Please wait a minute...
Acta Metall Sin  2016, Vol. 52 Issue (6): 734-740    DOI: 10.11900/0412.1961.2015.00502
Orginal Article Current Issue | Archive | Adv Search |
INTERFACIAL MICROSTRUCTURE AND MECHANI-CAL PROPERTIES OF INDIRECT BRAZED GRAPHITE/COPPER JOINT
Wei FU1,2(),Xiaoguo SONG1,2,Long LONG2,Jianhang CHAI2,Jicai FENG1,2,Guodong WANG2
1 State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
2 Shandong Provincial Key Lab of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China
Cite this article: 

Wei FU,Xiaoguo SONG,Long LONG,Jianhang CHAI,Jicai FENG,Guodong WANG. INTERFACIAL MICROSTRUCTURE AND MECHANI-CAL PROPERTIES OF INDIRECT BRAZED GRAPHITE/COPPER JOINT. Acta Metall Sin, 2016, 52(6): 734-740.

Download:  HTML  PDF(807KB) 
Export:  BibTeX | EndNote (RIS)      
Abstract  

Graphite and metal composite structures were widely used in aerospace, electrical engineering and electronics. Because of its conveniences and less cost, brazing was widely used to bond graphite and metals. Due to the differences in microstructure, graphite was difficult to be wetted by traditional braze alloys. To improve the wettability of traditional brazing alloys on graphite, active brazing process and indirect brazing process were developed to braze graphite to metals. As to active brazing process, active elements (such as Ti, Cr, Zr) were added into traditional brazing alloys, a high brazing temperature, was essential to guarantee the reaction of active elements with graphite. However, the mechanical properties of metals will degrade under high temperature. Electroplating and chemical plating were the general techniques for indirect brazing process. The covered coating had a mechanical combination which decreased the joint strength, rather than metallurgical bonding with graphite. Therefore, in this work, a new metallization method was proposed. On the one hand, a metallurgical bonding was formed between metallization layer and graphite substrate. On the other hand, graphite could be brazed to metal at a relatively low temperature. Firstly, graphite was metalized by Ti-containing Sn0.3Ag0.7Cu metallization powder at 950 ℃ for 30 min. Then metalized graphite was brazed with copper by Sn0.3Ag0.7Cu successfully. The typical interfacial structure of brazed joint was copper/Cu3Sn/Cu6Sn5/β-Sn/TiC/graphite. Element Ti of metallization powder played an important role in metallization process for a reaction layer TiC was formed on the interface of graphite and metallization layer. Nevertheless, Ti contents had no effect on interfacial structure and shear strength of brazed joint. With the increase of brazing temperature, more and more element Cu dissolved into molten solder and formed Cu-Sn compounds by reacting with Sn. Furthermore, shear strength was improved slightly. Fracture analysis reveals that cracks extended along β-Sn layer and presented ductile fracture. When Cu-Sn compounds occupied the entire brazing seam (joint brazed at 600 ℃), shear strength improved remarkably and reached 30 MPa. Additionally, the joint was fractured in graphite entirely.

Key words:  metallization      graphite      copper      indirect brazing     
Received:  25 September 2015     
Fund: Supported by National Natural Science Foundation of China (No.51405099) and Aerospace Science and Technology Innovation Foundation of Shanghai (No.SAST2015045)

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2015.00502     OR     https://www.ams.org.cn/EN/Y2016/V52/I6/734

Fig.1  Schematic of assembling brazing joint (unit: mm)
Fig.2  SEM image of metallization layer with Ti content of 1.4%
Fig.3  XRD spectra of graphite, metallization layer and reaction layer

(1)

Fig.4  Effect of Ti contents on the interfacial structure of metallization layer with Ti contents of 1.0% (a) and 1.8% (b)
Point in Fig.2 Sn Ag Cu Ti C Possible phase
A 98.34 0.52 1.07 0.07 - β-Sn
B 2.51 0.01 0.06 49.56 47.86 TiC
C 93.72 0.47 0.85 0.38 4.58 β-Sn
Table 1  EDS results of the metallization layer in Fig.2
Fig.5  Low (a) and locally high (b) magnified SEM images of copper/graphite joint brazed at 520 ℃ for 5 min with Ti content of 1.6%

(2)

