本文選題：γ-Y_2Si_2O_7多孔陶瓷 + Y_2SiO_5多孔陶瓷　； 參考：《中國科學技術大學》2015年博士論文

【摘要】：多孔陶瓷具有孔隙率高、比強度高、密度低和熱導率低的優(yōu)點,其重要應用之一是作為高溫絕熱材料。但是,目前常見的多孔陶瓷絕熱材料(SiO2、Al2O3、YSZ和莫來石多孔陶瓷等)存在一些不足之處,比如：Si02多孔陶瓷的強度較低而且工作極限溫度低、A1203多孔陶瓷的熱導率較高、YSZ多孔陶瓷的燒結收縮率很大而且密度較高,以及莫來石多孔陶瓷強度較低等。所以,研發(fā)綜合性能更加優(yōu)良的新型多孔陶瓷是未來的趨勢。本工作選取熔點高、熱導率極低且高溫熱學和化學穩(wěn)定性好的γ-Y2Si207和X2-Y2Si05作為新型多孔陶瓷的基體材料,通過有機泡沫浸漬法和原位反應發(fā)泡-注凝法制各樣品并詳細表征其微觀結構,深入研究所制各樣品的微觀結構與性能(壓縮強度和熱導率)間的關系及其高溫性能。 首次制備出γ-Y2Si2O7多孔陶瓷。以Y2SiO5粉末和硅溶膠為原料,采用有機泡沫浸漬法結合反應燒結過程成功制備了高孔隙率和純相的γ-Y2Si207多孔陶瓷。制備的材料是白色開孔的網(wǎng)眼狀多孔陶瓷,孔尺寸分布為200～700μm,孔道相互連通且孔筋分布均勻。增加涂覆漿料次數(shù)可顯著提高樣品的性能。另外,由PEI預處理海綿模板得到樣品的性能最佳,如高孔隙率(84.5%)、相對較高的壓縮強度(1.28MPa)和低密度(0.62g/cm3)。 以Y203和Si02粉末為原料,N-羥甲基丙烯酰胺為單體,通過原位反應發(fā)泡-注凝法制備出具有獨特多級孔結構的γ-Y2Si207多孔陶瓷,包括70～250gm的球形大孔和骨架上0.1～1.5μm的小孔。多級孔結構中小孔的形成機制主要來自于原位反應燒結過程,而且該結構的熱穩(wěn)定性極佳,可維持到1700℃。此外,改進制備工藝—使用無毒環(huán)保的明膠作為凝膠劑,通過原位反應發(fā)泡-注凝法合成出高性能的γ-Y2Si207多孔陶瓷。樣品具有優(yōu)異的力學和熱學性能,當孔隙率為64.3～89.3%時,樣品的壓縮強度可達46.5～3.4MPa；對于孔隙率為57.2～90.0%的樣品,室溫熱導率為0.918～0.147W/(m·K). γ-Y2Si207多孔陶瓷還具有優(yōu)良的高溫性能,包括良好的高溫強度和較低的熱循環(huán)燒結收縮率。所制備的γ-Y2Si207多孔陶瓷具有輕質、高孔隙率、高強度、低熱導率和熱穩(wěn)定性高的優(yōu)點。 采用發(fā)泡-注凝工藝,通過研究制備途徑(原位反應燒結和直接燒結法)和燒結溫度對樣品結構與性能的影響,發(fā)現(xiàn)了目前Y2Si05多孔陶瓷相關研究工作中存在較大燒結收縮率的原因：所使用的原料為精細的Y2Si05粉末,其燒結活性較高；另外漿料的固含量較低。隨后提出了解決辦法：以Y203和Si02粉末為原料,使用高固含量的漿料并通過原位反應發(fā)泡-注凝法來制備Y2Si05多孔陶瓷。獲得的Y2Si05多孔陶瓷擁有優(yōu)良的綜合性能,如1.0～4.7%的低收縮率、0.79～0.88g/cm3的低密度、82.1-80.1%的高孔隙率和3.54～6.90MPa的高強度(燒結溫度1350～1550℃。另外,樣品還具有較低的熱導率、優(yōu)異的高溫相穩(wěn)定性和較高的熱穩(wěn)定性。 采用無毒的明膠為凝膠劑,經原位反應發(fā)泡-注凝法制備出高性能的Y2SiO5多孔陶瓷,并研究了材料的結構與強度和熱導率之間的關系以及其高溫性能。樣品具有獨特的多級孔結構和相互連通的三維網(wǎng)絡結構。Y2SiO5多孔陶瓷具有優(yōu)異綜合性能,如高孔隙率(60.2-87.1%)、線收縮率小(6.3～4.5%)、體密度低(1.74～0.52g/cm3)和壓縮強度高(38.2～0.90MPa)。樣品還有極低的熱導率,室溫下的熱導率僅有0.513～0.119W/(m.K)(孔隙率：60.2～87.1%)。Y2SiO5多孔陶瓷還具有優(yōu)異的高溫熱穩(wěn)定性和高溫力學性能。 本論文發(fā)展出兩類釔硅氧多孔材料的可控制備方法,通過調節(jié)工藝參數(shù)能夠控制樣品的孔徑尺寸或者孔隙率(結構),從而獲得不同性能的樣品。制備的釔硅氧多孔陶瓷具有輕質、低熱導率、高孔隙率、高強度、優(yōu)良的熱穩(wěn)定性,以及優(yōu)異的高溫力學性能的優(yōu)點,可成為應用前景廣闊的高溫絕熱材料。
[Abstract]:Porous ceramics have the advantages of high porosity, high specific strength, low density and low thermal conductivity. One of the important applications of porous ceramics is to be a high-temperature thermal insulation material. However, there are some shortcomings in the common porous ceramic insulation materials (SiO2, Al2O3, YSZ and mullite porous ceramics), for example, the low strength and working limit of Si02 porous ceramics. Low temperature, high thermal conductivity of A1203 porous ceramics, high sintering shrinkage of YSZ porous ceramics and high density of porous ceramics, and low strength of mullite porous ceramics. Therefore, it is the future trend to develop a new porous ceramic with better comprehensive properties. This work selects high melting point, very low thermal conductivity, high temperature thermal and chemical stability. Good gamma -Y2Si207 and X2-Y2Si05 are used as matrix materials of new porous ceramics. The microstructure of each sample is characterized by organic foam impregnation and in situ reaction foaming and coagulation method. The relationship between microstructure and properties (compressive strength and thermal conductivity) of the samples and its high temperature properties are investigated.
