挤出成型制备重结晶碳化硅热端材料的研究
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摘要
传统的碳化硅电热元件——硅碳棒存在着电阻离散性大、致密度差、使用温度低、使用寿命短等问题。这些难题制约着国内的硅碳棒行业发展。因此探索碳化硅电热元件的新型制备工艺、探讨其结晶性能，对于改善其使用性能，提高其使用温度和使用寿命都是非常必要的。近年来，由于我国工业窑炉高温技术的发展，硅碳棒的需求量越来越大，对硅碳棒的性能以及其使用温度和使用寿命也提出了更高的要求。
本研究利用高纯碳化硅作为原料，加入润滑剂和塑化剂，利用挤出成型制备高密度的碳化硅坯体，主要研究了颗粒级配对瘠性料碳化硅挤出成型的影响，确定了挤出成型中颗粒的合理级配；比较几种高效的增塑剂和润滑剂，研究其对成型压力和坯体密度的影响；探讨了模具的结构对挤出成型的影响。研究了烧结温度对细粉的蒸发的影响；通过测量试样的性能，确定最佳的工艺参数。
实验结果发现，当PX用量为0.6％、聚氧化乙烯蜡乳液用量为1.8％时，碳化硅泥料含水在6％左右可以挤出。当采用三级级配，粒径分别为800μm、100μm、5μm，比例为7.2：1：1.8时，生坯密度达到最高，为2.565g／cm~3。在真空度为2×10~(-2)Pa时，2400℃下烧结，保温1h，可以得到密度为2.486g／cm3的重结晶硅碳棒热端材料，其电导率为0.314Ω.cm，抗折强度为39MPa。通过SEM照片可以看到，细粉完全蒸发，大颗粒分布均匀。
研究表明，颗粒级配对碳化硅泥料的挤出成型也有很大的影响。大颗粒粒径增大，含量多，有利于挤出坯体的密度提高。但是当大颗粒粒径增大到一定值，反而不利于泥料成型的密度提高。对碳化硅泥料来说，PX是一种有效的塑化剂，氧化聚乙烯蜡乳液是良好的润滑剂，能有效的改善挤出过程中泥料的内外润滑。
Silicon carbide rod as a conventional electro-heating materials has some disadvantages of big resistance discreteness, bad density, low usage temperature and short operating life. These problems restrict the technology development of silicon carbide electro-heating element industry. So it is necessary to grope new preparation technology and probe into crystal property for improving application properties and increasing operating life and developing new style electro-heating element. Currently, with the development of Chinese industry furnace and high temperature technology, the requirement of silicon carbide rod is increased, at the same time the usage temperature, operating life and property need to be heightened.
This paper prepared high density SiC body for high performance SiC electro-heating element using the high pure SiC and efficient lubricate and plasticizer. The article mainly researching content including:
(1)The effect of grain composition on the extrusion of SiC was studied. The optimal grain composition of SiC was obtained;
(2) The effect of efficient lubricates and plasticizer on the molding pressure and body' density of extrusion was studied. The appropriate dosage of the plasticizer and lubricate was obtained.
(3)The effect of the die's structure on extrusion was studies. The appropriate die's parameter which was suitable for extrusion was found.
(4) Applying vacuum furnace to sinter SiC body, the optimal sintering temperature was found.
(5)The cross-section pattern was analyzed through SEM. Crystallization of the fine particle and crystal structure was observed.
The better extrusion effect was achieved by using 0.6wt% of polyscrylamide, 1.8wt% of oxidized polyethylene wax 6wt% moisture content of SiC pug. The highest body density (2.565g/cm3) was obtained by applying particle of 800μm,100μm,5μm. And the proportion of the particle was 7.2:1:1.8 respectively.
The suitable sintering parameters were: 2×10(-2) Pa of vacuum degree, 2400°C of sintering temperature and (?)hour of sintering time; under above parameters, its sintering density, conductivity, bending strength was 2.486g/cm~3, 0.3140.cm, 39MPa respectively. Through the SEM picture, it was found that the fine particle was boiled off entirely and coarse particle was uniform distribution.
These researches showed that grain composition had a great effect on extrusion. The higher body density was obtained when the coarse particle have bigger particle diameter and more content. But the body's density would become lower when the coarse particle diameter exceeded a fixed value. PX was a efficient plasticizer and oxidized polyethylene wax was a efficient lubricate. These two additives can improve internal-external lubricating of extrusion.
