本文選題：層狀陶瓷材料　切入點：多晶微結(jié)構　出處：《西北工業(yè)大學》2016年博士論文　論文類型：學位論文

【摘要】：由于層狀陶瓷復合材料具有獨特的疊層結(jié)構,研究者能從宏觀結(jié)構的角度對其進行層內(nèi)和層間設計,從而制備綜合性能優(yōu)異的新型陶瓷材料。層狀陶瓷材料微觀多晶結(jié)構和宏觀多層結(jié)構共同決定了材料的性能。然而,在目前的數(shù)值模擬研究中,大部分僅對陶瓷塊材多晶微結(jié)構進行模擬,缺乏從原子尺度、多晶微結(jié)構尺度和層狀結(jié)構對層狀陶瓷的“結(jié)構-力學響應”關系開展數(shù)值模擬,也尚無相關計算軟件。本文針對層狀陶瓷基復合材料,從材料的微觀多晶和宏觀多層結(jié)構出發(fā),綜合采用第一性原理、蒙特卡羅方法和有限元數(shù)值計算方法,分析具有多晶微結(jié)構的層狀陶瓷材料的力學響應,發(fā)展層狀結(jié)構陶瓷材料參數(shù)化設計軟件,為制備新型層狀陶瓷基復合材料提供指導依據(jù)。主要研究內(nèi)容與結(jié)果如下:(1)采用蒙特卡羅方法模擬了多晶微結(jié)構演變,并采用有限元數(shù)值方法對多晶微結(jié)構進行了力學響應分析。研究結(jié)果表明:多晶微結(jié)構的平均晶粒隨著模擬時間的增大而增大,平均應力大小與平均晶粒大小符合Hall-Petch關系。(2)在單層多晶結(jié)構的基礎上,采用蒙特卡羅方法模擬層狀材料多晶微結(jié)構演變,并進行了有限元力學響應分析,重點研究了層數(shù),層厚比,模量比等材料參數(shù)對層狀結(jié)構材料力學響應的影響規(guī)律。研究結(jié)果表明:(a)對于三層材料,當層厚比變化時,材料硬(軟)層所占比例隨之變化,相應微結(jié)構模型的平均應力也發(fā)生變化。當內(nèi)外層模量比大于2時,平均應力隨著內(nèi)層材料厚度增大而增大,當模量比小于1時,平均應力隨著內(nèi)層材料的厚度增大而減小。(b)對于強晶界材料,不論材料的疊層順序是外層為硬層還是為軟層,材料平均應力均隨著晶粒長大而減小。對于外層為硬層時,材料的平均應力隨著材料層數(shù)增多而減小,而對于外層為軟層時,材料平均應力隨著材料層數(shù)增多而增大。(c)對于均勻材料,平均應力與模量比呈線性增長關系;對于非均勻材料,平均應力與模量比呈非線性增長關系。(3)計算了層狀結(jié)構陶瓷復合材料的殘余應力及表觀斷裂韌性,并研究了材料層數(shù)、層厚比、燒結(jié)溫度以及模量比等參數(shù)對層狀陶瓷材料殘余應力及表觀斷裂韌性的影響規(guī)律。研究結(jié)果表明:(a)當奇偶層層厚比等于1時,隨著層數(shù)增多,單層越薄,受壓層應力增大,受拉層應力減小。當裂紋尖端處于外層受壓層時,表觀斷裂韌性隨材料層數(shù)的增多而增大。當內(nèi)外層總厚度比等于1時,拉壓層的應力大小相等,且不隨層數(shù)的變化而改變。當層數(shù)增多時,在壓/拉層界面處的表觀斷裂韌性降低,但在拉/壓層界面處的表觀斷裂韌性增大。(b)當奇偶層層厚比增大時,壓應力大小降低,而拉應力大小增大。當裂紋尖端處于受壓層,表觀斷裂韌性隨層厚比的增大而增大。(c)燒結(jié)溫度越高,在壓/拉界面處的表觀斷裂韌性越大,在拉/壓界面處的表觀斷裂韌性越小,但二者變化幅度均不大,說明燒結(jié)溫度影響較小。(d)在壓/拉界面處,模量比越大,表觀斷裂韌性越小,而在拉/壓界面處,模量比越大,表觀斷裂韌性也越大。(4)采用面向?qū)ο蟪绦蛟O計,在OMTDesk軟件平臺下開發(fā)了交互式圖形用戶界面軟件PCLab(Partical Cloud Laboratory),軟件集成MC和FEM模塊,可進行多層多晶微結(jié)構演變模擬與力學響應分析,能快速有效的研究層狀材料結(jié)構的力學性能等多物理場問題。(5)提出了綜合第一性原理、蒙特卡羅及有限元模擬的層狀結(jié)構復合材料宏微觀設計思路,并從原子尺度、多晶微結(jié)構尺度和層狀結(jié)構對所設計的HfC/BN、Zr B2/BN和SiC/BN三種層狀材料的“結(jié)構-力學響應”關系進行了數(shù)值模擬,研究結(jié)果表明:相同多晶結(jié)構及晶粒界面效果作用下HfC/BN的承載能力最強,ZrB2/BN次之,SiC/BN最低;不同的多晶結(jié)構或不同的晶粒效果作用下,三種材料具有相同或相近的力學響應。
[Abstract]:Because of the laminated ceramic composite laminate with unique, researchers from the perspective of macro structure layer and layer design, and preparation of new ceramic materials with excellent properties. The layered ceramic material micro structure and macroscopic polycrystalline multilayer structure determines the properties of the material. However, in the study at present, the numerical simulation of ceramics, most only polycrystalline microstructure is simulated, the lack of the atomic scale, polycrystalline structure and layered structure of micro scale layered ceramics "structure mechanical response" to carry out numerical simulation, no related calculation software. According to the layered ceramic matrix composites, starting from the micro crystal the material and the macroscopic multilayer structure, the first principle calculation method, Monte Carlo method and the finite element numerical analysis of mechanical layered ceramic materials with polycrystalline microstructure of the ring The development of software design, layered structure parameters of ceramic materials, and provide guidance for the preparation of new layered ceramic matrix composites. The main research contents and results are as follows: (1) using Monte Carlo method to simulate the microstructure evolution of the polycrystalline, and by using the finite element numerical method of polycrystalline microstructures were studied. The mechanical response analysis the results showed that the average grain size of polycrystalline microstructure increases with the increase of simulation time, the average stress and average grain size is consistent with the Hall-Petch. (2) based on the polycrystalline structure of monolayer, using the Monte Carlo method to simulate the evolution of polycrystalline layered material micro structure, and the finite element analysis of mechanical response. Focus on the layer, the layer thickness ratio, modulus ratio and material parameters effect on the mechanical response of layered materials. The results show that: (a) for the three layer material, when the thickness ratio changes, material