煅烧温度对环保型莫来石多孔陶瓷结构和性能的影响

Effect of Sintering Temperature on Structure and Properties of Environmentally Friendly Mullite Porous Ceramics

摘要:

莫来石多孔陶瓷因其高强度和耐腐蚀等性能得到广泛地应用。然而，由于合成莫来石的原料高岭土的不可再生性及持续上涨的价格，寻找廉价易得的替代原料对于合成莫来石多孔陶瓷迫在眉睫。建筑废弃物的成分与高岭土相似，可作为高岭土的可行替代品之一。以建筑废弃物和Al₂O₃为主要原料，AlF₃为晶须催化剂，B₂O₃为烧结助剂，成功制备了环保型莫来石多孔陶瓷。通过阿基米德排水法、XRD和SEM等表征手段，深入探究了多孔陶瓷的晶相、微观形貌和物理化学特性。同时，研究了煅烧温度对莫来石多孔陶瓷结构和性能的影响规律及作用机制。结果表明，适当提升煅烧温度有助于莫来石晶须的生成，但过高的温度会导致晶须粗化和晶粒增大。当煅烧温度为1 200 ℃时，莫来石晶须的生长形貌最佳，晶须直径约为0.05—0.1 μm、长度为0.5—1 μm、长径比在15—20之间。随着煅烧温度增加，莫来石多孔陶瓷的开口孔隙率不断降低，抗折强度不断增强。当煅烧温度为1 200 ℃时，样品的开口孔隙率达到（61.78±0.72 ）%，抗折强度达到（3.74±0.46） MPa。因此，以建筑废弃物为主要原料可成功制备具有高气孔率的莫来石多孔陶瓷。本研究为建筑废弃物合成莫来石多孔陶瓷提供了可靠的理论支持，对降低生产成本及推动建筑废弃物资源化再利用等有重要理论价值和实际意义。

Abstract:

Mullite porous ceramics are widely used owing to their high strength and corrosion resistance. However， the escalating price and non-renewable nature of kaolin， the primary raw material for mullite synthesis， underscore the urgency of identifying cost-effective and readily available alternatives. The composition of construction waste is similar to kaolin， so it can be used as a viable alternative to kaolin. his study explores the utilization of construction waste and Al₂O₃ as the main raw materials， with AlF₃ serving as a whisker catalyst， and B₂O₃ as a sintering agent， in the fabrication of eco-friendly mullite porous ceramics. The crystalline phase composition， micro-morphology and physicochemical properties of porous ceramics were investigated by means of Archimedean drainage method， XRD and SEM. The effect of sintering temperature on its structure and properties and its mechanism were studied. Findings reveal that an optimal increase in sintering temperature facilitates mullite whisker formation， with whisker length exhibiting an initial growth followed by a decline as temperature escalates. When the sintering temperature was 1 200 ℃， the mullite whisker attains its optimum growth morphology， featuring a diameter of approximately 0.05—0.1 μm， length ranging between 0.5—1 μm， and a length-to-diameter ratio falling within 15—20 . Excessive sintering temperatures result in coarsening of mullite whiskers and enlargement of grain size. With the increase of sintering temperature， the open porosity of mullite porous ceramics decreased and the bending strength increased. Specifically， at 1 200 ℃， the sample achieved an open porosity of 61.78±0.72% and a bending strength of 3.74±0.46 MPa. Then， the mullite porous ceramics with high porosity can be successfully prepared by using construction waste as the main raw material. This study provided reliable theoretical underpinnings for the synthesizing mullite porous ceramics from construction waste， with profound implications for reducing the production costs and advancing construction waste recycling initiatives.