本研究利用高纯碳化硅作为原料，加入润滑剂和塑化剂，利用挤出成型制备高密度的碳化硅坯体，主要研究了颗粒级配对瘠性料碳化硅挤出成型的影响，确定了挤出成型中颗粒的合理级配；比较几种高效的增塑剂和润滑剂，研究其对成型压力和坯体密度的影响；探讨了模具的结构对挤出成型的影响。研究了烧结温度对细粉的蒸发的影响；通过测量试样的性能，确定最佳的工艺参数。
实验结果发现，当PX用量为0.6％、聚氧化乙烯蜡乳液用量为1.8％时，碳化硅泥料含水在6％左右可以挤出。当采用三级级配，粒径分别为800μm、100μm、5μm，比例为7.2：1：1.8时，生坯密度达到最高，为2.565g／cm~3。在真空度为2×10~(-2)Pa时，2400℃下烧结，保温1h，可以得到密度为2.486g／cm3的重结晶硅碳棒热端材料，其电导率为0.314Ω.cm，抗折强度为39MPa。通过SEM照片可以看到，细粉完全蒸发，大颗粒分布均匀。
研究表明，颗粒级配对碳化硅泥料的挤出成型也有很大的影响。大颗粒粒径增大，含量多，有利于挤出坯体的密度提高。但是当大颗粒粒径增大到一定值，反而不利于泥料成型的密度提高。对碳化硅泥料来说，PX是一种有效的塑化剂，氧化聚乙烯蜡乳液是良好的润滑剂，能有效的改善挤出过程中泥料的内外润滑。
Silicon carbide rod as a conventional electro-heating materials has some disadvantages of big resistance discreteness, bad density, low usage temperature and short operating life. These problems restrict the technology development of silicon carbide electro-heating element industry. So it is necessary to grope new preparation technology and probe into crystal property for improving application properties and increasing operating life and developing new style electro-heating element. Currently, with the development of Chinese industry furnace and high temperature technology, the requirement of silicon carbide rod is increased, at the same time the usage temperature, operating life and property need to be heightened.
This paper prepared high density SiC body for high performance SiC electro-heating element using the high pure SiC and efficient lubricate and plasticizer. The article mainly researching content including:
(1)The effect of grain composition on the extrusion of SiC was studied. The optimal grain composition of SiC was obtained;
(2) The effect of efficient lubricates and plasticizer on the molding pressure and body' density of extrusion was studied. The appropriate dosage of the plasticizer and lubricate was obtained.
(3)The effect of the die's structure on extrusion was studies. The appropriate die's parameter which was suitable for extrusion was found.
(4) Applying vacuum furnace to sinter SiC body, the optimal sintering temperature was found.
(5)The cross-section pattern was analyzed through SEM. Crystallization of the fine particle and crystal structure was observed.
The better extrusion effect was achieved by using 0.6wt% of polyscrylamide, 1.8wt% of oxidized polyethylene wax 6wt% moisture content of SiC pug. The highest body density (2.565g/cm3) was obtained by applying particle of 800μm,100μm,5μm. And the proportion of the particle was 7.2:1:1.8 respectively.
The suitable sintering parameters were: 2×10(-2) Pa of vacuum degree, 2400°C of sintering temperature and (?)hour of sintering time; under above parameters, its sintering density, conductivity, bending strength was 2.486g/cm~3, 0.3140.cm, 39MPa respectively. Through the SEM picture, it was found that the fine particle was boiled off entirely and coarse particle was uniform distribution.
These researches showed that grain composition had a great effect on extrusion. The higher body density was obtained when the coarse particle have bigger particle diameter and more content. But the body's density would become lower when the coarse particle diameter exceeded a fixed value. PX was a efficient plasticizer and oxidized polyethylene wax was a efficient lubricate. These two additives can improve internal-external lubricating of extrusion.
