Coagulation
Coagulation is the process where fine precipitates or phase particles grow together, reducing the specific surface area. This lowers the interfacial energy and improves mechanical properties.
Physical-Chemical Mechanism
Coagulation is the merging of fine particles or precipitates in a liquid. It occurs through adsorption of molecules onto particle surfaces, slowly bringing them together into larger clusters. The specific surface area of clusters is less than the sum of individual particle surfaces, reducing overall energy.
Metallurgical Relevance & Welding Risks
In welding, coagulation can influence the behavior of molten metal and precipitates. Too rapid coagulation can lead to uneven precipitate patterns, impairing weld quality. Too slow coagulation can result in dense precipitation or heavy molten metal, complicating filling and cooling.
Workshop Practice & Procedures
To achieve optimal coagulation, control melting temperature and time. High temperature or short time can cause rapid coagulation, while low temperature or long time can cause slow coagulation. For specific metals or alloys, determine the coagulation curve and adhere to it in the workshop.