MSP试验法评价PZT陶瓷的循环疲劳寿命

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邓启煌, 王连军, 许虹杰, 王宏志, 江莞. MSP试验法评价PZT陶瓷的循环疲劳寿命. 无机材料学报, 2012, 27(10): 1047-1052
DENG Qi-Huang, WANG Lian-Jun, XU Hong-Jie, WANG Hong-Zhi, JIANG Wan. Fatigue Life Investigation of PZT Ceramics by MSP Method. Journal of Inorganic Materials, 2012, 27(10): 1047-1052 复制到剪切板

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MSP试验法评价PZT陶瓷的循环疲劳寿命

邓启煌¹, 王连军¹, 许虹杰², 王宏志¹, 江莞¹

1. 东华大学纤维材料改性国家重点实验室, 上海 201620

2. 上海柯瑞冶金炉料有限公司, 上海 200072

江莞, 教授. E-mail:wanjiang@dhu.edu.cn

邓启煌(1982-), 男, 博士研究生. E-mail:dengqihuang@mail.dhu.edu.cn

基金:上海市科学技术委员会基础研究重点项目(10JC1400500); 上海市重点学科项目(B603); 航空科学基金(201108M2001);

摘要

采用小样品力学性能试验方法(Modified Small Punch Tests, 简称MSP)对Pb(Zr,Ti)O₃陶瓷(PZT)实施了不同大小应力下的循环疲劳实验, 循环应力越大, 样品的残余强度和压电常数衰减越快, 这是由应力循环过程中大量微裂纹的产生和扩展所致. 通过最大强度值与疲劳寿命的对应关系求得100 Hz循环疲劳下该样品的裂纹扩展指数n为395, 由此推测了PZT陶瓷样品的使用寿命, 在循环应力的最大值不超过79.1 MPa的条件下, 该样品的连续使用寿命可达5年以上.

关键词: PZT陶瓷; 小样品力学性能试验法; 循环疲劳; 声发射

中图分类号:TQ032 文献标志码:A 文章编号:1000-324X(2012)10-1047-06

Fatigue Life Investigation of PZT Ceramics by MSP Method

DENG Qi-Huang¹, WANG Lian-Jun¹, XU Hong-Jie², WANG Hong-Zhi¹, JIANG Wan¹

1. State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China

2. Shanghai Career Metallurgy Furnace Materials Co. Ltd., Shanghai 200072, China

Fund:Shanghai Science and Technology Committee, Key Project of Foundation Research (10JC1400500); Shanghai Leading Academic Discipline Project (B603); Aeronautical Science Foundation of China Project (201108M2001);

Abstract

The cycle fatigue of PZT ceramic under different stress was investigated by modified small punch (MSP) tests. The research results show that residual strength and piezoelectric constant decrease with increasing cycle stress, which is attributed to crack propagation during cyclic stress process. The value of fatigue crack propagation (n) is calculated to be 395 according to the relationship between maximum stress and fatigue life. The fatigue life under series cycle maximum stress can be induce by fatigue crack propagation. Below the maximum strength of 79.1 MPa, the PZT ceramics can be used over 5 years.

Keyword: PZT ceramic; modified small punch test; cycle fatigue; acoustic emission

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压电陶瓷材料具有优良的机电耦合效应和对外电场的响应能力, 己被广泛用于制作大容量电容器、传感器等常规元器件以及微驱动器、微执行器等高科技电子产品^{[ 1, 2]}. 然而, 用于压电压力传感器和微执行器中的压电陶瓷需在循环往复电场和力场下服役, 在经过大量周期性疲劳加载后, 它会发生疲劳损伤, 导致器件功能退化和失效, 表现为随着循环加载次数的增加, 压电陶瓷的压电常数减小, 力学性能下降^{[ 3]}. 因此, 从使用和安全设计方面考虑, 研究其疲劳机理, 了解循环负荷下的疲劳断裂特性具有重要的意义.

球压法是目前评价陶瓷材料循环疲劳性能的常用方法^{[ 4, 5, 6, 7]}, 该方法样品固定简单, 但在测试过程中, 特别是测试初期, 应力集中明显, 导致评价结果夸大疲劳的影响. 此外, 采用球压法进行疲劳加载后仍需采用其它方法评价剩余强度, 但很难保证剩余强度的测试点与疲劳测试的加载点相对应. MSP力学性能测试系统具有样品制备简便、固定方便、可以很精确测试陶瓷材料的位移等特点, 已在陶瓷^{[ 8, 9, 10, 11]}及其复合材料^{[ 12, 13, 14, 15]}、特别是功能陶瓷^{[ 16, 17, 18]}等领域得到了很好应用. 采用该系统施加循环疲劳时, 对样品在疲劳加载实验后可以直接进行MSP强度测试, 因此能够保证剩余强度测试与疲劳加载实验的对应性.