Hard (soft) layer proportion changes, the corresponding average micro structure model of stress is changed. When the inner and outer layer modulus ratio is greater than 2, the average stress increases with the inner layer thickness increases, when the modulus ratio is less than 1, the average stress decreases with the increase in the thickness of the inner material. (B for the strong grain boundary) materials, regardless of stacking sequence of materials is as hard as the outer layer or soft material layer, the average stress decreases with grain growth. The outer layer is a layer of hard material, the average stress decreases with the material layer increased, while the outer layer is a soft material layer, the average stress with increasing number of layers increased. (c) for a homogeneous material, the average stress and modulus ratio increases linearly; for nonhomogeneous materials, the average stress and modulus ratio increased in non-linear relationship. (3) the residual layer structure ceramic composite material and stress calculation table The concept of fracture toughness, and the number of layers, layer thickness ratio, sintering temperature and the modulus ratio on the residual stress of laminated ceramic materials and effect on the law of fracture toughness. The results show that: (a) when the parity layers thickness ratio is equal to 1, with the number of layers increases, single layer thinner, compression layer the tensile force increases, the stress decreases. When the crack tip in the outer layer of compression, the apparent fracture toughness increased with the number of layers increases. When the total thickness of the inner layer and the outer layer is equal to 1, the tensile and compressive stress layer of equal size, and does not change with the number of layers change. When the layer number increase. The concept of fracture toughness decrease in compressive or tensile layer at the interface of the table, but the tension / compression interface, the apparent fracture toughness increases. When the thickness of the layer (b) parity ratio increases, the compressive stress size decreases, and the magnitude of tensile stress increases. When the crack tip in compression layer, apparent fracture with the increase of the thickness ratio of toughness Large increases (c). The higher the sintering temperature, the fracture toughness values in the push / pull at the interface of the table, in the tension / compression at the interface of the apparent fracture toughness is small, but the two changes were not significant, indicating little influence of sintering temperature. (d) in the push / pull at the interface. Modulus ratio increases, the apparent fracture toughness is small, and the tension / compression interface, modulus ratio increases, the apparent fracture toughness is also greater. (4) using object oriented programming, interactive graphical user interface software developed in the PCLab OMTDesk software platform (Partical Cloud Laboratory), MC software integration and the FEM module, can be multi crystal microstructure evolution simulation and mechanics analysis of layered material structure effective mechanical properties of multi physics problems. (5) proposed a comprehensive first principle, Monte Carlo and layered structure of composite material of macro finite element simulation of the micro design ideas, and from the original Sub scale, polycrystalline microstructure scale and layered structure to design HfC/BN, Zr B2/BN and SiC/BN three kinds of layered materials "structure - mechanical response relationship was simulated, the results show that: the same interface effect of polycrystalline structure and the grain bearing capacity of the strongest HfC/BN, the lowest SiC/BN ZrB2/BN. The polycrystalline structure; different grain size effect under the action of three kinds of materials with the same or similar mechanical response.

【學位授予單位】：西北工業(yè)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TQ174.1

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