Scanning electron microscopic study and mechanical property examination of a bond bridge: development of a porous metal bonded diamond wheel

Abstract In order to establish a fundamental method of creating a strong, hard bond bridge for a porous metal bonded diamond wheel, the phosphorate treatment, the heat treatment under high air pressure and the sub-zero treatment have been discussed. However, the relationships between the mechanical properties of the specimen and the surface conditions of the bond bridge remain to be clarified. In particular, it will be necessary to analyze the surface changes of the bond bridge during vacuum sintering and each step of the treatment. Furthermore, the method of strengthening the bond bridge must be discussed in connection with the investigation of its surface changes. The following conclusions can be made based on the investigation of the mechanical properties of the specimen and the surface conditions of the bond bridge. (1) At low temperature, the melted alloy of Ni–Cu is not sufficient for bond bridge formation. At the higher temperatures of 1173 and 1273 K, bond bridges composed of some form of crystals develop among all of the abrasive grains. (2) In the case of Ni–Cu–Sn metals, the alloying is more clearly comparable to that of Ni–Cu alloy. By intrusion of Sn metal into Ni–Cu metals, the alloying of these metals is more pronounced. (3) By sub-zero treatment of a specimen that was heated under high air pressure of 9800 kPa, the surface was made smooth. Martensite transformation by the sub-zero treatment makes the specimen hard and strong. (4) The phosphor-bronze is formed by the diffusion of phosphorus with oxide by heating under high air pressure.