Study of crack healing effect in dimethyl phthalate crystals by mechanical spectroscopy

Zhou Heng-Wei; Wang Li-Na; Guo Xiu-Zhen; Wu Na-Na; Zhang Li; Zhang Jin-Lu; Huang Yi-Neng

doi:10.7498/aps.59.2120

Abstract

The recently developed method to detect the stress-cracking and crack healing of glasses in real-time （called the RMS-CH in short，Wu et al.，Appl. Phys. Lett. 92，011918-1（2008）） is applied to the detections of crystals. The experimental results of dimethyl phthalate crystal indicate that，under the condition of constant heating rate：1） the crack-healing rate shows a sharp peak as a function of temperature，the peak temperature can be taken as the characteristic temperature Tcch of the crack-healing ，and Tcch=206 K；2） the peak is not symmetric，and the low temperature side is wider than the high temperature side，which means that the crack-healing has started at lower temperatures and the amount of healing below Tcch is more than that above Tcch. This behavior is similar to that in glasses，but Tcch is higher than that of glassy state. Moreover，Tcch is much lower than the melting point of the crystal，which indicates that the crack-healing mechanism is quite different from that of recrystallization. We would like to point out that two dynamical loss peaks related to the crack-healing process are observed for the first time，which will be helpful to the understanding of the mechanisms. The above results also show the feasibility and validity of the RMS-CH method to investigate the stress-cracking and crack-healing in crystals as in glasses.

Keywords:

Authors and contacts

(1)伊犁师范学院新疆凝聚态相变与微结构重点实验室，伊宁 835000; (2)伊犁师范学院新疆凝聚态相变与微结构重点实验室，伊宁 835000；南京大学物理系国家固体微结构重点实验室，南京 210093

