Effect of mechanical stirrer on graphite particles and SiCP in C-SiC/Cu semi-solid slurry
-
摘要: 利用直桨叶搅拌器在圆柱坩埚内机械搅拌C-SiC/Cu半固态浆料,研究搅拌速度为200 r/min、搅拌器上下移动速度为10 mm/s时C-SiC/Cu半固态浆料中石墨颗粒和SiC颗粒(SiCP)的均匀性。结果表明:直桨叶与水平面的夹角γ与两种颗粒在坩埚顶部和底部含量偏差都存在二次关系,当γ=30°时石墨颗粒和SiCP在坩埚中轴向分布均匀,但同一水平面内的SiCP仍存在偏聚现象,说明SiCP的偏聚是导致常规直桨叶机械搅拌C-SiC/Cu半固态浆料整体不均匀的主要原因;利用双层桨叶搅拌器代替常规直桨叶搅拌器,通过调整叶片层间距h,当h=10~20 mm时可以消除SiCP的偏聚现象;通过对单层桨叶搅拌器和双层桨叶搅拌器机械搅拌铸造获得的C-SiC/Cu复合材料进行磨损试验发现,单层桨叶搅拌器不同部位磨损率存在差异,双层桨叶搅拌器磨损率几乎相同。说明SiCP的偏聚可以通过增大机械搅拌剪切力度得以消除,利用双层桨叶搅拌器进行机械搅拌可以获得均质的C-SiC/Cu半固态浆料。Abstract: The mechanical stirring of C-SiC/Cu semi-solid slurry was conducted in a cylindrical crucible by a straight-blade stirrer. The distribution of graphite particles and SiC particles (SiCP) in the C-SiC/Cu semi-solid slurry was studied under 200 r/min for stirring speed and 10 mm/s for speed of moving up and down of stirrer. The results show that there is a quadratic relationship between the angle γ between the straight blade and the horizontal plane and the content of the graphite particles and SiCP in the top and bottom of the crucible. When γ=30°, the axial distributions in the crucible of graphite particles and SiCP are homogeneous, but the SiCP are still segregated, which indicates that the segregation of SiCP leads to the unhomogeneity of C-SiC/Cu semi-solid slurry in conventional straight-blade mechanical stirring. The double-blade agitator is used instead of the conventional straight blade agitator to adjust the blade layer spacing h to 10–20 mm, which can eliminate the segregation of SiCP. The wear tests of the C-SiC/Cu composites obtained by mechanical stirring casting with single blade stirrer and double-layer blade stirrer were carried out. The wear rates of different parts of C-SiC/Cu composites in the single blade mechanical stirring casting are different, however, they are nearly the same in the double-layer blade. It shows that the segregation of SiCP can be eliminated by increasing the mechanical agitation shearing action. The uniform distribution of C-SiC/Cu semi-solid slurry can be achieved by double-layer-stirrer mechanical stirring.
