| At present, blast furnace slag is a waste of great emissions in our country’s metallurgical industry. Although it can be used as cement raw materials, but most of it cannot be used very well. The deposition of blast furnace slag will not only occupy large amount of land, but also cause severe environment pollution problem. However, there are plentiful calcium oxide and silicon oxide included in the blast furnace slag which can be used for recycling. We can produce foamed glass-ceramic which centralized favorable properties of both foam glass and glass ceramic by adding appropriate amount of agents and heating the batch. This thesis introduces the characters of foam glass-ceramic which has a small density, low coefficient of thermal expansion, high mechanical strength and good chemical stability etc. Based on this, we can solve the problems in which the waste of resources and environment pollution, at the same time, a qualified product can be achieved for daily life use.This paper mainly explores the feasibility to prepare foamed glass-ceramic by using blast furnace smelting slag of Baosteel Group Corporation. We choose blast furnace slag and cullet as raw materials and use TiO2and ZrO2and CaF2as composite nucleation agents. Our research focus on the content of blast furnace slag, the types and content of foaming agent, the content of foam stabilizer, the content of flux, the temperature and time of nucleation and crystallization.Through bulk density, water absorption rate, bending strength, chemical stability, infrared spectroscopy, thermal expansion coefficient and XRD diffraction pattern tests we can characterize the performance of foamed glass-ceramic, and then we find out the best conditions for the preparation of foamed glass-ceramic. Foaming temperature make a great influence on the distribution of the bubbles structure in the samples. If the foaming temperature is higher than980℃, the bubbles are easy to flowing. At this time, the samples will form the connected holes, and the distribution of bubbles is uneven. If the foaming temperature is below980℃, the bubbles in the samples are very small, their walls are thick. We cannot achieve good performance of foamed glass-ceramic at both conditions. Foaming time influence the size of bubbles. If the foaming time is longer than30min, the tiny bubbles will gather into large bubbles to form connected holes. If the foaming time is shorter than30min, the foaming agent will be able to play the role as impurities, which can affect the performance of foamed glass-ceramic. The best foaming temperature is980℃, foaming time is30minutes.We can improve the efficiency of slag by increasing the its content of samples. But the content of slag is not the more the better, we cannot get good performance of the sample with more slag content. When slag content is50%, the comprehensive performance of foamed glass-ceramic is the best, the bulk density is788kg/m3, water absorption is2.71%, the bending strength is14.20MPa, mass change rate is up to0.81%in acid solution, mass change rate is up to0.53%in alkali solution, and the average thermal expansion coefficient from50℃to300℃is8.6452×10-6/℃.Different foaming agents have different effects on the samples, we need to choose foaming agent according to the batch. After comparison, when the content of slag is50%, CaCO3is a good choice which the content is5-6%. The comprehensive performance of foamed glass-ceramic is the best, the bulk density is788-802kg/m3, water absorption is2.58～2.71%, the bending strength is14.50～14.75MPa, mass change rate is1.08～1.12%in acid solution, mass change rate is0.36～0.38%in alkali solution, and the average thermal expansion coefficient from50℃to300℃is8.6452×10-6/℃.In addition to the foaming agent, foam stabilizer and flux will also affect the performance of samples. We choose Na3PO4as foam stabilizer, and the best content is5～7%. The comprehensive performance of foamed glass-ceramic is the best, the bulk density is788-822kg/m3, water absorption is2.46～2.71%, the bending strength is14.20～14.68MPa. We choose Na2B4O7as flux, and the best content is7～8%. The comprehensive performance of foamed glass-ceramic is the best, the bulk density is763～788kg/m3, water absorption is2.71～2.88%, the bending strength is13.74～14.20MPa.Micro-crystallization process can influence the number and size of crystalline grain, so that it can affect the performance of the sample. We know the main crystalline phase is diopside(Ca(Mg,Al)(Si,Al)2O6) by the analysis of XRD diffraction spectrum, and there is a small amount of clinopyroxene(Ca(Ti,Mg,Al)(Si,Al)2O6). According to the analysis of single factor experiment, we can find out that the best nucleation temperature is750℃, the nucleation time is3hours, the crystallization temperature is950℃, and the crystallization time is2hours. |
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