本文選題：多孔陶瓷 + 陶瓷膜　； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)》2017年博士論文

【摘要】：多孔陶瓷具有耐高溫、抗酸堿、耐有機腐蝕、良好的生物惰性、使用壽命長、再生性能好等優(yōu)點,廣泛應(yīng)用在過濾、隔熱、吸音及生物骨骼等領(lǐng)域中。目前,多孔陶瓷制備所用的原料多為形貌不規(guī)則的顆粒,這些顆粒在燒結(jié)過程中的可控性差,存在不均勻的團聚收縮,導(dǎo)致陶瓷中出現(xiàn)死孔、半通孔,并伴隨孔率的燒結(jié)損失,影響了多孔陶瓷的實際應(yīng)用效果。本論文針對陶瓷孔結(jié)構(gòu)難以調(diào)控的問題,提出采用熱等離子體制備的球形致密顆粒進行多孔陶瓷制備。球形顆粒堆積體經(jīng)過燒結(jié),獲得孔結(jié)構(gòu)均勻、貫通、可調(diào)的多孔陶瓷。主要工作為:(1)以球形致密的SiO_2顆粒為原料進行緊密堆積造孔,球形顆粒堆積體經(jīng)過燒結(jié),相互接觸的顆粒之間形成頸部連接,獲得孔隙均勻貫通的多孔氧化硅陶瓷。結(jié)合動力學(xué)分析,對多孔陶瓷的燒結(jié)行為進行研究,結(jié)果發(fā)現(xiàn)球形致密的SiO_2顆粒具有熱穩(wěn)定性,在顆粒間頸部強化過程中孔隙得到完好的保留,制備的多孔陶瓷具有很好的燒結(jié)可控性。研究了顆粒堆積緊密度對陶瓷結(jié)構(gòu)和機械強度的影響,分析了球形顆粒造孔的特點。同時,獲得了原料粒徑對陶瓷孔徑的調(diào)控規(guī)律。最后,開展了 SiO_2多孔陶瓷滲透性研究,并探索了其在固液分離、油水分離和顆粒粒徑分級上的應(yīng)用性能。(2)為應(yīng)用于高溫環(huán)境,采用球形致密的Al_2O_3顆粒制備具有均勻貫通孔道的Al_2O_3多孔陶瓷。采用硅溶膠包覆原料顆粒的方法,有效降低了高強度氧化鋁陶瓷的燒結(jié)溫度,同時完好地保留了均勻、貫通、光滑的孔結(jié)構(gòu)。分析了硅溶膠包覆層與氧化鋁顆粒在燒結(jié)中生成莫來石頸部的過程,同時結(jié)合動力學(xué)分析開展了頸部生成的控制機理研究,結(jié)果表明莫來石頸部的生成受Al_2O_3顆粒表面Al3+釋放速率的控制。根據(jù)陶瓷微觀孔結(jié)構(gòu)的燒結(jié)變化,優(yōu)化了硅溶膠包覆量。同時,對莫來石強化陶瓷的作用機理進行了研究。最后,驗證了氧化鋁多孔陶瓷的高滲透性。(3)以超細(xì)球形Al_2O_3顆粒為原料堆積造孔,制備孔徑更小的Al_2O_3陶瓷膜。研究了超細(xì)球形Al_2O_3顆粒的燒結(jié)演化行為,發(fā)現(xiàn)球形顆粒堆積孔經(jīng)過均勻的燒結(jié)演化,成為均勻貫通的孔結(jié)構(gòu),展現(xiàn)出良好的燒結(jié)可控性。從超細(xì)球形顆粒的傳質(zhì)機理研究中,發(fā)現(xiàn)球形顆粒通過表面擴散進行傳質(zhì),燒結(jié)活化能達到721±12kJ/mol,說明顆粒有很好的熱穩(wěn)定性。在膜層與過渡層的匹配研究中,得到了膜層的優(yōu)化厚度4.8μm和適宜的燒結(jié)區(qū)間1200-1400℃。通過膜層和過渡層的一步燒結(jié)機理研究,發(fā)現(xiàn)介穩(wěn)相的納米球形Al_2O_3顆粒轉(zhuǎn)化為穩(wěn)定的α相后才發(fā)生顆粒間的傳質(zhì)燒結(jié),然而相轉(zhuǎn)化溫度與過渡層顆粒的燒結(jié)溫度基本一致,使兩層膜能夠?qū)崿F(xiàn)一步燒結(jié)。最后,將陶瓷膜用于懸浮顆粒分離,證明了其良好的應(yīng)用性能。(4)將孔結(jié)構(gòu)的可控?zé)Y(jié)技術(shù)運用到閉孔隔熱陶瓷領(lǐng)域,利用SiO_2空心顆粒殼體致密、高強的特點,制備了閉孔結(jié)構(gòu)支撐的SiO_2隔熱陶瓷。通過調(diào)控?zé)Y(jié)溫度和燒結(jié)助劑,研究了隔熱陶瓷孔結(jié)構(gòu)的燒結(jié)可控性,結(jié)果發(fā)現(xiàn)致密的顆粒殼體能夠很好地保護陶瓷閉孔結(jié)構(gòu),在高強頸部形成過程中,空心顆粒僅收縮3.3%。同時,通過添加燒結(jié)助劑進行了陶瓷晶型結(jié)構(gòu)的調(diào)控研究,揭示了方石英對隔熱陶瓷性能的影響機理。通過調(diào)節(jié)空心顆粒的大小和壁厚,實現(xiàn)了多孔陶瓷結(jié)構(gòu)和性能的調(diào)控。最后,建立了閉氣孔支撐結(jié)構(gòu)的隔熱性能模擬模型,模擬結(jié)果與實驗結(jié)果一致。
[Abstract]:Porous ceramics have the advantages of high temperature resistance, acid alkali resistance, organic corrosion resistance, good biological inertness, long service life, good regeneration performance and so on. It is widely used in the fields of filtration, heat insulation, sound absorption and biological skeleton. At present, the materials used in the preparation of porous ceramics are mostly irregular particles, and the controllability of these particles in the sintering process is poor. The existence of uneven agglomeration contraction leads to the appearance of dead pores, half through holes in ceramics and the sintering loss of pore ratio, which affects the practical application effect of porous ceramics. In this paper, spherical compact particles prepared by thermal plasma are prepared for porous ceramics. Through sintering, porous ceramics with uniform pore structure, through and adjustable are obtained. The main work is as follows: (1) dense spherical SiO_2 particles are used as raw materials for tight packing and pore formation. The sintering behavior of porous ceramics was studied. The results showed that the spherical compact SiO_2 particles had thermal stability. The pores were retained well during the strengthening of the intergranular neck. The prepared porous ceramics had good sintering controllability. The effects of particle packing tightness on the structure and mechanical strength of the ceramics were studied, and the spherical particles were analyzed. At the same time, the regulation of pore size of the raw material was obtained. Finally, the permeability of SiO_2 porous ceramics was studied and its application performance on solid liquid separation, oil water