本工作采用MSP力学性能测试系统评价了PZT陶瓷的循环疲劳性能, 并依据循环疲劳寿命的预测方法讨论PZT陶瓷在不同最大值下的循环应力作用下的疲劳性能, 进而论证了MSP力学性能测试系统用于评价PZT陶瓷循环疲劳的可行性和可靠性.

1 实验方法

1.1 材料制备

PZT压电陶瓷样品由保定市宏声声学电子器材有限公司提供, 型号为PZT-5, 组分中的 n(Zr)/ n(Ti)为52/48, 尺寸为φ10 mm×0.6 mm.

1.2 MSP试验

MSP力学性能测试系统是一种适合陶瓷、玻璃等脆性材料的小样品力学性能评价方法. 它在评价陶瓷材料的循环疲劳时, 不仅能保证加载位置的稳定性, 还能精确控制加载循环力场的大小. 本实验中所用的MSP力学性能测试系统采用了具有循环加载功能的INSTRON动态数字液压试验机, 以保证实验过程中循环加载.

图1给出了循环疲劳测试的实验装置和试样承载时的受力示意图. 由图1(a)图可以看出MSP实验装置主要包括冲杆、上模、下模和高精度位移传感器. 循环疲劳加载的条件如下: 频率为100 Hz, 波形为正弦波, 载荷的最低值设定在1~3 N之间, 以保证压头和样品之间良好的接触, 循环加载的振幅分别为32和28 N, 次数分别为10³、10⁴、10⁵、和10⁶. 循环疲劳加载结束后, 直接用该系统测试样品的剩余强度, 加载速率为0.05 mm/min. 每组样品测试五次并通过统计得到平均值. 断裂强度均可以通过下面的公式计算出来^{[ 9]}:

(1)

其中 P为断裂载荷, γ为泊松比, a和 b为图2(b)中的承载模内孔半径和圆柱形压杆半径, a和 b分别为2 mm和1 mm, t为试样厚度.

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	图1 MSP试验法示意图(a)及强度计算模型(b)Fig. 1 Schematic drawing of MSP-testing apparatus (a) and model for strength calculation (b)

1.3 循环疲劳寿命的推测

陶瓷的疲劳是一个累积损伤的过程, 从微观上来说, 陶瓷的疲劳机理非常复杂, 主要是晶界的空穴、杂质和微裂纹的不断增加, 用某一个缺陷的发展变化来表征疲劳过程非常困难的. 从宏观来看, 强度衰减速率是陶瓷疲劳的主要因素, 而用强度衰减理论进行寿命预测是一个值得重视的方向^{[ 19]}.

图2为疲劳强度衰减模型示意图, 可以简单描述为: 假设材料的初始强度为 σ₀, 在外加载荷 σ(t)作用下, 经过时间 t后的残余强度为 σ_T, 则 σ_T为时间 t的一个递减函数, 陶瓷的疲劳断裂准则可以描述如下: 试样上作用一个外力 σ( σ< σ₀)后, σ_T从初始强度 σ₀开始衰减, 经过时间 T_c后, σ_T衰减到与外加载荷水平时发生断裂, 称 T_c为在应力 σ作用下的疲劳寿命^{[ 20]}.

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	图2 疲劳衰减模型示意图Fig. 2 Schematic of fatigue strength degradation

对于陶瓷材料来说, 在低于门槛值的亚临界裂纹慢速扩展速度和应力强度因子均存在Power-law 经验关系^{[ 21]}:

(2)

公式(2)中, v为裂纹的扩展速率, a为裂纹的尺寸, t为加载时间. K_I为I型应力强度因子, K_IC为临界I型的应力强度因子(即断裂韧性). A和n为常数, 其中n为应力扩展指数.

根据式(2)可以推导得到公式(3)^{[ 22, 23]}:

(3)

其中, N_f为循环疲劳寿命, n为裂纹缓慢扩展指数, σ_max为循环应力最大值, a₀为初始裂纹长度, a_f为断裂时裂纹的长度, A和Y为常数.

