Study On Preparation And Properties Of Boriding In Microwave Field

In this paper, the temperature effect between boriding medium and microwave field and preparation of steels boriding in two microwave cavity (single-mould cavity and multi-mould cavity) were studied. The boriding medium can absorb microwave as the diffusion resource. The microwave boriding was carefully investigated by metallographic observation, SEM, X-ray diffraction and mechanics testing. Their properties were compared with those of conventional boriding. We also designed a novel temperature measurement and control device because the infrared thermoscope is not precise in microwave field.It is showed that the long-term stable temperature could be obtained by coupling the microwave power and the mass of boriding medium. The boriding temperature could be adjusted by either the microwave power or the mass of boriding medium. The thickness of boriding layer increases with the treating time. The boriding velocity in microwave field is faster than that in conventional boriding whatever in single-mould cavity or in multi-mould cavity. The microstructure of microwave boriding and conventional boriding has the same jagged characteristic. The Fe₂B phase and FeB phase grow along <002> tropism and form by nucleation and growth in both boriding methods. The activated boron atoms come from the boron atoms which decomposed by boriding medium and gaseous boride. It is proved that the activated boron atoms decomposed by boriding medium are more than those decomposed by gaseous boride.The hardness of microwave boriding is higher than that of conventional boriding. And their wear resistance are also better than that of conventional boriding. But their corrosion resistance is contradicted. The corrosion resistance of microwave boriding is better in 20% NaCl aqueous solution but less in 15% H₂SO₄ and 30% NaOH aqueous solution than that of conventional boriding.