簡易檢索 / 詳目顯示

回結果列表
研究生： 鄭維仁
Wei-Jen Cheng
論文名稱： 鉻鉬鋼熱浸鋁矽後鋁化層之顯微結構與高溫相變化行為
Microstructure and High-temperature Phase Transformation Behavior of Hot-dipped Al-Si Aluminide Layer on Cr-Mo Steel
指導教授： 王朝正
Chaur-Jeng Wang
口試委員: 林招松
Chao-Sung Lin
開物
Wu Kai
郭瑞昭
Jui-Chao Kuo
朱瑾
Jinn P. Chu
李志偉
Jyh-Wei Lee
學位類別： 博士
Doctor
系所名稱： 工程學院 - 機械工程系
Department of Mechanical Engineering
論文出版年： 2012
畢業學年度： 100
語文別： 中文
論文頁數： 146
中文關鍵詞： 電子背向散射繞射 、鋁化層 、相鑑定 、熱浸鍍鋁 、鉻鉬鋼
外文關鍵詞： Electron backscattered diffraction, Aluminide layer, Cr-Mo steel, Hot-dip aluminizing, Phase identification
相關次數： 點閱：245  下載：7 
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報

    • 本研究採用低碳鋼與5Cr-0.5Mo鋼經熱浸純鋁與鋁-10 wt.%矽後，於750 °C空氣氣氛下進行擴散。藉由電子背向散射繞射技術，以了解鋼材含鉻及鋁湯添加矽對於熱浸鋁化鋼材隨高溫擴散所伴隨的顯微結構與組成相變化之影響。
    在所有熱浸鋁化試片中，鋁化層可區分為外層的純鋁或鋁矽塗層與內層的Fe-Al或Fe-Al-Si介金屬層。低碳鋼熱浸純鋁之鋁化層會因為所形成的Fe2Al5相其晶體結構之c軸具有空孔，造成Fe2Al5相會固定其c軸平行鐵鋁交互擴散之方向快速成長，並且在介金屬層/低碳鋼基材界面形成高低起伏之形貌。然而，在低碳鋼熱浸鋁-10 wt.%矽、5Cr-0.5Mo鋼熱浸純鋁及鋁-10 wt.%矽之鋁化層中，鋁湯的矽與鋼材的鉻皆會減緩介金屬層的鐵鋁交互擴散，使得鋁化層會具有較薄之介金屬層較平坦的介金屬層/鋼料基材界面。
    熱浸純鋁試片在經過高溫擴散後，鋁化層的組成相變化皆是由Fe-Al相組成，鋁含量由高至低各別為FeAl3、Fe2Al5、FeAl2與FeAl相。其相變化過程可分為(1)純鋁塗層仍存在，(2)純鋁塗層消失，(3) FeAl2與FeAl相形成與(4) Fe2Al5相消失等四個階段。其中，由於5Cr-0.5Mo鋼熱浸試片的Fe2Al5相在靠近鍍層表面具有等軸細晶粒，因此FeAl2相除了會於Fe2Al5相與FeAl相之間形成，還會選擇Fe2Al5相的等軸細晶粒處析出。
    在經過高溫擴散的熱浸鋁-10 wt.%矽試片中，鋁化層除了具有和熱浸純鋁試片相同的Fe-Al相外，還可發現Fe-Al-Si相的生成，矽含量由高至低各別為τ4-Al3FeSi2、τ1-(Al,Si)5Fe3、τ6-Al4FeSi、τ5(H)-Al7Fe2Si或τ5(C)-Al7(Fe,Cr)2Si相。其相變化過程可分為(1)鋁矽塗層仍存在，(2)鋁矽塗層消失/FeAl(Si)相形成，(3) τ1-(Al,Si)5Fe3相消失/FeAl2相形成與(4) Fe2Al5相消失等四個階段。兩種熱浸鋁化試片皆會因為FeAl相在Fe-Al相中擁有最高的矽固溶度，並且具有與τ1-(Al,Si)5Fe3相類似之成分，因此使得τ1-(Al,Si)5Fe3相會傾向轉變為FeAl(Si)相。另一方面，由於FeAl2相在Fe-Al相中具有最低的矽固溶度，所以固溶於Fe2Al5相的矽會抑制FeAl2相的出現，而造成其比FeAl(Si)相還要晚形成。

    Mild steel and 5Cr-0.5Mo steel were coated by hot-dipping into the molten baths containing pure aluminum and Al-10 wt.%Si. The effects of chromium in the steel and silicon in the molten bath on the evolution of microstructure and phase constitution in the hot-dipped aluminide steels during diffusion at 750 °C in static air was analyzed by electron backscattered diffraction.
