本文關(guān)鍵詞： 熱障涂層 氧化鋯 熱物理性能 熱導(dǎo)率 晶格缺陷　出處：《清華大學(xué)》2016年博士論文　論文類(lèi)型：學(xué)位論文

【摘要】：隨著工業(yè)的發(fā)展,燃?xì)廨啓C(jī)和飛機(jī)發(fā)動(dòng)機(jī)的工作溫度不斷提高,這對(duì)高溫合金部件的熱防護(hù)提出了越來(lái)越嚴(yán)苛的要求。具有極低熱導(dǎo)率的熱障涂層可以有效的降低合金部件表面的溫度,從而延長(zhǎng)其使用壽命,提高熱機(jī)工作效率。目前,應(yīng)用最為廣泛的熱障涂層材料是具有t′相結(jié)構(gòu)的6-8%氧化釔穩(wěn)定氧化鋯(YSZ)。本文以YSZ等稀土氧化物和氧化鋯組成的二元固溶體為基礎(chǔ),通過(guò)摻雜構(gòu)造多元固溶體材料體系,系統(tǒng)研究了缺陷對(duì)材料晶格結(jié)構(gòu)以及熱物理性能的影響,并對(duì)氧化鋯基多元氧化物固溶體作為熱障涂層新材料的潛力進(jìn)行了初步的評(píng)估。具體研究?jī)?nèi)容包括:首先,我們分別采用Ti~（4+）、Sn~（4+）和Th~（4+）取代8YSZ中的Zr~(4+),構(gòu)造三元固溶體材料體系,研究了四價(jià)離子半徑對(duì)8YSZ晶格結(jié)構(gòu)以及t′相穩(wěn)定性的影響。此外,我們還測(cè)試了材料的硬度、彈性模量、斷裂韌性、熱導(dǎo)率以及熱膨脹系數(shù)這些對(duì)熱障涂層性能有重要影響的熱物理性能,并深入研究了晶格缺陷與晶格畸變對(duì)材料熱導(dǎo)率的影響�；诰Ц窠Y(jié)構(gòu)的穩(wěn)定性以及熱物理性能,我們對(duì)四價(jià)離子摻雜8YSZ固溶體作為熱障涂層新材料的潛力進(jìn)行了初步的評(píng)估。其次,我們?cè)?YSZ中增加稀土元素含量,以L(fǎng)n_2Zr_2O_7型稀土鋯酸鹽為基礎(chǔ),在晶格Ln位和Zr位同時(shí)引入摻雜,構(gòu)造(Ca_2Nb_2O_7)_x(Gd_2Zr_2O_7)_(1-x)、(Nd_2Sn_2O_7)_x(Yb_2Zr_2O_7)_(1-x)和(Sm_2Sn_2O_7)_x(Yb_2Zr_2O_7)_(1-x)三個(gè)四元固溶體材料體系。我們研究了摻雜對(duì)焦綠石結(jié)構(gòu)和螢石結(jié)構(gòu)之間有序無(wú)序相變的影響,并在相變臨界點(diǎn)附近觀(guān)察到材料硬度、彈性模量和斷裂韌性的特殊變化。此外,我們還分別討論了晶格結(jié)構(gòu)對(duì)材料聲子熱導(dǎo)和輻射熱導(dǎo)的影響,提出了在整個(gè)溫度范圍內(nèi)獲得低熱導(dǎo)率材料的設(shè)計(jì)原則。最后,我們?cè)贚n_2Zr_2O_7型稀土鋯酸鹽中進(jìn)一步增加稀土元素含量,構(gòu)造Zr_3Ln_4O_(12)型固溶體(Ln=Gd、Y、Er、Yb),研究了稀土離子半徑對(duì)材料晶格結(jié)構(gòu)以及顯微形貌的影響。同時(shí),我們還測(cè)試了材料的硬度、彈性模量、斷裂韌性以及熱導(dǎo)率和熱膨脹系數(shù),并對(duì)Zr_3Ln_4O_(12)型固溶體與8YSZ構(gòu)造多層或梯度熱障涂層的潛力進(jìn)行了初步的評(píng)估。
[Abstract]:With the development of industry, the working temperature of gas turbine and aircraft engine is increasing. The thermal barrier coating with extremely low thermal conductivity can effectively reduce the surface temperature of alloy parts, thus prolong its service life and improve the efficiency of heat engine. The most widely used thermal barrier coating material is 6-8% yttrium oxide stabilized zirconia with t 'phase structure. Based on the binary solid solution composed of rare earth oxides and zirconia such as YSZ, the multicomponent solid solution system is constructed by doping. The effects of defects on the lattice structure and thermal physical properties of the materials are systematically studied, and the potential of zirconia based polyoxide solid solution as a new material for thermal barrier coating is preliminarily evaluated. The ternary solid solution material system was constructed by replacing the Zr~(4 in 8YSZ with Ti~(4 / Sno _ 4) and Th~(4), respectively. The effects of tetravalent ion radius on the lattice structure and t'phase stability of 8YSZ were studied. In addition, the hardness and elastic modulus of the material were measured. Fracture toughness, thermal conductivity and thermal expansion coefficient are the thermal physical properties which have important influence on the properties of thermal barrier coatings. The effects of lattice defects and lattice distortion on the thermal conductivity of materials are studied. The potential of tetravalent ion doped 8YSZ solid solution as a new material for thermal barrier coating is preliminarily evaluated. Secondly, we increase the content of rare earth elements in 8YSZ based on Ln_2Zr_2O_7 rare earth zirconate. At both the Ln and Zr sites of the crystal lattice, the addition of dopants to the structure of the structure of the Quaternary solid solution material system has been constructed. We have studied the effect of doping on the orderly phase transition between the pyrochlore structure and the structure of the fluorite structure. We have studied the effect of doping on the orderly phase transition between the pyrochlore structure and the structure of the fluorite structure, and the structure of the ternary solid solution material system, we have studied the effect of the doping on the orderly phase transition between the pyrochlore structure and the fluorite structure, and the structure of the Nd2Sn2O7xYb2Zr2O7 and the Nd2Sn2O2Zr2O7 structure, we have studied the effect of doping on the ordered phase transition between the pyrochlore structure and the structure of the pyrochlore. Special changes in hardness, elastic modulus and fracture toughness are observed near the critical point of phase transition. In addition, the effects of lattice structure on phonon thermal conductivity and radiation thermal conductivity are discussed, respectively. The design principles for obtaining low thermal conductivity materials in the whole temperature range are proposed. Finally, we further increase the content of rare earth elements in Ln_2Zr_2O_7 rare earth zirconate. In this paper, the effect of the radius of rare earth ions on the lattice structure and the microstructure of the material has been studied. At the same time, the hardness, elastic modulus, fracture toughness, thermal conductivity and thermal expansion coefficient of the material have also been tested. The potential of the structure of multilayer or gradient thermal barrier coatings with the structure of Tix _ 3Ln _ 4O _ 2O _ (12) type solid solution and 8YSZ has been preliminarily evaluated.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TG174.4

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本文編號(hào)：1533635