-
图 1 搅拌装置示意图
Figure 1. Schematic diagram of agitator((a) Whole setup configuration; (b) Cross section of A-A; (c) Cross section of B-B)
1—Stirrer; 2—Crucible; 3—Cooling-pipes; 4—Heating-rods; 5—Cover; 6—Ar gas pipe; 7—Thermocouple; 8—Semi-solid slurry; 9—Center stopple; 10—Lower side stopple; 11—Upper side stopple; 12—Lower bracket; 13—Water tank; 14—Rotating motor; 15—Rotating gearing; 16—Moving board; 17—Moving screw; 18—Moving gearing; 19—Moving motor; 20—Lower switch; 21—Upper switch; 22—Upper bracket
表 1 C-SiC/Cu复合材料成分配比
Table 1. Composition proportion of C-SiC/Cu composite
Cu/vol% Graphite/vol% SiC/vol% Impurities/vol% 89 10 1 <0.5 表 2 不同位置的石墨颗粒和SiC颗粒(SiCP)含量及含量偏差d
Table 2. Contents of graphite particles and SiC particles(SiCP) at different positions and content relative deviation d
Sample Cct/vol% Ccb/vol% Cst/vol% Csb/vol% d 1 10.0 10.1 0.99 1.00 ≈0 2 9.9 10.0 1.01 1.00 ≈0 3 10.1 10.0 1.00 1.01 ≈0 Notes: Cct, Ccb—Graphite particles content at top and bottom of crucible, respectively; Cst, Csb— SiCP content at top and bottom of crucible, respectively; d— Particles content reative deviation. 表 3 不同搅拌器获得的C-SiC/Cu复合材料不同部位的磨损率
Table 3. Wear rates of different parts of C-SiC/Cu composites stirred by different stirrers
Sampling point Rst Rsc Rsb Rdt Rdc Rdb 1 0.255 0.241 0.251 0.248 0.247 0.248 2 0.241 0.254 0.249 0.249 0.248 0.248 3 0.245 0.258 0.241 0.249 0.248 0.248 4 0.260 0.243 0.240 0.248 0.248 0.247 5 0.240 0.250 0.254 0.249 0.248 0.247 6 0.252 0.240 0.251 0.247 0.247 0.248 7 0.243 0.250 0.252 0.248 0.248 0.249 Notes: Rst, Rsc, Rsb—Wear rates of top, center and bottom of ingot casting in simple blade stirrer mechanical stir casting, respectively; Rdt, Rdc, Rdb—Wear rates of top, center and bottom of ingot casting in double-layer blade stirrer mechanical stir casting, respectively. -
[1] 李国辉, 刘勇, 国秀花, 等. TiB2/Cu复合材料的电弧侵蚀行为[J]. 复合材料学报, 2018, 35(3):616-622.LI Guohui, LIU Yong, GUO Xiuhua, et al. Arc erosion behavior of TiB2/Cu composites[J]. Acta Materiae Compositae Sinica,2018,35(3):616-622(in Chinese). [2] AKBARPOUR M R, NAJAFI M, ALIPOUR S, et al. Hardness, wear and friction characteristics of nanostructured Cu-SiC nanocomposites fabricated by powder metallurgy route[J]. Materials Today Communications,2019,18:25-31. doi: 10.1016/j.mtcomm.2018.11.001 [3] KOVÁČIK J, EMMER Š. Cross property cinnection between the electric and the thermal conductivities of copper-graphite composites[J]. International Journal of Engineering Science,2019,144:103130. [4] GRANDIN M, WIKLUND U. Wear phenomena and tribofilm formation of copper/copper-graphite sliding electrical contact materials[J]. Wear,2018,398-399:227-235. [5] 朱成才, 张鹏, 杜云慧, 等. 性能卓越的铜石墨受电弓滑板[J]. 铁道机车车辆, 2006, 26(3):62-66. doi: 10.3969/j.issn.1008-7842.2006.03.022ZHU Chengcai, ZHANG Peng, DU Yunhui, et al. Copper-graphite pantograph slide plate with superexcellent performance[J]. Railway Locomotive & Car,2006,26(3):62-66(in Chinese). doi: 10.3969/j.issn.1008-7842.2006.03.022 [6] MEHER A, CHAIRA D. Effect of graphite and SiC addition into Cu and SiC particle size effect on fabrication of Cu-graphite-SiC MMC by powder metallurgy[J]. Transactions of the Indian Institute of Metals,2017,70(8):2047-2057. doi: 10.1007/s12666-016-1026-1 [7] KANG H K, KANG S B. Thermal decomposition of silicon carbide in a plasma-sprayed Cu/SiC composite deposit[J]. Materials Science and Engineering A,2006,428(1-2):336-345. [8] JAMWAL A, PRAKASH P, KUMAR D, et al. Microstructure wear and corrosion characteristics of Cu matrix reinforced SiC-graphite hybrid composites[J]. Journal of Composite Materials,2019,53(18):2545-2553. [9] ZHANG W Y, DU Y H, ZHANG P, et al. Air-isolated stir casting of homogeneous Al-SiC composite with no air entrapment and Al4C3[J]. Journal of Materials Processing Technology,2019,271:226-236. [10] 常海, 黄勇, 胡小石. 