Comparison between Cobalt and Niobium as a Matrix Component for Diamond Impregnated Tools used for Stone Cutting

摘要

This investigation examines the possibility of adding niobium (Nb) to the Fe-Cu system in order to obtain, after powder compaction and sintering, a binder material (bonding matrix) with the adequate wear properties needed for the fabrication of diamond impregnated tools for stone cutting. The main objective is the replacement of cobalt (Co) by Nb in the Fe-Cu-Co alloys that are currently used in diamond tools. For this purpose, a comparative study has been conducted on some selected compositions of matrices integrated in cutting discs. Results of diamond impregnated 25wt%Fe-50wt%Cu-25wt%Nb and 25wt%Fe-50wt%Cu-25wt%Co matrices are directly compared because all tests were conducted under similar conditions. Two types of diamonds were used: without coating and Ti-coated. After the hot-pressing cycles, the main mechanical properties of the sintered bodies were evaluated. Cutting tests under real conditions, in Porrino granite, were carried out to compare the performance of the tools. Although the mechanical properties of the matrices with Nb were different from those found in the matrices with Co, the results obtained from the cutting tests have revealed that the tools made of 25wt%Fe-50wt%Cu-25wt%Nb and 25wt%Fe-50wt%Cu-25wt%Co matrices, both with 50/60 mesh diamonds, show quite similar behaviour during the cutting operations, thus indicating that replacement of Co by Nb is a promising route to be followed in the near future.