根据式(3)可知在对数坐标下, 陶瓷材料的循环疲劳寿命与循环应力最大值之间呈线性关系, 直线的斜率为裂纹的应力扩展指数 n.

2 结果与讨论

图3分别为PZT陶瓷在疲劳初期10³次和疲劳后期10⁶次后残余强度测试的载荷-位移曲线和与其对应的声发射事件数及能量曲线. 其中, 声发射事件数为声发射信号超过预置门槛的次数, 声发射能量表示声发射事件释放的总的弹性能. 产生的声发射信号大致可分为三个阶段, 第一阶段为微裂纹产生阶段, 声发射信号是由陶瓷内部的微缺陷引起的, 如微裂纹、气孔缺陷或杂质等. 在局部应力作用下这些微缺陷被诱发, 产生的声发射信号、能量低. 第二阶段为微裂纹的稳定扩展阶段, 微裂纹在材料中萌生以后, 随着外加载荷增大, 微裂纹会缓慢的扩展, 表现为声发射的事件数在激增. 第三阶段为微裂纹的非稳定扩展阶段, 随着载荷的进一步增大, 微裂纹扩展成宏观裂纹, 材料发生断裂. 这一阶段材料释放出大量弹性能, 声发射信号幅值达到最大值. 比较疲劳初期和疲劳后期陶瓷的声发射信号可知, 在微裂纹产生阶段有较大差别, PZT陶瓷在疲劳初期产生大量的信号, 而疲劳后期产生的声发射信号则较少. 在疲劳实验过程中, 材料内部已经产生了大量由一些微小缺陷引发的微裂纹, 这些微缺陷能量的提前释放, 使得PZT陶瓷在疲劳后期测试的声发射信号中产生的声发射信号相对较少. 同时, 疲劳实验过程中裂纹的逐步扩展是导致载荷下降的主要原因.

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	图3 PZT陶瓷的载荷-位移曲线和对应的声发射曲线Fig. 3 Load-displacement and AE curves of PZT ceramics(a) AE hit of early stage of fatigue; (b) AE energy of early stage of fatigue; (c) AE hit of later stage of fatigue; (d) AE energy of later stage of fatigue

图4为PZT陶瓷在不同振幅下的MSP剩余强度随疲劳循环次数的变化曲线. 从图中可知, 当PZT陶瓷的循环次数大于10³次时, 随着循环次数的增加, 剩余强度和循环疲劳次数的对数基本呈线性衰减关系. 当最大应力值为28 N时, PZT陶瓷的MSP剩余强度下降的较为缓慢; 当应力最大值增加到32 N, PZT陶瓷的MSP剩余强度随着疲劳次数增加急剧下降. 这可能是因为PZT陶瓷材料没有塑性变形能力, 在循环应力作用下裂纹的形核与扩展造成累积损伤, 具体形式表现为微裂纹扩展^{[ 24, 25]}, 图3中声发射的事件数及能量变化都可以说明这一点. 图4还给出了PZT陶瓷在不同最大应力值下的MSP剩余强度和循环次数的直线拟合曲线. 在应力最大值为28 N和32 N的循环疲劳下, PZT陶瓷的剩余强度与循环次数的对数大致呈线性关系, 通过直线拟合得到它们的斜率分别为-2.47和-8.45. 根据前面叙述的疲劳强度衰减模型, 在周期性的应力作用下, 当剩余强度衰减到与循环应力的最大值相等时材料发生断裂, 这段时间所循环的次数称为材料的 N_f, 即循环疲劳寿命. 把图4中拟合直线外延到循环应力的最大值时, 得到PZT陶瓷在最大强度值为 69.1 MPa(对应于28 N)和78.9 MPa(对应于32 N), 循环疲劳下对应的疲劳寿命分别为3.6×10³³和4.6×10¹⁰次. 根据测定任意2个循环应力值下的疲劳寿命, 即可推算出该材料的裂纹缓慢扩展指数 n, 为此, 把上面两个疲劳寿命测试值代入公式(3), 再把两式相减计算得到PZT陶瓷在100Hz循环疲劳下的裂纹扩展指数 n为395. 通过对最大强度值与对应的疲劳寿命作图, 可以得到lg( σ_max)和lg( N_f)的关系, 如图5所示. 图中连接两实验点的直线即裂纹扩展指数.

