Lesson plan
Premelting
Premelting (also surface melting) refers to a quasi-liquid film that can occur on the surface of a solid even below the bulk material's melting point ( T_m ). The thickness of the film is temperature ( T )-dependent. This effect is common for all crystalline materials. Premelting shows its effects in frost heave, and, taking grain boundary interfaces into account, maybe even in the movement of glaciers. Considering a solid-vapour interface, complete and incomplete premelting can be distinguished. During a temperature rise from below to above T_m , in the case of complete premelting, the solid melts homogeneously from the outside to the inside; in the case of incomplete premelting, the liquid film stays very thin during the beginning of the melting process, but droplets start to form on the interface. In either case, the solid always melts from the outside inwards, never from the inside.
Article summary
Premelting (also surface melting) refers to a quasi-liquid film that can occur on the surface of a solid even below the bulk material's melting point ( T_m ). The thickness of the film is temperature ( T )-dependent. This effect is common for all crystalline materials. Premelting shows its effects in frost heave, and, taking grain boundary interfaces into account, maybe even in the movement of glaciers. Considering a solid-vapour interface, complete and incomplete premelting can be distinguished. During a temperature rise from below to above T_m , in the case of complete premelting, the solid melts homogeneously from the outside to the inside; in the case of incomplete premelting, the liquid film stays very thin during the beginning of the melting process, but droplets start to form on the interface. In either case, the solid always melts from the outside inwards, never from the inside.
Key claims
No claims recorded.
Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
No sources recorded.
Key claims and bibliography are generated from the same tracked claims and sources as the article page.