A s u r f a c e heater was developed using a g r a p h i t e fiber-epoxy composite as t h e h e a t i n g element. This heater can be thin, h i g h l y e l e c t r i c a l l y and t h e r m a l l y conductive, and can conform t o i r r e g u l a r surface. e l e c t r i c i t y was found t o penetrate through t h e composite i n t h e transverse d i r e c t i o n t o make an acceptably low foil-composite contact r e s i s t a n c e . When conductlng c u r r e n t , t h e heater temperature increase reached 50 percent o f t h e steady s t a t e value w i t h i n 20 sec.heater provided t h e r e was no water corrosion. Such bonding f a i l u r e may be avoided if p e r f o r a t e d n i c k e l f o i l i s used, so t h a t t h e composlte p l l e s can bond t o each other through t h e p e r f o r a t e d 'holes and t h e r e f o r e M1ockll t h e f o i l i n place.There was no overheating a t t h e ends o f t h e

and Michael E. D i l l e h a y and Mark S t a h l Cleveland S t a t e U n i v e r s i t y Cleveland, Ohio 44115 SUMMARY A s u r f a c e heater was developed using a g r a p h i t e fiber-epoxy composite as t h e h e a t i n g element. This heater can be thin, h i g h l y e l e c t r i c a l l y and t h e r m a l l y conductive, and can conform t o i r r e g u l a r surface. e l e c t r i c i t y was found t o penetrate through t h e composite i n t h e transverse d i r e c t i o n t o make an acceptably low foil-composite contact r e s i s t a n c e . When conductlng c u r r e n t , t h e heater temperature increase reached 50 percent o f t h e steady s t a t e value w i t h i n 20 sec.heater provided t h e r e was no water corrosion. Such bonding f a i l u r e may be avoided if p e r f o r a t e d n i c k e l f o i l i s used, so t h a t t h e composlte p l l e s can bond t o each other through t h e p e r f o r a t e d 'holes and t h e r e f o r e M1ockll t h e f o i l i n place.There was no overheating a t t h e ends o f t h e

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Hexagonal BN is an unusual material in that it is both highly thermally conductive as well as an electrical insulator. Additionally, hBN is also thermally stable in air. This unusual combination of properties makes hBN of significant interest for thermal management. Unfortunately, hBN is not easily consolidated into substrates without the addition of second phases which generally result in poorer thermal performance. This research investigates the potential to utilize this material to dissipate heat from high‐voltage, high‐power electrical devices. Specifically, a process to coat individual platelets of commercial hexagonal BN powder with a layer of amorphous aluminum oxide was developed. The coated hexagonal BN was then hot‐pressed to form a highly thermally conductive substrate. The process to coat hexagonal BN platelets with aluminum oxide was accomplished by mixing hexagonal BN with AlCl3 containing some water, then evaporation of excess AlCl3 to form a Al, Cl, and O layer on hexagonal BN. This product was then heated in air to convert the surface layer into aluminum oxide. Following hot pressing to 1950°C and 10 ksi, the consolidated composite has through‐plane and in‐plane thermal conductivity of 14 and 157 W·(m·K)−1, respectively, at room temperature.