本文選題：熔鹽法 + 氧化鎂粉體　； 參考：《武漢科技大學(xué)》2010年博士論文

【摘要】： 熔鹽合成法是近代發(fā)展起來(lái)的一種無(wú)機(jī)材料合成方法。它采用一種或幾種低熔點(diǎn)的鹽類作為反應(yīng)介質(zhì),在高溫熔融鹽中完成合成反應(yīng),然后采用合適的溶劑將鹽類溶解,經(jīng)過(guò)濾、洗滌得到合成產(chǎn)物。由于熔鹽合成法具有工藝簡(jiǎn)單、成本低廉、合成溫度低、保溫時(shí)間短、合成產(chǎn)物的化學(xué)成分穩(wěn)定均勻等優(yōu)點(diǎn),因而在合成高熔點(diǎn)氧化物粉體和電子陶瓷粉體及其它功能粉體材料等領(lǐng)域廣泛應(yīng)用。 本論文在LiCl熔鹽介質(zhì)中合成了氧化鎂粉體,研究了原料種類、反應(yīng)溫度和保溫時(shí)間、熔鹽的相對(duì)含量對(duì)氧化鎂產(chǎn)物性能的影響,研究發(fā)現(xiàn)：熔鹽介質(zhì)中,采用MgCl2、CaCO3原料合成氧化鎂粉體,Mg2+離子與Ca2+離子發(fā)生置換反應(yīng),生成碳酸鎂等中間產(chǎn)物,其結(jié)晶程度比天然菱鎂礦高,分解反應(yīng)的反應(yīng)級(jí)數(shù)接近1,平均表觀活化能Ea=221.23kJ/mol;采用MgCl2、CaCO3原料和MgCl2、CaO原料制備的氧化鎂粉體,大小分布較均勻,主要由近似球狀形貌的顆粒組成,采用MgCl2·6H2O、CaCO3原料和MgCl2、MgCa(CO3)2原料制備的氧化鎂粉體形貌不一,大小分布不均勻,四種原料中,MgCl2·6H2O、CaCO3原料制備的氧化鎂活性相對(duì)較好；反應(yīng)溫度的升高和保溫時(shí)間的延長(zhǎng)有利于氧化鎂晶體的生長(zhǎng),氧化鎂產(chǎn)物晶胞體積變小,真密度增大,活性降低；增大LiCl的加入量有利于氧化鎂晶體的生長(zhǎng),氧化鎂產(chǎn)物的結(jié)晶度增大,平均粒徑增大,活性降低。 將熔鹽介質(zhì)中合成的氧化鎂水解,通過(guò)加入不同表面活性劑控制氫氧化鎂前驅(qū)體的形貌,從而制備不同形貌的氧化鎂粉體,研究了不同形貌氧化鎂粉體對(duì)硅鋼坯體性能的影響,結(jié)果表明：MgCl2·6H2O、CaCO3、LiCl反應(yīng)體系熱處理后,經(jīng)PEG溶液浸泡得到纖維狀氫氧化鎂,經(jīng)EDTA-PEG溶液浸泡得到四面體形貌氫氧化鎂,纖維狀的氫氧化鎂分解得到鏈狀形貌氧化鎂,四面體形貌的氫氧化鎂分解為氧化鎂后仍保持四面體形貌；MgCl2、CaCO3、LiCl反應(yīng)體系熱處理后,經(jīng)PEG溶液浸泡得到纖維狀氫氧化鎂,經(jīng)EDTA-PEG溶液浸泡,得到片狀形貌氫氧化鎂,纖維狀的氫氧化鎂分解得到多孔棒狀形貌氧化鎂,片狀形貌氫氧化鎂分解為氧化鎂后仍保持片狀形貌。分別將四種不同形貌的氧化鎂粉體噴涂于硅鋼坯體表面,經(jīng)退火處理后,通過(guò)對(duì)硅鋼坯體涂層的顯微結(jié)構(gòu)和硅鋼坯體磁性性能檢測(cè)發(fā)現(xiàn),多孔棒狀形貌氧化鎂噴涂的硅鋼坯體質(zhì)量較好,四面體形貌氧化鎂噴涂的硅鋼坯體質(zhì)量較差。 以熔鹽法制備氧化鎂為基礎(chǔ),在熔鹽介質(zhì)中合成了鎂鉻尖晶石和鎂鋁尖晶石,研究了原料和熔鹽種類、反應(yīng)溫度和保溫時(shí)間對(duì)鎂鉻尖晶石和鎂鋁尖晶石形成與生長(zhǎng)的影響。研究發(fā)現(xiàn)：原料和熔鹽種類對(duì)鎂鉻尖晶石形成與生長(zhǎng)影響顯著,選用NaCl-KCl復(fù)合熔鹽作為反應(yīng)介質(zhì),分別采用MgCl2、MgCl2·6H20和CaCO3原料替代MgO原料與Cr2O3反應(yīng),所合成的鎂鉻尖晶石晶體發(fā)育良好；反應(yīng)溫度的升高和保溫時(shí)間的延長(zhǎng)有利于鎂鉻尖晶石晶體的生長(zhǎng),鎂鉻尖晶石產(chǎn)物結(jié)晶程度增大,真密度增大,平均粒徑增大。鎂鋁尖晶石產(chǎn)物的形貌則與氧化鋁的形貌有關(guān),熔鹽種類對(duì)鎂鋁尖晶石產(chǎn)物的影響主要通過(guò)反應(yīng)物在不同熔鹽介質(zhì)中溶解度的不同來(lái)實(shí)現(xiàn)；反應(yīng)溫度的升高和保溫時(shí)間的延長(zhǎng)有利于鎂鋁尖晶石晶體的生長(zhǎng),鎂鋁尖晶石產(chǎn)物結(jié)晶程度增大,真密度增大,平均粒徑變大。 與NaCl和Na2C03單一熔鹽相比,NaCl-KCl復(fù)合熔鹽更有利于鎂鉻尖晶石和鎂鋁尖晶石晶體的形成與生長(zhǎng)。NaCl-KCl復(fù)合熔鹽介質(zhì)中合成鎂鉻尖晶石和鎂鋁尖晶石,“模板生長(zhǎng)”機(jī)理和“溶解-析出”機(jī)理同時(shí)并存,然而在合成鎂鉻尖晶石晶體過(guò)程中“溶解-析出”機(jī)理占主導(dǎo)地位,合成鎂鋁尖晶石晶體過(guò)程中,“模板生長(zhǎng)”機(jī)理起主要作用。
[Abstract]:The synthetic method of molten salt synthesis is an inorganic material synthesis method developed in modern times. It uses one or several kinds of low melting point salts as reaction medium to complete synthesis reaction in high temperature molten salt, then dissolve salt with suitable solvent, filter and wash the synthetic products. Because of the simple process and low cost of the molten salt synthesis process. Low temperature, short heat preservation time and stable and uniform chemical composition of synthetic products have been widely used in the synthesis of high melting point oxide powder, electronic ceramic powder and other functional powder materials.
In this paper, magnesia powder was synthesized in LiCl molten salt medium. The influence of the variety of raw materials, reaction temperature and holding time, the relative content of molten salt on the properties of Magnesium Oxide products was studied. It was found that in molten salt medium, magnesia powder was synthesized by using MgCl2, CaCO3 materials, Mg2+ ions and Ca2+ ions were replaced, and magnesium carbonate was formed. The intermediate product has a higher degree of crystallization than the natural magnesite. The reaction series of the decomposition reaction is close to 1 and the average apparent activation energy is Ea=221.23kJ/mol. The size distribution of magnesia powders prepared by MgCl2, CaCO3 raw materials and MgCl2, CaO raw materials is more uniform, mainly composed of particles similar to spherical morphology, using MgCl2 6H2O, CaCO3 raw materials and MgCl2, MgCa (CO3). The morphology of magnesia powder prepared by 2 raw materials is different and the size distribution is uneven. Among the four kinds of raw materials, MgCl2. 6H2O and CaCO3 are relatively good in the activity of Magnesium Oxide. The increase of the reaction temperature and the prolongation of the heat preservation time are beneficial to the growth of the Magnesium Oxide crystal, the smaller the size of the Magnesium Oxide product, the increase of the true density, the decrease of the activity, and the increase of the LiCl. The addition of Magnesium Oxide is beneficial to the growth of Magnesium Oxide crystals, the crystallinity of Magnesium Oxide products increases, the average particle size increases, and the activity decreases.