    All of the aluminide layers were composed of an outer pure aluminum or Al-Si topcoat and an inner Fe-Al or Fe-Al-Si intermetallic layer. The aluminide layer of mild steel hot-dipped into pure aluminum possessed a thick intermetallic layer and a rough interface between the intermetallic layer and mild steel substrate. This is due to Fe2Al5, the major phase of intermetallic layer, possesses vacancies along its c-axis of the crystal structure. These vacancies caused Fe2Al5 to grow preferentially by fixing its c-axis along the diffusion direction during hot-dipping. However, in the aluminide layers of mild steel hot-dipped into Al-10 wt.%Si and 5Cr-0.5Mo steel hot-dipped into pure aluminum and Al-10 wt.%Si, silicon from the Al-10 wt.%Si molten bath and chromium from the 5Cr-0.5Mo steel can decrease the Fe/Al inter-diffusion rate of the intermetallic layers. This resulted in the reduction of the intermetallic layers and planarization of the intermetallic layer/steel substrate interfaces.
    After high-temperature diffusion, the phase transformations of the aluminide layers formed by hot-dipping into pure aluminum were dominated by the Fe-Al phases, ranked by high to low aluminum content as FeAl3, Fe2Al5, FeAl2 and FeAl, respectively. The phase transformation behavior of these aluminide layers can be categorized into the following four stages: (1) the existence of aluminum topcoat, (2) the consumption of aluminum topcoat, (3) the formation of FeAl2 and FeAl, and (4) the consumption of Fe2Al5. In addition, FeAl2 in the aluminide layer of 5Cr-0.5Mo steel hot-dipped into pure aluminum was not only formed between Fe2Al5 and FeAl, but aslo precipitated at the equiaxed fine grains of the Fe2Al5.
    In the aluminide layers formed by hot-dipping into Al-10 wt.%Si after high-temperature diffusion, the Fe-Al phases presented in the case of hot-dipping pure aluminum were also existed. In addition, the Fe-Al-Si phases, ranked by high to low silicon content as τ4-Al3FeSi2, τ1-(Al,Si)5Fe3, τ6-Al4FeSi, τ5(H)-Al7Fe2Si or τ5(C)-Al7(Fe,Cr)2Si, respectively, can form in these aluminide layers. The phase transformation behavior of these aluminide layers can also be categorized into the following four stages: (1) the existence of Al-Si topcoat, (2) the consumption of Al-Si topcoat/the formation of FeAl(Si), (3) the consumption of τ1-(Al,Si)5Fe3/the formation of FeAl2, and (4) the consumption of Fe2Al5. Besides, the transformation of τ1-(Al,Si)5Fe3 into FeAl(Si) was observed in the case of hot-dipping Al-10 wt.%Si, This can be attributed to the high silicon solubility of FeAl, highest among all Fe-Al intermetallic phases, and the similar composition between τ1-(Al,Si)5Fe3 and FeAl. Compared to the results of hot-dipping pure aluminum, it was found that FeAl2 formed later than FeAl(Si). The reason for this is due to the solid solution of silicon in Fe2Al5 restrained the formation of FeAl2, which possesses the lowest silicon solubility among all Fe-Al intermetallic phases.

