Study On QPQ Fast Nitriding By Direct Current Field

The key of QPQ technology is nitriding process including preheating,salt bath nitriding and oxidation,and the advancement of integral property with workpiece is relation with nitriding technology.So nitriding process is studied profoundly by differdent ages of researchers in order to discovery good nitriding process,more suitable temperature and more excellent nitriding layer.The development of nitriding process is using from poison CN-to harmless CNO-and is more suitable to demand with the development of enviroment protection at present.And the dEpth of nitration case is from several micrometers to dozens of micrometer,all kinds of performance index of which are increased and the applied range of which is also expanded gradually.One kind of physics acceleration means-power supplied to sample is studied during salt bath and nitriding on the basis of QPQ nitriding proces.Nitration case is hard to form in some process,for example,the formation of nitration case is fast by bubbled into direct current under containing low cyanogen acid group and low temperature.Three kinds of materials including 45#steel,42CrMo and 316L are chose and nitration case of formation is studied under low cyanogen acid group in differdnt temperature.The result show that the balance point between corrode condition of sample and nitration case of formation is good under CNO-of 22 percent and ampere density of 0.1 A.Sample is measured by means of metallographical microscope,microhardness,X-ray diffraction instrument,scanning electronic microscope and electrochemical corrosion.The results show that the thickness of nitriding under the condition of electricity increase 50 percent than which under unpowered,and microhardness of the former condition is reduced 10%-20%.The measure result of XRD show that the content of component increase in sample after the power is supplied,and microstructure of nitration case is not compaction and the content of nitrogen element is higher than untreatment by observation under scanning electronic microscope,after the power is supplied.The detection result of electrochemical corrosion show that corrosion resistant of sample fall down after the power is supplied.Additional motivation force item0.22/(RT)[0.1]is deduced by studying mechanism of supplied power.