Thermal diffusion o versinte ring of ShKh powder

Conclusions

Experiments have shown that to oversinter powders in air and obtain a layer with high mechanical properties and porosity it is necessary to (a) add to the mixture elements which activate adhesion and oversintering, and (b) to heat quickly and reduce the time of holding at temperature.

For oversintering ShKh alloy steel powder it is satisfactory to add boron and silicon to the mixture and high frequency induction heat the layer for 80–100 sec at 1250°C. This produces high adhesion of the layer to the base and complete sintering.

To produce a porosity of 40–50% the layer is placed on the surface of the parts by spreading a pasty mixture. Less porosity may be obtained by pressing the mixture with a pressure of 2–4 tons/cm². In oversintering ShKh powder hydrolyzed ethyl silicate may be used as a plasticizer.