    第一章　前言 1 第二章　文獻回顧 3 2.1　熱浸鍍鋁 3 2.1.1　目的與原理 3 2.1.2　影響熱浸鋁化層生成之參數 4 2.1.3　熱浸鋁湯的種類 6 2.2　鋁化層中介金屬相的形成與相變化 8 2.2.1　Fe-Al與Fe-Al-Si介金屬相 8 2.2.2　熱浸純鋁之鋁化層 12 2.2.3　熱浸鋁矽之鋁化層 16 2.2.4　孔洞的生成 19 2.3　電子背向散射繞射 21 2.3.1　材料微觀分析 21 2.3.2　電子背向散射繞射原理 22 2.3.3　電子背向散射繞射的應用 28 第三章　實驗方法 30 3.1　鋼材熱浸鍍鋁 32 3.1.1　試片製作 32 3.1.2　熱浸鍍鋁製程 32 3.1.3　高溫擴散實驗 33 3.2　分析設備與方法 35 3.2.1　分析設備 35 3.2.2　分析方法 36 第四章　實驗結果 40 4.1　低碳鋼熱浸純鋁 40 4.1.1　鋁化層之顯微結構與組成相 40 4.1.2　鋁化層經高溫擴散後之顯微結構與相變化 46 4.1.3　鋁化層之晶粒尺寸與取向分布 51 4.2　5Cr-0.5Mo鋼熱浸純鋁 55 4.2.1　鋁化層之顯微結構與組成相 55 4.2.2　鋁化層經高溫擴散後之顯微結構與相變化 57 4.2.3　鋁化層之晶粒尺寸與取向分布 62 4.3　低碳鋼熱浸鋁-10矽 66 4.3.1　鋁化層之顯微結構與組成相 66 4.3.2　鋁化層經高溫擴散後之顯微結構與相變化 70 4.3.3　鋁化層之晶粒尺寸與取向分布 75 4.4　5Cr-0.5Mo鋼熱浸鋁-10矽 79 4.4.1　鋁化層之顯微結構與組成相 79 4.4.2　鋁化層經高溫擴散後之顯微結構與相變化 84 4.4.3　鋁化層之晶粒尺寸與取向分布 91 第五章　討論 96 5.1　鋁化層的生成 96 5.1.1　低碳鋼熱浸純鋁 96 5.1.2　5Cr-0.5Mo鋼熱浸純鋁 99 5.1.3　低碳鋼熱浸鋁-10矽 99 5.1.4　5Cr-0.5Mo鋼熱浸鋁-10矽 100 5.2　鋁化層的高溫相變化行為 102 5.2.1　低碳鋼熱浸純鋁 102 5.2.2　5Cr-0.5Mo鋼熱浸純鋁 107 5.2.3　低碳鋼熱浸鋁-10矽 112 5.2.4　5Cr-0.5Mo鋼熱浸鋁-10矽 119 5.3　鋼材含鉻及鋁湯含矽對鋁化層之顯微結構與組成相分布的影響 124 5.3.1　鋁化層之顯微結構 124 5.3.1.1　介金屬層厚度與介金屬層/鋼料基材界面形貌 124 5.3.1.2　Fe2Al5相晶粒尺寸分布 125 5.3.1.3　孔洞的生成 126 5.3.2　鋁化層之組成相分布 127 第六章　結論 131 參考文獻 133 附錄A　鋁化層組成相的EBSP及其辨識結果 140 未來研究之建議 144 作者簡介 145

