烧结气氛对钢渣陶瓷晶相和性能的影响

利用钢渣制备陶瓷材料是钢渣资源化大宗利用的一条新途径.开展不同烧结气氛对钢渣陶瓷影响规律的研究,对推动钢渣陶瓷技术的应用具有重要意义.以20%钢渣和80%黏土为原料,分别在空气和氮气气氛下,制备了钢渣陶瓷样品,分析了其晶相转变和性能变化规律,并定量研究了氧分压对钢渣陶瓷中铁元素价态转变的影响机理.研究表明,在空气条件下烧结时,原料中的Fe2+发生氧化形成赤铁矿相,烧结样品物理性能要优于在氮气条件下烧结的样品,其抗压强度和吸水率为310 MPa和3.7%;而在氮气条件下烧结时,Fe2+形成铁铝尖晶石和铁辉石,烧结样品中形成的气孔大小和数量要大于和多于空气条件下的样品,这是导致其力学性能较差的一个主要原因.铁元素赋存晶相转变的氧分压临界范围为0.5%~0.75%:当分压低于0.5%时,可以获得以铁铝尖晶石和铁辉石为主的黑色或褐色陶瓷样品;当氧分压超过0.75%时,Fe2+开始发生氧化并形成Fe3+,逐渐形成赤铁矿并带来样品颜色为褐黄色或褐红色.增加烧结环境中氧气分压量是减少钢渣陶瓷产品黑心的一个重要手段.

Influence of sintering atmosphere on crystals and performance of slag ceramics

The preparation of ceramic materials is a new way of utilizing steel slag. It is important to investigate the influence of different sintering atmosphere on steel slag ceramics, which is of great significance in promoting the application of steel slag ceramic technology. In this paper, 20% of steel slag and 80% of clay were used as the main raw materials under different atmospheres, namely, air and nitrogen, and were prepared into steel slag ceramic bricks. The ceramic bricks' crystal phase evolvement and performance were analyzed, and the effect of partial oxygen pressure on the oxidation of Fe2+ in the steel slag ceramics was investigated quantitatively. The results show that under air conditions, the Fe2+ in raw materials is oxidized to form the hematite phase, and the compressive strength and water absorption of sintered samples were 310 MPa and 3. 7%, respectively, which is better than those of sintered samples under nitrogen conditions. Under nitrogen condition, the Fe2+ in the raw material is kept unchanged to form hercynite and pyroxene, and the size and quantity of pores in the sintered samples are greater than those under air conditions. This contributes to its poor mechanical properties. The critical range of the oxygen' s partial pressure for the transformation of Fe2+ and its crystals is 0. 5%-0. 75%. When the partial pressure is less than 0. 5%, a black or brown ceramic sample can be obtained and is mainly composed of hercynite and pyroxene. When the partial pressure exceeds 0. 75%, Fe2+ begins to oxidize to Fe3+, hematite begins to form gradually, and its color changes from a brown or brownish red color. Increasing oxygen partial pressure in the sintering environment is an effective way for avoiding black core in the sintered steel slag brick.