2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、<p>  Preparation and properties of glass–ceramics derived from blast-furnace</p><p>  slag by a ceramic-sintering process</p><p><b>  Abstract</b></p><p>  Glass–c

2、eramics 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 the sintering properties of blast-furna

3、ce slag glass and the results glass–ceramics have desirable mechanical properties. The main crystalline phase of the obtained glass–ceramic is gehlenite (2CaO_Al2O3_SiO2). A high microhardness of 5.2 GPa and a bending st

4、rength higher than 85 MPa as well as a water absorpti</p><p>  1. Introduction</p><p>  Glass–ceramics are fine-grained polycrystalline materials formed when glasses of suitable compositions are

5、 heat-treated and thus undergo controlled crystallization to reach a lower energy crystalline state [1]. Since the early 1960s, using waste to prepare glass–ceramics has been developed in Russia, by employing slag of fer

6、rous 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 from waste incin</p><p>  The conventional approa

7、ches to sinter glass–ceramics usually include two steps: first vitrifying raw materials at a high temperature (1300–1500 8C) and then following a nucleation and crystal growth step. The disadvantage of the conventional r

8、oute is that it is difficult to vitrify 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

9、fine glass powders take place simulta</p><p>  The blast-furnace slag is formed in the processes of pig iron manufacture from iron ore, contains combustion residue of coke, fluxes of limestone or serpentine,

10、 and other materials. If the molten slag was cooled quickly by high-pressure water, fine grain glass of vitreous Ca–Al–Mg silicate can be formed [10]. This suggests the blast-furnace slag can be used as a glass source to

11、 make sintered glass–ceramics and vitrifying raw materials at high-temperature step can be omitted. The free glass surfa</p><p>  2. Experimental procedure</p><p>  The slag (provided by Anyang

12、iron Corporation of China) was pulverized by ball milling for about 24 h (size in the range of 10–20 mm), and then blended with 5–10 wt% potash feldspar powder. The mixtures were ball milling for 2 h. We use K5, K8 and K

13、10 to denote the weight percent of potash feldspar in the samples.</p><p>  The process used in our study is illustrated in Fig. 1. The blended powders were uniaxially pressed in a steel die at room temperat

14、ure, using a hydraulic pressure of 40–60 MP a without any binder. The obtained green bodies were sintered in air at nucleation temperature of 720–760℃ and crystallization temperature of 800–900℃ for different times (from

15、 20 to 60 min), with heating rates of 2–5 ℃/min, followed by a hightemperature treatment at 1200℃</p><p>  The blended powders were examined by differential scanning calorimetry (DSC) (Labsys, Setaram, Franc

16、e) in air with a heating rate of 10 ℃/min from room temperature to 1100 ℃. The phase of the blast-furnace slag and obtained glass–ceramics were examined by X-ray diffraction (XRD) (Model D/MAX-3B, RIGAKU, Japan). The sam

17、ples surfaces were polished and corroded in HF (5 vol%) for 20 s and then observed by scanning electron microscopy (SEM) (Model JSM-5610LV, JEOL, Japan). The density of the samples</p><p>  3. Results and di

18、scussion</p><p>  Table 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

19、 of the blast-furnace slag.</p><p>  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 grea

20、tly enhance the crystallization. Due the presence of Fe2O3 and TiO2, other nucleating agents are not needed. A small amount of gehlenite exists in the amorphous glass( Fig.2). The primary-precipitated phase can act as he

21、terogeneous nucleating centers. In fact, crystallization is favored at the surface of glass particles and prim</p><p>  Fig.3shows the DSC curves of the blended mixture. The small endothermic peak (737–741 ℃

22、) indicates the molecular rearrangement in this temperature. The exothermic peak (800–900 ℃) corresponds to the crystallization reaction of the glass. With 5 wt% potash feldspar additive, the glass powders have an intens

23、e exothermic effect at 840 ℃, indicating the formation and growth crystals. With more potash feldspar additive, the exothermic peak increases slightly. Therefore, a nucleation</p><p>  temperature in the ran

24、ge of 720–760 ℃ and a crystallization temperature in the range of 800–900 ℃ were employed, respectively.</p><p>  Fig.4shows the SEM images of the samples. The results show that crystallization is mainly ind

25、uced by surface nucleation in samples K8 and K10, but by both surface and bulk nucleation in sample K5 since crystallization take place throughout the entire volume in the sample. Uniform, ultrafine crystalline grains wi

26、th sizes of 2–5 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 t</p><p>  制備及鼓風(fēng)爐產(chǎn)生的玻

27、璃陶瓷渣性能燒結(jié)過程</p><p><b>  摘要</b></p><p>  微晶玻璃利用地面合成高爐礦渣和鉀肥由傳統(tǒng)陶瓷燒結(jié)路線長石添加劑。結(jié)果顯示5 wt%的鉀長石可以提高高爐礦渣微晶玻璃的燒結(jié)性能,結(jié)果玻璃陶瓷具有理想的力學(xué)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和彎曲強度高于85兆帕以

28、及吸水率低于0.14%獲得?!?009愛思唯爾集團有限公司和Techna S.r.l.保留所有權(quán)利。</p><p><b>  1.簡介</b></p><p>  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(jié)晶接受較低的能源結(jié)晶狀態(tài)。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(jīng)制定了雇用采礦和化學(xué)工業(yè),黑色和有色金屬冶金,灰燼和廢物渣

