1、Preparation and properties of glassceramics derived from blast-furnaceslag by a ceramic-sintering processAbstractGlassceramics were synthesized using ground blast-furnace slag and potash feldspar additives by a conventional ceramic-sintering route. The results show 5 wt% potash feldspar can enhance

2、the sintering properties of blast-furnace slag glass and the results glassceramics have desirable mechanical properties. The main crystalline phase of the obtained glassceramic is gehlenite (2CaO_Al2O3_SiO2). A high microhardness of 5.2 GPa and a bending strength higher than 85 MPa as well as a wate

3、r absorption lower than 0.14% were obtained. 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.1. IntroductionGlassceramics are fine-grained polycrystalline materials formed when glasses of suitable compositions are heat-treated and thus undergo controlled crystallization to reach a lowe

4、r energy crystalline state 1. Since the early 1960s, using waste to prepare glassceramics has been developed in Russia, by employing slag of ferrous and non-ferrous metallurgy, ashes and wastes from mining and chemical industries 2. Lately, the waste of coal combustion ash, fly ash and filter dusts

5、from waste incinerators, mud from metal hydrometallurgy, pass cement dust, different types of sludge and glass cullet or mixtures of them have been considered for the production of glass ceramics 37. Using waste to prepare glassceramics is significant for industrial applications as well as for envir

6、onment protection 8The conventional approaches to sinter glassceramics usually include two steps: first vitrifying raw materials at a high temperature (13001500 8C) and then following a nucleation and crystal growth step. The disadvantage of the conventional route is that it is difficult to vitrify

7、the raw materials and the high energy consumption in this step. An alternative manufacturing method to produce sintered glass. ceramics, in which sintering and crystallization of fine glass powders take place simultaneously, has recently been reported9. In such route fine glass powders are pressed a

8、nd sintered, and the crystallization occurs with densification. However, this route also needs a short time to vitrify raw materials at high temperature for preliminary glass-making.The blast-furnace slag is formed in the processes of pig iron manufacture from iron ore, contains combustion residue o

9、f coke, fluxes of limestone or serpentine, and other materials. If the molten slag was cooled quickly by high-pressure water, fine grain glass of vitreous CaAlMg silicate can be formed 10. This suggests the blast-furnace slag can be used as a glass source to make sintered glassceramics and vitrifyin

10、g raw materials at high-temperature step can be omitted. The free glass surfaces are preferable sites for devitrification and thus crystallization may occur without any nucleating agent. Therefore, the finely ground slag powder can used as the main component of parent glass. Comparing with the two s

11、intered methods mentioned above, a remarkable advantage of the present study is absent of vitrification step because of the using of blast-furnace slag. Thus a low energy cost and manufacture simplicity can be expected. However, in our previous studies glassceramics prepared with pure blastfurnace s

12、lag show poor properties 11. Therefore, some sintering additives are needed. In this study, we show when using blast-furnace slag to prepare glassceramics by a conventional ceramics route, if suitable amount of potashfeldspar is added. Glassceramics with high microhardness andbending strength as wel

13、l as lower water absorption can be obtained.2. Experimental procedureThe slag (provided by Anyang iron Corporation of China) was pulverized by ball milling for about 24 h (size in the range of 1020 mm), and then blended with 510 wt% potash feldspar powder. The mixtures were ball milling for 2 h. We

14、use K5, K8 and K10 to denote the weight percent of potash feldspar in the samples.The process used in our study is illustrated in Fig. 1. The blended powders were uniaxially pressed in a steel die at room temperature, using a hydraulic pressure of 4060 MP a without any binder. The obtained green bod

15、ies were sintered in air at nucleation temperature of 720760 and crystallization temperature of 800900 for different times (from 20 to 60 min), with heating rates of 25 /min, followed by a hightemperature treatment at 1200The blended powders were examined by differential scanning calorimetry (DSC) (

16、Labsys, Setaram, France) in air with a heating rate of 10 /min from room temperature to 1100 . The phase of the blast-furnace slag and obtained glassceramics were examined by X-ray diffraction (XRD) (Model D/MAX-3B, RIGAKU, Japan). The samples surfaces were polished and corroded in HF (5 vol%) for 2

17、0 s and then observed by scanning electron microscopy (SEM) (Model JSM-5610LV, JEOL, Japan). The density of the samples was measured by the Archimedes method. The microhardness was measured by a microhardness-tester (Model HX- 1000TM, Taiming, China) with a measuring force of 9.807 N and a load time

18、 20 s. Samples for bending strength tests with dimensions of 3 mm _ 4 mm_ 30 mm were carefully polished and tested by a universal testing machine (Zwick/Roell Z030, Germany). The chemical resistance of glassceramics was tested by a chemical etch method. The samples were corroded in the HCl (0.5 vol%

19、) and NaOH (0.5 vol%) solution for 95 h and then the residual rate was calculated.3. Results and discussionTable 1 shows the chemical composition of blast-furnace slag obtained by X-ray fluorescence. The nominal composition of the blended mixture is given in Table.2. Fig.2 shows the XRD patterns of

20、the blast-furnace slag.It can be seen that the chemical composition of the slag involves SiO2, CaO, Al2O3, and MgO as its major components. Fe2O3 and TiO2 that act as nucleating agents can greatly enhance the crystallization. Due the presence of Fe2O3 and TiO2, other nucleating agents are not needed

21、. A small amount of gehlenite exists in the amorphous glass( Fig.2). The primary-precipitated phase can act as heterogeneous nucleating centers. In fact, crystallization is favored at the surface of glass particles and primary-precipitated phase, since nuclei may be formed without the impedance of t

22、he surrounding materials, taking into account the volume variation from glass to crystal.Fig.3shows the DSC curves of the blended mixture. The small endothermic peak (737741 ) indicates the molecular rearrangement in this temperature. The exothermic peak (800900 ) corresponds to the crystallization

