|
Author(s) |
Purohit, R. D.; Nair, S. R.; Prakash, D.; Sinha, P. K.; Sharma, B. P.; Sreekumar, K. P.; Ananthapadmanabhan, P. V.; Das, A. K.; Gantayet, L. M. |
|
In order to realize SOFC as power generating devices, multiple cells are connected in series through an
interconnect material to accumulate the voltage output. The interconnect should have very low permeability for the
gases used. A novel solution combustion process has been developed for producing the phase pure,
well-sinterable powders of Ca-doped LaCrO3 interconnect material. A process has been developed to produce the coarse
granules as a feed material using combustion-synthesized powder for plasma spray through (a) preparation of
granules through cold iso-static pressing followed by breaking and sieving (b) sintering of the green granules
followed by sieving. The flow ability and deposition efficiency studies on +45-75 and 75-125
µm powders suggested that +45-75 powder is more suitable for the plasma spray coating. The plasma process parameters; plasma
power, flow rate of carrier gases and distance between substrate and plasma gun have been optimized to achieve
required coating characteristics. The as-produced coating using 20 kW power plasma gun on the porous
Sr-doped LaMnO3 cathode substrates has been examined by SEM. An adherent coating of about 100
µm has been observed in the micrographs. No large cracks were observed throughout the coating. However, the coating was not found to be
impervious in nature. Also the micrographs showed incomplete melting of the plasma-coated material. The similar
experiments were performed using a higher power ( »
60 Kw) plasma gun. The coated coupons were tested for leakage
by checking water penetration. It was found that water did not penetrate for quite a long time. Therefore, the
coupon was further tested for leakage by keeping it over a port connected to vacuum pump. The vacuum attained was
7x10-3 mbar and it was maintained for four consecutive days. The SEM studies on the coated sample showed a
quite dense coating along with a very few small local pores. |
|
|
|