Caracterização de um reator de radiofrequência com acoplamento capacitivo para nitretação a plasma

Abstract

The thermochemical treatment of nitriding is characterized by the introduction of nitrogen on the crystalline structure of some alloys, one of the means of carrying out this treatment is through plasma reactors. Nowadays a lot of reactors type can be used for this purpose, where the most used is the directly current reactor, however studies with capacitively coupled radiofrequency (rfccp) reactors are not só plentiful. Then in this work nitriding in a rfccp plasma was studied as there’re few studies about the advantages that type of reactor can offer. Thus, this work is about the assembly and characterization of a rfccp reactor, and nitriding experiments of AISI H13 quenched and spheroidized, and the stainless steel UNS 3131673, having as main parameters the treatment pressure and the area asymmetry coefficient of the electrodes. The results indicate a good correlation between the parameters variation and expanded phases formations as well as greater amount of some iron nitrides. There was an indication that how higher the pressure and asymmetry higher the plasma reactivity and consequently more nitrogen introduction, that leads to increase number of nitrides, furthermore the reactor characterization was effective because all the proposed conditions for the rfccp regime had a similar behavior when performed with a directly current power supply in the same reactor. For the UNS 3131673 the treatment pressure of 5 torr and the asymmetry factor of 10-4 promote a homogenous surface treatment, while the AISI H13 quenched showed a good homogeneity in surface treatment for all the proposed conditions showing different hardness mechanisms, besides that the H13 spheroidized had a more homogenous treatment with 5 torr of pressure in two asymmetry conditions, in 0,06 and 10-4. Finally, it is concluded that the rfccp reactor is capable of nitriding and can be used in future works.