1. Usoro nhicha nke akụrụngwa n'ihi na WBN, HBN, pyrophyllite, graphite, magnesium, iron na adịghị ọcha ndị ọzọ na-anọgide na CBN ntụ ntụ;Tụkwasị na nke ahụ, ya na ntụ ntụ na-ekekọta nwere adsorbed oxygen, vapor water, wdg, nke na-adịghị mma na-agbakọta.Ya mere, usoro nchacha nke r ...
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