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采用KH-560与KH-550反应得到新的硅烷偶联剂改性纳米碳化硅(SiC);再以2,4-甲苯二异氰酸酯(TDI)、聚氧化丙烯醚二醇(PPG2000)为原料合成预聚体,改性纳米SiC为填料、3,3’-二氯-4,4’-二氨基二苯甲烷(MOCA)为扩链剂,制备了改性纳米SiC/聚氨酯弹性体(PUE)复合材料。讨论了改性前后的纳米SiC添加量对复合材料的力学性能、耐磨性能和热稳定性的影响,并用扫描电镜分析了改性前后的纳米SiC在基体中的分散性。结果表明,改性后的纳米SiC在基体中的分散性优于纳米SiC,当改性纳米SiC质量分数为9%时,改性纳米SiC/PUE复合材料的力学性能达到最佳,耐磨性能明显改善,热失重温度提高了33℃。 相似文献
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为改善硼粉(B)的性能和纳米氧化铁(Fe_2O_3)在固体推进剂中的分散性,用静电喷雾法制备了B/Fe_2O_3/NC复合物,采用扫描电镜(SEM)表征了复合物的表面形貌,用TG-DSC分析了复合物的热性能及其对HTPB/AP推进剂热性能的影响,并用燃速测试和密闭爆发器实验研究了该复合物对HTPB/AP推进剂燃烧性能的影响。结果表明,所制备的B/Fe_2O_3/NC复合物均以团聚体的形式存在,复合物中B的活性提高,其氧化反应温度提前;团聚硼粉对HTPB/AP推进剂燃烧性能的改善效果明显优于原料硼粉;加入Fe_2O_3后,会进一步改善含硼推进剂的燃烧性能,而且随Fe_2O_3含量的增加,在密闭爆发器中HTPB/AP推进剂达到最高压力所需的时间逐渐减小。当Fe_2O_3的质量分数为8%时,推进剂在常压空气中的燃速最大,为不添加B/Fe_2O_3/NC复合物的HTPB/AP推进剂的2.77倍。B/Fe_2O_3/NC复合物对推进剂的热分解具有一定催化作用,且随Fe_2O_3含量的增加催化作用增强。 相似文献
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w-十一烯酸改性纳米碳酸钙工艺研究 总被引:1,自引:1,他引:0
采用正交实验,以w-十一烯酸作为表面改性剂,无水乙醇为分散介质,在一定的温度下对纳米碳酸钙粉体进行表面改性研究,确定改性纳米碳酸钙的最佳工艺条件为:改性剂用量3.0%,改性温度60℃,改性时间30 min.改性后的纳米碳酸钙的吸油量(液体石蜡)降为40 mL/100g,活化率提高到99.52%,表明改性后的纳米碳酸钙粒子亲油性得到显著提高.沉降速率和透射电镜(TEM)测试结果表明:改性后的纳米碳酸钙在亲油性溶剂中的分散性得到显著改善,粒度分布更加均匀. 相似文献
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ω-十一烯酸改性纳米碳酸钙工艺研究 总被引:1,自引:0,他引:1
采用正交实验,以ω-十一烯酸作为表面改性剂,无水乙醇为分散介质,在一定的温度下对纳米碳酸钙粉体进行表面改性研究,确定改性纳米碳酸钙的最佳工艺条件为:改性剂用量3.0%,改性温度60℃,改性时间30min。改性后的纳米碳酸钙的吸油量(液体石蜡)降为40mL/100g,活化率提高到99.52%,表明改性后的纳米碳酸钙粒子亲油性得到显著提高。沉降速率和透射电镜(TEM)测试结果表明:改性后的纳米碳酸钙在亲油性溶剂中的分散性得到显著改善,粒度分布更加均匀。 相似文献
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为了改善聚苯硫醚(PPS)纤维的光稳定性能,将苯并三唑与纳米二氧化钛(Ti O2)按一定比例复配与PPS切片进行共混熔融纺丝,制得改性PPS纤维,研究了改性PPS纤维的可纺性及其性能。结果表明:苯并三唑/纳米Ti O2复配物的质量分数大于1.5%时,改性PPS纤维的可纺性变差;当复配物质量分数小于等于1.5%时,改性PPS纤维的表观形貌和可纺性满足工业生产要求;随着苯并三唑/纳米Ti O2的添加量增加,改性PPS纤维的断裂强度有所降低,断裂伸长率和热性能变化不大;当苯并三唑质量分数为1.5%,Ti O2为0时,PPS的结晶速率最大,改性PPS纤维的光稳定性能最好,光照前后的色度变化值为14.02。 相似文献
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以固化剂乙二胺与(环氧树脂)进行固化反应,经过钛酸酯偶联剂TC-WT对纳米碳酸钙进行表面处理,选择超声波分散和高速剪切分散,添加纳米碳酸钙制备复合材料。红外光谱分析结果表明:表面改性后的纳米碳酸钙粒子表面呈疏水性,在有机溶剂中分散性变好,碳酸钙粒子与改性剂之间发生了化学键合。TEM照片分析结果表明,改性纳米碳酸钙分散性得到了较好的改善,这种模糊的界面说明纳米碳酸钙与有机基体有较好的相容性。通过DTA曲线分析和TG表征可知,改性纳米CaCO3能够有效提高环氧树脂固化物耐热稳定性。在330~450℃,改性纳米Ca-CO3复合材料的热失质量较空白基体的热失质量小,复合材料的热稳定性略有提高。 相似文献
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采用纳米聚丙烯酸酯乳液改性纳米Mg(OH)2,通过单螺杆挤出机制备了纳米Mg(OH)2/低密度聚乙烯(LDPE)复合材料,利用红外光谱、扫描电镜、透射电镜等方法对改性前后的Mg(OH)2及Mg(OH)2/LDPE复合材料进行了表征。结果表明:纳米Mg(OH)2表面经纳米聚丙烯酸酯乳液改性后吸附上了一层聚丙烯酸酯;纳米聚丙烯酸酯乳液改性提高了纳米Mg(OH)2的热稳定性,分解温度提高了27℃;改性纳米Mg(OH)2在LDPE基体中分散更为均匀;改性纳米Mg(OH)2的用量为LDPE的15%时复,合材料的拉伸强度比纯LDPE提高了6.5%。 相似文献
