氧化钨/碳SPS原位合成WC硬质合金的XPS研究

XPS Study on WC Bulk in-Situ Synthesized through Directly Carbonized Tungsten Oxide by SPS

摘要:

以WO3＋14.5%C（质量分数,下同）的混合粉作为原始粉末,采用放电等离子烧结（SPS）在不同温度下烧结保温3 min,直接一步合成致密WC硬质合金.借助于X射线光电子能谱（XPS）分析了合成样品的元素价态变化,探讨了SPS原位合成的过程和机理.结果表明：随着烧结温度的升高,样品中的W元素的价态逐步由氧化态的W＋6,W^＋5,W^＋4过渡到单质W^0＋和碳化物态的W^＋2;而样品中的碳元素价态却逐步由单质碳转变为化合碳,氧化物态的晶格氧强度逐渐降低,以碳氧键存在吸附的氧强度逐渐增强.XPS分析结果表明,在SPS原位合成中,WO3首先被碳还原,并经历了一系列中间钨氧化物状态后得到金属钨,然后金属钨进一步发生碳化反应最终形成WC.

Abstract:

The WC bulk was in-situ synthesized with mixed WO3 +14.5%C powders by spark plasma sintering at different temperatures. The chemical valence state of W, C, O in the samples were investigated by XPS. The results indicates that the element W changes from W+6, W+5, W+4 in oxidative state to metallic W0 and W+2 in carbide state with the rising of synthesizing temperature. It reveals that WO3 is firstly reduced by carbon to form intermediate tungsten oxides such as WO2.72, WO2, and metallic W in the reduction process, then the carbonization reaction occurs, and the WC is formed finally.