Study on the Synthesized Black Low-Magnetism Diamond

Based on the testing of the magnetic susceptibility of the raw materials and the final products: graphite, Ni70Mn25Co5, general diamond, black diamond and melting NiMnCoC in the synthesis of diamond and the analyzing of the fracture surface of black diamond and general diamond by the Scanning Electron Microscope, it is found that the magnetism of the synthetic diamond is caused by NiMnCoC inclusions. There are many inclusions in the fracture surface of general diamond, but there are no inclusions in the fracture surface of black diamond, merely many cavities existed. The low magnetism existing in black diamond is from the poor quality and more-cracked diamond caused by higher temperature and lower pressure in the synthesis of diamond. A lot of cracks exit between diamond surface and inclusion. Because the magnetic catalyst inclusions are removed by acids through the cracks during the process of chemical treatment, the black diamond has low magnetism.