separation and particle size classification was explored. (2) the preparation of spherical compact Al_2O_3 particles for the application in high temperature environment has uniform penetration. The Al_2O_3 porous ceramics of the channel. The sintering temperature of high strength alumina ceramics was effectively reduced by the method of coating material particles by silica sol. At the same time, the uniform, through and smooth pore structure were well preserved. The process of producing mullite neck in the sintering of the silica sol coating and alumina particles in the sintering was analyzed, and the kinetic analysis was combined. The control mechanism of the neck formation was studied. The results showed that the formation of mullite neck was controlled by the Al3+ release rate on the surface of Al_2O_3 particles. According to the sintering changes of the micro pore structure of the ceramics, the coating amount of the silica sol was optimized. At the same time, the mechanism of the action of mullite strengthened ceramics was studied. Finally, the porous alumina ceramics were verified. High permeability. (3) the pore forming of superfine spherical Al_2O_3 particles was deposited and the Al_2O_3 ceramic membrane with smaller pore size was prepared. The sintering evolution behavior of the ultrafine spherical Al_2O_3 particles was studied. It was found that the spherical particles accumulated through the uniform sintering evolution and became uniform and permeable Kong Jie structure, showing good sintering controllability. In the study of mass transfer mechanism of the particles, it is found that the spherical particles are mass transfer through the surface diffusion, and the activation energy of the sintering is 721 + 12kJ/mol, indicating that the particles have good thermal stability. In the matching study of the film layer and the transition layer, the optimum thickness of the film layer is 4.8 Mu and the suitable sintering interval is 1200-1400 degrees. One step through the diaphragm and transition layer is obtained. The sintering mechanism was studied. It was found that the spherical Al_2O_3 particles in the metastable phase were converted to the stable alpha phase only after the mass transfer sintering. However, the phase conversion temperature was basically consistent with the sintering temperature of the transition layer particles, which made the two layers a one-step sintering. Finally, the ceramic membrane was applied to the separation of suspended particles, which proved its good application. (4) the controllable sintering technology of the pore structure is applied to the field of closed heat insulation ceramics. The SiO_2 insulation ceramics with closed structure support are prepared by using the compact and high strength characteristics of the SiO_2 hollow particle shell. The sintering controllability of the porous structure of the insulating ceramic is studied by controlling the sintering temperature and the sintering aids, and the compact particle shell is found. In the forming process of high strength neck, the hollow particles only shrink 3.3%., and the crystal structure of ceramics is regulated by adding sintering aids. The influence mechanism of the quartz on the properties of the insulating ceramics is revealed. The porous ceramic structure is realized by adjusting the size of the hollow particles and the thickness of the wall. Finally, a simulation model of the thermal insulation performance of the closed hole supporting structure is established, and the simulation results are consistent with the experimental results.

【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院過程工程研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TQ174.1

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