电子束熔炼法制备高纯金属钒的实验研究

Preparation of High Purity Metallic Vanadium by Electron Beam Melting

金属钒粉通过冷等静压成型和真空烧结成钒坯条后,采用电子束熔炼对钒坯条进行提纯研究。利用EPMA-1720电子探针(EPMA),Olympus-PMG3型光学显微镜(OM)、电感耦合等离子体发射光谱仪(ICP-AES)和氧氮氢分析仪分别对钒坯条和熔炼后钒锭的微观形貌、金相组织以及纯度进行观察和检测。实验研究结果表明:钒坯条存在孔隙,显微组织不致密,而电子束熔炼使得钒晶间孔隙得以消除,钒基体晶界结合紧密,组织变得致密均匀。经电子束熔炼,钒金属间隙杂质元素C,O,N的含量显著降低,去除率分别达到56.41%,79.17%和52.38%。而元素H由于本身含量较少,从熔炼前80×10-6降低到50×10-6,去除率为37.50%。钒金属非间隙杂质元素Si,Al,Mg,P,Cd的蒸气压与V的蒸气压压差较大,去除效果较明显。元素Mo,B属于高熔点难熔杂质,蒸气压比V的蒸气压小去除率偏低,钒金属经电子束熔炼后纯度达到99.932%。

After cold isostatic pressing and vacuum sintering of vanadium powder into vanadium billet,the purification of vanadium billet was studied by electron beam smelting.EPMA-1720 electron microprobe(EPMA),Olympus-PMG3 optical microscope(OM),inductively coupled plasma-atomic emission spectrometry(ICP-AES)and oxygen-nitrogen-hydrogen analyzer were used to investigate the micro-morphology,metallographic structure and purity of vanadium billet and melted vanadium ingot,respectively.The experimental results showed that voids existed in the vanadium billet and the microstructure was not compact.The electron beam melting could eliminate the intergranular pore,and the grain boundary of vanadium matrix was tightly bonded and the structure became compact and uniform.The contents of interstitial impurities C,O and N in vanadium metal decreased significantly after electron beam melting.The removal rates were 56.41%,79.17%and 52.38%,respectively.The removal rate of element H was only 37.50%because of its low content,which decreased from 80×10-6 to 50×10-6.As the vapor pressure differences between Si,Al,Mg,P,Cd and V were large,so the removal effect was obvious.Mo and B were refractory impurities with high melting point,and the vapor pressures were lower than that of V,so the removal rates were lower.The purity of vanadium metal was 99.932%after electron beam melting.