Study On Process And Mechanism Of Ion N-C-O Multielements Penetration In An Atmosphere Of Air And Organic Liquid

The ion chemical heat treatment has been applied extensively because it can improve the surface of metal materials performance remarkably. But currently, the pure NH3 or N2-H2 mixtures has been adopted for the production and study, there have been some hidden troubles in nitriding heat process because NH3 can pollute the environment and the used high-pressure bottle and H2 gas exist safety hidden troubles. As is well known, the saving energy and reducing wastage"green heat treatment"are developing tendency in nowadays. The environmental protection and safe problems of media in ion nitriding and multi-element penetration processes are deserved alike.The air is zero costs gas source. There is no ways more than enough to go around in nature, and more it will not result in the pollution of the environment. In this disseratation, the process and mechanism of ion N-C-O multi-element penetration in an atmosphere of air and organic liquid are studied according to the discharge theory of plasma and principle of chemical heat treatment in low temperature. In order to prepare the basic study on ion N-C-O multi-element penetration in an atmosphere of air and organic liquid, the ion nitrocarburizing of nitrogen and methane is carried out. Then the ion N-C-O multi-element penetration in an atmosphere of air and gasoline or ethanol is designed and studied. The microstructure, phase composition and hardness gradient distribution of multi-element penetrating layers of 40Cr steel which were ion N-C-O multi-element penetrated in different voltage and media have been researched by some test methods such as Microhardness apparatus, Microcopy and X-ray diffractometer etc. what's more the abrasion and causticity of samples which were ion multi-element penetrated are mensurated by wearing test and electrochemical analysis.The theoretical analysis and experimental results show that: (1) The ion N-C-O multi-element penetration process in an atmosphere of air and organic liquid is feasible. (2) There are similar microstructures and phase compositions in the penetrating layers of the samples which were nitrocarburized in an atmosphere of nitrogen and methane, ion N-C-O multi-element penetrated in an atmosphere of air and gasoline or ethanol. The penetrating layers are composed of light layer, diffusion layer and basis. And the penetrating layer depth and phase compositions relate with media species, cathode voltage and mixture ratio of gases. The parameter matches of cathode voltage and mixture ratio of gases that benefiting to media dissociated to yield active nitrogen atoms will increase the volume percent ofε-Fe3N phase with high nitrogen content in the penetrating layers, the proper nitrogen, carbon and oxygen contents enhance their surface hardness. (3) The common speciality is existing active nitrogen atom which mostly comes from the ionization of nitrogen molecule because of non-elastically collision between the H2+,H+ion produced by methane, gasoline and ethanol and the neutral nitrogen molecule in nitrocarburizing in an atmosphere of nitrogen and methane and ion N-C-O multi-element penetration in an atmosphere air and gasoline or ethanol. (4) With the increment of ratio of methane, gasoline and ethanol, the multi-element penetration effect existes a maximum. The effect is best when the ratio of nitrogen and methane, air and gasoline, air and ethanol is 25:3, 25:2.5 and 25:6 respectively. The overfull flux of methane, gasoline and ethanol will produce quantities active carbon atoms which baffle the diffusion of nitrogen atom. (5) In plasma gasoline and ethanol oxidation reforming reaction takes place. On the one hand it decreases oxygen press. On the other hand, it can produce hydrogen which can promote the production of active nitrogen. (6) The increment of cathode voltage is propitious to increase electric field energy which facilitates the production of active atoms. But the exorbitant cathode voltage with correspond lower gas pressure reduces the content of active atoms. There are best effects when the cathode voltages are 600V and 640V respectively in nitrocarburizing in nitrogen and methane and ion N-C-O multi-element penetration in air and ethanol.A study of C,N,O adsorption on the Fe(111) surface at different coverage , the formation energy of compound and solid solutions in the Fe-C(N,O) system and the diffusion of C,N,O in theα-Fe are carried out with the first principles calculation. The calculation results show that: (1) C,N,O adsorption on the Fe(111) are strong chemical adsorption. O adsorption is easy at the low coverage, while N and C with wider coverage scope. (2) The carbide of iron forms the most easily, then are Fe3N,Fe4N,FeN and Fe2N. With the increase of nitrogen content, the formation energy decreases. The formation of solid solution with nitrogen in austenitic is easier than in ferrite. (3) The formation energy of Fe2-3(C,N) is lower than that of Fe2-3N. A few of carbon can promote the formation of nitride. (4) C,N and O assemble and diffuse in octahedral clearance of iron easily. The diffusion activation energy of N among C,N and O is the smallest, and superfluous carbon will result in the increase of the diffusion activation energy of N.Ion N-C-O penetration process in air-organic liquid comprises three courses which are condition of each other and close interaction: the production of active atoms, the reactions of atoms with the surface and the diffusion of atom in sample. Among them, the production of active atom is manipulative step. The ion N-C-O multi-element penetration process presented in this thesis posses wide application value.