Research On Microwave Sintering Technology Of Ceramic Bond Diamond Agglomerat

In this paper,microwave sintering technology is used to study vitrified bonded diamond samples.By means of theoretical analysis,sintering experiment and numerical simulation,the components of vitrified bonded diamond samples,microwave equivalent dielectric parameters of agglomerates and microwave sintering process are studied respectively.The vitrified bonded diamond samples with good comprehensive properties were developed.In addition,in order to explore the batch microwave sintering technology,the batch microwave sintering furnace is designed and its the temperature field characteristics are analyzed.The vitrified bond is based on SiO₂-B₂O₃-Al₂O₃-Na₂O system.Mg O is selected as the main network modifier oxide,and the vitrified bond is modified by adding Zr O_2.When the content of Zr O₂ is 3mol%,the vitrified bond has the best mechanical property and the bending strength can reach 168MPa.SEM shows that the vitrified bond is closely combined with diamond abrasive.The effects of random distribution of spherical auxiliary abrasives and doping volume fraction on the inversion results of microwave equivalent dielectric parameters of vitrified bonded diamond samples were studied.The results show that the random distribution of SiC auxiliary abrasive has little effect on its microwave equivalent dielectric parameters.With the increase of doping volume fraction,the absolute values of real part and imaginary part of relative dielectric constant of vitrified bonded diamond samples increase.The microwave equivalent dielectric parameters of vitrified bonded diamond samples are determined.The real part of the relative dielectric constant is 5.15 and the imaginary part of the relative dielectric constant is-0.17.The sintering position height H=240mm is determined,which can not only realize the rapid temperature rise of vitrified bonded diamond samples,but also ensure the uniform temperature distribution of each part of the samples.The optimum sintering process was determined.When the sintering temperature was700℃,the holding time keeping 10min.The mechanical properties of vitrified bonded diamond samples were the best,in which the porosity was about 21%,the bending strength was up to90MPa and the average hardness was up to 95HRB.SEM images show that the vitrified bond achieves a good wetting and coating effect on diamond abrasives,connects independent diamond abrasives into a whole,and the two are closely combined.The optimum content of pore forming agent is determined.When the addition amount of pore forming agent is 10vol%,the porosity of vitrified bonded diamond samples can reach about 30vol%,the average bending strength is 60MPa and the average hardness is 85HRB.At this time,the vitrified bonded diamond samples can not only maintain appropriate porosity,but also have good mechanical properties.A batch special microwave sintering furnace is designed,and the size of the resonant cavity is 1400mm×800mm×800mm,the number of feeders is 9,the distance in X direction is 350mm,the distance in Y direction is 180mm,and the maximum design power is 9000W.The time-varying electric field of the batch vitrified bonded diamond samples by moving heating makes the energy absorbed by each part more balanced,which is conducive to improving the heating uniformity.The temperature uniformity is 16%higher than that by static heating.It is determined that the moving distance of the sample is 183mm,which can maintain the high temperature rise speed and uniform temperature distribution.