Point in Fig.5a Sn Ag Cu Ti Possible phase
A 24.65 0.30 75.05 0 Cu3Sn
B 44.92 0.15 54.88 0.05 Cu6Sn5
C 97.93 0.47 0.85 0.75 β-Sn
Table 2  EDS results of points marked in Fig.5a
Fig.6  Interfacial microstructures of copper/graphite joints brazed at 520 ℃ for 5 min with Ti contents of 1.2% (a) and 1.8% (b)
Fig.7  Effect of Ti content on the shear strength of brazed joints
Fig.8  SEM-SE image (a) and XRD spectrum (b) of fracture of copper/graphite joint brazed at 520 ℃ for 5 min with Ti content of 1.6%
Fig.9  Effects of brazing temperature on the interfacial microstructure of copper/graphite joints brazed at 540 ℃ (a) and 600 ℃ (b) with Ti content of 1.6%
Fig.10  Effect of brazing temperature on the shear strength of copper/ graphite joints with Ti content of 1.6%
Fig.11  Fracture morphology of copper/graphite joint brazed at 600 ℃
[1] Zhong Z H, Zhou Z J, Ge C.J Mater Process Technol, 2009; 209: 2662
[2] Sueyoshi H, Fukudome H.Mater Trans, 2008; 49: 2063
[3] Xiong H P, Wan C G, Zhou Z F.Acta Metall Sin, 1999; 35: 527
[3] (熊华平, 万传庚, 周振丰. 金属学报, 1999; 35: 527)
[4] Chen B, Xiong H P, Mao W, Guo W L, Cheng Y Y, Li X H.Acta Metall Sin, 2007; 43: 1181
[4] (陈波, 熊华平, 毛唯, 郭万林, 程耀永, 李晓红. 金属学报, 2007; 43: 1181)
[5] Liu Y, Jiang G F, Xu K, Luo X M, Chen D Q, Li W.Acta Metall Sin, 2015; 51: 209
[5] (刘毅, 江国锋, 许昆, 罗锡明, 陈登权, 李伟. 金属学报, 2015; 51: 209)
[6] Ray A K, Kar A, Kori S A, Pathak L C, Sonnad A N.J Mater Eng Perform, 2013; 22: 258
[7] Makimura S, Ozaki H, Okamura H, Futakawa M, Naoe T, Miyake Y, Kawamura N, Nishiyama K, Kawai M.J Nucl Mater, 2008; 377: 28
[8] Caturla F, Molina F, Molina-Sabio M, Rodriguez-Reinoso F, Esteban A.J Electrochem Soc, 1995; 142: 4084
[9] Moutis N, Jimenez C, Azpiroz X, Speliotis T, Wilhelmi C, Messoloras S, Mergia K.J Mater Sci, 2010; 45: 74
[10] Wang Y Y, Li S J, Yan L S.Rare Met Mater Eng, 2005; 34: 970
[10] (王艳艳, 李树杰, 闫联生. 稀有金属材料与工程, 2005; 34: 970)
[11] Li Y Q, Zhang Z D, Den C Q, Su Y S.Mater Charact, 2000; 44: 425
[12] Zhang Z H, Zhou Z J, Song S X, Du J, Ge C C.Rare Met Mater Eng, 2006; 35: 117
[12] (钟志宏, 周张健, 宋书香, 都娟, 葛昌纯. 稀有金属材料与工程, 2006; 35: 117)
[13] Singh M, Smith C, Asthana R, Gyekenyesi A.Int J Appl Ceram Technol, 2013; 10: 790
[14] Song X G, Cao J, Liu J K, Wang Y F, Feng J C. Chin Pat, 10094289.8, 2014(宋晓国, 曹健, 刘甲坤, 王义峰, 冯吉才. 中国专利,10094289.8, 2014)
[15] Okamoto H. J Phase Equilib Diff, 2010; 31: 202
[16] Singh M, Shpargel T P, Morscher G N, Asthana R.Mater Sci Eng, 2005; A412: 123
[17] Wang B Y. Mater Thesis, China University of Petroleum, Dong- ying, 2009
[17] (王宝阳. 中国石油大学硕士学位论文, 东营, 2009)
[18] Naidich Y.Curr Opin Solid State Mater Sci, 2005; 9: 161
[19] Standing R, Nicholas M.J Mater Sci, 1978; 13: 1509
[20] Singh M, Smith C, Asthana R, Gyekenyesi A.Int J Appl Ceram Technol, 2013; 10: 790
[21] Yu W Y, Liu S H, Liu X Y, Liu M P, Shi W G.J Mater Process Technol, 2015; 221: 285
[22] Zhu W J, Wang J, Liu L B, Liu H S, Jin Z P, Leinenbach C.Comput Mater Sci, 2013; 78: 74
[23] Laurila T, Vuorinen V, Kivilahti J K.Mater Sci Eng, 2005; R49: 1
[24] Hwang C W, Kim K S, Suganuma K.J Electron Mater, 2003; 32: 1249
[25] Gong J, Liu C, Conway P P, Silberschmidt V V.Acta Mater, 2008; 56: 4291
