en·crus·ta·tion
noun/ˌɪnkrʌˈsteɪʃn/
/ˌɪnkrʌˈsteɪʃn/
(also incrustation)
[uncountable, countable]- the process of forming a hard outer layer over something; the layer that is formed
结壳：在某物上形成坚硬的外层的过程；形成的层单词起源 Word Originearly 17th cent. (originally as incrustation): from late Latin incrustatio(n-), from the verb incrustare, from in- ‘into’ + crusta ‘a crust’.