References

[1]	［1］Bronisz S E，Douglass D L 1970 Phys. Stat. Sol. 29 K95
[2]	［2］Lange F F，Gupta T K 1970 J. Am. Ceram. Soc. 53 54
[3]	［3］Roberts J T A，Wrona B J 1973 J. Am. Ceram. Soc. 56 297
[4]	［4］Gupta T K 1976 J. Am. Ceram. Soc. 59 259
[5]	［5］Evans A G，Charles E A 1977 Acta Metallugica 25 919
[6]	［6］Smith D L，Evans B 1984 J. Geophys. Res. 89 4125
[7]	［7］Scott C，Tran V B 1985 Am. Ceram. Soc. Bull. 64 1129
[8]	［8］Yasutake K，Iwata M，Yoshii K，Umeno M，Kawabe H 1986 J. Mat. Sci. 21 2185
[9]	［9］Ohya Y，Nakagawa Z E，Hamano K 1988 J. Am. Ceram. Soc. 71 C232
[10]	］Wang Z，Li Y Z，Harmer M P，Chou Y T 1992 J. Am. Ceram. Soc. 75 1596
[11]	］Powers J D，Glaeser A M 1993 J. Am. Ceram. Soc. 76 2225
[12]	］Zhang Y H，Edwards L，Plumbridge W J 1998 J. Am. Ceram. Soc. 81 1861
[13]	］Ando K，Ikeda T，Sato S，Yao F，Kobayashi Y 1998 Fatigue Fract Engng Mater Struct 21 119
[14]	］Wei D B，Han J T，Xie J X 1999 Materials Review 13 10 （in Chinese）［韦东滨、韩静涛、谢建新 1999 材料导报13 10］
[15]	］Wei D B，Han J T，Xie J X 2000 Materials Review 14 37 （in Chinese）［韦东滨、韩静涛、谢建新 2000 材料导报 14 37］
[16]	］Zhou Y Z，Qin R S，Xiao S H，He G H，Zhou B L 2000 J. Mat. Res. 15 1056
[17]	］White S R，Scottos N R，Moore J，Geublle P，Kessler M，Brown E，Suresh S，Viswanathan S 2001 Nature 409 794
[18]	］Lv J，Jin Z H，Zheng Z X，Ding H F 2001 Journal of Inorganic Materials 16 535 （in chinese）［吕珺、金志浩、郑治祥、丁厚福 2001 无机材料学报 16 535］
[19]	］Gao K W，Qiao L J，Chu W Y 2001 Acta Metallurgica Sinica 37 118 （in Chinese）［高克玮、乔利杰、褚武扬 2001 金属学报37 118］
[20]	］Ando K，Furusawa K，Chu M C，Hanagate T，Tuji K，Sato S 2001 J. Am. Ceram. Soc. 84 2073
[21]	］Yang D Z 2002 Intelligent Materials and Intelligent systems （Tianjin：University of Tianjin Press （in chinese）［杨大智 2002 智能材料与智能系统（天津：天津大学出版社）］
[22]	］Chen X X，Dam M A，One K 2002 Science 295 1698
[23]	］Ando K，Shirai Y，Nakatani M 2002 J. Euro. Ceram. Soc. 22 121
[24]	］Kessler M R，Sottos N R，White S R 2003 Composite A 34 743
[25]	］Kim Y W，Ando K，Chu M C 2003 J. Am. Ceram. Soc. 86 465
[26]	］Greenwood J A 2004 J. Phys. D 37 2557
[27]	］Zhang H L，Huang P Z，Sun J，Gao H 2004 Appl. Phys. Lett. 85 1143
[28]	］Toohey K S，Sottos N R，Lewis J A，Moore J S，White S R 2007 Nature Mat. 6 581
[29]	］Kim H S，Kim M K，Kang S B，Ahn S H，Nam K W 2008 Mat. Sci. Eng. A 483-484 672
[30]	］Dementsov A，Privman V 2008 Phy. Rev. E 78 021104-1-6
[31]	］Caruso M M，Blaiszik B J，White S R，Sottos N R，Moore J S 2008 Adv. Fun. Mat. 18 1898
[32]	］Wool R P 2008 Soft Matter 4 400