搅拌铸造法制备短纤维/AZ91复合材料的组织与性能[J]. 复合材料学报, 2019, 36(1):159-166.CHANG Hai, HUANG Yong, HU Xiaoshi. Microstructure and mechanical properties of short carbon fiber/AZ91 composite fabricated by stir-casting[J]. Acta Materiae Compositae Sinica,2019,36(1):159-166(in Chinese). [11] 胡勇, 倪旭武. 搅拌铸造法制备纳米SiCP/AZ91D复合材料的研究[J]. 热加工工艺, 2015, 44(24):116-118.HU Yong, NI Xuwu. Study on nano SiCP/AZ91D composite prepared by cast with stirring[J]. Hot Working Technology,2015,44(24):116-118(in Chinese). [12] DONG Y, WANG X, XIE Y, et al. Tunable microstructures and tensile mechanical properties of oxide-dispersion-strengthened Cu by extrusion and secondary processing[J]. Journal of Alloys and Compounds,2020,812:152112. [13] 赵敏, 姜龙涛, 武高辉. 挤压铸造TiB2P/Al复合材料室温力学性能[J]. 复合材料学报, 2007, 24(5):1-5. doi: 10.3321/j.issn:1000-3851.2007.05.001ZHAO Min, JIANG Longtao, WU Gaohui. Ambient mechanical properties of TiB2P/Al composites by squeeze casting[J]. Acta Materiae Compositae Sinica,2007,24(5):1-5(in Chinese). doi: 10.3321/j.issn:1000-3851.2007.05.001 [14] 李乃拥, 肖寒, 熊迟, 等. 半固态挤压铸造铜合金的组织和力学性能[J]. 稀有金属材料与工程, 2018, 47(9):2813-2820.LI Naiyong, XIAO Han, XIONG Chi, et al. Microstructure and mechanical properties of semi-solid squeeze casting copper alloy[J]. Rare Metal Materials and Engineering,2018,47(9):2813-2820(in Chinese). [15] 朱成才. 铜—石墨复合材料的半固态制备及其摩擦性能研究[D]. 北京: 北京交通大学, 2006.Zhu Chengcai. Preparation for copper-graphite by semi-solid forming method and the frictional behavior study[D]. Beijing: Beijing Jiaotong University, 2006(in Chinese). [16] NAGESWARAN G, NATARAJAN S, RAMKUMAR K R. Synthesis, structural characterization, mechanical and wear behavior of Cu-TiO2-Gr hybrid composite through stir casting technique[J]. Journal of Alloys and Compounds,2018,768:733-741. doi: 10.1016/j.jallcom.2018.07.288 [17] DU Y H, ZHANG P, ZHANG J, et al. Radial distribution of SiC particles in mechanical stirring of A356-SiCP liquid[J]. Journal of Materials Science & Technology,2012,28(10):951-955. [18] 李昊, 桂满昌, 周彼德. 搅拌铸造金属基复合材料的热力学和动力学机制[J]. 中国空间科学技术, 1997(1):9-16.LI Hao, GUI Manchang, ZHOU Bide. Thermodynamics and dynamics of stirring cast process for metal matrix composites[J]. Chinese Space Science and Technology,1997(1):9-16(in Chinese). [19] 郝斌, 崔华, 蔡元华, 等. 搅拌铸造法制备金属基复合材料的热力学与动力学机制[J]. 稀有金属快报, 2005, 24(6):22-25.HAO Bin, CUI Hua, CAI Yuanhua, et al. The thermodynamic and kinetic mechanism of metal matrix composite prepared by agitation casting[J]. Rare Metals Letters,2005,24(6):22-25(in Chinese). [20] 张桢林, 张志峰, 徐骏, 等. SiCP/Al复合材料搅拌铸造新型搅拌器流场及工艺研究[J]. 材料导报, 2017, 31(10):141-145. doi: 10.11896/j.issn.1005-023X.2017.010.029ZHANG Zhenlin, ZHANG Zhifeng, XU Jun, et al. Study on flow field and process of new stirrer for stir casting of SiCP/Al composites[J]. Materials Review,2017,31(10):141-145(in Chinese). doi: 10.11896/j.issn.1005-023X.2017.010.029