**4. Conclusion**

132 Heat Treatment – Conventional and Novel Applications

– 164.65kJ/mol (energy of ionization - 1.69 eV) (8)

NH3+ → N + + 3H – 2298.29kJ/mol (energy of ionization and dissociation-23.67 eV) (9)

NH3+ = N + 2H +Н+ – 2216.96 kJ/mol (energy of ionization and dissociation - 22.83 eV) (10)

NH3 = NH2 + H+ + e- – 1656.08 kJ/mol (energy of ionization and dissociation - 17.05eV) (11)

NH2 = NH + H+ + e- – 1582.16 kJ/ mol (energy of ionization and dissociation – 16.29 eV) (12)

NH+ = N + H+ – 334.67 kJ/ mol (energy of ionization and dissociation – 3.44 eV) (14)

H2↔2H – 434.95 kJ/ mol (energy of dissociation – 4.48 eV) (16)

N2↔2N – 948.54 kJ/ mol (energy of dissociation – 9.77 eV) (17)

**Figure 12.** Reactions, going in close proximity of the cathode space in a medium of ammonia, carbon

On the basis of the above exposed data the following probable mechanism of carbonitriding

As the energy of dissociation and ionization of ammonia and carbon dioxide is higher, in the area of the cathode fall of the glow discharge probably atomic carbon should form initially

dissociation of the ammonia molecule and the breakage of the carbon-oxygen bonds go close to the cathode in the zone of the negative glowing. Consequently, processes of ionization of

→ С + О2 and atomic nitrogen by the reaction NH3+ = N + 3H. The

in a saturating medium of ammonia and corgon could be suggested:

– 1242.47 kJ/ mol (energy of ionization and dissociation – 12.79eV) (13)

– 1381.51 kJ/ mol (energy of ionization and dissociation – 14.22 eV) (15)

NH3 → HN3 + + e-

NH = NH+ + e-

N = N+ + e-

dioxide and argon

by the reaction СО2+ + е-


ionization of the ammonia molecules and the carbon dioxide molecules, close to the cathode in the zone of the negative glowing diffusion capable nitrogen and carbon are obtained, which impact the surface and diffuse at a certain distance into the material. The process of saturation of the metal surface depends only on the concentration of the atomic carbon and nitrogen in the plasma and the temperature of the article, while the electron/ion impact plays role for ensuring the necessary temperature of the details.

**Chapter 7** 

© 2012 Biedunkiewicz, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Biedunkiewicz, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Methodology of Thermal Research** 

The mechanism of nanostructural carbides synthesis, and chemical activity of nanoparticles in oxidizing environments, even occurring in trace amounts in high-purity gases, require application of precise methods and performing investigations for a wide range of parameters. The methodology of investigation and the way of determination of selected synthesis conditions have been described in this work. Appropriate selection of investigation methodology enables understanding of process mechanisms, performing

Good basis for analysis of the processes proceeding with participation of solids are kinetic studies. Kinetic studies can be carried out under isothermal or non-isothermal conditions. The transitions with participation of solid reagents usually proceed in many stages. Each step should be treated as an independent process. The measurements indispensable for identification of process stages and reagents are usually carried out by methods of thermal analysis. There are elaborated different methods of kinetic studies. They are the subject of

Methods of process kinetics are of great significance for materials engineering. In work [2], for example, kinetics of carbothermal synthesis of β-SiC was investigated; in work [3,4] kinetics and mechanism of carbothermal reduction of MoO3 to Mo2C; in work [5] kinetics of thermal decomposition of NH4VO3; in work [6] kinetics of nanometric ceramic materials

Kinetic studies of manufacturing process of carbides of the metals, e.g. titanium, vanadium, niobium, tantalum or silicon, are of particular significance. These metal carbides belong to the group of ceramic materials known as conventionally hard materials, high wear and oxidation resistance. This results from the character of chemical bound and crystallographic structure. The fabrication of ultrafine-grain ceramics by powder- metallurgical processes

quantitative analysis and then correct determination of their conditions.

synthesis in argon and their oxidation in dry air were investigated.

**in Materials Engineering** 

Additional information is available at the end of the chapter

Anna Biedunkiewicz

http://dx.doi.org/10.5772/51415

**1. Introduction** 

ongoing discussion [1].

## **Author details**

Angel Zumbilev *Technical University of Sofia-Plovdiv Branch, Bulgaria* 
