The Study On Brazed Sintering Process And Bonding Interface Of Diamond Bit

Brazed bit have a lot of chemical reaction on the contract surface, for example dissolution and infiltration. It enhances the holding affect of casing. Under the SEM, the micro cracks were found on the surface of clad layer, which is one of main reasons of bits lost its function. We study cutting edge’s mechanical properties, crack propagation and matrix performances of common core bits, rope core bit with elastic-plastic mechanics and fracture mechanics theory. Our main evolves are focus on three aspects.Firstly, by analyzing the elastic-plastic mechanics, found thick of wall’s effects on stress in bit cooling process. The result is as following. Different tangential stress is caused by various walls thick. Compared the common core bits and rope core bits, the common core bits seems more easily to be cracked with the same external diameter but larger inner diameter, which means the thicker the easier crack produced. By analyzing the elastic-plastic mechanics, found the influence of external control force on the stress distribution during cutting edge cooling process.Secondly, we use Giffith theory to analysis crack propagations in the bit, found stress intensity factor is influenced by temperature, bit size, direction of crack initiation and location. The directions of crack propagations are not only along the vertical axis. Crack growth trend becomes smaller along the increase of wall thickness.Finally, we use Giffith theory to analysis crack propagations in the transition layer based on the complexity of transition layer material composition and crack irregularity of transition layer, found stress intensity factor is influenced by temperature, bit size, direction of crack initiation and location. The directions of crack propagations are mainly perpendicular to the axis of chromium carbide prism on the surface of diamond. Crack growth trend with temperature gets bigger and bigger. Crack propagations trends are not obviously infected by wall thickness. Stress intensity factor of free diamond’s transition layer is far above the Stress intensity factor of diamond controlled by bit. Crack propagations trends become bigger and bigger in the process of dissolving sample.