Gamma -Y2Si2O7 porous ceramics were prepared for the first time. With Y2SiO5 powder and silica sol as raw materials, high porosity and pure phase of gamma -Y2Si207 porous ceramics were prepared by organic foam impregnation and reaction sintering process. The preparation materials were white open hole mesh porous ceramics with Kong Chi inch distribution of 200~700 mu m, interconnected channels and holes. The distribution of the reinforcement is uniform. Increasing the number of coating sizes can significantly improve the performance of the sample. In addition, the PEI pretreatment of the sponge template has the best performance, such as high porosity (84.5%), relatively high compression strength (1.28MPa) and low density (0.62g/cm3).
Using Y203 and Si02 powders as raw materials and N- hydroxymethyl acrylamide as a monomer, the porous structure of gamma -Y2Si207 porous ceramics with unique multilevel pore structure was prepared by in situ reaction foaming and coagulation method, including 70 to 250gm spherical pores and 0.1 to 1.5 micron pores on the skeleton. The formation mechanism of the small pores in the multistage pore structure mainly comes from the in-situ reaction sintering. The thermal stability of the structure is excellent and can be maintained at 1700 degrees C. In addition, the preparation process is improved - using non-toxic environmental gelatin as a gel, the high performance gamma -Y2Si207 porous ceramics are synthesized by in situ reaction foaming coagulation method. The sample has excellent mechanical and thermal properties. When the porosity is 64.3 to 89.3%, the sample is compressed. The strength can reach 46.5 to 3.4MPa; for the samples with porosity of 57.2 to 90%, the thermal conductivity of the chamber is 0.918 ~ 0.147W/ (M. K). The porous ceramics of gamma -Y2Si207 also has excellent high temperature properties, including good high temperature strength and low thermal cycle sintering shrinkage. The prepared gamma -Y2Si207 porous ceramics are light, high porosity, high strength and low. The advantages of high thermal conductivity and high thermal stability.
By studying the effect of the preparation methods (in situ reaction sintering and direct sintering) and the sintering temperature on the structure and properties of the samples, the reasons for the larger sintering shrinkage of Y2Si05 porous ceramics are found: the raw materials used are fine Y2Si05 powder, and their sintering activity is higher. In addition, the solid content of the slurry is low. Then the solution is put forward: using Y203 and Si02 powder as the raw material, using the slurry with high solid content and using in situ reaction foaming and coagulation to prepare the Y2Si05 porous ceramics. The obtained Y2Si05 porous ceramics have excellent comprehensive properties, such as 1 to 4.7% low shrinkage, 0.79 to 0.88g/cm3 low density, 82. The high porosity of 1-80.1% and the high strength of 3.54 ~ 6.90MPa (sintering temperature 1350~1550 C). In addition, the sample also has low thermal conductivity, excellent high-temperature phase stability and high thermal stability.
High performance Y2SiO5 porous ceramics were prepared by in situ reaction foaming and coagulating method with non-toxic gelatin. The relationship between the structure and the strength and thermal conductivity of the materials and its high temperature properties were studied. The samples have unique multi-stage structure and interconnected three-dimensional network structure of.Y2SiO5 porous ceramics with excellent synthesis. Properties, such as high porosity (60.2-87.1%), low linear shrinkage (6.3 ~ 4.5%), low bulk density (1.74 ~ 0.52g/cm3) and high compressive strength (38.2 ~ 0.90MPa). Samples have very low thermal conductivity. The thermal conductivity at room temperature is only 0.513 to 0.119W/ (m.K) (porosity: 60.2 to 87.1%).Y2SiO5 porous ceramics with excellent thermal stability and high temperature force. Learning performance.
In this paper, two types of yttrium silicon oxygen porous materials have been developed to control the sample size or porosity (structure) by adjusting the parameters of the process. The prepared yttrium silicon oxygen porous ceramics have light, low thermal conductivity, high porosity, high strength, excellent thermal stability and excellent thermal stability. The advantages of high temperature mechanical properties can be applied to high temperature insulation materials.
【學位授予單位】：中國科學技術大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TQ174.1

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本文編號：2071005