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Kathy Lu Xiaojing Zhu Karthik Nagarathnam 《Journal of the American Ceramic Society》2009,92(7):1500-1505
Sintering of pure B4 C and Ni2 B nanolayer-coated B4 C was studied from 1300° to 1600°C, with the holding time at the peak temperatures being 2 or 10 h. Compacts were made by uniaxial die compaction and combustion-driven compaction. Pure B4 C sample shows less sintering at all conditions. Ni2 B-coated B4 C sample shows more extensive densification, neck formation, and grain shape accommodation. The combustion driven compaction process accelerates sintering by offering higher green density to start with. The Ni2 B species on the B4 C particle surfaces melts into a nickel–boron-containing liquid phase during heating, remains as liquid during sintering, and then transforms into Ni4 B3 and NiB during cooling. High-resolution composition analysis shows that there is no nickel diffusion into bulk B4 C during the sintering process. However, there is boron diffusion into the Ni2 B coating layer. Carbon diffusion cannot be directly measured but is believed to be a simultaneous process as boron diffusion. A multievent sintering process has been proposed to explain the observations. 相似文献
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Robert Ruh Kimberly Y. Donaldson D. P. H. Hasselman 《Journal of the American Ceramic Society》1992,75(10):2887-2890
Because of their preferred orientation, the addition of boron nitride dispersions to hot-pressed boron carbide was found to result in a considerable degree of anisotropy in thermal conductivity of the resulting composite, indicated by an increase in the thermal conductivity perpendicular to the hot-pressing direction by as much as a factor of 3 at the highest boron nitride volume fractions of this study, and a decrease in the thermal conductivity parallel to the hot-pressing direction by as much as a factor of 2. The composite data were found to be below the values expected from composite theory, which may represent indirect evidence for the existence of an interfacial thermal barrier. 相似文献
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采用电感耦合等离子体原子发射光谱法( ICP-AES )探讨硼铸铁中硼的测定。以盐硝混酸(3+1+6)和硫酸溶液(1+3)在低温下溶解样品,溶解完毕后定容,在设定的仪器工作条件下测定。硼检出限为0.027 mg/L。用该方法可测定硼铸铁中0.0034%~0.38%硼含量,连续测定6个平行样测定结果的相对标准偏差均小于4.52%,其回收率在93%~108%、相对误差在3.03%以内。 相似文献
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P. D. OWNBY 《Journal of the American Ceramic Society》1975,58(7-8):359-360
