| Autor: |
Sidorenko, V. M., Sidorak, I. I., Parkheta, R. G. |
| Zdroj: |
Materials Science; November 1976, Vol. 11 Issue: 6 p642-647, 6p |
| Abstrakt: |
1.The anomalous behavior of hydrogen in technical iron at temperatures below 300°C is a result of a change in the character of diffusion of the grain-boundary component of the hydrogen flow in iron.2.Even a short-term exposure of technical iron at elevated temperatures to hydrogen at a low pressure leads to the formation of a network of through submicroscopic cracks and pores permeable by inert gases.3.Changes in the linear dimensions of cementite as a result of the magnetic transformation near 200°C lead to a large increase in the size of micropores at temperatures below 200°C.4.The character of the diffusion of hydrogen along grain boundaries in technical iron varies with temperature. At temperatures below 200°C the grain-boundary component of the diffusion constitutes largely a viscous laminar flow of molecular hydrogen through large-diameter pores. At temperatures above 200°C the grain-boundary flow of hydrogen in iron constitutes thermally activated molecular flow of a single layer of partially dissociated hydrogen migrating along the walls of small-diameter submicroscopic pores. With rising temperature and increasing degree of dissociation of hydrogen the dependence of the grain-boundary flow on the gas pressure on the specimen inlet side approaches more and more closely the square root law. |
| Databáze: |
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