Research On Preparation And Wear Resistance Of Complex Boriding Layer On Three Cone Bit

Gas carburized steel of 20CrMo is complexly boronized by using the method of power embedding while boron carbide and ferroboron are taken as the boronizing agent, ferrocyanide as nitriding agent, Na₂S₂O₃ and FeS as Sulfur infiltration agent. Analysing the organization and micro structure of infiltrated layer by metallographic microscope and X-ray diffractometer. The hardness, abrasive wear resistance and adhesive wear resistance of infiltrated layers are also tested.The result of XRD indicates that:Fe₂B, FeB, Fe₃C are produced in composite infiltrated layer of B-C; Fe₂B, Fe₃N, FeS, Fe₃C are produced in composite infiltrated layer of B-C-N-S. B-C and B-C-N-S composite infiltrated layers of ferroboron and the ones of boron carbide were produced in the experiment,whose maximum microhardness were respectively HV1932.6, HV1582.7 and HV1825.6, HV1445.9 and thicknesses of were respectively 51 ?m,38?m,42?m.m,62?m.The composite infiltrated layers are closely related with the base. Abrasion wear resistance Test:under different types of sandpaper, the relative wear resistance of corresponding composite infiltrated layers are increased 4.01?5.21 times,1.20?1.33 times,2.44-3.25 times,1.46?1.78 times when compared with the carburizing layer. Under different additional loads, the relative wear resistance are increased 1.89?4.01 times,1.09?1.29 times,1.54?2.47 times,1.29?1.46 times. Adhesive wear resistance test:under dry friction conditions, the relative wear resistance is increased 1.38?1.59 times,2.91?3.34 times,1.16?1.46 times,3.92-4.54 times; The friction coefficient decreased from 0.846 of the carburized layer to 0.687,0.500,0.753, 0.424 respectively. Under oil friction conditions, the relative wear resistance is increased 1.38?1.91 times,2.93-4.03 times,1.21?1.41 times,5.48?6.45 times;The friction coefficient decreased from 0.596 to 0.412,0.198,0.494,0.155 respectively. The abrasive wear resistance of ferroboron B-C composite infiltrated layer is the highest,and the adhesive wear resistance of boron carbide B-C-N-S composite infiltrated layer is the best.It can double the wear resistance of carburized parts when B-C and B-C-N-S composite infiltrated layer was prepared on the carburized parts. It is valuable to have further study to make the technology be applied to actual production of three-cone drill in the carburized surface.