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Robert Ruh Michael Kearns Avigdor Zangvil Youren Xu 《Journal of the American Ceramic Society》1992,75(4):864-872
Boron carbide–boron nitride particulate composites were fabricated by vacuum hot-pressing. Near-theoretical densities of B4 C were obtained, but percent theoretical densities decreased with increasing amounts of BN. The grain size of B4 C and BN was not affected by composition, but the amount of twinning in B4 C decreased with increasing BN content. No third phase was found at the B4 C–BN interface by analytical STEM analysis. Lattice parameter measurements indicated slight solubility of B4 C in BN, but no solubility of BN in B4 C for samples hot-pressed at 2250°C. Room-temperature flexural strength measurements revealed a sharply decreasing strength with increasing BN content up to 40% BN, and then relatively constant values with greater amounts of BN. 相似文献
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Satoshi Nakano Hiroyuki Ikawa Osamu Fukunaga 《Journal of the American Ceramic Society》1992,75(1):240-243
Cubic boron nitride ( c -BN) was synthesized by the decomposition of Mg3 BN3 under high pressure and high temperature. The minimum pressure for c -BN synthesis was 4 GPa, which was 1 GPa lower than that of the conventional catalytic process. The decomposition of Mg3 BN3 was observed only when H2 O was added. Therefore, the reaction was as follows: Mg3 BN3 + 3H2 O = 3MgO + c -BN + 2NH3 . The c -BN crystals obtained were tetrahedron in shape and about 10 μ m in diameter. 相似文献
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硼酐碳热法合成碳化硼的研究 总被引:2,自引:0,他引:2
用X-射线衍射分析方法,研究了温度及反应物中B2O3摩尔量对碳热合成B4C粉末中残留含量的影响,同时探讨其反应机理,实验表明,碳化硼粉末中的残留碳含量不仅取决于反应而且与B2O3的摩尔量有关。在碳管炉内合成B4C的反应以液固反应为主,在反应时间一定条件下B2O3摩尔量为5-6mol的反应物料,在1650℃Ar气氛中反应,其残留碳含量最低,其相对量为10%左右。 相似文献
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Nathan Jacobson Serene Farmer Arthur Moore Haluk Sayir 《Journal of the American Ceramic Society》1999,82(2):393-398
High-temperature oxidation of monolithic boron nitride (BN) is examined at 900–1200°C. Hot-pressed BN and both low- and high-density chemically vapor-deposited BN are studied. The oxidation product is B2 O3 ( l ) and the oxidation kinetics are sensitive to crystallographic orientation, porosity, and impurity levels. The B2 O3 product also reacts readily with ambient water vapor in the test furnace (ppm levels) to form the volatile species HBO2 ( g ), leading to overall paralinear kinetics. The linear rate constant extracted from these experiments agreed with that predicted from diffusion of HBO2 ( g ) across a static boundary layer. 相似文献