    1. C.J. Wang and S.M. Chen, Surf. Coat. Technol. 200 (2006) 6601.
    2. Y.N. Chang and F.I. Wei, J. Mater. Sci. 24 (1989) 14.
    3. S.R. Pillai, N.S. Barasi and H.S. Khatak, Oxid. Met. 53 (2000) 193.
    4. A.P. Greeff, C.W. Louw and H.C. Swart, Surf. Interface Anal. 30 (2000) 120.
    5. Zs. Tokei, H. Viefhaus and H.J. Grabke, Appl. Surf. Sci. 165 (2000) 23.
    6. L. Yajiang, W. Juan, Z. Yonglan and X. Holly, Bull. Mater. Sci. 25 (2002) 635.
    7. D. Wang and Z. Shi, Appl. Surf. Sci. 227 (2004) 255.
    8. A. Bahadur and O.N. Mohanty, Mater. Trans. JIM. 32 (1991) 1053.
    9. S.G. Denner and R.D. Jones, Met. Technol. 4 (1977) 167.
    10. N.A. EI-Mahallawy, M.A. Taha, M.A. Shady, A.R. EI-Sissi, A.N. Attia and W. Reif, Mater. Sci. Technol. 13 (1997) 832.
    11. R.W. Richards, R.D. Jones, P.D. Clements and H. Clarke, Int. Mater. Rev. 39 (1994) 191.
    12. S. Kobayashi and T. Yakou, Mater. Sci. Eng. A 338 (2002) 44.
    13. T. Sasaki and T. Yakou, Surf. Coat. Technol. 201 (2006) 2131.
    14. H. Glasbrenner and J. Konys, Fusion Eng. Des. 58-59 (2001) 725.
    15. H. Glasbrenner, K. Stein-Fechner and J. Konys, Fusion Eng. Des. 51-52 (2000) 105.
    16. H. Glasbrenner, K. Stein-Fechner and J. Konys, J. Nucl. Mater. 283-287 (2000) 1302.
    17. W. Deqing, Appl. Surf. Sci. 254 (2008) 3026.
    18. T.S. Shih and S.H. Tu, Mater. Sci. Eng. A 454-455 (2007) 349.
    19. J.C. Viala, M. Peronnet, F. Barbeau, F. Bosselet and J. Bouix, Compos. Part A: Appl. Sci. Manuf. 33 (2002) 1417.
    20. O. Dezellus, B. Digonnet, M. Sacerdote-Peronnet, F. Bosselet, D. Rouby and J.C. Viala, Int. J. Adhes. Adhes. 27 (2007) 417.
    21. S. Shankar and D. Apelian, Metall. Mater. Trans. B 33 (2002) 465.
    22. J.L. Song, S.B. Lin, C.L. Yang and C.L. Fan, J. Alloy. Compd. 488 (2009) 217.
    23. G. Eggeler, H. Vogel, J. Friedrich and H. Kaesche, Prakt. Metallog. 22 (1985) 163.
    24. K. Bouche, F. Barbier and A. Coulet, Mater. Sci. Eng. A 249 (1998) 167.
    25. M.V. Akdeniz, A.O. Mekhrabov and T. Yilmaz, Scri. Metall. Mater. 31 (1994) 1723.
    26. G.M. Bedford and J. Boustead, J. Mater. Sci. 13 (1978) 253.
    27. E. Serra, H. Glasbrenner and A. Perujo, Fus. Eng. Des. 41 (1998) 149.
    28. S.P. Gupta, Mater. Charact. 49 (2003) 269.
    29. T. Maitra and S.P. Gupta, Mater. Charact. 49 (2003) 293.
    30. S. Pontevichi, F. Bosselet, F. Barbeau, M. Peronnet and J.C. Viala, J. Phase Equilib. Diffus. 25 (2004) 528.
    31. T.L. Hu, H.L. Huang, D. Gan and T.Y. Lee, Surf. Coat. Technol. 201 (2006) 3502.
    32. A. Aguero, F.J. Garcia de Blas, M.C. Garcia, R. Muelas and A. Roman, Surf. Coat. Technol. 146-147 (2001) 578.
    33. Y. Zhang, B.A. Pint, K.M. Cooley and J.A. Haynes, Surf. Coat. Technol. 200 (2005) 1231.
    34. H.C. Akuezue and D.P. Whittle, Met. Sci. 17 (1983) 27.
    35. R. Sivakumar and E.J. Rao, Oxid. Met. 17 (1982) 391.
    36. C. Houngninou, S. Chevalier and J.P. Larpin, Appl. Surf. Sci. 236 (2004) 256.
    37. W.T. Tsai and K.E. Huang, Thin Solid Films 366 (2000) 164.
    38. Y.Y. Chang, C.C. Tsaur and J.C. Rock, Surf. Coat. Technol. 200 (2006) 6588.
    39. G. Eggeler, W. Auer and H. Kaesche, J. Mater. Sci. 21 (1986) 3348.
    40. ASM, in: Metals handbook, 9th ed. Vol. 5 (ASM International, Metals Park, OH, USA, 1983) p.333.
    41. S.G. Denner and R. D. Jones, Met. Technol. 4 (1977) 167.
    42. H. Lundin, N. Bergen and H. M. Lundin, United States Patent 2686355 (1954).
    43. C.J. Wang and S.M. Chen, Surf. Coat. Technol. 201 (2006) 3862.
    44. D. Naoi and M. Kajihara, Mater. Sci. Eng. A 459 (2007) 375.
    45. W. Deqing, S. Ziyuan and Z. Longjiang, Appl. Surf. Sci. 214 (2003) 304.
    46. A. Bouayad, C. Gerometta, A. Belkebir and A. Ambari, Mater. Sci. Eng. A 363 (2003) 53.
    47. D.O. Gittings, D.H. Rowland and J.O. Mack, Tran. ASM 43 (1951) 587.
    48. K.G. Coburn, Met. Eng. Quart. 4 (1964) 54.
    49. W.J. Cheng and C. J. Wang, Mater. Charact. 61 (2010) 467.
    50. T.B. Massalski, H. Okamoto, P.R. Subramanian and L. Kacprzak, in: Binary Alloy Phase Diagrams, Vol. 1. (ASM International, Metals Park, OH, USA, 1990) p.212.
