The very best sandpaper for tough metals for example iron or steel is aluminum oxide, although the top sandpaper for softer metals for example aluminum or brass is silicon carbide. The earlier experiments showed the thermal conductivity of cubic boron arsenide is nearly ten times better than that of silicon. https://www.facebook.com/permalink.php?story_fbid=pfbid02xUArEpapo69Dr4U6qjpTMNcMtWCTM1MtC54Z5bMPZfEXne3eZoA4LpjFRnptZ7DLl&id=61562415773754&__cft__[0]=AZU43H4WB62fYXxtf3cVK3Yk9f6mzUpGkJGsDLBIsCTC-yZI9VmqJ6cPcy1lWuwjre9K6RTl0ZgCxjnYufbf_t0xWO7zYe6_LSAqJzB6h6kqoFETM1FG1d8txL0cZmN8sphUu9RLnbgdewDSSUxqzuHrJq-Xf2yDe3Zh3Ok-vqJlTQ&__tn__=%2CO%2CP-R