The Magnesium Oxide hydrolysate in the molten salt medium was prepared by adding different surface active agents to control the morphology of magnesium hydroxide precursor, thus preparing different morphologies of magnesia powder. The effect of different morphologies of magnesia powder on the properties of silicon steel body was studied. The results showed that after the heat treatment of MgCl2. 6H2O, CaCO3, LiCl reaction system, PEG solution was used. Magnesium hydroxide was soaked in EDTA-PEG solution, and magnesium hydroxide was soaked in tetrahedron. The fibrous magnesium hydroxide was decomposed to the chain shape Magnesium Oxide. The tetrahedral magnesium hydroxide was decomposed to Magnesium Oxide to retain the tetrahedral morphology, and the MgCl2, CaCO3, LiCl reaction system was soaked in PEG solution after heat treatment. Magnesium hydroxide is soaked in EDTA-PEG solution, and the sheet shape magnesium hydroxide is obtained. The fibrous magnesium hydroxide is decomposed into a porous Magnesium Oxide. The sheet shape magnesium hydroxide is decomposed to Magnesium Oxide and remains flaky. Four different morphologies of magnesia powder are sprayed on the surface of the silicon steel body. After annealing, the magnesium hydroxide has been annealed. The microstructure of the coating of silicon steel body and the magnetic properties of silicon steel body have been detected. It is found that the quality of the porous silicon steel body is better than that of the porous bar shape Magnesium Oxide, and the quality of the silicon steel body with the tetrahedral morphology of Magnesium Oxide is poor.
Magnesium chromium spinel and magnesium aluminum spinel were synthesized on the basis of the preparation of Magnesium Oxide by molten salt method. The effects of raw material and molten salt on the formation and growth of magnesium chromium spinel and magnesia spinel were studied. NaCl-KCl composite molten salt is used as reaction medium, and MgCl2, MgCl2, 6H20 and CaCO3 are used to react with MgO as raw materials to react with Cr2O3. The synthesized magnesium chromium spinel crystal is well developed. The increase of reaction temperature and prolongation of heat preservation time are beneficial to the growth of magnesium chromium spinel crystal, and the crystallinity of magnesia chromium spinel products increases, and the true density is true. The morphology of magnesium aluminum spinel products is related to the morphology of alumina, and the effect of the variety of molten salt on the products of magnesia aluminum spinel is mainly achieved by the difference of the solubility of the reactants in different molten salt medium. The increase of reaction temperature and the prolongation of the heat preservation time are beneficial to the growth of magnesium aluminum spinel crystal. The crystallinity of Al spinel increased, the true density increased, and the average particle size increased.
Compared with the single molten salt of NaCl and Na2C03, the NaCl-KCl compound molten salt is more beneficial to the formation of magnesium chromium spinel and magnesium aluminum spinel crystals and the synthesis of magnesium chromium spinel and magnesia spinel in the.NaCl-KCl compound molten salt medium. The mechanism of "template growth" and the "dissolution precipitation" mechanism coexist at the same time. However, the synthesis of magnesium chromium spinel crystals has been found in the synthesis of magnesium chromium spinel crystals. The mechanism of "dissolution precipitation" plays a dominant role in the process. In the process of synthesizing mg Al spinel crystal, the "template growth" mechanism plays a major role.

