Experiences and Issues with Carbon Foam at BNL & Yale BNL: David Lynn, Marc-Andre Pleier, Anatoli Gordeev, Russ Burns, Ken Sexton Yale: Paul Tipton, Will Emmet, Tom Hurteau

Three sources of CF foams considered Koppers Poco Allcomp Koppers is closed-cell and has an extremely non-uniform cell size Poco varies in density through thickness Allcomp is open-cell, has a fairly uniform pore size-easiest to machine and can manufactured in different densities All are more-or-less comparable in cost Note higher density

Allcomp has been used for the Stave/Stavelet 09 Program BNL/Yale uses CGL thermal gel at the foam/tube interface Concerns about migration of CGL through Allcomp open-cell foam Solution: apply coating of Hysol to foam surface and cure prior to CGL and tube assembly Before and after Applied to inner endpiece Applied to outer endpiece

Poco top/Koppers k-foam bottom Allcomp 0.5 g/cc Allcomp with hysol seal Open vs closed CGL drawn away Seal? Difficult, needs more work Need to compare machining again and cell sizes Note jagged edge

Possible solution to Allcomp “ragged edge” problem (per DL) Create a 1-2 mm thick layer of Hysol on interface surface of foam and allow to cure; Machine with ball endmill as before; Apply coating of Hysol as before to seal pores on semi-cylindrical surface… Apply Hysol layerMachine foam as before Note improved edge

Problem of tube-foam interface stresses Do we want a rigid bond (Hysol), a flexible bond (CGL thermal gel), or no bond at all (conduction across micron air gap)? Anatoli Gordeev, BNL mechanical engineer has done a detailed ANSYS FEA of a quarter model of the tube-foam interface. A worst-case scenario of zero bond gap was assumed. A more detailed analysis of the no-bond option is pending.

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY 0.1mm box mesh POCO FOAM K=125, UNIFORM; E = 0.5 GPa; CTE = 0.7x SS 304 K =16.2 CTE = 1x BONDED CONTACT

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY TEMPERATURE LOAD INNER PIPE SURFACE 1.PIPE : L =80mm; OD = 2.77mm; ID = 2.17mm. 2.FOAM: 50mm long; 12.7mm wide; 4mm height. 3.¼ TAKEN FOR ANALYSES

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY T – DISTRIBUTION. VIEW # 3

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY THERMAL LOAD ONLY; SYMMETRICAL CONSTRAINT

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY TOTAL DEFORMATION; VIEW # 1

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY TOTAL DEFORMATION; VIEW # 3

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY EQUIVALENT STRESS; VIEW # 1

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY EQUIVALENT STRESS; VIEW # 4

Gordeev, BNL POCO FOAM – SS 304 PIPE CONNECTION STUDY SHEAR STRESS; VIEW # 1

Allcomp Foam Thermal Conductivity Measurements (per Dave Lynn) Foam AL Calibration Block Foam SS Calib Block Al Measurement gives K = 79 W/m-K SS Measurement gives K = 93 W/m-K