Platinum is being explored as an alternative to the sprayed boron nitride mandrel release coating under study at GSFC
for the International X-ray Observatory (IXO). Two and three inch diameter, polished (PFS) and superpolished (SPFS)
fused silica flat mandrels, were used for these tests. Pt was applied to the mandrels by DC magnetron sputtering. The
substrate material was 400 micron thick D263 glass, the material which has been proposed for the IXO segmented
optics. These substrates were placed on the mandrels and thermally cycled with the same thermal profile being used at
GSFC in the development of the BN slumping for IXO. After the thermal cycle was complete, the D263 substrates were
removed; new D263 substrates were placed on the mandrels and the process was repeated. Four thermal cycles have
been completed to date. After initially coating the mandrels with Pt, no further conditioning was applied to the mandrels
before or during the thermal cycles. The microroughness of the mandrels and of the D263 substrates was measured
before and after thermal cycling. Atomic force microscopy (AFM) and 8 keV X-ray reflectivity data are presented.
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