[33]	］Chen D Y，Chen K J，Guo S H，Huang R，Huang X F，Li W，Ma Z Y，Wei D Y，Xu J，Xu L，Yao J，Zhou，J 2008 Chin. Phys. B 17 303
[34]	］Zhang J M，Huang Y H，Xu K W，Ji V 2007 Chin. Phy. 16 210
[35]	］Yin T，Zhou L，Rong M Z，Zhang M Q 2008 Smart Mater. Struct. 17 015019
[36]	］Cheng Z Q, Sun X W, Xia G Q, Li H Q, Sheng H M, Qian R 2000 Acta Phys. Sin. 49 375 （in Chinese）［程知群、孙晓玮、夏冠群、李洪芹、盛怀茂、钱蓉 49 375］
[37]	］Li Y C, Luo Z C, Wei D, Zhang G Y, Zhang H 2009 Acta Phys. Sin. 58 444 （in Chinese）［李昱材、罗志成、魏丹、张国英、张辉 2009 58 444］
[38]	］Chen Z, Huo J L, Lu Y L, Wang Y X, Zhang J, Zhao Y, Zhen H H 2009 Acta Phys. Sin. 58 631 （in Chinese）［陈铮、霍进良、卢艳丽、王永欣、张静、赵彦、甄辉辉 2009 58 631］
[39]	］Cui C, Ma X Y, Yang D R 2008 Acta Phys. Sin. 57 1037 （in Chinese）［崔灿、马向阳、杨德仁 2008 57 1037］
[40]	］Gu S Y, Wu Q, Zhao H P, Zhou Z C 2008 Acta Phys. Sin. 57 1025 （in Chinese）［顾苏怡、吴倩、赵宏平、周正存 2008 57 1025］
[41]	］Li Y J, Xu A G, Yang Q L, Zhang G C, Zhao Y H 2008 Acta Phys. Sin. 57 940 （in Chinese）［李英骏、许爱国、杨其利、张广财、赵艳红 2008 57 940］
[42]	］Jin H M, Felia Adriana, Aroyave Majorri 2008 Acta Phys. Sin. 57 561 （in Chinese）［靳刊明, Felix Adriana, Aroyave Majorri 2008 57 561］
[43]	］Li W W, Sun K 2006 Acta Phys. Sin. 55 1921 （in Chinese）［李万万、孙康 2006 55 1921］
[44]	］Li W W, Sun K 2007 Acta Phys. Sin. 56 6514 （in Chinese）［李万万、孙康 2007 56 6514］
[45]	］Zhang G Y, Zhang H, Liu C M, Zhou Y J 2005 Acta Phys. Sin. 54 1771 （in Chinese）［张国英、张辉、刘春明、周永军 2005 54 1771］
[46]	］Wu W H，Zhang J L，Zhou H W，Guo X Z，Huang Y N 2008 Appl. Phys. Lett. 92 011918-1-3
[47]	］Ying X N，Yuan Y H，Zhang L，Huang Y N，Wang Y N，Wang X L，Zhou D S，Xue G 2006 Rev. Sci. Instru. 77 053902-1-12
[48]	］Huang Y N，Zhang J L，Ying X N 2006 Progress in Physics 26 359 （in Chinese）［黄以能、张晋鲁、应学农 2006 物理学进展 26 359］
[49]	］Ying X N，Yuan Y H，Zhang L，Huang Y N，Yang Z，Wang Y N 2006 Progress in Physics 26 408 （in Chinese）［应学农、袁颖憨、张亮、黄以能、杨震、王业宁 2006 物理学进展 26 408］
[50]	］Zhou H W，Zhang J L，Huang Y N，Ying X N，Zhang L，Wu W H，Shen Y F 2007 Acta Phys.Sin. 56 6547 （in Chinese）［周恒为、张晋鲁、黄以能、应学农、张亮、吴文惠、沈异凡 2007 56 6547］
[51]	］Zhang J L，Zhang L L，Wu W H，Zhou H W，Guo X Z，Huang Y N 2008 Appl. Phys. Lett. 92 131906-1-3
[52]	］Guo X Z，Zhou H W，Zhang J L，Wu W H，Zhang J L，Huang Y N 2009 Acta Phys.Sin. 59 417 （in Chinese）［郭秀珍、周恒为、张丽丽、吴文惠、张晋鲁、黄以能 2009 59 417］
[53]	］Mullin J W 1997 Crystallization （Oxford：Butterworth-Heinemann）
[54]	］Huang Y N，Wang Y N，Shen H M 1992 Phys. Rev. B 46 3290
[55]	］Huang Y N，Li X，Ding Y，Wang Y N，Shen H M，Zhang Z F，Fang C S，Zhou S H，Fang P C W 1997 Phys. Rev. B 55 16159