引文
[1] 张路宁，许克强，刘东义．硅碳棒在铝业保温炉上的应用．冶金能源，2006，5：38-40
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[4] 国兴杰．硅碳棒成型素烧工艺学[M]郑州：国家机械委机床工业局，1987：134-152
[5] 宋慎泰，潘慧英，王寿增．氧化锆发热元件及超高温电炉的研究．钢铁研究学报，1996，8(6)：53-57
[6] 冯培忠，曲选辉．二硅化钼发热元件的研究与应用进展．中国钼业，2005，29(2)：38-43
[7] 刘伟明，李胜利，孙良成等．铬酸镧电热元件的结构特征研究．金属热处理，2002，27(12)：5-7
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[13] KITAHAMA HIROAKI. Production of Dense Silicon Carbide Heating Elemenet.Japan Patent 2000256068, 2000,9,19
[14] P.O.Robert,J.Fouletier and L.Menneron. New Experiment Approaches to Characterise Silicon Carbide Hot Rods Journal of the European Ceramic Society [J], 1999, (19):875-878
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[31] WangChang.an,HuangYong,ZhaiHongxiang.The effect of whisker orientation in SiC whisker-reinforced Si3N4 ceramic matrix composites.Journal of the European Ceramic Society,1999,19:1903-1909
[32] Liang Z,Blackburn S. Design and characterization of a co-extruder to produce trilayer ceramic tubes semi-continuously. Journal of the European Ceramic Society. 2001,21:883-892
[33] 张文法．美国砖瓦硬塑挤出成型技术．机械设备，2005．2：53-55
[34] Russella B D,Lasenbyb J,Blackburnc S,etal. Characterising paste extrusion behaviour by signal processing of pressure sensor data. Powder Technology, 2003,132:233-248
[35] 吴成义，张丽英．粉体成形力学原理，北京：冶金工业出版社，2003：240-243
[36] 蔡祖光．陶瓷制品螺旋挤出成形压力的选定．陶瓷，2006，3：31-34
[37] 徐晓红，周燕，吴建峰等．累托石坯料可塑性的研究．硅酸盐通报，2002，2：51-53
[38] Nabzar L, Pefferkorn E, Varoqui R. Polyacrylamide-sodium kaolinite interactions: flocculation behavior of polymer clay suspcnsions [J]. J. Colloid and Interface Sci., 1984, 102(2): 380—388
[39] Theng B K G. Clay-polymer interaction: summary and perspectives [J]. Clays and Clays Minerals. 1982, 30:1—10.
[40] 杨帆，文生平．控制技术在现代挤出过程中的应用．工程塑料应用，2005，2：37-39
[41] 叶金文，刘颖，连利仙等．添加剂对注射成型钕铁硼粘结磁体性能的影响．电子元件与材料，2005，3：14-16
[42] 陈邦峰，杨霞，果世驹．EBS蜡静电荷电和模壁润滑特性研究．粉末冶金技术，2005，23(5)：368-371
[43] 宋磊．石蜡改性的研究．[硕士学位论文]．安徽理工大学．2005，4：45-48
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[2] 邵名承．硅碳棒成型工艺学[M]北京：机械工业出版社，1987：210-232
[3] 许伟．硅碳棒烧成工艺学[M]北京：机械工业出版社，1987：186-194
[4] 国兴杰．硅碳棒成型素烧工艺学[M]郑州：国家机械委机床工业局，1987：134-152
[5] 宋慎泰，潘慧英，王寿增．氧化锆发热元件及超高温电炉的研究．钢铁研究学报，1996，8(6)：53-57
[6] 冯培忠，曲选辉．二硅化钼发热元件的研究与应用进展．中国钼业，2005，29(2)：38-43
[7] 刘伟明，李胜利，孙良成等．铬酸镧电热元件的结构特征研究．金属热处理，2002，27(12)：5-7
[8] K.Pelissier, T.Chartier M.Laurent. Silicon Carbide heating Elements. Ceramics International[J], 1998, 24:371-377
[9] 薛天瑞．一种硅碳棒冷挤压成型带端部一次烧成的方法．中国专利，95100397．6，1997．3．12
[10] 刘振林，潘邵华，沈智中．碳化硅电热元件及生产工艺．中国专利，01107837．5，2002，9，25
[11] C.J.Smith, M.A.Merers, V ENESTERENKO. And S. J. Chen Damage Evolution in Dynamic Deformation of Silicon Carbide. Acta. Material[J], 2000,(48) :2399-2420
[12] Guanjun Qiao, Jiqiang Gao, Zhihao Jin. Resources consumption and wastes emission analysis for two manufacture progress of siliconit Resources, Conservation and Recycling[J] 2002, (36): 355-363
[13] KITAHAMA HIROAKI. Production of Dense Silicon Carbide Heating Elemenet.Japan Patent 2000256068, 2000,9,19
[14] P.O.Robert,J.Fouletier and L.Menneron. New Experiment Approaches to Characterise Silicon Carbide Hot Rods Journal of the European Ceramic Society [J], 1999, (19):875-878
[15] Kriengesman J. Sintering phenomena of recrystallized,pressureless sintered, hot-pressed and hot-isostatic pressed of silicon carbide [J] cfi/Ber, DKG, 1987,87(9):301-303.
