Surface Coatings & Tests for LARP Coil Endparts Task Force D.W.Cheng LBNL February 24, 2012

Overview Coating candidates How do we qualify these candidates? –Environmental conditions –Battery of Tests –Sample coupon design Initial Plasma Spray Results Summary and Status 2/24/12 D.W.Cheng 2

Coating Candidates Plasma Spray (Aluminum Oxide) Not specifically covered in here: –Spray-on coatings (Cerakote®) –Surface conversion (micro-arc oxidation) –Vapor deposition 2/24/12 D.W.Cheng 3

Plasma Spray Details Sulzer Metco powders (Aluminum Oxide) Bond layer options –Without bond layer LBNL experience in D20, etc. –With NiCr (80%/20%) bond layer CERN experience in SMC coils –With Al-clad NiCr (6%/94%) bond layer Vendor indicates that the Aluminum component undergoes an “exothermic reaction at application” that helps the Al 2 O 3 adhere better 2/24/12 D.W.Cheng 4

Overview Coating candidates How do we qualify these candidates? –Environmental conditions –Battery of Tests –Sample coupon design Initial Plasma Spray Results Summary and Status 2/24/12 D.W.Cheng 5

Environmental Conditions Known conditions: –Heat Treatment to ~650+ C –Epoxy impregnation –Cryogenic temperatures (77 K and below) –Insulation compatibility –Conductor compatibility Possible conditions: –Parts may come into direct contact with cable (broken insulation, etc.); must provide electrical isolation 2/24/12 D.W.Cheng 6

Battery of Tests Electrical hipot to >1000V –Uses the same equipment that we hipot coils with Material Compatibility (HT at ~665 C in Argon) –In contact with Conductor and Insulation materials Thermal Stability –High-temperature & Cryogenic (77K) excursions –Post-cycle adhesion testing Thickness (QA) Metallography 2/24/12 D.W.Cheng 7

Sample Coupon Design Basic Coupon: 2” squares, 1/8” thick –Ti 6Al4V –Stainless 304, Stainless 316 –(Other materials can also be used) These samples can be used for all tests –Electrical hipot tests –Thermal and material compatibility tests –Adhesion tests –Metallography And we can also use actual part geometries 2/24/12 D.W.Cheng 8

Sample Coupon Design 2/24/12 D.W.Cheng 9

Other Samples We can also use actual part geometries 2/24/12 D.W.Cheng 10

Electrical Hipot System Has adjustable spring-loaded pressure Has ¼” ball bearing contact Uses existing hipot electronics 2/24/12 D.W.Cheng 11

Material Compatibility Testing Tube furnace (Argon atmosphere) –Heat treatment schedule (abridged HQ HT cycle): 210 C for 24 hours 400 C for 24 hours 665 C for 48 hours 50 C/hour ramps between temperatures. Samples placed in contact with Insulation (S2-glass in this case) CTD Matrix-cured S2-glass and Nextel AF-10 Cable 2/24/12 D.W.Cheng 12

Thermal Stability Tests Post-HT tests –Cryogenic (77K) cooldown –Post HT Hipot –Post HT Adhesion tests DeFelsko PosiTest AT tester (conforms to ASTM D4541/D7234) Can be compared with pre-HT test results 2/24/12 D.W.Cheng 13

Cryogenic Dunking Standard 77K Cooldown test 2/24/12 D.W.Cheng 14

Thickness Testing DeFelsko Positector 6000 –Uses magnetic/eddy-current principles to measure coating thicknesses on ferrous and non-ferrous base materials Can be used for regular QA 2/24/12 D.W.Cheng 15

Overview Coating candidates How do we qualify these candidates? –Environmental conditions –Battery of Tests –Sample coupon design Initial Plasma Spray Results Summary and Status 2/24/12 D.W.Cheng 16

First Plasma-Sprayed Sample Process Sample: –HQ endshoe (old design), SS 304 Surface treatment: –Plasma Spray Al 2 O 3, no bond layer Hipot Test (pre-HT) Metallography Heat Treat –In contact with Matrix-cured Nextel Fabric 77K Cooldown Test Hipot Test (Post-HT) 2/24/12 D.W.Cheng 17

Initial Results of Plasma-Spray Test Hipot Test (pre-HT) – >1800V first attempt – >1100V subsequent attempts (same point) Metallography (see next slide) Heat Treated In contact with Matrix-cured Nextel Fabric –No visible surface reaction (although glass appeared black—but not conductive) 77K Cooldown Test –No additional flaking/chipping observed after two cycles Post-HT Hipot Test (see following slide) 2/24/12 D.W.Cheng 18

Metallography 2/24/12 D.W.Cheng  m 183  m 134  m 122  m 73  m0  m 85  m 15 mm D.R. Dietderich Feb. 23, 2012 Inner surface OD Outer Surface 134  m ID

Post-HT Hipot Test Points 2/24/12 D.W.Cheng V -> 3750 V 3150 V -> 2720 V 3550 V -> 2780 V 2850 V -> 3040 V 1300 V 1440 V 1210 V 2080 V -> 2200 V 1 st attempt -> 2 nd attempt M. Martchevskii Feb. 23, 2012

First Plasma-Spray Sample Summary Coating thickness (metallography) shows approximately.005” -.007” –A bond layer will add another ~.005” of thickness Surface is porous –Visible “wicking” with moisture and curing Matrix –Wicked curing matrix apparently improves hipot after reaction (pores filled) We still need to perform adhesion test (using standard CTD epoxy) using standard sample coupon 2/24/12 D.W.Cheng 21

Summary and Current Status We have samples designed & fabricated –Stainless 304/316, Ti 6Al4V, others A battery of tests have been defined Sample parts have been sent out to vendors –A few already received –Others ~1-2 week turnaround time The first plasma-sprayed sample has been tested –Initial results appear promising enough for near-term coil fabrication (HQ Coil 17, etc.) Other surface treatments continue to be explored 2/24/12 D.W.Cheng 22