Rare shingle for a Gemini spacecraft, measuring 18″ x 22″, with attached metal tag imprinted with "52-35030-537, Vendor-Part." The panel has several cuts along the edges and one corner excised, where material was removed for analysis.
NASA transferred this panel to Dr. John F. Radavich of Purdue University. Dr. Radavich's obituary makes note of his distinguished career as a researcher: 'His principal contribution to high temperature material technology had been his pioneering work in the transition of analytical procedures from optical to electron microscopy. In so doing, he developed preparation procedures that opened the doors to all future metallographic studies of superalloys. The current state-of-the-art practices for phase extraction and identification are dependent upon the fundamental knowledge that he developed.'
The shingles of the Gemini capsules were composed of a nickel-based high temperature alloy called René 41, used due to its ability to retain high strength at extreme temperatures. Based on his expertise in this specific field, it is evident why Dr. Radavich would have been chosen to receive these shingles for study. In August 1962, he published a paper entitled 'Microstructural Changes Produced in Orbited Rene' 41 Heat Shingles,' in which he noted that the panel surfaces displayed no obvious meteorite impacts; that the outer oxide layer undergoes an enrichment of chromium oxide relative to preflight material; and that the amount of M6C carbide phase in flown material decreases relative to the TiC phase, among other observations.
