Analysis of the Economics of Turning Titanium Alloys with Polycrystalline Diamond Tools

摘要

Diamond grains from north Jakutija, whilst shown by X-ray structural analysis to contain admixtures of hexagonal modification of carbon-lonsdalite, and hence belonging broadly speaking to the carbonado class, cannot be regarded as typical carbonado - Orlov's Type X - and accordingly have been designated Type XI. Type XI carbonado grains were first reported in 1967 in north Jakutija river alluvia, when M A CUMAK and Z V BARTOSINSKII noted the unusual form of these grains and named them jakutite. However, the results of these detailed investigations were never published and the proposed designation failed to become established. Type XI polycrystalline diamond aggregate (= carbonado with lonsdalite-jakutite) has irregular grains ranging from opaque dark-grey to semi-opaque yellow, not greatly dissimilar to typical Brazilian carbonado (Type X) but with the XI grains presenting, in addition to irregular to rounded form, vestiges of hexagonal outline.