I recall reading a story in a comic book in the 1970s (although it could have been older - it was in my uncle's collection).
What I can recall is that an astronaut/explorer is converted into a robot to visit another planet. There he discovers a race of robots who interrogate him. It's possible that the reason for his conversion was to speak to them as equals. I seem to recall he crash landed back on Earth and his girlfriend didn't believe it was him?
The design of the robots was striking - they had rounded conical heads and a thin neck, with smooth metallic bodies. I think their eyes were triangular and the mouth was a rectangle.
Does anyone know what this is?