The brazing of diamond

摘要

Diamond grits held in metal matrix (sintered or electroplated) are retained primary by mechanical locking. Because of this weak attachment, the pullouts of diamond from matrix are inevitable during the cutting process. Moreover, the working grits have low protrusion heights, so the cutting speed of the tool is limited.Furthermore, the rubbing of metal matrix and the work object can cause thermal damages of diamond and other materials, and power increase for the operation.Diamond can be firmly held in a metal matrix by brazing. Because of the presence of strong chemical bonding, diamond grits can protrude twice as high without being knocked off from the matrix. As a result, the cutting speed of the tool may be doubled.When the braze melts, the carbide formers will migrate toward diamond to form carbide at the interface.This reaction may be excessive as to degrade diamond significantly. In this ease, a coating on diamond may be needed to moderate the reaction.When diamond is brazed on the surface of a substrate, the melt tends to pull the grits closer together that may thicken the braze layer locally. The clustering of grits can reduce the cutting effectiveness of the diamond tool. A diamond grid design is necessary to maintain the uniform thickness of the braze layer. Moreover, the controlled melting of braze alloy can form a gentle slope around each diamond grit. Such a massive support can allow aggressive cutting of the diamond tool with a low power consumption.