Infrared characterization and high heat flux testing of plasma sprayed layers

Four series of plasma sprayed actively cooled mock-ups have been evaluated by infrared measurements and heat flux testing. Infrared characterization s howed heat transfer capability of the plasma sprayed layer bonded to the su bstrate. Even if the thermal conductivity of the B4C plasma sprayed coating is only 5% of the bulk material, the coating can easily survive 1000 cycle s at 7.5 MW/m(2) if the thickness is less than 150 mum Thick tungsten coati ngs (3-5 mm) were more fragile, depending on the plasma spray technology. T he highest heat flux acceptable for 1000 cycles is 4 MW/m(2) with a vacuum plasma spray coating and a Ni-Al-Si-W precoating, accounting for a reductio n in the thermal conductivity by a factor of 3. (C) 2000 Elsevier Science B .V. All rights reserved.