纳米NbC-Co复合粉末的原位合成及其在烧结硬质合金中的应用  

In situ synthesis of nanoscale NbC-Co composite powder and its application in sintered cemented carbides

作　　者：王海滨[1] 占王彬 刘雪梅[1] 刘超 侯超[1] 宋晓艳[1] WANG Haibin;ZHAN Wangbin;LIU Xuemei;LIU Chao;HOU Chao;SONG Xiaoyan(College of Materials Science and Engineering,Key Laboratory of Advanced Functional Materials,Education Ministry of China,Beijing University of Technology,Beijing 100124,China;Xiamen Tungsten Co.,Ltd.,Xiamen 361009,China)

机构地区：[1]北京工业大学材料科学与工程学院,新型功能材料教育部重点实验室,北京100124 [2]厦门钨业股份有限公司,福建厦门361009

出　　处：《粉末冶金工业》2021年第1期9-16,共8页Powder Metallurgy Industry

基　　金：国家自然科学基金资助项目(51631002,51621003);北京市自然科学基金资助项目(2202011)。

摘　　要：首先探究了以Nb2O5、Co和炭黑的原位反应制备纳米NbC-Co复合粉末的最佳工艺,然后以此复合粉作为添加剂,研究了其对低压烧结制备WC-Co硬质合金组织和性能的影响。热力学计算和原位反应实验结果表明,原料粉末中未添加Co时存在明显的Nb2O5→NbO2→NbC两段反应过程,而添加Co不仅显著降低了反应发生温度,还使Nb2O5的还原、碳化两步反应几乎同时进行。通过优化原料粉末的配碳量、反应温度,制备的NbC-Co复合粉物相纯净,具有较低的氧含量,平均粒径为82 nm。添加纳米NbC-Co使制备的WC-Co硬质合金的晶粒尺寸由0.7μm降低至0.48μm,组织更为均匀,室温和高温硬度均明显提高。即使温度达到800℃,制备的WC-12Co-1NbC硬质合金的硬度仍维持在890HV30。The optimum synthesis process of nanoscale NbC-Co composite powder by in situ reactions of Nb2O5,Co and carbon black was investigated in the present work.Then the obtained composite powder was used as an additive of WC-Co to prepare cemented carbide bulk material by HIP-sintering.The effects of the additive on the microstructure and property of the WC-Co cemented carbide were studied.By means of thermodynamic calculations and in situ reaction experiments,it shows that the transition of Nb2O5 in the reactions with carbon black proceeds in the sequence of Nb2O5→NbO2→NbC.The addition of Co,not only decreases the reaction temperature,but also results in simultaneous occurrence of reduction and carburization reactions which normally take place in two steps.After the optimization of the carbon content and reaction temperature,the synthesized NbC-Co composite powder has no impurity phases,a low oxygen content and a mean particle size is 82 nm.The addition of nanoscale NbCCo lead to a decrease in grain size from 0.70μm to 0.48μm and a more homogeneous microstructure in the prepared WC-Co cemented carbide.Moreover,the hardness of the cemented carbide is significantly enhanced at both room and high temperatures due to the addition of nanoscale NbC-Co.Particularly at 800 oC,the WC-12 Co-1 NbC cemented carbide still maintaines a hardness of 890 HV30.

关 键 词：纳米NbC-Co复合粉 原位合成 硬质合金 高温硬度 

分 类 号：TG135.5[一般工业技术—材料科学与工程]