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Si3N4—MgAl2O4—Al2O3系材料无压烧结的研究 总被引:3,自引:0,他引:3
本文对Si3N4-MgAl2O4-Al2O3系复合材料的无压烧结进行了研究,讨论了Al2O3含量对材料性能的影响及烧结工艺对材料性能和显微结构的相互关系。实验表明:两段法烧结可以得到性能良好的Si3N4-MgAl2O4-Al2O3复合材料。 相似文献
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Al2O3基泡沫陶瓷的研究 总被引:5,自引:0,他引:5
以Al2O3和锆英石为主要原料制备了具较高强度及抗热震性的泡沫陶瓷并进行了性能研究与应用试验。结果表明:当锆英石含量为30%时,材料的抗弯强度最大,达3.84MPa;随锆英石含量的提高,抗热震性能增强;泡沫陶瓷的孔隙率与锆英石含量无关,为80-81%,泡沫陶瓷过滤器能有效滤除铸液中夹杂物。 相似文献
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无压烧结制备Al2O3/SiC纳米复合陶瓷 总被引:2,自引:0,他引:2
用沉淀法包裹微米级SiC颗粒,通过常压、埋烧制备Al2O3/SiC纳米复合陶瓷。通过XRD、TG和SEM等分析了煅烧和烧结过程中相组成的变化、烧成收缩和显微结构。结果表明:利用SiC粉埋烧及碳粉制造还原气氛,含8wt%SiC(平均粒径为5mm)的复合粉末经800℃煅烧、成型,试样于1550℃,2h烧结,可制备Al2O3/SiC纳米复合陶瓷,其相对体积密度达95.2%,在烧结过程中由SiC氧化形成的无定形SiO2及与基质氧化铝反应形成的莫来石前躯体可大大促进烧结。 相似文献
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MgO引入量对反应烧结ZrO2增韧Al2O3复相陶瓷性能的影响 总被引:2,自引:0,他引:2
以锆英石粉和α-Al2O3粉为原料,同时引入不同量的MgO(分别占ZrO2含量的0、3.5%、5%、8%、10%和20%)作烧结助剂和t-ZrO2的稳定剂,采用反应烧结法,分别于1500 ℃、1550 ℃、1600 ℃和1650 ℃保温4 h制备了ZrO2增韧Al2O3复相陶瓷.结果表明MgO的引入能促进ZrO2增韧Al2O3复相陶瓷的烧结,并提高了t-ZrO2的含量,但同时对生成物相产生影响,抑制了莫来石的生成;在ZrO2含量为5%(w),MgO引入量为ZrO2含量的8%时,试样经1600 ℃烧成后,性能达到最佳,常温抗折强度和断裂韧性分别达到220 MPa和6.2 MPa·m1/2. 相似文献
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无压烧结Si3N4—3YZrO2复相陶瓷材料的力学性能和增韧机理研究 总被引:4,自引:2,他引:2
在以4%Al2O3作为烧结助剂的Si3N4基体中分别添加5%,10%,20%,30%的3YZrO2,经1800℃无压烧结。共室温断裂韧性在到5.2-7.6MPa.m^1/2,是基体材料的2.4-3.5倍。 相似文献
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Pressureless Sintering of Alumina-Titanium Carbide Composites 总被引:3,自引:0,他引:3
The densification of Al2 O3 -TiC composites is detrimentally affected by chemical reactions between Al2 O3 and TiC. These reactions must be suppressed in order to promote sintering. In this study, the specific reactions occurring in Al2 O3 -TiC composites were modeled, using thermodynamic calculations, and verified by experiments. The reaction between Al2 O3 and TiC was suppressed by the use of specially prepared embedding powders allowing pressureless sintering to closed porosity. The Al2 O3 -TiC composites were subsequently hot isostatically pressed to > 99% of theoretical density without encapsulation. Typical flexural strength and fracture toughness of Al2 O3 -30 wt% TiC composites were 690 MPa and 4.3 MPa · m1/2 , respectively. 相似文献
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以部分碳化钛为增强相投入到碳化硅基体材料中,并投入微量炭黑和碳化硼为烧结活化剂,利用无压固相烧结技术制造了碳化硅基陶瓷复合材料。评测了其力学性能,凭借扫描电镜(SEM)观测了试样的断口形貌与表观形貌,并探讨了其氧化行为。结果表明:在碳化硅中投加部分碳化钛,对复合材料的力学性能有非常大地益处,于9 wt%时达到顶峰,弯曲强度497 MPa,相对密度98.9%,断裂韧性4.79 MPa·m1/2。复合材料的显微组织构造紧致密实,TiC颗粒在SiC材料中的离散作用而激发的钉扎效果和裂纹偏移转向为其主要的增韧原理。在设定的氧化条件下(1200℃保温2 h),试样表面形成了一层较为致密并可以弱化氧化进程的氧化膜层。 相似文献
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Pressureless sintering of SiC-whisker-reinforced Al2 O3 composites was investigated. In Part II of the study, the effects of Y2 O3 /MgO sintering additives and green body infiltration on densification behavior and microstructure development are reported. Both sintering additives and green body infiltration resulted in enhanced densification. However, the infiltration approach was more effective for samples with high SiC whisker concentrations. Samples with 27 vol% whiskers could be pressureless sintered to ∼93% relative density and ∼3% open porosity. Fracture toughness values and microstructural features (e.g., grain size) for the infiltrated samples remained approximately the same as observed in the uninfiltrated samples. 相似文献
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Pressureless sintering of SiC-whisker-reinforced Al2 O3 composites was investigated. In Part I of the study, the effect of the matrix (Al2 O3 ) powder surface area on densification behavior and microstructure development is reported. Compacts prepared with higher surface area Al2 O3 powder showed enhanced densification at lower whisker concentrations (5 and 15 vol%). Samples with 15 vol% whiskers could be pressureless sintered to ∼97% relative density with zero open porosity and ∼1.6-μm matrix average grain intercept size. 相似文献
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Yongjie Jia Xinghua Su Yajuan Wu Zhenjun Wang Leichao Meng Xiqing Xu Anni Zhang 《Journal of the American Ceramic Society》2020,103(4):2351-2361
Preparation of 3YSZ/Al2O3-platelet composites always requires high temperature, long duration, and/or high pressure. Herein, 3YSZ/Al2O3-platelet composites are prepared at low temperature of 492°C-645°C in 30 seconds by flash sintering under the electric field of 300-800 V/cm. The influence of electric field and current limit on the densification and grain growth of composites is investigated. The onset temperature for flash sintering is determined by electric field, which is decreased with increasing the electric field. Under the constant electric field, the current limit has a great effect on the density and grain size of composite. The flash-sintered 3YSZ/Al2O3-platelet composites exhibit relatively high hardness and elastic modulus. Both Joule heating and defects generation are proposed to be responsible for the rapid densification in flash sintering. This work demonstrates the feasibility of employing the flash sintering to prepare ceramic composites with fine grain size. 相似文献
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常压烧结莫来石/氧化锆/碳化硅复相陶瓷的研究 总被引:2,自引:1,他引:2
本文对莫来石/氧化锆/碳化硅复相陶瓷进行了N2气氛中常压烧结的研究。实验结果表明:SiC粒子添加量≤20vol%,材料均可致密烧结并可获得均匀的微观结构。SiC粒子的加入使材料人力学性能较莫来石/氧化锆陶瓷有明显的提高,并在SiC含量为10vol%时达到峰值,室温强度和断裂韧性分别为601MPa和5.8MPa^C2,接近热压材料。 相似文献