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	图4 PZT陶瓷在不同振幅下的MSP剩余强度和循环次数的直线拟合曲线Fig. 4 Fitting curves of residual MSP strength vs number of cycles for different amplitudes

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	图5 lg σ_max和lg N_f的变化关系Fig. 5 Relation between lg σ_max and lg N_f

根据图5可推算材料在任意循环疲劳下的使用寿命, 也可以通过设定材料的一个使用寿命反推它在使用中能够承受的循环应力的最大值的临界点, 这对设计材料及评价材料的安全性具有重要意义. PZT陶瓷在电子产品中所设计的连续使用寿命一般为3~5年, 如果设定压电器件的连续使用寿命为5年, 根据实验中得到的循环应力的最大值和寿命之间的关系可以求得本研究采用的PZT陶瓷的最大循环应力值不得超过79.1 MPa(平均值). 换言之, 当循环应力强度最大值不超过79.1 MPa的条件下, PZT陶瓷在连续使用的情况下可以安全使用5年以上.

图6为PZT陶瓷在不同振幅下的压电常数 d₃₃随疲劳循环次数的变化曲线. 由图可知, PZT陶瓷的压电常数 d₃₃随着循环疲劳的加载而下降, 当应力最大值为28 N时, 压电常数 d₃₃下降较为缓慢, 当应力最大值增加到32 N后, PZT陶瓷的压电常数 d₃₃开始急剧下降, 在100万次循环疲劳加载后, 压电常数 d₃₃下降到476. 当最大应力为32 N时, 连续使用五年后, 它的压电常数约为442(降幅为13%), 这可能是因为在疲劳过程中, 电畴在交变性的力场作用下不断翻转中产生结构畸变积累内应力, 导致内部产生大量微裂纹, 和图3声发射信号分析中得出的结果相吻合, 即在疲劳过程中产生大量的微裂纹, 引起点缺陷在晶界或畴界等处聚集^{[ 26]}, 当循环力场振幅越大时, 电畴翻转引起的缺陷越多, 导致材料的压电性能下降得越明显.

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	图6 PZT陶瓷在不同振幅下的压电常数 d₃₃和疲劳循环次数的关系Fig. 6 Piezoelectric constant d₃₃ of PZT ceramic vsnumber of cycles for different amplitude

3 结论

采用MSP力学性能测试系统评价了PZT陶瓷的循环疲劳性能, 并利用实验结果结合循环疲劳模型预测了PZT陶瓷的循环使用寿命, 获得主要结论如下:

1) PZT陶瓷在最大应力值分别为69.1和 78.9 MPa时的循环疲劳寿命分别为3.6×10³³和 4.6×10¹⁰次, 由此算出PZT陶瓷在100 Hz循环疲劳下的裂纹扩展指数 n为395.

2)通过最大强度值与疲劳寿命的对应关系可以推测PZT陶瓷在不同应力下的使用寿命, 当循环应力的最大值不超过79.1 MPa的条件下, PZT陶瓷的连续使用寿命可达5年以上.

3)循环疲劳是一个损伤累积的过程, 在疲劳过程中大量微裂纹的产生与扩展是导致材料的断裂强度和压电常数下降的主要原因.

4)MSP测试系统能够简单、精确地评价压电材料的循环疲劳寿命.

