K_2O,Na_2O,MgO对CBN的侵蚀机理研究

Corrosion mechanism of K_2O,Na_2O and MgO to cubic boron nitride

本文研究了K2O、Na2O、MgO等金属氧化物在高温下对立方氮化硼(CBN)的侵蚀程度及反应机理。结果表明:CBN在1200℃空气中处理1小时后,质量损失百分比为6.36%,单颗粒抗压强度从5.94 kg降为5.01 kg。CBN与K2O、Na2O、MgO分别按摩尔比2:1混合后同样在1200℃空气中处理1小时后,相应质量损失百分比分别为29.9%、25.2%和18.7%,单颗粒抗压强度分别降为2.37、2.84和3.00 kg。CBN的侵蚀程度与碱金属氧化物中金属元素的电负性有关,电负性越小,反应程度越大。氧化后CBN表面有许多裂纹和凹坑,这使CBN颗粒的强度降低,也表明CBN表面的氧化反应为各向异性。

The effect of K2O, Na2O and MgO on the corrosion properties of cubic boron nitride （CBN） and the reaction mechanism at high temperature were studied in this work. The results showed that when the CBN powders were heated in air atmosphere at 1 200℃ for 1h,6.36% of mass was lost and the single particle compressive strength was reduced from 5.94 kg to 5.01 kg. When CBN particles were mixed with K2O, Na2O, MgO respectively in the same molar ratio of 2 ： 1 and heated in the atmosphere at 1200℃ for lh, the mass loss of CBN was 29.9% , 25.2% , 18.7% ,and the strength was reduced to 2.37 kg, 2.84 kg, 3.00 kg correspondingly. The smaller the electro-negativity of metal element in the metal oxides, the bigger the mass loss of cubic boron nitride. There were many cracks on the surface of CBN, which resulted in the decreased strength of CBN and showed anisotropic oxidation on the surface.