[16] 沈一丁，李小瑞．陶瓷添加剂．化学工业出版社．2004．7：165-182
[17] 江培秋．影响多孔陶瓷挤出成型工艺因素探讨．现代技术陶瓷，2004，1：7-9
[18] Hurysz K.M,Cochran J K. The application of models for high solids content suspensions to pastes. Journal of the European Ceramic Society .2003,23:2047-2052
[19] S.Ananthakumar, Warrier K G K. Extrusion characteristics of alumina/aluminium titanate composite using boehmite as a reactive binder. Journal of the European Ceramic Society,2001.21:71-78
[20] Ananthakumar S,Menon A R R,Prabhakaran K, et al. Rheology and packing Characteristics of alumina extrusion using boehmite gel as a binder. Ceramic International,2001,27:231-237
[21] Greenwood R, KendallK, Bellon O. A method for making alumina fibers by co-extrusion of an alumina and starch paste. Journal of the European Ceramic Society,2001,21(4):507-513
[22] Tones Sanchez R M,Garcia A B,Cesio A M. Changes in surface characteristics of silicon nitride prepared for extrusion.Journal of the European Ceramic Society, 1996,16:1127-1132
[23] Prabhakaran K,Ananthakumar S,Pavithran C. Preparation of extrudable alumina paste by coagulation of electrosterically stabilized aqueous slurries. Journal of The European Ceramic Society,2002,22:153-158
[24] Kaya C,Butler E G. Plastic forming and microstructural development of α-alumina ceramics from highly compacted green bodies using extrusion. Journal of the European Ceramic Society,2002,22:1917-1926
[25] Yasvo Kovsakd. Powder technology Handbood. 1990,74-85
[26] A.R. Westman and H.R.Hugill.J.Amer.Ceram.Soc.1930
[27] J.E.Funk, D. R.Dinger. Am. Ceram. Soc. Bull., 1988,67(5):890
[28] D.R.Dinger, J.E.funk.Amer.Ceram.Soc.Bull.,1989,68(8):1406-1420
[29] Zhang Rongzeng.Mathematical Models of CWF Preparation.23rd Annual Meeting of Fine Particle Society, U.S.A.,1992
[30] 曾凡，胡永平，杨毅等．矿物加工颗粒学．中国矿业大学出版社，2001，91-107
[31] WangChang.an,HuangYong,ZhaiHongxiang.The effect of whisker orientation in SiC whisker-reinforced Si3N4 ceramic matrix composites.Journal of the European Ceramic Society,1999,19:1903-1909
[32] Liang Z,Blackburn S. Design and characterization of a co-extruder to produce trilayer ceramic tubes semi-continuously. Journal of the European Ceramic Society. 2001,21:883-892
[33] 张文法．美国砖瓦硬塑挤出成型技术．机械设备，2005．2：53-55
[34] Russella B D,Lasenbyb J,Blackburnc S,etal. Characterising paste extrusion behaviour by signal processing of pressure sensor data. Powder Technology, 2003,132:233-248
[35] 吴成义，张丽英．粉体成形力学原理，北京：冶金工业出版社，2003：240-243
[36] 蔡祖光．陶瓷制品螺旋挤出成形压力的选定．陶瓷，2006，3：31-34
[37] 徐晓红，周燕，吴建峰等．累托石坯料可塑性的研究．硅酸盐通报，2002，2：51-53
[38] Nabzar L, Pefferkorn E, Varoqui R. Polyacrylamide-sodium kaolinite interactions: flocculation behavior of polymer clay suspcnsions [J]. J. Colloid and Interface Sci., 1984, 102(2): 380—388
[39] Theng B K G. Clay-polymer interaction: summary and perspectives [J]. Clays and Clays Minerals. 1982, 30:1—10.
[40] 杨帆，文生平．控制技术在现代挤出过程中的应用．工程塑料应用，2005，2：37-39
[41] 叶金文，刘颖，连利仙等．添加剂对注射成型钕铁硼粘结磁体性能的影响．电子元件与材料，2005，3：14-16
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