Research On Atmospheric Dielectric Barrier Discharge Plasma Nitriding

Under the condition of atmosphere,non-equilibrium plasma can be obtained by means of Dielectric barrier discharge (DBD) .It can deal with the surface modification of organic substance and the composition of ozone. DBD is a newer technology obtaining non-equilibrium plasma than before. It can restrain current from augmenting unboundedly,by using dielectric. It also can eliminate sparkle discharge and arc discharge in discharge clearance. Because DBD has the characteristics of high electric field and high electronic energy. In the discourse,nitriding parameters are studied,such as discharge voltage,discharge gap,nitriding temperature and nitriding time. These parameters can influence the performance of nitriding layer. Orthogonal design is made to better nitriding technology. By means of emission spectrum diagnose,the nitriding mechanism of atmospheric non-equilibrium plasma is analyzed. So main conclusions were gotten as follow:1. Nitriding technology at atmospheric pressure completed for 38CrMoAl controlled by DBD has been studied. This kind of technology can avoid the shortcomings of former technique and has the virtues of quick speed nitriding,deep thickness of white layer and diffusion layer.2. It can be found that activated particles mainly produced in the electric field are propitious to nitriding and the sample far away from electric field is nitrided depending on the activated particles produced by thermos-decomposition by experimental results. Improving surface hardness and thickness of nitride layer depend on increasing discharge voltage,reducing discharge gap,enhancing nitriding temperature and delaying nitriding time.3. The better technique parameters by means of orthogonal experiment were found out. They are discharge voltage of 11.25kV,discharge gap of 1mm,nitriding temperature of 500C and nitriding time of 4h. Experiential formula of relationships between trial factors and thickness of nitriding layer by means of regression analysis were also concluded,which establishes the basis of further research.4. Piston material 42CrMo was treated using DBD nitriding technology and tribological experiments of the nitrided 42CrMo were performed. The result indicated that wear-resistance of 42CrMo treated by atmospheric pressure DBD nitriding plasma technology was better than that of glow plasma nitrided 42CrMo.5. By means of emission spectrum diagnose,plasma state of N2and NHs formed in DBD was studied. The results indicated that DBD could obtain electrons of high energy. These electrons can produce plasma including Nj,electron,N,NH,N2+,H,H+ etc. by ionizing and decomposing NHs. Since these particles of high energy exist,nitriding technique at atmospheric pressure can be realized.