Similar to the conventional method to form glass by fusion of raw materials, by sol-gel method, is needed a sudden cooling to avoid crystallization? or the glass is formed only by heat treatment after the drying of gel depending only by the conditions of the sol-gel procedure?
As the sol-gel method is typically performed at low temperature, less than 100oC, there is NO need to sudden cooling. However, it is important to note that in many cases, it is difficult to avoid the crystallization of the gel even at low temperatures.
Hello. It depends on the composition of the system, its tendency to crystallization. In the literature they write that gelation (for example, based on ethyl silicate) comes with the release of heat. It is logical that if heat is removed (that is, the system is cooled), then a gel will form more intensively. As for crystallization, it is necessary to check experimentally (by X-ray phase analysis). Without calcination, the composition is usually an amorphous structure (like glass). During calcination, crystalline phases are most often formed if the system is to form them (for example, LiO2 - Al2O3 - SiO2)
Rafael Eduardo Ochoa Rodríguez
It will be useful for you to read the answers to a similar question. You are right, glass is formed only during heat treatment after the gel has dried, depending only on the conditions of the sol-gel process.
https://www.researchgate.net/post/In_sol_gel_process_how_to_convert_a_gel_into_glass@
- Badges
- Science topic
- Similar topics
- Psychology
- Cognitive Science
- Mind