Cited By

[1]	［1］Bronisz S E，Douglass D L 1970 Phys. Stat. Sol. 29 K95
[2]	［2］Lange F F，Gupta T K 1970 J. Am. Ceram. Soc. 53 54
[3]	［3］Roberts J T A，Wrona B J 1973 J. Am. Ceram. Soc. 56 297
[4]	［4］Gupta T K 1976 J. Am. Ceram. Soc. 59 259
[5]	［5］Evans A G，Charles E A 1977 Acta Metallugica 25 919
[6]	［6］Smith D L，Evans B 1984 J. Geophys. Res. 89 4125
[7]	［7］Scott C，Tran V B 1985 Am. Ceram. Soc. Bull. 64 1129
[8]	［8］Yasutake K，Iwata M，Yoshii K，Umeno M，Kawabe H 1986 J. Mat. Sci. 21 2185
[9]	［9］Ohya Y，Nakagawa Z E，Hamano K 1988 J. Am. Ceram. Soc. 71 C232
[10]	］Wang Z，Li Y Z，Harmer M P，Chou Y T 1992 J. Am. Ceram. Soc. 75 1596
[11]	］Powers J D，Glaeser A M 1993 J. Am. Ceram. Soc. 76 2225
[12]	］Zhang Y H，Edwards L，Plumbridge W J 1998 J. Am. Ceram. Soc. 81 1861
[13]	］Ando K，Ikeda T，Sato S，Yao F，Kobayashi Y 1998 Fatigue Fract Engng Mater Struct 21 119
[14]	］Wei D B，Han J T，Xie J X 1999 Materials Review 13 10 （in Chinese）［韦东滨、韩静涛、谢建新 1999 材料导报13 10］
[15]	］Wei D B，Han J T，Xie J X 2000 Materials Review 14 37 （in Chinese）［韦东滨、韩静涛、谢建新 2000 材料导报 14 37］
[16]	］Zhou Y Z，Qin R S，Xiao S H，He G H，Zhou B L 2000 J. Mat. Res. 15 1056
[17]	］White S R，Scottos N R，Moore J，Geublle P，Kessler M，Brown E，Suresh S，Viswanathan S 2001 Nature 409 794
[18]	］Lv J，Jin Z H，Zheng Z X，Ding H F 2001 Journal of Inorganic Materials 16 535 （in chinese）［吕珺、金志浩、郑治祥、丁厚福 2001 无机材料学报 16 535］
[19]	］Gao K W，Qiao L J，Chu W Y 2001 Acta Metallurgica Sinica 37 118 （in Chinese）［高克玮、乔利杰、褚武扬 2001 金属学报37 118］
[20]	］Ando K，Furusawa K，Chu M C，Hanagate T，Tuji K，Sato S 2001 J. Am. Ceram. Soc. 84 2073
[21]	］Yang D Z 2002 Intelligent Materials and Intelligent systems （Tianjin：University of Tianjin Press （in chinese）［杨大智 2002 智能材料与智能系统（天津：天津大学出版社）］
[22]	］Chen X X，Dam M A，One K 2002 Science 295 1698
[23]	］Ando K，Shirai Y，Nakatani M 2002 J. Euro. Ceram. Soc. 22 121
[24]	］Kessler M R，Sottos N R，White S R 2003 Composite A 34 743
[25]	］Kim Y W，Ando K，Chu M C 2003 J. Am. Ceram. Soc. 86 465
[26]	］Greenwood J A 2004 J. Phys. D 37 2557
[27]	］Zhang H L，Huang P Z，Sun J，Gao H 2004 Appl. Phys. Lett. 85 1143
[28]	］Toohey K S，Sottos N R，Lewis J A，Moore J S，White S R 2007 Nature Mat. 6 581
[29]	］Kim H S，Kim M K，Kang S B，Ahn S H，Nam K W 2008 Mat. Sci. Eng. A 483-484 672
[30]	］Dementsov A，Privman V 2008 Phy. Rev. E 78 021104-1-6
[31]	］Caruso M M，Blaiszik B J，White S R，Sottos N R，Moore J S 2008 Adv. Fun. Mat. 18 1898
[32]	］Wool R P 2008 Soft Matter 4 400
