组成及热处理对直接烧结尾矿微晶玻璃性能的影响

发布时间：2018-06-13 13:28

  本文选题：铁尾矿 + 微晶玻璃　； 参考：《沈阳建筑大学》2015年硕士论文

【摘要】：微晶玻璃是一种通过对晶化过程的有效控制将基础玻璃制成由晶相和玻璃相均匀分布的材料。它具有热膨胀系数低,机械强度大以及显著的耐腐蚀、耐磨、抗风化性能和良好的抗热震性能。在建筑、军事、航空、生物医学、机械工程等领域有广阔的应用前景。我国每年排放近五亿余吨金属尾矿,其中绝大部分被当作废弃物进行处理,这不仅破坏生态,污染环境,还会造成浪费资源。铁尾矿中Si O2含量一般都在60%以上,其余的成分也都符合玻璃的组成范围,适用于微晶玻璃的制备。本文以铁尾矿作为主要原料,制备Ca O-Mg O-Al2O3-Si O2系统微晶玻璃。目前微晶玻璃的制备方法主要有整体析晶法(熔融法)和烧结法,这两种方法都要经过高温熔融过程,生产周期长,能耗较高。本文针对上述问题,在考虑最大限度利用铁尾矿的前提下,重点围绕如何降低制备温度这一关键问题,提出配合料直接烧结制备尾矿微晶玻璃的新途径,并分别从基础氧化物组成配比,助熔剂的种类、掺量以及热处理制度的优化三方面开展对铁尾矿微晶玻璃烧结和析晶性能的影响研究。对基础氧化物组成的研究结果表明:四种主要氧化物对微晶玻璃析晶温度的影响主次为Ca OSi O2Al2O3Mg O,其中Ca O的掺量对析晶温度影响显著。随着Ca O掺量的增加,微晶玻璃的核化温度和晶化温度均呈逐渐下降趋势;试样的耐酸性能,体积密度和抗压强度都呈现先升后降的趋势。以析晶温度为考核指标,通过正交试验确定的基础氧化物组成为Si O2:55%,Ca O:18%,Mg O:10%,Al2O3:7%。该组成配合料的核化温度为830℃,晶化温度为925℃,析出的主晶相为透辉石,次晶相为钙长石。为了降低配合料的烧结温度,在有限的烧制时间内获得更好的烧结质量,本文在最佳基础氧化物组成的基础上添加不同种类、掺量的助熔剂,以起始烧结温度、烧结范围、烧结试样的体积密度为考核指标研究助熔剂对玻璃配合料烧结性能的影响。研究结果表明,Na2O+K2O与Ca F2复掺,掺量分别为4%时助熔效果最好,与掺不加助熔剂时相比,可使得起始烧结温度降低70℃,烧结温度范围扩大55℃,体积密度增大1.06g/cm3。在上述确定的基础氧化物组成及复掺助熔剂的基础上,本文又对配合料直接烧结法的热处理制度进行了研究。研究结果表明:随着烧结时间、晶化时间的增加,铁尾矿微晶玻璃的晶化率先增后减,晶体尺寸逐渐增大,试样的体积密度先升后降。在保证晶化率达到50%以上的前提下,以体积密度为考核指标,经正交优化后,最终确定热处理制度为烧结保温时间为60 min,晶化保温时间为60 min,烧结温度至晶化温度的升温速率10℃/min。
[Abstract]:Glass-ceramics is a kind of material which is made from crystalline phase and glass phase by controlling the crystallization process effectively. It has low coefficient of thermal expansion, high mechanical strength, excellent corrosion resistance, wear resistance, weathering resistance and good thermal shock resistance. In architecture, military, aviation, biomedical, mechanical engineering and other fields have broad application prospects. Nearly 500 million tons of metal tailings are discharged every year in China and most of them are treated as wastes which not only destroy the ecology pollute the environment but also cause waste of resources. The content of Sio _ 2 in iron tailings is generally over 60%, and the other compositions are in accordance with the glass composition range, which is suitable for the preparation of glass-ceramics. In this paper, CaO-Mg O-Al _ 2O _ 3-SiO _ 2 glass-ceramics were prepared from iron tailings. At present, the main preparation methods of glass-ceramics are monolithic crystallization (melting method) and sintering method. Both of these two methods need high temperature melting process, long production cycle and high energy consumption. In this paper, on the premise of making maximum use of iron tailings and focusing on the key problem of how to reduce the preparation temperature, a new way of directly sintering tailings glass-ceramics is put forward in this paper. The effects of the composition of basic oxides, the kinds of fluxes, the amount of fluxes and the optimization of heat treatment on the sintering and crystallization properties of iron tailings glass-ceramics were studied. The results show that the effect of four main oxides on crystallization temperature of glass-ceramics is mainly CaOSiO2Al2O3MgO, in which the amount of Cao has a significant effect on crystallization temperature. With the increase of Cao content, the nucleation temperature and crystallization temperature of glass-ceramics decreased gradually, and the acid resistance, bulk density and compressive strength of the samples increased first and then decreased. The basic oxide composition determined by orthogonal test is Sio _ 2: 55 and Ca _ O: 18, mg O _ (10) 10 and Al _ 2O _ 3: 7. The nucleation temperature and crystallization temperature are 830 鈩，

本文编号：2014175