Actually you are right if you heat the drive that much it will probably wipe it. Initially I was thinking the melting point for aluminum is 1220F and for glass it can be much higher, but in reality the drive only needs to be heated until the magnetic substrate reaches its curie temperature, at which point it should be equivalent to having randomly wiped it magnetically. But 1000-1500 might not be enough to melt a given platter, I know aluminum has a melting point of 1220F not sure the melting point of the glass sometimes used for drive platters but a quick search shows glass melting points as ranging from about 1500F-4200F depending on the specific type. I just did a bit of research on this though, and it doesn't matter if the platter melts because once something magnetic reaches its curie temperature it is randomized. Wikipedia claims that '; the effect is reversible' but doesn't appear to detail how. So I guess my final answer is that perhaps raising the drive to that temperature will be enough to wipe it, I did a little research and found the curie points of the magnetic substrates on platters as being a bit under 1000F so unless that randomization can indeed be reversed somehow it seems like it would be secure. Personally I would just use ATA secure erase or dban though.