参考文献

View Option

[1]	Newnham R E, Xu Q C, Kumar S, et al. Smart ceramics. Ferroelectrics, 1990, 102(117): 259-266. [本文引用:1] [JCR: 0.415]
[2]	Duiker H M, Beale P D, Scott J F, et al. Fatigue and switching in ferroelectric memories- theory and experiment. Journal of Applied Physics, 1990, 68(11): 5783-5791. [本文引用:1] [JCR: 2.21]
[3]	Jiang Q Y, Cross L E. effects of porosity on electric fatigue behavior in PLZT and PZT ferroelectric ceramics. Journal of Materials Science, 1993, 28(16): 4536-4543. [本文引用:1] [JCR: 2.163]
[4]	Lee K Y, Ludema K C. Fatigue wear mechanism of alumina, simulated by synchronized biaxial repeated indentations. Wear, 1997, 205(1/2): 200-205. [本文引用:1] [JCR: 1.262]
[5]	Alfredsson B, Olsson M. Inclined stand ing contact fatigue. Fatigue & Fracture of Engineering Materials & Structures. 2003, 26(7): 589-602. [本文引用:1] [JCR: 1.976]
[6]	Song Y S, Park I, Jang J W, et al. In vitro Hertzian Fatigue Properties of Glass Infiltrated Ceramic Composites for Dental Crowns. 6_th International Symposium on Eco-Materials Processing and Design, Jinju, South Korea, 2005. [本文引用:1]
[7]	Fett T, Ernst E, Rizzi G, et al. Sphere contact fatigue of a coarse-grained Al₂O₃ ceramic. Fatigue & Fracture of Engineering Materials & Structures, 2006, 29(11): 876-886. [本文引用:1] [JCR: 1.976]
[8]	Li J F, Wang S A, Wakabayashi K, et al. Properties of modified lead zirconate titanate ceramics prepared at low temperature (800℃) by hot isostatic pressing. Journal of the American Ceramic Society. 2000, 83(4): 955-957. [本文引用:1] [JCR: 2.107]
[9]	Li J F, Pan W, Sato F, et al. Mechanical properties of polycrystalline Ti₃SiC₂ at ambient and elevated temperatures. Acta Materialia, 2001, 49(6): 937-945. [本文引用:2] [JCR: 3.941]
[10]	Wang G, Jiang W, Bai G Z, et al. Effect of additions of oxide on microstructure and BDTT of MoSi₂/oxide composites. Composite Materials III, 2003, 249: 91-95. [本文引用:1]
[11]	Xiong Z, Jiang W, Shi Y, et al. Evaluation of high-temperature strength of Mo/PSZ composites by modified small punch tests. Materials Transactions, 2005, 46(3): 631-636. [本文引用:1] [JCR: 0.588]
[12]	Jiang W, Bai G Z, Wang G, et al. High temperature strength of Mo/PSZ composites as evaluated by MSP test (II). Journal of Inorganic Materials, 2002, 17(5): 1034-1040. [本文引用:1] [JCR: 0.531] [CJCR: 1.106]
[13]	Jiang W, Li J F. Compositional dependence of thermal and mechanical properties for sintered Mo/PSZ composites. Acta Metallurgica Sinica, 2002, 38(4): 438-442. [本文引用:1] [JCR: 0.612] [CJCR: 0.835]
[14]	Jiang W, Wang G, Wu L B, et al. High temperature strength of Mo/PSZ composities as evaluated by MSP test (I). Journal of Inorganic Materials, 2002, 17(4): 827-832. [本文引用:1] [JCR: 0.531] [CJCR: 1.106]
[15]	Li J F, Kawai M, Kikuchi K, et al. Strength proof evaluation of diffusion-jointed W/Ta interfaces by small punch test. Journal of Nuclear Materials, 2003, 321(2/3): 129-134. [本文引用:1] [JCR: 1.211]
[16]	Li J F, Takagi K, Terakubo N, et al. Electrical and mechanical properties of piezoelectric ceramic/metal composites in the Pb(Zr, Ti)O₃/Pt system. Applied Physics Letters, 2001, 79(15): 2441-2443. [本文引用:1] [JCR: 3.794]
[17]	Zhang H L, Li J F, Zhang B P. Fabrication and evaluation of PZT/Ag composites and functionally graded piezoelectric actuators. Journal of Electroceramics, 2006, 16(4): 413-417. [本文引用:1] [JCR: 1.143]
[18]	Zhang H L, Li J F, Zhang B P, et al. Enhanced mechanical properties in Ag-particle-dispersed PZT piezoelectric composites for actuator applications. Materials Science and Engineering A, 2008, 498(1/2): 272-277. [本文引用:1] [JCR: 2.108]
[19]	Evans A. Fatigue in ceramics. International Journal of Fracture, 1980, 16(6): 485-498. [本文引用:1] [JCR: 1.25]
[20]	Wang N, Xie L, Song W, et al. Residual Strength Degradation Model for Low-Alloy Steel in High Cycle Fatigue Load. 2^nd International Conference on Advances in Product Development and Reliability, Shenyang, China, 2010. [本文引用:1]
[21]	Wang H, Wereszczak A A. Effects of electric field and biaxial flexure on the failure of poled Lead zirconate titanate. IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2008, 55(12): 2559-2570. [本文引用:1] [JCR: 1.822]
[22]	Liu S Y, Chen I W. Fatigue of yttria-stabilized zirconia. 1. fatigue damage, fracture origins, and lifetime prediction. Journal of the American Ceramic Society, 1991, 74(6): 1197-1205. [本文引用:1] [JCR: 2.107]
[23]	Liu S Y, Chen I W. Fatigue of yitria-stabilized zirconia. 2. crack-propagation, fatigue striations, and short-crack behavior. Journal of the American Ceramic Society, 1991, 74(6): 1206-1216. [本文引用:1] [JCR: 2.107]
[24]	Hill M D, White G S, Hwang C S, et al. Cyclic damage in lead zirconate titanate. Journal of the American Ceramic Society, 1996, 79(7): 1915-1920. [本文引用:1] [JCR: 2.107]
[25]	Becher P F. Microstructural design of toughened ceramics. Journal of the American Ceramic Society, 1991, 74(2): 255-269. [本文引用:1] [JCR: 2.107]
[26]	Brennan C. Model of ferroelectric fatigue due to defect/domain interactions. Ferroelectrics, 1993, 150(1): 199-208. [本文引用:1] [JCR: 0.415]