[33]	］Chen D Y，Chen K J，Guo S H，Huang R，Huang X F，Li W，Ma Z Y，Wei D Y，Xu J，Xu L，Yao J，Zhou，J 2008 Chin. Phys. B 17 303
[34]	］Zhang J M，Huang Y H，Xu K W，Ji V 2007 Chin. Phy. 16 210
[35]	］Yin T，Zhou L，Rong M Z，Zhang M Q 2008 Smart Mater. Struct. 17 015019
[36]	］Cheng Z Q, Sun X W, Xia G Q, Li H Q, Sheng H M, Qian R 2000 Acta Phys. Sin. 49 375 （in Chinese）［程知群、孙晓玮、夏冠群、李洪芹、盛怀茂、钱蓉 49 375］
[37]	］Li Y C, Luo Z C, Wei D, Zhang G Y, Zhang H 2009 Acta Phys. Sin. 58 444 （in Chinese）［李昱材、罗志成、魏丹、张国英、张辉 2009 58 444］
[38]	］Chen Z, Huo J L, Lu Y L, Wang Y X, Zhang J, Zhao Y, Zhen H H 2009 Acta Phys. Sin. 58 631 （in Chinese）［陈铮、霍进良、卢艳丽、王永欣、张静、赵彦、甄辉辉 2009 58 631］
[39]	］Cui C, Ma X Y, Yang D R 2008 Acta Phys. Sin. 57 1037 （in Chinese）［崔灿、马向阳、杨德仁 2008 57 1037］
[40]	］Gu S Y, Wu Q, Zhao H P, Zhou Z C 2008 Acta Phys. Sin. 57 1025 （in Chinese）［顾苏怡、吴倩、赵宏平、周正存 2008 57 1025］
[41]	］Li Y J, Xu A G, Yang Q L, Zhang G C, Zhao Y H 2008 Acta Phys. Sin. 57 940 （in Chinese）［李英骏、许爱国、杨其利、张广财、赵艳红 2008 57 940］
[42]	］Jin H M, Felia Adriana, Aroyave Majorri 2008 Acta Phys. Sin. 57 561 （in Chinese）［靳刊明, Felix Adriana, Aroyave Majorri 2008 57 561］
[43]	］Li W W, Sun K 2006 Acta Phys. Sin. 55 1921 （in Chinese）［李万万、孙康 2006 55 1921］
[44]	］Li W W, Sun K 2007 Acta Phys. Sin. 56 6514 （in Chinese）［李万万、孙康 2007 56 6514］
[45]	］Zhang G Y, Zhang H, Liu C M, Zhou Y J 2005 Acta Phys. Sin. 54 1771 （in Chinese）［张国英、张辉、刘春明、周永军 2005 54 1771］
[46]	］Wu W H，Zhang J L，Zhou H W，Guo X Z，Huang Y N 2008 Appl. Phys. Lett. 92 011918-1-3
[47]	］Ying X N，Yuan Y H，Zhang L，Huang Y N，Wang Y N，Wang X L，Zhou D S，Xue G 2006 Rev. Sci. Instru. 77 053902-1-12
[48]	］Huang Y N，Zhang J L，Ying X N 2006 Progress in Physics 26 359 （in Chinese）［黄以能、张晋鲁、应学农 2006 物理学进展 26 359］
[49]	］Ying X N，Yuan Y H，Zhang L，Huang Y N，Yang Z，Wang Y N 2006 Progress in Physics 26 408 （in Chinese）［应学农、袁颖憨、张亮、黄以能、杨震、王业宁 2006 物理学进展 26 408］
[50]	］Zhou H W，Zhang J L，Huang Y N，Ying X N，Zhang L，Wu W H，Shen Y F 2007 Acta Phys.Sin. 56 6547 （in Chinese）［周恒为、张晋鲁、黄以能、应学农、张亮、吴文惠、沈异凡 2007 56 6547］
[51]	］Zhang J L，Zhang L L，Wu W H，Zhou H W，Guo X Z，Huang Y N 2008 Appl. Phys. Lett. 92 131906-1-3
[52]	］Guo X Z，Zhou H W，Zhang J L，Wu W H，Zhang J L，Huang Y N 2009 Acta Phys.Sin. 59 417 （in Chinese）［郭秀珍、周恒为、张丽丽、吴文惠、张晋鲁、黄以能 2009 59 417］
[53]	］Mullin J W 1997 Crystallization （Oxford：Butterworth-Heinemann）
[54]	］Huang Y N，Wang Y N，Shen H M 1992 Phys. Rev. B 46 3290
[55]	］Huang Y N，Li X，Ding Y，Wang Y N，Shen H M，Zhang Z F，Fang C S，Zhou S H，Fang P C W 1997 Phys. Rev. B 55 16159

