Papers by Keyword: Diamond Composites

Abstract: The thermal and mechanical properties assessed respectively by dynamic mechanical analysis and flexural bend tests as well as the abrasive behavior obtained by wear tests of diamond particles incorporated epoxy matrix composites were investigated. Diamond particles with sizes in the range of 45 to 115 µm, synthesized at high pressure and temperature, were mixed in amounts of 20 and 40 wt% with dyglycidyl of the bisphenol A, DGEBA, epoxy resin cured with stoichiometric ratio of tetraetylenepentamine, TEPA, hardener. These composites were dynamic mechanical, DMA analyzed and three points bend tested. The behavior of the composites as abrasive tool for industrial polishing of ornamental rocks was evaluated by wear tests. The results showed an improved performance of the DGEBA/TEPA composites with incorporation of diamond particles.

Abstract: Cu-Si-B alloys are a new generation of metal matrix for producing composites incorporated with diamonds for cutting tools. These alloys have been developed as a special matrix in order to improve the thermal properties of the diamond composites used in machining tool bits. Despite the industrial interest, not much has been reported on this type of composite matrix. In this work, samples of Cu-Si-B alloys were processed at high pressure and high temperature (HPHT) sintering conditions. The microstructure changes that occurred were evaluated. Microstructural aspects were observed by SEM. Compounds formed during sintering were studied by EDS. Wear tests were performed in sintered diamond particle incorporated composites. The results revealed significant advantages of Cu-Si-B alloy as matrix for these composites.

Abstract: In this paper, semi-solid metal (SSM) processing was first applied to fabricate Al-based matrix and diamond composites. A kind of Al-Cu alloy with an adequate solidification range was chosen. Samples of Al-Cu alloys were fabricated by rheocasting with different processing parameters. Specimens of Al-based matrix and diamond composites were fabricated by rheocasting and hot press sintering technology respectively. Microstructures, transverse rupture strength (TRS), hardness and wear resistance were studied. Experimental results revealed that the TRS of the Al-based matrix and diamond composites fabricated by rheocasting increased by 157% and 115% respectively compared to the ones fabricated by hot press sintering technology. The fracture surfaces of the rheocasting specimens exhibited ductile cup and cone behavior as well as strong bonding between the matrix and diamond grits.

Abstract: Two groups of porous metal bonded diamond composites (PMBDC), with and without rare earth (RE), were compacted and sintered under the same conditions. The effects of RE on the transverse rupture strength (TRS) and fractography of fracture surfaces (FFS) of PMBDC having different porosity were investigated. From the TRS and FFS’s perspective, the composites with RE are better than those without RE. Furthermore, the result suggests that there is a critical porosity where there are very apparent effects on the TRS and FFS. If the porosity of the composites is less than the critical value, the effects of RE increase with the porosity; if the porosity is larger than the critical value, the effects drop with the porosity instead.

Abstract: This work aims at the study of the behavior of the powder systems Fe-Cu e Fe- Cu-Diamond under compaction, using the stoichiometries Fe-20Cu (wt%) e Fe-20Cu-4 Diamond (wt%). It was applied pressures at the interval 100 to 600 MPa, and it was used the Balshin and Rong-De’s equations to establish the exact behavior of the systems under pressing: accommodation, plastic deformation and particle’s rearrangement.

Abstract: Effects of TiH2 on the mechanical properties and microstructures of Fe-based diamond composites as well as the performance of diamond segments in circular sawing of granites are presented in this paper. Experimental results reveal that the addition of 2%TiH2 into the Fe-based matrix leads to decreases in the mechanical properties of both matrix and diamond composites. The wear resistance of the saw-blade segments decreases by 7.3%. Microscope observations reveal that the specimen without TiH2 shows fewer pores and denser structures in the base matrix. The fracture surfaces of the bending test specimens exhibit ductile cup and cone behavior and strong bonding between the matrix and diamond. SEM micrographs indicate that there are much more pull-outs of diamond grits, much more serious wear of diamond particles and erosion of metal matrix on the worn surface of saw-blades segments with 2% TiH2 in the matrix.