    51. J. Grin, U. Burkhardt, M. Ellner and K. Peters. Z. Kristallogr. 209 (1994) 479.
    52. U. Burkhardt, Yu. Grin, M. Ellner and K. Peters, Acta Crystallogr. Sect. B: Struct. Sci. 50 (1994) 313.
    53. R.N. Corby and P.J. Black, Acta Crystallogr. Sect. B: Struct. Sci. 29 (1973) 2669.
    54. Y. Guo, J. Liang, X. Zhang, W. Tang, Y. Zhao and G. Rao, J. Alloy. Compd. 257 (1997) 69.
    55. E. Popiel, M. Tuszynski, W. Zarek and T. Rendecki, J. Less-Common Met. 146 (1989) 127.
    56. T.B. Massalski, H. Okamoto, P.R. Subramanian and L. Kacprzak, in: Binary Alloy Phase Diagrams, Vol. 1. (ASM International, Metals Park, OH, USA, 1990) p.148.
    57. Y. Du, J.C. Schuster, Z.K. Liu, R. Hu, P. Nash, W. Sun, W. Zhang, J. Wang, L. Zhang, C. Tang, Z. Zhu, S. Liu, Y. Ouyang, W. Zhang and N. Krendelsberger, Intermetallics 16 (2008) 554.
    58. T.I. Yanson, M.B. Manyako, O.I. Bodak, N.V. German, O.S. Zarechnyuk, R. Cerny, J.V. Pacheco and K. Yvon, Acta Crystallogr. Sect. C-Cryst. Struct. Commun. 52 (1996) 2964.
    59. D. Munson, J. Inst . Met. 95 (1967) 217.
    60. N.V. German, V.E. Zavodnik, T.I. Yanson, and O.S. Zarechnyuk, Kristallografiya 34 (1989) 738.
    61. C. Gueneau, C. Servant, F. d'Yvoire and N. Rodier, Acta Crystallogr. Sect. C-Cryst. Struct. Commun. 51 (1995) 177.
    62. R.N. Corby and P.J. Black, Acta Crystallogr. Sect. B: Struct. Sci. 33 (1977) 3468.
    63. M. Cooper, Acta Crystallogr. 23 (1967) 1106.
    64. V. Hansen, B.C. Hauback, M. Sundberg, C. Romming and J. Gjonnes, Acta Crystallogr. Sect. B: Struct. Sci. 54 (1998) 351.
