(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用粉末冶金法制備六方氮化硼(hBN)含量為8%、10%和12%(質(zhì)量分數(shù))的Ni-20Cr/hBN自潤滑復(fù)合材料，研究其在600、700和800 ℃的高溫氧化行為，繪制氧化動力學(xué)曲線，并利用XRD和SEM分析氧化層的成分和形貌。結(jié)果表明：Ni-20Cr/hBN復(fù)合材料在600 ℃氧化300 h后氧化反應(yīng)不明顯；在700和800 ℃氧化300 h后出現(xiàn)較明顯的氧化產(chǎn)物，主要有Cr2O3、NiCr2O4和CrBO3。氧化反應(yīng)前100 h的氧化行為符合氧化增量動力學(xué)曲線，800 ℃的氧化拋物線速率常數(shù)比700 ℃的高一個數(shù)量級；而氧化100 h后，由于B2O3的熔融，試樣質(zhì)量保持不變或甚至呈下降趨勢；在700 ℃下連續(xù)氧化膜基本形成，起到較好的保護作用，在800 ℃時氧化膜出現(xiàn)不同程度的腐蝕。
關(guān)鍵字: 鎳基自潤滑復(fù)合材料；hBN；高溫氧化；動力學(xué)
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The Ni-20Cr/hBN self-lubricating composites were prepared by powder metallurgy with hBN contents of 8%, 10% and 12% (mass fraction). Its oxidation behaviors were studied in air at 600, 700 and 800 ℃. The oxidation kinetics curves were gained, and the oxide compositions and morphologies were analyzed by XRD and SEM. The results show that the oxidation of Ni-20Cr/hBN composites oxidized at 600 ℃ for 300 h is not obvious. The oxide products consist of Cr2O3, NiCr2O4 and CrBO3 at 700 and 800 ℃ for 300 h. The kinetic curves of the composites obey the parabolic rate law at the beginning oxidation of 100 h, and the oxidation parabolic rate at 800 ℃ is a magnitude higher than that at 700 ℃. Meanwhile, the masses of Ni-20Cr/hBN composites become stable or even decrease after 100 h due to melt of B2O3. The oxide scales are complete and do well in protection at 700 ℃, while are corroded to some extend at 800 ℃.
Key words: Ni-based self-lubricating composites; hBN; high temperature oxidation; kinetics