1990

0.415

0.0

Ferroelectrics. 1990, 102(117):259-266

Smart ceramics

Newnham R E , Xu Q C , Kumar S

... 压电陶瓷材料具有优良的机电耦合效应和对外电场的响应能力, 己被广泛用于制作大容量电容器、传感器等常规元器件以及微驱动器、微执行器等高科技电子产品^[1,2] ...

1990

2.21

0.0

Journal of Applied Physics. 1990, 68(11):5783-5791

Fatigue and switching in ferroelectric memories- theory and experiment

Duiker H M , Beale P D , Scott J F

1993

2.163

0.0

Journal of Materials Science. 1993, 28(16):4536-4543

effects of porosity on electric fatigue behavior in PLZT and PZT ferroelectric ceramics

Jiang Q Y , Cross L E

... 然而, 用于压电压力传感器和微执行器中的压电陶瓷需在循环往复电场和力场下服役, 在经过大量周期性疲劳加载后, 它会发生疲劳损伤, 导致器件功能退化和失效, 表现为随着循环加载次数的增加, 压电陶瓷的压电常数减小, 力学性能下降^[3] ...

1997

1.262

0.0

Wear. 1997, 205(1/2):200-205

Fatigue wear mechanism of alumina, simulated by synchronized biaxial repeated indentations

Lee K Y , Ludema K C

... 球压法是目前评价陶瓷材料循环疲劳性能的常用方法^[4,5,6,7], 该方法样品固定简单, 但在测试过程中, 特别是测试初期, 应力集中明显, 导致评价结果夸大疲劳的影响 ...

2003

1.976

0.0

Fatigue & Fracture of Engineering Materials & Structures.. 2003, 26(7):589-602

Inclined standing contact fatigue

Alfredsson B , Olsson M

2005

0.0

2006

1.976

0.0

Fatigue & Fracture of Engineering Materials & Structures. 2006, 29(11):876-886

Sphere contact fatigue of a coarse-grained Al₂O₃ ceramic

Fett T , Ernst E , Rizzi G

2000

2.107

0.0

... MSP力学性能测试系统具有样品制备简便、固定方便、可以很精确测试陶瓷材料的位移等特点, 已在陶瓷^[8,9,10,11]及其复合材料^{[12,13,14,15]}、特别是功能陶瓷^[16,17,18]等领域得到了很好应用 ...

2001

3.941

0.0

Acta Materialia. 2001, 49(6):937-945 DOI:10.1016/S1359-6454(01)00011-8

Mechanical properties of polycrystalline Ti₃SiC₂ at ambient and elevated temperatures

Abstract

Dense polycrystalline Ti₃SiC₂ samples were fabricated by reactively hot-isostatic pressing (HIPing) a mixture of elemental Ti, Si and C powders. The mechanical properties, including load–strain response, bending strength, fracture toughness and crack propagation, were investigated from ambient temperature to 1573 K. Non-linear stress–strain responses were observed in the polycrystalline Ti₃SiC₂ materials at ambient temperature. It is conceivable that the inelastic deformation is attributable to micro-deformations that consist of slip between micro-lamellae within individual grains and the formation of microcracks between grains. The polycrystalline Ti₃SiC₂ exhibited a brittle-to-ductile transition at about 1473 K; above this the Ti₃SiC₂ samples deformed plastically and exhibited high strains (>1.5%), whereas below 1373 K only limited inelastic deformation was observed prior to fracture. The mode I fracture toughness, K_IC, was measured by the single-edge notched beam (SENB) method to be 4.52 MPa m^1/2 at ambient temperature. Both fracture strength and fracture toughness decrease only slightly with increasing temperature up to 1273 K, above which they decrease more rapidly and reach half of their room-temperature values by 1473 K.

