Intensification of the carbonitriding process with the aid of dc

Conclusions

• 1. Connecting the specimen to the cathode and a copper rod to the anode of a dc source with current density i=0.35 A/cm² on the outer surface of the specimen brings about an approximate halving of the time of liquid carbonitriding.

• 2. When the specimen is connected to the anode, and the copper rod to the cathode of the dc source with i=0.35 A/cm², saturation does not occur.

• 3. Increased dissociation of salt at increased current density (to 0.8 A/cm²) leads to reduced content of diffusing elements in the saturated layer and to reduced hardness of the specimens.

• 4. Saturation occurs on account of positively charged carbon and nitrogen ions.

• 5. In thermochemical treatment using dc the repulsive energy between the metal atoms of the specimen increases. The smaller the difference between the attractive and repulsive energies of the atoms is, the higher is the rate of direct diffusion, and the higher is the degree of polarization of the surface atoms by the electrons of the electron cloud.

• 6. If the attractive energy of the metal atoms is greater than the repulsive energy, direct diffusion occurs; if the opposite applies, then reverse diffusion occurs.