23、reaction of the glass. With 5 wt% potash feldspar additive, the glass powders have an intense exothermic effect at 840 , indicating the formation and growth crystals. With more potash feldspar additive, the exothermic peak increases slightly. Therefore, a nucleationtemperature in the range of 720760

24、 and a crystallization temperature in the range of 800900 were employed, respectively.Fig.4shows the SEM images of the samples. The results show that crystallization is mainly induced by surface nucleation in samples K8 and K10, but by both surface and bulk nucleation in sample K5 since crystallizat

25、ion take place throughout the entire volume in the sample. Uniform, ultrafine crystalline grains with sizes of 25 mm exist in sample K5. In contrast, there are only small amounts of crystalline phases in K8 and K10 as shown by XRD patterns (Fig.5). Alkali feldspar crystals are known to give excellen

26、t glasses but they are unable to be crystallized in practical periods of time. They have been successfully developed by exploiting the tendency of powdered glass to devitrify during appropriate heat treatments in recent works . Our results show glass powder with 5 wt% potash feldspar can be successf

27、ully devitrified during the heat treatment because potash feldspar can act as fluxing agents during sintering process thus decrease the sintering temperature and reduce the viscosity of glass. The value of viscosity during sintering and crystallization is very important. If the value of viscosity is

28、 too low, crystallization will be too fast, which can hinder sintering and creates a large amount of porosities. On the other hand, if the value of viscosity is too high, crystallization is difficult. Therefore, controlling the glass viscosity is very important. With more potash feldspar additive, t

29、he crystallization rate of the glass will decrease. According to our experimental data add 5 wt% potash feldspar will be an appropriate amount.制備及鼓風爐產生的玻璃陶瓷渣性能燒結過程摘要微晶玻璃利用地面合成高爐礦渣和鉀肥由傳統陶瓷燒結路線長石添加劑。結果顯示5 wt的鉀長石可以提高高爐礦渣微晶玻璃的燒結性能，結果玻璃陶瓷具有理想的力學性能。所獲得的主要晶相玻璃Ceramic是gehlenite（2CaO氧化鋁二氧化硅）。高硬度的5.2 GPa和彎曲強度

30、高于85兆帕以及吸水率低于0.14獲得。2009愛思唯爾集團有限公司和Techna S.r.l.保留所有權利。1簡介微晶玻璃是細晶材料時形成合適的眼鏡組成熱處理，從而達到控制結晶接受較低的能源結晶狀態。20世紀60年代初以來，利用廢舊準備微晶玻璃在俄羅斯已經制定了雇用采礦和化學工業，黑色和有色金屬冶金，灰燼和廢物渣。最近，煤炭燃燒廢棄物粉煤灰，粉煤灰從濕法冶煉金屬灰和過濾粉塵廢棄物焚化爐，泥漿，通過水泥粉塵，污泥和玻璃碎玻璃或它們的混合物，不同類型的被認為對玻璃陶瓷3生產-7。用廢準備玻璃陶瓷工業應用對環境的保護以及顯著。對燒結玻璃陶瓷的傳統方法通常包括兩個步驟：首先在一個較高的玻璃化溫度的原

31、材料（1300-15008C條），然后下面的成核和晶體生長的一步。而傳統路由的缺點是，它是很難玻璃化的原材料和在此步驟中能耗高。另一種制造方法，生產燒結玻璃。陶瓷，其中玻璃燒結和細粉末結晶同時發生，最近有報道。該高爐礦渣是在豬鐵從鐵礦石制造過程中形成的，包含燃燒殘留焦炭，石灰石或蛇紋石通量和其他材料。如果冷卻液渣用高壓水，玻璃體鈣鋁鎂硅酸鹽細晶玻璃能迅速形成。這表明，高爐爐渣可作為源使用，使玻璃在高溫燒結步玻璃陶瓷和玻璃化原料可以省略。免費的脫玻化玻璃表面是最好的網站，因此沒有任何可能發生的結晶成核劑。因此，磨細礦渣粉可以作為家長玻璃的主要成分。與上述兩種燒結方法相比，一本研究的顯著優點是由于

32、玻璃化高爐礦渣使用STEP缺席。因此，一個低能源成本和制造簡單可以預期。然而，在我們以前的研究顯示玻璃與陶瓷材料制備純礦渣性能差。因此，一些燒結添加劑是必要的。在這項研究中，我們證明在使用高爐礦渣準備通過一條路線傳統陶瓷玻璃陶瓷，如果potashfeldspar適量添加。玻璃硬度高andbending強度以及低吸水性，陶瓷可以得到。2實驗過程礦渣（由安陽鋼鐵公司提供的中國）是由球磨粉碎約24小時（1020毫米范圍的大小），然后用510 wt的鉀長石粉混合。該混合物球磨2小時我們使用K5號的K8和K10來表示鉀肥樣品中長石重量百分比。在我們的研究中使用的過程如圖所示。1。混合粉末的單軸壓在在室溫下鋼模具，采用無任何粘結劑40-60國會議員的液壓壓力。所獲得的綠色尸體在空氣中燒結溫度為720-760成核和結晶800-900不同時間（從20到60分鐘）溫度，加熱速率2-5/分鐘一個高溫之后，在1200處理。該混合粉末進行了研究用差示掃描量熱法（DSC）在空氣中（Labsys，塞塔拉姆，法國）108C/min速率從室溫加熱到11008C條。該高爐礦渣，并獲得微晶玻璃相，用X射線衍射儀（XRD）（型號D/MAX-3B，日本理學，日本）。樣品表面進行了拋光和侵蝕的短波20秒（5 vol的），然后用掃描電子顯微鏡（SE