    65. C. Gueneau, C. Servant, F. d'Yvoire and N. Rodier, Acta Crystallogr. Sect. C: Cryst. Struct. Commun. 51 (1995) 2461.
    66. N.V. German, V.K. Bel'skii, T.I. Yanson and O.S. Zarechnyuk, Kristallografiya 34 (1989) 735.
    67. I.C. Stone and H. Jones, Mater. Sci. Eng. A 226 (1997) 33.
    68. M.H. Mulazimoglu, A. Zaluska, J.E. Gruzleski and F. Paray, Metall. Mater. Trans. A 27 (1996) 929.
    69. C. Hsu, K.A.Q. O'Reilly, B. Cantor and R. Hamerton, Mater. Sci. Eng. A 304-306 (2001) 119.
    70. M. Dehmas, R. Valdes, M.C. Lafont, J. Lacaze and B. Viguier, Scr. Mater. 55 (2006) 191.
    71. S.G. Shabestari, Mater. Sci. Eng. A 383 (2004) 289.
    72. M. Warmuzek, W. Ratuszek and G. Sek-Sas, Mater. Charact. 54 (2005) 31.
    73. S.C. Kwon and J.Y. Lee, Can. Metall. Q. 20 (1981) 351.
    74. A. Rahmel and W. Schwenk, in: Korrosion und Korrosionsschutz von Stahlen (Verlag Chemie, Weinheim 1977).
    75. H. Glasbrenner and J. Konys, Fusion Eng. Des. 58-59 (2001) 725.
    76. H. Glasbrenner and H. U. Borgstedt, J. Nucl. Mater. 212-215 (1994) 1561.
    77. M.V. Akdeniz and A.O. Mekhrabov, Acta Mater. 46 (1998) 1185.
    78. T. Heumann and S. Dittrich, Z. Metallkde. 50 (1959) 617.
    79. A.K. Kurakin, Fiz. Metal. Metalloved. 30 (1970) 108.
    80. D.A. Layner and A.K. Kurakin, Fiz. Met. Metalloved. 18 (1964) 134.
    81. S. Takeda and K. Mutazaki, J. Iron Steel Inst. Jpn. 26 (1940) 335.
    82. A.D. Smigelskas and E.O. Kirkendall, Trans. AIME 171 (1947) 130.
    83. T. Kimata, K. Uenishi, A. Ikenaga and K. F. Kobayashi, Intermetallics 11 (2003) 947.
    84. 黃宏勝、林麗娟，FE-SEM/CL/EBSD分析技術簡介，工業材料雜誌，第201卷，2003，第99~108頁。
    85. 陳厚光、張立，科儀新知，掃描式電子顯微鏡中之背向電子繞射分析技術，科儀新知，第27卷第6期，2006，第22~30頁。
    86. 廖忠賢、黃志青，電子背向繞射系統之介紹－掃瞄式電子顯微鏡的新利器，科儀新知，第19卷第5期，1998，第43~51頁。
    87. A.J. Schwartz, M. Kumar and B.L. Adams, in: Electron Backscatter Diffraction in Materials Science (Kluwer Academic, New York, 2000).
    88. T.J. Nijdam and W.G. Sloof, Mater. Charact. 59 (2008) 1697.
    89. M. Kulka, A. Pertek and L. Klimek, Mater. Charact. 56 (2006) 232.
    90. Y.H. Zhu, W.B. Lee, C.F. Yeung and T.M. Yue, Mater. Charact. 46 (2001) 19.
    91. A.W. Wilson, J.D. Madison and G. Spanos, Scr. Mater. 45 (2001) 1335.
    92. Y. Zhong, J. Liu, R.A. Witt, Y.H. Sohn and Z.K. Liu, Scr. Mater. 55 (2006) 573.
    93. R.L. Higginson, B. Roebuck and E.J. Palmiere, Scr. Mater. 47 (2002) 337.
    94. M. Karadge, X. Zhao, M. Preuss and P. Xiao, Scr. Mater. 54 (2006) 639.
    95. F.J. Humphreys, Scr. Mater. 51 (2004) 771.
    96. H.U. Hong, B.S. Rho and S.W. Nam. Mater. Sci. Eng. A 318 (2001) 285.
    97. J. Cho, C.M. Wang, H.M. Chan, J.M. Rickman and M.P. Harmer, J. Mater. Sci. 37 (2002) 59.
    98. K. Robson and P.J. Black, Philos. Mag. 44 (1953) 1392.
    99. H.R. Shaverdi, M.R. Ghomashchi, S. Shabestari and J. Hejazi, J. Mater. Process. Technol. 124 (2002) 345.
    100. V. Sivan, Met. Finish. 78 (1980) 21.
    101. D.M. Dovey and A. Waluski, Metallurgia 67 (1963) 211.
    102. X. Hou, H. Yang, Y. Zhao and F. Pan, Mater. Lett. 58 (2004) 3424.
    103. P. Furrer and H. Warlimont, Mater. Sci. Eng. 28 (1977) 127.
    104. Y.H. Sohn and M.A. Dayananda, Scr. Mater. 40 (1999) 79.
    105. L. Xu, Y.Y. Cui, Y.L. Hao and R. Yang, Mater. Sci. Eng. A 435-436 (2006) 638.
    106. V.C. Srivastava, P. Ghosal and S.N. Ojha, Mater. Lett. 56 (2002) 797.
    107. G. Ghosh, in: G. Effenberg and S. Ilyenko, Editors, Light metal ternary systems: phase diagrams, crystallographic and thermodynamic data (Springer-Verlag, Berlin, Heidelberg, Germany, 2005) p.359.

    QR CODE