Sintering of Tin Powder

Abstract

MOST powdered metals will sinter together appreciably when heated to a temperature which, in the absence of extraneous factors, is about three-quarters of their absolute melting point; metals of low melting point tend to be exceptions, however, to this generalization in that they can be heated nearly to their melting point before sintering takes place. There is no evidence, in fact, that tin has ever been observed to sinter¹. Tin powder is usua0lly made by the atomization of the molten metal and particles of the powder become coated with a film of stannic oxide; this oxide cannot be reduced below the melting point of tin by any atmosphere normally used in sintering. It has already been found² that sintering previously pressed powder leads to no further densifieation of the compact and confers no beneficial properties on it. The inability of tin to undergo sintering has been generally assumed, but never shown, to be due to the presence of unreduced oxide films.