored Low Activation Ferritic Steel Objective: select and optimize methods for bonding tungsten to LAF steel and assess the integrity of these coatings under HAPL- relevant thermal fatigue conditions. Approach: -Evaluate methods for applying tungsten coatings to substrates. Fabricate and study adherence and thermal stability. Is there a viable material? FY-04 Milestone. -Given W thickness, model interface fatigue stresses and fatigue crack growth performance of underlying LAF. FY-04 Milestone. -Screen coupon coatings using thermal fatigue facility. Select candidate monolithic armor system or move to “engineered structure.” FY-05 Milestone. -Phase 1 Endpoint : Perform scaling studies and carry out prototype thermal fatigue at IFE relevant conditions: > 10 5 cycles, <100  s pulse width > 10 3 MW/m 2 (during pulse) > 10 cm 2 sample face ! ! !

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 15 Viable W/Low Activation Ferritic? Screening material processing options. Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD Processing Method Method of Screening Thermal stability of interface Thermal Fatigue Interfacial Strength

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 16 Viable W/Low Activation Ferritic? Screening material processing options. Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD Processing Method IR processing: 2350W/cm 2 (Flash: 6sec) Initial runs showed promise, though somewhat non-uniform surface. Considered back-up.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 17 Viable W/Low Activation Ferritic? Screening material processing options. Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD Processing Method Initial runs showed promise: high-thermal conductivity and good uniformity. Cracks were present due to CTE mismatch and phase change. Considered back-up.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 18 Vacuum Plasma Spraying of Tungsten Powders Coating ConditionsPost-Spray Treatment Feed Gas Argon / Hydrogen 100 – 300 torr NoneH anneal 800C/4h H anneal + HIP 800C/4h/30ksi 100µm tungsten only (-45/+20µm) 600ºC Preheat – Mach samples 100  m tungsten only (-45/+20µm) No Preheat – Mach 1 5 samples 100  m tungsten only (-45/+20µm) 600  C Preheat - Mach 1 5 samples 200μm-thick graded layer of 50% steel blended with 50% tungsten plus 100  m-thick tungsten top coat (-45/+20μm). No preheat –Mach 1 5 samples 300µm-thick tungsten only (-45/+20μm) No preheat -Mach 1 5 samples 100µm-thick tungsten only (-20µm) No Preheat - Mach 1 5 samples VPS coatings were produced at Plasma Processes of Huntsville, Alabama Preliminary VPS coating looked promising. An array of coatings were then ordered for evaluation

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 19 VPS Tungsten on F82H Steel : Post-Spray Treatments  Post-spray hydrogen anneal at 800°C/4hrs provides stress relief. Annealing limited to 800°C due to steel substrate. Temps of 1700°C required for sintering VPS W coatings may be achieved with IR processing.  Post spray hot isostatic pressing 800°C / 35ksi achieved some densification of the coating (enhancing thermal conductivity.) As Sprayed Hot Isostatic Pressing

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 20 Microstructural stability of F82H will limit the interface temperature to under 900C  Coarsening of carbides above 800C and dissolution around 900C will degrade mechanical properties.  The alpha – gamma - alpha phase transformation will impart large strains at the interface.  A critical thickness of tungsten will be required to dissipate the heat pulses to maintain the interface in an acceptable temperature regime.  Furnace cycling experiments will be performed to better understand interface stability.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 21 VPS coatings were produced with W/steel intermediate layer to minimize thermal strain mismatch.  Blended constituents will result in an average thermal expansion.  The intermediate layer is rather heterogeneous due to the coarse size of available steel powder.  Significant porosity will impart compliance to the coating (but reduce conductivity.)

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY Milestone : Go/No Go on tungsten armor. Is there a viable material? ! Where are we ??? All coating studied had promise. Vacuum plasma sprayed W on F82H low activation ferritic is being focused on. Previous thermal fatigue showed promise. Long-term stability of interface is still required, but it looks like a Go. IR Thermal Fatigue Facility Rep rate: 10Hz, 1000 cycles Max. flux: 20.9MW/m 2 (20ms) Min. flux: 0.5MW/m 2 (80ms) Substrate temp. (bottom): 600 ºC

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 23 Questions ???

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 24 Moving Towards Phase II Materials Development February 6, 2004 Georgia Institute of Technology

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 25 Development of Armor Fabrication process and repair He management Mech. & thermal fatigue testing “ Engineered Structures ” Ablation Underlying Structure bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness detailed structural analysiis thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer/coating Development of W/LAF : Phase 1 Effort and Milestones ! ! ! ! } ! scopingoptimizationscaling ! ! scoping & modelingoptimization !!

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 26 HAPL Program Plan

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 27 At the end of Phase 1 (constant dollars), assuming that a flat-plate or simple “engineered” armored structure appears workable, we will have materials ready for serious development. --there is a concern that significant time at the beginning of Phase 2 will be eaten optimizing a material, delaying the time consuming effort of property testing and proof testing. At what point do we need irradiation data? There is fair data on LAF, but no data on its fatigue properties. The behavior of this tungsten, and the W/LAF interface is essentially not known. Can we wait until the end of Phase 2 for bad news here? As we move towards Phase 2, the issue of fatigue will require seriously studied. High-cycle thermomechanical fatigue of prototype size component will be necessary. As this is very time consuming, any delay in delivery of the candidate armor will lengthen Phase 2. Leading up to Phase 2 we should include in the MWG a specialist in design of vibrating structures and one on NDE. Code qualifications may bite us. Following Rene’s logic, we need qualified primary candidate at least two years prior to ETF. Is there enough time?

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 28

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 29

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 30 Computer LabVIEW DAQ Card Power Controller Cup Control Infrared Thermometer Sample Controls implant dose Reads sample temperature Controls sample temperature Current Integrator (Faraday Cup) Current Integrator (BPM) Automation Hardware Schematic

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 31 Thermal Fatigue Test Plan Test Conditions Test Articlespecimen Mock-ups Area Tested (cm 2 ) Maximum Flux (MW/m 2 ) 2130 Pulse Width (ms) Rep Rate (Hz)10 ? Duration (cycles)1K10K to 100K Substrate Temperature © 600°C 600°C LAF 800°C ODS 600°C LAF DiagnosticsBack face T Surface T Back Face T Surface T Flux