The Residual Stress Of Polycrystalline Diamond Compact And The Failure Mechanisms Of Drill Anchor

Polycrystalline Diamond Compacts (PDC) is a type of super-hard composite, which takes diamond powder as raw material, WC cemented carbide as substrate, is sintered through special synthesis technology under high pressure and high temperature. Compact has both advantages of high hardness, good abrasion resistance performance in diamond, and excellent impact resistance in cemented carbide. Nowadays the compact’s application in deep well-drilling extends to all fields of deposit exploration and machining and gradually replace single crystal diamond as the most important member of super-hard material. Main content and conclusion of the thesis are as follows:1. The theory of composite of the PDC under the high temperature and the high pressure is simply introduced. The experimental samples are the system of1308and1304of the PDC which have the different interface morphology and the different synthesis pressure by the Cubic press.2. The micro structure, the composition distribution, the particle size distribution of the selected PDC is analyzed with the JXA-8230type electronic probe, as well as to the influence of the residual stress. According to the synthesis technology, some factors are studied.3. The INVIA type microscopic confocal laser Raman spectrometer is used to test the graphitization and the residual stress. Through the Raman peak wavenumber of characteristics analyzes the graphitization, internal residual and calculate the of the residual stress by the formula.4.The analytical results of the1308system of the PDC which have the different interface morphology show that cobalt has enrichment because of the large synthesis pressure.The distribution of cobalt has difference from the center to the edge,and particle size distribution is not homogeneous.The cobalt enrichment also causes the residual stress increasing, and the axial distribution is not rectangular, even appearing the tensile stress in the PCD layer. The1304system of the PDC which have the different interface morphology shows that the large synthesis pressure doesn’t cause cobalt enrichment. Cobalt is even distribution in the center and the edge of the PCD layer. The particle size distribution under small synthesis pressure is homogeneous.Internal of the PCD layer also have residual stress, but it is rectangular distribution in the axial regions. When there are the same raw materials, the different surface morphology and synthesis pressure cause large residual stress in interior of the PCD layer and reduce the properties of PDC.5.Designed the Mirco-drill experiment of the anchor drill, also analyzed the failure of the drill anchor, draw the failure mechanism, and give the corresponding improved method.