... 断裂强度均可以通过下面的公式计算出来^[9]: ...

2003

0.0

2005

0.588

0.0

Materials Transactions. 2005, 46(3):631-636

Evaluation of high-temperature strength of Mo/PSZ composites by modified small punch tests

Xiong Z , Jiang W , Shi Y

2002

0.531

1.106

Journal of Inorganic Materials. 2002, 17(5):1034-1040

High temperature strength of Mo/PSZ composites as evaluated by MSP test (II)

1. State Key Lab of High Performance Ceramics and Superfine Microstructure; Shanghai Institute of Ceramics; Chinese Academy of Sciences; Shanghai 200050; China; 2. Department of Materials and Engineering; Tsinghua University, Beijing 100084, China

In present work, the mechanical properties of Mo/PSZ (partially stabilized zirconia) composites were
investigated at a temperature range from room temperature to 1573K by means of the modified small punch test (MSP) and the dependence of MSP strength for Mo/PSZ
composites on composition and microstructure was discussed in detail. It was found that the change of MSP strength with the composition at various test
temperatures was different: it took the shape of “W” at room temperature; at temperatures up to 873K and 1273K, the MSP strength approached its peak,
respectively at the compositions where the Mo phase was dispersed or both compositional phases were continuous. The results show that MSP strength
depends not only on the composition but also on the composite microstructure.

首先利用图像处理系统对Mo/PSZ系两相复合材料的微观组织进行了定量分析,然后在不同的实验温度下利用MSP试验法对该系复合材料的高温力学性能进行了测试,详细讨论了该系复合材料不同温度下的MSP强度与其组成,特别是与其对应的微观组织结构特征的关系.实验结果表明,不同温度下复合材料的MSP强度显示出不同的组织依存性,室温时呈W形状变化,在873K、1273K时分别在Mo分散组成和两相连续组成范围呈极大值,这种变化趋势依赖于复合材料所具有的微观组织结构.

2002

0.612

0.835

Acta Metallurgica Sinica. 2002, 38(4):438-442

Compositional dependence of thermal and mechanical properties for sintered Mo/PSZ composites

在全组成范围内对Mo/PSZ系两相复合材料进行了组织结构的定量表征和热物理性能及高温力学性能的测试,详细讨论了两相复合材料在不同温度下热传导特性和变形、破坏特性与复合组织的依存关系.实验结果证明,Mo/PSZ系复合材科的热传导率、变形及破坏举动等特性不仅与测定温度和组成有关,而且强烈依存于复合材料的组织特征.

2002

0.531

1.106

Journal of Inorganic Materials. 2002, 17(4):827-832

High temperature strength of Mo/PSZ composities as evaluated by MSP test (I)

The mechanical properties of molybdenum/partially stabilized zirconia (PSZ) composites were investigated
from room temperature to 1573K by means of modified small punch (MSP) test which has been found to be suitable for the mechanical evaluation of brittle
materials. The temperature dependences of the deformation, strength and fracture behavior of the composites were examined in detail. The results of this paper
have shown that the high temperature strength can be simply determined by the MSP test and there exists a good linear relationship between MSP strength and
conventional 4-point bending strength. Using such correspondence the bending strength can be estimated from the MSP strength.

利用 MSP试验在全组成范围和不同的实验温度下对 Mo/PSZ系两相复合材料进行了高温力学性能的测试,详细讨论了各组成复合材料在不同温度下的破坏模式和强度与温度的依存性.实验结果证明,利用简便的MSP实验法不仅可以精确地表征Mo/PSZ系复合材料的破坏行为,而且MSP强度与抗弯强度有很好的对应关系,利用这种关系可以从测得的MSP强度来预测抗弯强度.

