Ua ntej yuav muas hlau rau coj mus muag los yog industrial purposes, Tuam txhab uas muag yuav tsum paub seb cov hardness ntawm hlau yog. Hardness hais txog yuav ua li cas ib hlau yog thaum nws tawm los resisting yas deformation thiab indentation. Nws kuj hais txog li cas zoo li cas ib hlau yog kom deb li deb uas qhia kuj scratching thiab tej. Muaj cov… Nyeem ntxiv »
