Research On The Holding Strength Of Bond To Diamond Grain In Metallic Bond

Metallic bond is a common binding agent in diamond tools. The gripping forceof bond to diamond is key to diamond tools’ life. In this article, CuFe-based bond wasdesigned to overcome the shortcomings of copper-based bond which had poorgripping force to diamond and low transverse rupture strength(TRS). A certainamount of iron was added to the copper-based bond in order to improve the TRSof thematrix and the interfacial bond strength between the bond and diamond grain.Tofurther improve the holding strength of bond to diamond grain, a certain content oftitanium was added and titanium coated diamond was used.Sintering process ofCuFe-based bond was optimized also. In addition, aluminum-based bond diamondtools are very rare in China. Research on this subject is in its infancy,so reports of theliterature on this subject are also very few at present. The effects of adding strongcarbide forming elements such as Cr, V and Ti on the wettability of aluminum on thediamondwere preliminary studied and it was compared with the holding strengthcalculation data. The relationship of strong carbide forming elements’ impacts onwettability and holding strength was analyzed. The conclusions are as follows:When the content of Fe was30wt.%, the TRS and HRB of the matrix was highand the holding strength coefficient was relatively high. When the content of Ti was4wt.%, the TRS and HRB of the matrix was relatively high and the holding forcecoefficient was not low. Therefore, taking the mechanical properties and the holdingstrength into consideration, the ratio of bond composition was50%Cu,30%Fe,8%Ni,8%Sn and4%Ti.Comparison of the mechanical properties of not coated and titaniumcoated diamond segments, it was found that the TRS of titanium coated diamondsegments sintering at four temperatures (690℃,720℃,750℃and780℃) has ahigher value than the TRS of not coated diamond segments. That is to say, usingtitanium-coated diamond increased the holding strength.When the mixing time was20h, the TRS, HRB and relative density ofCuFe-based bond reached the maximum. Further extending the mixing time, the mechanical properties of the CuFe-based bond began to decrease. So, the best mixingtime of CuFe-based bond was20h.When the sintering temperature was720℃, theTRS, HRB and relative density of CuFe-based bond reached the maximum. When thesintering temperature reached to750℃, the TRS, HRB and relative density ofCuFe-based bond had a little decline, but the drop rate was not large. Thus the suitablesintering temperature should be between720℃and750℃.The wetting process of Al and AlCr, AlV andAlTi alloyson the high-puritygraphite substrate can besimplydivided into three stages. the stage that is fastspreading, spreading slower phase, the droplet deformation stage.That was fastspreading stage, spreading slowdown stage, the droplet deformation stage.The adding of chromium had no improvement on the wettability of the aluminum tographite, but itincreased the holding strengthto diamond grain. The holding strengthcoefficient was65.25%when the content of chromium was0%, sequentiallyincreasedto77.1%,87.68%and95.98%when the content of chromium wererespectively1%,3%and5%.The adding of vanadium and titanium can both improvewettability of aluminum to graphite. At the same time,the holding strengthwas alsoenhanced. The holding strength coefficient was65.25%when the content of vanadiumwas0%, sequentially increasedto67.92%,68.73%and71.85%when the content ofvanadium were respectively1%,3%and5%. The holding strength coefficient was65.25%when the content of titanium was0%, sequentially increasedto66.52%,72.72%and75.57%when the content of titanium were respectively1%,3%and5%.