共查询到19条相似文献,搜索用时 140 毫秒
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复合材料挤出成型过程中晶须的定向排布 总被引:1,自引:0,他引:1
研究了含SiC晶须的Si3N4混合粉料的挤制成型过程。从挤制腔内泥料的受力分析出发,探讨了挤制成型过程中晶须定向排布的原理,并着重研究了挤制压力、和挤出口的尺寸对晶须定向度的影响。 相似文献
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复合材料挤制成型过程中晶须的定向排布 总被引:3,自引:1,他引:2
研究了含SiC晶须的Si3N4混合粉料的挤制成型过程.从挤制腔内泥料的受力分析出发,探讨了挤制成型过程中晶须定向排布的原理,并着重研究了挤制压力、挤制速率、泥料含水率和挤出口的尺寸对晶须定向度的影响. 相似文献
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Al2O3/SiCW陶瓷刀具材料中晶须的取向对其力学和切削性能的影响 总被引:4,自引:0,他引:4
Al2O3/SiCW陶瓷刀具材料由于热压过程的影响,造成晶须在基体中定向排布于垂直热压方向的平面上,因此不同方向的补强、增韧效果有所差异。本工作测量了Al2O3/SiCW陶瓷刀具材料不同方向上的断裂韧性和抗弯强度,分析了晶须的取向对该陶瓷刀具材料力学性能的影响。切削试验表明晶须的取向对晶须增韧陶瓷刀具材料的磨损和破损性能有较好的影响。根据切削加工过程中刀具的受力特点,提出了有利于切削加工的刀具前、 相似文献
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层状氮化硅陶瓷的性能与结构 总被引:8,自引:1,他引:8
从结构设计的角度出发研究了层状复合Si3N4陶瓷材料,利用轧膜使层内的晶粒,晶须产生定向增韧,通过调整外部层状复合结构得到材料的两级增韧效果,并实验制备了高韧性层状复合Si3N4基陶瓷材料。 相似文献
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本文对稻壳合成β-SiC晶须的工艺条件进行了研究,结果表明,温度,硅碳化对SiC晶须转化率有较大影响,Ar气流量的影响较小,在最佳工艺条件下,生成物中SiC晶须含量可达30%以上,并从理论上探讨了SiC晶须的生长机理。 相似文献
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陶瓷复合体中晶须的作用研究 总被引:1,自引:0,他引:1
研究了SiC,TiN晶须增韧Al2O3+TiC,Si3N4+TiC基陶瓷复合体的力学行为,验证和讨论了P.F.Becher提出的晶须增韧方程,并通过实验对晶须增韧陶瓷复合体的机械性能和切削性能进行了研究。 相似文献
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SiC晶须对Al2O3/TiB2/SiCw陶瓷刀具材料高温断裂韧性的影响 总被引:3,自引:0,他引:3
研究了不同SiC晶须含量的Al2O3/TiB2/SiCw陶瓷刀具材料的断裂韧性随温度的变化规律。结果表明:Al2O3/TiB2/SiCW陶瓷材料的K1C在1000℃内随温度的升高而增大;晶须含量越大,通过计算分析表明,随温度的升高粘裂时拔出的晶须大大增多,当晶须体积含量(下同)为20%时,Al2O3/TiB2/SiCw陶瓷在室温时只有长径比小于2.87的晶须在断裂时才有可能产生拔出,而在900℃时 相似文献
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研究了晶须的取向对Al2O3/TiB2/SiCW陶瓷复合材料在下空气和氮气氢气中与硬质合金摩副往复滑动摩擦时的耐磨性能的影响。结果表明:该材料表面的耐磨性能随θ角的不同而变化,随θ角的增大,材料表面的耐磨性能提高。在高温空气氢气中摩擦时,由于SiC晶面的氧化使得材料表面晶须的增韧补强作用削弱,加速了材料的磨损。通入氮气有利于减轻SiC晶须的氧化,可提高瓣耐磨性能。 相似文献
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《Journal of the European Ceramic Society》1999,19(10):1903-1909
Si3N4 ceramic matrix composites reinforced by nearly unidirectionally aligned SiC whiskers have been prepared by extrusion and hot pressing. Unlike the case in traditional Si3N4 ceramic matrix composites reinforced by random SiC whiskers, the mechanical properties of the composites exhibit a significant dependence on whisker orientation. In the direction of whisker alignment for SiC(w)/Si3N4 composites, increments in bending strength and fracture toughness of 200 MPa and 3 MPa·m1/2 are obtained respectively, compared to the values in the direction perpendicular to whisker alignment. Based on microscopic fractographic observation and micromechanics analyses, the effects of whisker orientation on toughening mechanisms are discussed. The results indicate that the whisker orientation, θ, is a decisive factor for the essential toughening mechanisms of whiskers. Only in the case of small θ and weak interface can whisker pullout occur, and whisker has maximum toughening effect. The results show that effects of whisker strengthening and toughening can be improved simultaneously through whisker oriented alignment. © 相似文献
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SiC-whisker-reinforced Si3 N4 was fabricated by extrusion and hot-pressing. A unidirectional alignment of the whiskers was achieved through sheet forming by extrusion. The degree of whisker orientation changed with the thickness of the green sheets. Unidirectionally oriented whiskers increased fracture strength and toughness compared to samples with more randomly oriented whiskers. Anisotropy of fracture strength was observed. Bridging by whiskers impeded crack propagation when the whisker orientation was perpendicular to the crack plane. 相似文献
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Chang-An Wang Yong Huang Zhipeng Xie Ying Li Zhongtai Zhang 《Journal of the American Ceramic Society》2000,83(11):2689-2692
The effect of whisker orientation on the electrical properties of SiCw /Si3 N4 composites was investigated, using the principle of complex impedance. The impedance spectra of the composites exhibited significant dependence on whisker orientation. Based on the experimental results and the microstructure of the composites, the impedance mechanisms were discussed and a corresponding equivalent-circuit model was presented, which agreed well with the experiments. 相似文献
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以TiSi2为反应原料,SiC作稀释剂,燃烧合成制备Si3N4-TiN-SiC陶瓷.利用燃烧波"淬熄"法使反应各个阶段的物相得以保留,通过X射线衍射及扫描电镜分析TiSi2在燃烧合成中的反应过程及显微组织转化.结果表明:完全反应后产物的主相为Si3N4,其余为TiN和SiC.在燃烧过程中,TiSi2首先受热熔化,包覆于SiC颗粒表面,随后与N2反应生成TiN和Si.Si在高热作用下发生熔化、汽化,液态Si与未反应的TiSi2互溶.生成的Si与氮气发生反应,形成Si3N4晶核,并不断长大.燃烧合成反应过程中,Si3N4晶须的生长十分复杂,由气-液-固机制、气-固机制及蒸发凝聚的气相生长机制共同作用. 相似文献
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Edward S. Fisher Murli H. Manghnani Ji-Fan Wang Jules L. Routbort 《Journal of the American Ceramic Society》1992,75(4):908-914
A study of the elastic moduli of Al2 O3 and Si3 N4 ceramics reinforced with 0 to 25 wt% SiC whiskers has been performed. The Young's moduli, shear moduli, and longitudinal modulus are compared with calculated predictions for aligned fiber composites by Hill and Hashin and Rosen, and for fibers randomly oriented in three dimensions by Christensen and Waal. The measured values are in excellent quantitative agreement with those derived for the random orientation of the SiC whiskers. 相似文献