Effect Of Abrasive Modification On Sapphire Lapping Performance By Fixed Abrasive Pad

Sapphire has excellent physical properties and stable chemical properties, which has been widely used in military, aerospace, science and technology, and other fields. The fixed abrasive technology is a new technology of sapphire lapping and polishing, and it has very important application prospect. But in the process of grinding abrasive is easy to fall off, resulting in decreased efficiency and waste. In this paper a layer of Ni-P alloy is deposited on the surface of diamond by electroless plating, which enhance the bonding strength between diamond and matrix resins, and explore the effect of surface modification on the lapping performance of sapphire by fixed abrasive pad. The main research contents of this paper are as follows:(1) Electroless nickel plating on diamond surface was explored. The relationship between the surface morphology and the coating rate was investigated in the Ni-P alloy layer with different coating thickness on the grain size of 20~30 μm and 40~50 μm respectively. The research shows that electroless nickel plating can significantly change the surface morphology of the diamond, and with increase of coating ratio, the distribution and size of the protuberance significantly improved.(2) The effect of the coating rate on the properties of sapphire was studied by single factor experiment. The friction coefficient, the acoustic emission signal, the material removal rate and the surface roughness of the workpiece were measured by the CP-4 polishing platform, and the effect of the diamond coating on the lapping performance of sapphire was analyzed by nickel plated diamond abrasive pad with different particle sizes. The research shows that the depth and the stress of the coarse grinding process are higher, so the higher the amount of nickel is required in the process of grinding. In the grinding of sapphire, the removal rate of the material reached the maximum when the diamond coating rate was 50%, and the removal rate of the material reached the maximum at 30%.(3) The mechanism of the nickel plated diamond grinding sapphire was studied. The stress model of the single grain size of the abrasive pad is established, and the positive pressure and cut depth are derived. It is found that in the same situation as the large grain size of abrasive grains by cutting force and torque, making it easier to fall off from the polishing pad, so a larger amount of nickel is required to maintain control force of the matrix on the abrasive grain.; the requirements for the amount of nickel plating on sapphire were further verified by the acoustic emission signal of the grinding process.