Fundamental Research On New Type Of Brazing Filler Metal For Super-hard Abrasive Wheels

Based on the summary of existing brazing filler metals,a new brazing filler metal is developed by adding other modifying elements into Cu-Sn-Ti filler metal.Analyzing the performance of the new filler metal.The brazing diamond grinding wheel is made by using the selected brazing filler metal.The grinding wheel is used in rail grinding test,and the feasibility of using brazed diamond grinding wheel instead of resin grinding wheel for rail grinding is explored.The research work of this article is as follows:The advantages and disadvantages of the existing solder are summarized,and the Cu-Sn-Ti filler metals are selected to be modified by adding Fe,Al and Si elements.The size of the filler metal particles,the fabrication process of the pre mixed solder and the method of packaging and preservation are determined.17 kinds of filler metals are determined by the method of extreme vertex mixture design with both upper and lower boundaries.The shear test scheme,shear fixture and shear sample are designed.The brazing process and the production process of the shear sample are determined.Through the shear test,it is found that the performance of the solder is poor when the content of the Cu based filler metal is lower than wt95%,and the Fe,Al and Si elements will affect the performance of the solder.The sample fracture surface occurs in the solder layer,which shows that the performance of the filler metal has a greater impact on the quality of the tool.Through the analysis of SEM and EDS of the solder bonding at the interface between the solder and the base shows that the filler and the matrix existed element diffusion phenomenon,forming firm metallurgical combination joint.Fe and Ti element will form enrichment phenomenon at the interface.The pure Cu based filler metal forms Cu-Sn enrichment near the interface.The enrichment of Cu-Sn,Fe-Ti,Fe-Ti-Si will appear in the solder layer by adding Fe,Al and Si elements.The analysis of the deep corrosive diamond grits by SEM,EDS and Raman found: The overall morphology of diamond is good,the edges and corners are clear.TiC is formed at the interface of diamond.There are small pits on the surface of diamond after brazing of No.2solder.It shows that diamond is slightly etched and surface graphitization occurs when the content of Fe element is up to wt5%.There is no obvious etching on the diamond surface after brazing of No.9 brazing filler metal,and the dendrimer dense TiC layer is formed on the surface.The brazing strength of the filler metal to the diamond has been improved and it has good comprehensive performance.The brazing diamond grinding wheel used for rail grinding is designed and the amount of filler metal and diamond was calculated.The grinding wheels were made of No.1,No.9 and No.15 filler metal and used for rail grinding tests and their characteristics were compared.By comparing with the resin grinding wheel,it is found that the grinding efficiency,grinding current,surface roughness and grinding spark of diamond wheel are better than that of resin wheel.The comparison of diamond grinding wheel made by 3 kinds of brazing materials shows that the diamond grinding wheel made of No.9 filler metal(add wt1.7%Fe?wt1.7%Al?wt1.7%Si into Cu-Sn-Ti)is superior to the grinding wheel made of Cu-Sn-Ti for cutting edge and grinding force.