corrode vs crumble (away)

corrode

verb
  • To eat away bit by bit; to wear away or diminish by gradually separating or destroying small particles of, as by action of a strong acid or a caustic alkali. 

  • To have corrosive action; to be subject to corrosion. 

  • To consume; to wear away; to prey upon; to impair. 

crumble (away)

How often have the words corrode and crumble (away) occurred in a corpus of books? (source: Google Ngram Viewer )