Research On Sintering Technology Of Metal Bonded Diamond Tools

Diamond tool is known as “industrial teeth”, with its unique performance andirreplaceability, essential for hard brittle materials processing. The advantages oftraditional hot pressing technology manufacturing metal bond diamond tools are shortprocess time and simple adjustment. But the inherent disadvantage are: high energyconsumption, poor quality stability of product and low level of performance. Based onsummarizing hot pressing sintering theory, this paper selected Co-Cu-Sn powder asmetal matrix, forcused the research on the sintering technology of metal bond diamondtools. The main results were as follows:(1)Firstly, based on the same formulation, metal bonded diamond tools werefabricated with the method of HP, C-HP and HIP technology. The process parameterssuch as sintering temperature, holding time and pressure condition were optimized. Theoptimum process parameters of HP were760℃,4min,35MPa respectively; Theoptimum process parameters of C-HP were770℃,90min,30MPa respectively; Theoptimum process parameters of HIP were780℃,60min,80MPa respectively.(2)Secondly, under the optimized process conditions, WD sample, HD sampleand saw blade were prepared. Research results showed that: HP process wascharacterized by short process time, but an uneven temperature field distribution and ahigh porosity sintered body. Diamond was vulnerable to be ablated. The oxide on thesurface of metal particles was not favorable for the migration and diffusion of metalcomponents, and even became crack source; C-HP process had an uniform temperature field, the reducing atmosphere can activate metal atoms effectively so as toaccelerate densification; HIP process can reduce the porosity of sintered bodysignificantly, refine the grain size, improve the holding force of the matrix to diamond.The fracture morphology was characteristic of dimple. The comprehensivemechanical properties were best.(3)The sintering mechanism of Co-Cu-Sn matrix and diamondsegments were transient liquid phase sintering dominanted by solid phase sintering. Thedensification process included the desorption and escape of adsorption gas, thereduction of the oxides on metal surface, the formation and evolution of liquid phase,the diffusion and alloying of different contents. The metallic matrix prepared by thethree methods consisted of Cu5.6Sn and α-Co and the cystallization of HIP specimenwas relatively good.(4)Cutting test showed that the advantage of HIP saw was mainly manifested inthe service life which was increased by29%compared with the HP saw. For cuttingstability, HIP saw was relatively best, followed by C-HP and HP saw blade.(5)The ANSYS simulation showed that during HP sintering process, the powdercompacts can be heated rapidly when only considering the graphite mould as heatingelement. The temperature field can maintain uniform even at condition of rapid heating.But in fact, powder compacts often appear local high temperture because of densityheterogeneity. During C-HP sintering process, the heating rate of powdercompacts lagged behind the graphite mould. The power compact should be push fromthe preheating zone to the sintering zone at slow speed. It is favorable for densificationbecause of a small temperature gradient.