Study On Porous Metal Bond And Preparation Of Super Hard Abrasive

The traditional compact metal bonded grinding wheel has the characteristics of good thermal conductivity,high abrasive holding strength,strong bearing capacity and good wear resistance,etc.However,the problems of poor self-sharpness and high grinding temperature in the use process limit the improvement of grinding efficiency.By introducing pore structure,the porous metal bonded super hard abrasives can solve the above problems,but at the same time,it also weakens the holding force of the binder to the abrasive.Therefore,it is the key to improve the grinding efficiency to improve the holding force of the binder to the abrasive while ensuring the porosity.In this paper,metal powders of Fe-Al,Ni-Al and Ti-Al were used as porous metal bond,and pore forming mechanisms such as Kirkendall effect,the gap between powder particles and reactive pore forming were used to prepare super hard abrasive tools with controllable porosity through SPS constant volume sintering.The bending strength of FeAl porous metal bond in low temperature sintering was improved by adding Fe-P powder and low melting metal(Cu,Zn,Sn).At the same time,the particle size of the powder was changed,and the relationship between the pore structure and pore size distribution and the bending strength was analyzed.Finally,at 800 ? and 1100 ?,diamond abrasives and cubic Boron Nitride(c BN)abrasives of different concentrations and particle sizes with porosity of 30% were prepared respectively,and the interface bonding state of metal bond and abrasive(diamond,cBN)and its influence on the bending strength of abrasives were studied.The experimental results show that:1.Constant volume sintering can precisely control the porosity of the binder,and the porosity can reach 30%-60%.The sample with the same porosity ratio of Fe and Al has higher bending strength than the FeAl intermetallic compound with other ratios.Under the same porosity,the bending strength of FeAl porous metal bond samples was higher than that of Ni-Al and Ti-Al samples.2.The addition of Fe-P powder,low-melting metal Cu,Zn,Sn and other components reduced the sintering temperature of Fe and Al-based samples,and improved the bending strength of the samples sintered at 800 ?.When the content of Fe-P powder is 20%,the bending strength is up to 155 MPa.The bending strength of FeAl base porous metal bond mixed with Cu and Zn reached 163 MPa.3.The particle size of Fe and Al powder ranged from 5 m to 50 m.After sintering,the pore size of metal bond sample with porosity of 30% increased with the increase of powder size,while its bending strength and pore circular degree decreased linearly with the increase of powder size.With the same particle size of Fe powder and the same control porosity,the bond's bending strength and porosity roundness gradually decreased with the increase of Al particle size,and the pore size didn't change significantly.4.When the porosity is designed to be 30% and the particle size of the bond is 5 ?m,the bending strength of the abrasive tool gradually decreases with the increase of the particle size and concentration of the abrasive particle(diamond or cBN).The chemical combination of abrasive and bond at the interface improves the holding force of diamond and slows down the reduction of the breaking strength of abrasive tools to some extent.