2003

1.211

0.0

Journal of Nuclear Materials. 2003, 321(2/3):129-134

Strength proof evaluation of diffusion-jointed W/Ta interfaces by small punch test

Li J F , Kawai M , Kikuchi K

2001

3.794

0.0

Applied Physics Letters. 2001, 79(15):2441-2443

Electrical and mechanical properties of piezoelectric ceramic/metal composites in the Pb(Zr,Ti)O₃/Pt system

Li J F , Takagi K , Terakubo N

2006

1.143

0.0

Journal of Electroceramics. 2006, 16(4):413-417 DOI:10.1007/s10832-006-9890-4

Fabrication and evaluation of PZT/Ag composites and functionally graded piezoelectric actuators

1.State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084 P. R. China<br/>2.School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083 P. R. China<br/>

Metallic Ag as the second phase was added into PZT ceramic matrix to fabricate piezoelectric composites and functionally graded actuators by gradually altering Ag concentration, aimed to improve mechanical properties and to solve possible interfacial debonding usually observed in conventional bimorph-type piezoelectric actuator. The PZT/Ag composites were obtained by directly co-firing PZT and Ag powders at 1200^∘C for 1 h. The fracture strength σ_f and fracture toughness K _IC, as well as the corresponding piezoelectric properties, were firstly evaluated upon the PZT/Ag composites for Ag concentrations of 0–30 vol%. The mechanical properties for the PZT/Ag composites were found to be greatly enhanced compared with pure PZT ceramics: from 69 to 129 MPa for σ_f and from 1.0 to 3.7 MPa.m^1/2 for K _IC. With increasing Ag concentration, the piezoelectric constant d ₃₃ of PZT/Ag composites was found to decrease from 419 to 86 pC/N. Then, a functionally graded actuator was fabricated and evaluated in terms of electric-induced curvature k. The PZT/Ag FGM actuator with size of 12 mm × 3 mm × 1 mm has a curvature k of 0.03–0.17 m⁻¹ that corresponds to applied voltages of 100–500 V. A comprehensive comparison was made on the mechanical property enhancements by the metal particles dispersion, and the bending displacements produced by the FGM actuators between the PZT/Ag and previously fabricated PZT/Pt systems.

2008

2.108

0.0

Materials Science and Engineering A. 2008, 498(1/2):272-277

Enhanced mechanical properties in Ag-particle-dispersed PZT piezoelectric composites for actuator applications

Zhang H L , Li J F , Zhang B P

1980

1.25

0.0

International Journal of Fracture. 1980, 16(6):485-498

Fatigue in ceramics

Evans A

... 从宏观来看, 强度衰减速率是陶瓷疲劳的主要因素, 而用强度衰减理论进行寿命预测是一个值得重视的方向^[19] ...

2010

0.0

... 作用下的疲劳寿命^[20] ...

2008

1.822

0.0

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control. 2008, 55(12):2559-2570

Effects of electric field and biaxial flexure on the failure of poled Lead zirconate titanate

Wang H , Wereszczak A A

... 对于陶瓷材料来说, 在低于门槛值的亚临界裂纹慢速扩展速度和应力强度因子均存在Power-law 经验关系^[21]: ...

1991

2.107

0.0

... 根据式(2)可以推导得到公式(3)^[22,23]: ...

1991

2.107

0.0

... 根据式(2)可以推导得到公式(3)^[22,23]: ...

1996

2.107

0.0

Journal of the American Ceramic Society. 1996, 79(7):1915-1920

Cyclic damage in lead zirconate titanate

Hill M D , White G S , Hwang C S

... 这可能是因为PZT陶瓷材料没有塑性变形能力, 在循环应力作用下裂纹的形核与扩展造成累积损伤, 具体形式表现为微裂纹扩展^[24,25], 图3中声发射的事件数及能量变化都可以说明这一点 ...

1991

2.107

0.0

Journal of the American Ceramic Society. 1991, 74(2):255-269

Microstructural design of toughened ceramics

Becher P F

1993

0.415

0.0

Ferroelectrics. 1993, 150(1):199-208

Model of ferroelectric fatigue due to defect/domain interactions

Brennan C

... 当最大应力为32 N时, 连续使用五年后, 它的压电常数约为442(降幅为13%), 这可能是因为在疲劳过程中, 电畴在交变性的力场作用下不断翻转中产生结构畸变积累内应力, 导致内部产生大量微裂纹, 和图3声发射信号分析中得出的结果相吻合, 即在疲劳过程中产生大量的微裂纹, 引起点缺陷在晶界或畴界等处聚集^[26], 当循环力场振幅越大时, 电畴翻转引起的缺陷越多, 导致材料的压电性能下降得越明显 ...