[1] CHEN Kaixuan, LI Zongxuan, WANG Zidong, Demange Gilles, CHEN Xiaohua, ZHANG Jiawei, WU Xuehua, Zapolsky Helena. Morphological Evolution of Fe-Rich Precipitates in a Cu-2.0Fe Alloy During Isothermal Treatment[J]. 金属学报, 2023, 59(12): 1665-1674.
[2] ZHAO Naiqin, GUO Siyuan, ZHANG Xiang, HE Chunnian, SHI Chunsheng. Progress on Graphene/Copper Composites Focusing on Reinforcement Configuration Design: A Review[J]. 金属学报, 2021, 57(9): 1087-1106.
[3] PENG Wuqingliang, LI Qiang, CHANG Yongqin, WANG Wanjing, CHEN Zhen, XIE Chunyi, WANG Jichao, GENG Xiang, HUANG Lingming, ZHOU Haishan, LUO Guangnan. A Review on the Development of the Heat Sink of the Fusion Reactor Divertor[J]. 金属学报, 2021, 57(7): 831-844.
[4] HUANG Songpeng, PENG Can, CAO Gongwang, WANG Zhenyao. Corrosion Behavior of Copper-Nickel Alloys Protected by BTA in Simulated Urban Atmosphere[J]. 金属学报, 2021, 57(3): 317-326.
[5] Jianqiang REN, Shuhua LIANG, Yihui JIANG, Xiang DU. Research on the Microstructure and Properties of In Situ (TiB2-TiB)/Cu Composites[J]. 金属学报, 2019, 55(1): 126-132.
[6] Pengyue ZHAO, Yongbo GUO, Qingshun BAI, Feihu ZHANG. Research of Surface Defects of Polycrystalline Copper Nanoindentation Based on Microstructures[J]. 金属学报, 2018, 54(7): 1051-1058.
[7] Di ZHANG, Mengying YUAN, Zhanqiu TAN, Ding-Bang XIONG, Zhiqiang LI. Progress in Interface Modification and Nanoscale Study of Diamond/Cu Composites[J]. 金属学报, 2018, 54(11): 1586-1596.
[8] Tingting ZHAO, Zhixin KANG, Xiayu MA. Fabricating Superhydrophobic Copper Meshes by One-Step Electrodeposition Method and Its Anti-Corrosion and Oil-Water Separation Abilities[J]. 金属学报, 2018, 54(1): 109-117.
[9] Tingbiao GUO, Qi LI, Chen WANG, Feng ZHANG, Zhi JIA. Deformation Characteristics and Mechanical Properties of Single Crystal Copper During Equal Channel Angular Pressing by Route A[J]. 金属学报, 2017, 53(8): 991-1000.
[10] Xiaoyun LIU,Wenguang WANG,Dong WANG,Bolv XIAO,Dingrui NI,Liqing CHEN,Zongyi MA. Effect of Graphite Flake Size on the Strength and Thermal Conductivity of Graphite Flakes/Al Composites[J]. 金属学报, 2017, 53(7): 869-878.
[11] Jianxiong ZOU,Bo LIU,Liwei LIN,Ding REN,Guohua JIAO,Yuanfu LU,Kewei XU. Microstructure and Thermal Stability of MoC DopedRu-Based Alloy Films as Seedless Diffusion Barrier[J]. 金属学报, 2017, 53(1): 31-37.
[12] Zhisheng WANG, Xiang CHEN, Yanxiang LI, Huawei ZHANG, Yuan LIU. EFFECTS OF B ON HIGH TEMPERATURE MECHA-NICAL PROPERTIES AND THERMAL FATIGUE BEHAVIOR OF COPPER DIE-CASTING DIE STEEL[J]. 金属学报, 2015, 51(5): 519-526.
[13] ZHANG Lei, ZHAO Honglei, ZHU Mingfang. SIMULATION OF SOLIDIFICATION MICROSTRUC-TURE OF SPHEROIDAL GRAPHITE CAST IRON USING A CELLULAR AUTOMATON METHOD[J]. 金属学报, 2015, 51(2): 148-158.
[14] XUE Yingyu, TANG Jiancheng, ZHUO Haiou, YE Nan, WU Tong, ZHOU Xusheng. MICROSTRUCTURES AND PROPERTIES OF LEAD-FREE FREE-CUTTING GRAPHITE-BRASS PREPARED BY GRAPHITIZATION OF CEMENTITE[J]. 金属学报, 2015, 51(2): 223-229.
[15] Xinning ZHANG,Yingdong QU,Rongde LI,Junhua YOU. MECHANISM OF CRACK NUCLEATION AND PROPA- GATION OF FERRITE DUCTILE IRON DURING IMPACT FRACTURE UNDER LOW TEMPERATURES[J]. 金属学报, 2015, 51(11): 1333-1340.
No Suggested Reading articles found!