29、。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(chǎn)-7]。用廢準備玻璃陶瓷工業(yè)應(yīng)用對環(huán)境的保護以及顯著。</p><p>  對燒結(jié)玻璃陶瓷的傳統(tǒng)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材料(1300-15008C條),然后下面的成核和晶體生長的一步。而傳統(tǒng)路由的缺點是,它是很難玻璃化的原材

30、料和在此步驟中能耗高。另一種制造方法,生產(chǎn)燒結(jié)玻璃。陶瓷,其中玻璃燒結(jié)和細粉末結(jié)晶同時發(fā)生,最近有報道。</p><p>  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?zé)Y(jié)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(wǎng)站,因此沒有任何可能發(fā)生的結(jié)晶

31、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(jié)方法相比,一本研究的顯著優(yōu)點是由于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(yù)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(jié)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(tǒng)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。<

32、;/p><p><b>  2.實驗過程</b></p><p>  礦渣(由安陽鋼鐵公司提供的中國)是由球磨粉碎約24小時(10?20毫米范圍的大?。?,然后用5?10 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。</p><p>  在我們的研究中使用的過程如圖所示。1?;旌戏勰┑膯屋S壓在在

33、室溫下鋼模具,采用無任何粘結(jié)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(jié)溫度為720-760℃成核和結(jié)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。</p><p>  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

34、線衍射儀(XRD)(型號D/MAX-3B,日本理學(xué),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(SEM)(型號的JSM -5610LV,日本JEOL,日本)觀察。樣品的密度是衡量阿基米德方法。顯微硬度的測量采用硬度測試儀具有測量力的9.807ñ和負載時間為20(型號HX的-1000TM,太明,中國)第彎曲的3毫米_ 4 mm_強度試驗樣品尺寸三十○毫米精心打磨和測試,分別由一個萬能試驗

35、機(茲維克/羅爾Z030,德國)。對玻璃陶瓷的耐化學(xué)性進行了測試以化學(xué)蝕刻的方法。對樣品進行了腐蝕,在鹽酸(0.5%卷)和NaOH(0.5%卷)為95小時,然后計算出的剩余率的解決方案。</p><p><b>  3.結(jié)果與討論</b></p><p>  表1顯示了用X射線熒光取得高爐礦渣的化學(xué)成分。該混合物的名義成分混合情況見表2。圖.2顯示了高爐爐渣的X射線衍

36、射圖案。</p><p>  可以看出,涉及的渣化學(xué)成分二氧化硅,其主要成分為氧化鈣,氧化鋁和氧化鎂。 Fe2O3和TiO2的成核劑法,可大大提高結(jié)晶。由于二氧化鈦的Fe2O3和其他核劑的存在是沒有必要的。一gehlenite少量存在于非晶玻璃(圖.2)。該小學(xué)析出相可以作為異相成核中心。事實上,看好的結(jié)晶顆粒表面的玻璃和初級沉淀階段,因為沒有可能形成原子核周圍材料的阻抗,同時考慮到水晶玻璃體積變化。</p

37、><p>  圖.3顯示了在混合混合物的DSC曲線。小吸熱峰(737-741℃)表示,在此溫度下分子重排。放熱峰(800?900℃)對應(yīng)的玻璃晶化反應(yīng)。與5 wt%的鉀長石添加劑,玻璃粉末在840℃強烈放熱效果,表明晶體的形成和生長。隨著越來越多的鉀長石添加劑,放熱峰值略有增加。因此,核在720-760℃范圍內(nèi),并在800-900℃溫度范圍內(nèi)被雇用的結(jié)晶溫度分別。</p><p>  圖.4顯

38、示樣品的SEMimages。結(jié)果表明,誘導(dǎo)結(jié)晶,主要是通過表面的K8和K10樣品中的成核,但雙方在樣品表面,由于K5的成核結(jié)晶體在整個樣本中的整個卷的地方。制服,與2-5毫米大小的超細晶粒存在于樣品K5的。與此相反,也有在K8和經(jīng)X射線衍射圖案(圖.5)所示K10的階段,只有少量的結(jié)晶。堿性長石晶體是眾所周知的,但他們給優(yōu)秀眼鏡無法在實際的時間周期結(jié)晶。他們已成功研制開發(fā)的粉狀玻璃傾向在適當(dāng)?shù)臒崽幚韉evitrify在近期的作品。我們的

39、研究結(jié)果表明:玻璃5 wt%的鉀肥,可成功地在熱處理脫?;L石鉀長石粉,因為可以作為熔劑燒結(jié)過程從而降低燒結(jié)溫度,降低了玻璃的粘度代理商。在燒結(jié)過程中的粘度和結(jié)晶值是非常重要的。如果黏度值過低,結(jié)晶會太快,它可以阻礙燒結(jié),并創(chuàng)建大量的孔隙。另一方面,如果黏度值過高,結(jié)晶是困難的。因此,控制玻璃的粘度是非常重要的。隨著越來越多的鉀長石添加劑,玻璃的結(jié)晶速率會下降。根據(jù)我們的實驗數(shù)據(jù)中添加5 wt%的鉀長石將是一個適當(dāng)?shù)臄?shù)額。</p&

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