WEAR RESISTANT BORONIZED SURFACES AND BORONIZING METHODS

摘要

1435045 Carburizing and boronizing steel HUGHES TOOL CO 17 May 1974 [10 Aug 1973] 22084/74 Headings C7F and C7U Steel surfaces are made more wear resistant by the steps of carburizing, boronizing, quenching and tempering. The carburizing may be carried out using a gas containing CO and CH 4 , by pack diffusion in charcoal containing BaCO 3 and CaCO 3 , or in a salt bath containing sodium cyanide and BaCl 2 . The carburized case is boronized by pack diffusion in a mixture of B 4 C, graphite and KHCO 3 , or by gaseous diborane or by salt bath boronizing. The boronized surface is then quenched to give a martensitic structure, e.g. from T755‹C, which finally tempered at 143-265‹C for about one hour. The treatment of friction bearing surfaces in earth boring drill bits is referred to.