Study On Technology And Mechanics Of Microwave Boriding

In this paper, the special heat and microwave effect of microwave to some materials absorbing it were utilized to prepare the boriding layer on the surface of steels. The microwave boriding was carefully investigated by the observation and testing for layer microstructure,appearance and mechanics performance etal.. Their properties were compared with those of conventional boriding. In order to study the mechnics of microwave boriding, it was analysed and studied for the carbon content influence on microwave boriding microstructure and properties, and the same as the dynamics and the thermodynamics.It is showed that the boriding velocity in microwave field is faster than that in co -nventional boriding. Like conventional boriding, the microstructure of boriding layer is characteristic of typical "saw-tooth" shape which is vertical to the surface. The bori -ding layer is developed according to the mechanism of nucleating and growing up. T-he boron atoms for the formation of boronize layer in microwave field come from the activation boron atoms decomposed by medium and gaseous boride.With carbon content increasing in steels, the change law of microstructure character for boronize layer is same to that in conventional contiditions, the development mechanics of boronize layer isn't varied by the change of boriding way. There isn't an apparent rich carbon zone under boriding layer for low and middle carbon steels in microwave treatment. And the total thickness of boronize layer is descended with carbon content increasing, and its change rate is sharply lowered which compared with that of conventional process; for low and middle carbon content steel, the former change rate is about one third to one half of the latter's; the microhardness of boriding layer is somewhat becoming small with carbon content increasing in steel.The diffusion activation energy of microwave boriding is about 2.66×10⁵J·mol^-1, which is the same order with that of convention boriding, the diffusion process and mechnics for B atom in microwave condition is familiar with those of conventional treatment. Its diffusion coefficient constant D₀ is 0.163479m²/s, which is sharply increased compareing with that of conventional treatment.