Research On Etching Of Synthetic Diamond By Iron And Cobalt Salts

With the development of production and technology, production tools tend to be produced following the development direction of the high efficiency, high life and high economical. Synthetic diamond single crystal which has the excellent physical and chemical properties should be emerged and developed as one kind of materials which can be used for producing tools. But artificial diamond is difficult to combine with the binder and easy to fall off during the preparation process of producing tools because of the extremely smooth surface and high chemical stability.in this paper,the surface of synthetic diamond single crystal was etched by iron and and cobalt salts at high temperature.The influences of heat treatment temperature and holding time on the corrosion microstructure morphology and corrosion depth of diamond crystal surface were studied. The main research contents and results were as follows:1.The corrosion process of cobalt oxalate best are as follows:temperature 900℃, holding time 1 h; Ferric oxalate:temperature 900℃, holding time 1 h; Cobalt nitrate:temperature 870℃, holding time of 1 h. P-V of surface{100}and {111} are:3.25μm and 2.2μ.m,3.5μm and 2.5μm,5.12μm and 4.25μm。2.The corrosion behavior of the surface of synthetic diamond single crystal was researched and analyzed.The results showed that the{100} face of the diamond is easy to be etched than{111} face. The corrosion pits on the{100} surface tend extent in the longitudinal and the corrosion pits on the{111} surface tend to lateral spread laterally.The reversed pyramid-like etching pits were observed on etched{100} plane, while the triangular or hexagonal etching pits with a smooth flat bottom were observed on etched{111} plane.3.The corrosion mechanism of diamond surface was studied and inferred.XRD showed that metal and metal oxides was produced when metal salt was be treated at high temperature.Diamond Raman spectra showed that graphite was produced after diamond was treated. The mechanism:(1) metal was produced after metal salt was treated at high temperature because of the decomposition or REDOX.Then the molten metals could promote the carbon atoms from the diamond phase transform into the graphite phase, and graphite carbon diffused away from the diamond-metal interface in molten metals;(2)Metal oxides and C have an REDOX reaction.4. The diamond which was treated by three kinds of metal salt was made into diamond segment.The results showed that the treated preparation of diamond segment such as bending strength and hardness had a certain degree of increase compared with the diamond tool which was made of the untreated diamond. The performance of the diamond tool which was made by the diamond which was treated by cobalt nitrate treated is best. Bending strength of 1100 Mpa, increased by 22%, the hardness of HRB99, increased by 6%.