| 摘要 |
Use as ultrahard material of at least one oxide of formula MO2, in which M denotes at least one tetravalent metal chosen from Ti, Zr, Hf, V, Nb, Cr, Mo, U, Mn, Re, Ru, Os, Rh, Ir, Pd, Pt, Ce, Pr, Nd, Tb, Ge, Sn, Pb and Te, in the form of metastable phase obtained at high pressure or at high pressure and high temperature. When powders of such oxides are compressed, in fact, new phases are seen to appear whose hardness, estimated especially by determining the compression modulus, is very high. These ultrahard phases can be characterised especially by their X-ray diffraction pattern.
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