[1]	Hu Ting-He, Li Zhi-Hao, Zhang Qian-Fan. First principles and molecular dynamics simulations of effect of dopants on properties of high strength steel for hydrogen storage vessels. Acta Physica Sinica, 2024, 73(6): 067101. doi: 10.7498/aps.73.20231735
[2]	Tang Han-Yu, Wang Na, Wu Xue-Bang, Liu Chang-Song. Wet granular matter mechanical spectroscopy under low-frequency shear. Acta Physica Sinica, 2018, 67(20): 206402. doi: 10.7498/aps.67.20180966
[3]	Zhou Heng-Wei, Liu Jun, Lei Ting, Huang Yi-Neng. Application of reed-vibration mechanical spectroscopy of liquids for studying dehydration denaturation of protein hydrogel. Acta Physica Sinica, 2013, 62(7): 076203. doi: 10.7498/aps.62.076203
[4]	Liu Qi-Neng. Analytic method of studying defect mode of 1D doped phononic crystal. Acta Physica Sinica, 2011, 60(4): 044302. doi: 10.7498/aps.60.044302
[5]	Wang Kun-Peng, Yan Shi. S substituting for P point defect-induced laser damage in KDP crystals. Acta Physica Sinica, 2011, 60(9): 097401. doi: 10.7498/aps.60.097401
[6]	Guo Xiu-Zhen, Zhou Heng-Wei, Zhang Li-Li, Wu Wen-Hui, Zhang Jin-Lu, Huang Yi-Neng. Investigation on the crack healing effect in dimethyl phthalate series glassy materials. Acta Physica Sinica, 2010, 59(1): 417-421. doi: 10.7498/aps.59.417
[7]	Zhang Hai-Feng, Ma Li, Liu Shao-Bin. Defect mode properties of magnetized plasma photonic crystals. Acta Physica Sinica, 2009, 58(2): 1071-1076. doi: 10.7498/aps.58.1071
[8]	Ma Li, Zhang Hai-Feng, Liu Shao-Bin. Study on the defect mode properties of unmagnetized plasma photonic crystals. Acta Physica Sinica, 2008, 57(8): 5089-5094. doi: 10.7498/aps.57.5089
[9]	Jia Ren-Xu, Zhang Yi-Men, Zhang Yu-Ming, Guo Hui, Luan Su-Zhen. The relation between green-band luminescence of 4H-SiC homoepitaxial layer and defects. Acta Physica Sinica, 2008, 57(7): 4456-4458. doi: 10.7498/aps.57.4456
[10]	Cai Xu-Hong, Lin Xu-Sheng, Shi Quan, Zhao Nian-Shun. Resonant frequency shift in coupled photonic crystal defects described by the tight-binding method. Acta Physica Sinica, 2007, 56(5): 2742-2746. doi: 10.7498/aps.56.2742
[11]	Liu Hai-Lan, Gu Mu, Zhang Rui, Xu Rong-Kun, Li Guang-Wu, Ouyang Xiao-Ping. Electronic structure of intrinsic defects and mechanism of donor-acceptor pair luminescence in CuI crystal. Acta Physica Sinica, 2006, 55(12): 6574-6579. doi: 10.7498/aps.55.6574
[12]	Wan Wei, Tang Chun-Yan, Wang Yu-Mei, Li Fang-Hua. A study on the stacking fault in GaN crystals by high-resolution electron microscope imaging. Acta Physica Sinica, 2005, 54(9): 4273-4278. doi: 10.7498/aps.54.4273
[13]	LI LI-JUN, WANG ZUO-XIN, WU JIN-LEI. POSITRON ANNIHILATION TIME STUDY OF DEFECTS IN Hg1-xCdxTe SINGLE CRYSTALS. Acta Physica Sinica, 1998, 47(5): 844-850. doi: 10.7498/aps.47.844
[14]	GAO FEI, YANG SHUN-HUA. A STUDY ON MOVING SCREW DISLOCATION BY THE METHOD OF GAUGE FIELD THEORY FOR CRYSTAL DEFECTS. Acta Physica Sinica, 1990, 39(7): 81-87. doi: 10.7498/aps.39.81
[15]	GAO FEI. EDGE DISLOCATION IN CRYSTAL DEFECT GAUGE FIELD. Acta Physica Sinica, 1990, 39(10): 1591-1598. doi: 10.7498/aps.39.1591
[16]	YANG CUI-YING, ZHANG DAO-FAN, WU XING, ZHOU YU-QING, FENG GUO-GUANG. ANALYTICAL ELECTRON MICROSCOPY OF DEFECTS IN PHOTOREFRACTIVE BaTiO3 CRYSTAL. Acta Physica Sinica, 1989, 38(12): 2003-2007. doi: 10.7498/aps.38.2003
[17]	FENG XI-QI, YING JI-EENG, WANG JIN-CHANG, LIU JIAN-CHENG. THE OH ABSORPTION SPECTRUM As A PROBE FOR DEFECT STRUCTURE OF LiNbO3 CRYSTAL. Acta Physica Sinica, 1988, 37(12): 2062-2067. doi: 10.7498/aps.37.2062
[18]	WANG TIAN-MIN, MICHIO SHIMOTOMAI, MASAO DOYAMA. STUDY OF THE LATTICE DEFECTS IN NiAl BY POSITRON ANNIHILATION. Acta Physica Sinica, 1986, 35(6): 704-708. doi: 10.7498/aps.35.704
[19]	GUO CHANG-LIN. OBSERVATION OF DEFECTS IN β-SILICON CARBIDE EPITAXIAL FILM. Acta Physica Sinica, 1982, 31(11): 1526-1533. doi: 10.7498/aps.31.1526
[20]	FENG DUAN. PROGRESS IN THE STUDIES OF LATTICE DEFECTS. Acta Physica Sinica, 1979, 28(2): 141-151. doi: 10.7498/aps.28.141

Catalog

Vol. 59, Issue 3 - 2010-02-05

Metrics

Abstract views: 7930
PDF Downloads: 926
Cited By: 0

姓名
邮箱
手机号码
标题
留言内容
验证码

Search

Article

留言板