【學(xué)位授予單位】：武漢科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2010
【分類號(hào)】：TB383.3

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 鄭紅霞;廖新生;汪琦;李靜;;菱鎂礦粉及其料球分解的TG動(dòng)力學(xué)[J];遼寧科技大學(xué)學(xué)報(bào);2008年01期

2 蔣引珊,王玉潔,徐長(zhǎng)耀,薛俊;熱分析法研究礦物分解過(guò)程動(dòng)力學(xué)[J];長(zhǎng)春科技大學(xué)學(xué)報(bào);2000年01期

3 田中青,劉韓星,余洪滔,歐陽(yáng)世翕;微波介質(zhì)陶瓷粉體的合成方法研究[J];材料導(dǎo)報(bào);2003年12期

4 任慶利,劉斌,陳壽田;熱液環(huán)境下氫氧化鎂結(jié)晶形態(tài)機(jī)理研究[J];稀有金屬材料與工程;2004年01期

5 吳萬(wàn)伯;談?dòng)昧怄V礦生產(chǎn)輕質(zhì)碳酸鎂和氧化鎂[J];非金屬礦;1997年04期

6 李克;聶聰;呂功煊;劉建福;;Ni-Sm-MgO催化熱解CO制備碳納米管[J];分子催化;2005年06期

7 曹健，謝嘉寧，，張業(yè)鳳;熔鹽法合成BaFe_（11）Co_（0．5）Ti_（0．5）O_（19）磁性粉體[J];功能材料;1996年05期

8 朱伯銓;李雪冬;郝瑞;汪厚植;;在硫酸鈉熔鹽中合成莫來(lái)石的熱力學(xué)研究[J];硅酸鹽學(xué)報(bào);2006年01期

9 魯仁予;董俊;;菱鎂礦在氮?dú)鈿夥罩械臒岱纸鈩?dòng)力學(xué)[J];貴州大學(xué)學(xué)報(bào)(自然科學(xué)版);2009年02期

10 鄭榮光,方裕勛,羅明標(biāo),張燮;白云石循環(huán)法生產(chǎn)氧化鎂新工藝的研究[J];華東地質(zhì)學(xué)院學(xué)報(bào);1999年02期

本文編號(hào)：1841176