共查询到19条相似文献,搜索用时 78 毫秒
1.
2.
3.
碳化物陶瓷 碳化物陶瓷包括碳化硅、碳化硼。碳化锯、碳化钨、碳化钒、碳化锆等。该类陶瓷的突出特点是具有很高的熔点、硬度(近于金刚石)和耐磨性(特别是在侵蚀性介质中),缺点是耐高温氧化能力较差(约900~1000℃)、脆性大。碳化硅陶瓷具有很高的高温强度,在1400℃时抗弯强度仍保持在500-600MPa,工作温度可达1700℃。它具有很好的热稳定性、抗蠕变性、耐磨性、耐蚀性、导热性、耐辐射性及低的热膨胀性。碳化硼陶瓷的硬度极高,抗磨粒磨损能力很强,熔点高达2450℃左右。但在高温下会快速氧化,并且会与热或熔融的黑色金属发生反应,因此其使用温度限定在980℃以下。其主要用途是做磨料,有时用于超硬质工具材料。 相似文献
4.
为了解IC-6合金在高温氧化环境中的力学损伤行为,研究了900、1000、1100℃空气中预暴露100h后合金的组织变化和拉伸性能,合金在预暴露后的强度变化不大,且在不高于1000℃下预暴露后合金伸塑没有受到氧化损伤,与K17G镍基合金相比,IC-6合金所具有这些明显优势被归因子定向凝固方法消除了横向晶界、抑制了空气中的氧沿晶扩散所造成的 力学损伤,在1100℃预暴露后,由于在合金表面生成挥发性M 相似文献
5.
《中国测试》2020,(8)
高纯人造石墨中硼含量的测定通常将试样进行直接灰化处理,在灰化过程中,表面的碳化硼与氧气反应生成致密玻璃态氧化硼包裹住未被氧化的碳化硼,阻止其持续氧化,导致结果偏低。试验采用氢氧化钙溶液预处理样品后,在800℃灰化,灰化过程中,氢氧化钙分解为氧化钙,氧化钙再与玻璃态氧化硼反应,从而使碳化硼持续氧化。灰化后用硝酸溶解,建立电感耦合等离子体原子发射光谱法测定高纯人造石墨中硼含量的分析方法。结果表明,硼质量浓度在0.02~2.0 mg/L范围内与其对应的发射光谱强度呈线性,标准曲线的相关系数为0.999 9,方法检出限为0.03μg/g,测定值的变异系数(n=8)为2.5%~6.6%,加标回收率为95.2%~104.7%。 相似文献
6.
球磨时间对硼掺杂石墨材料抗氧化行为的影响 总被引:2,自引:1,他引:1
通过球磨分散方法制备了掺杂细颗粒碳化硼石墨材料。采用热分析仪考察了经不同球磨时间制备的复合材料在室温至1400℃温度范围内的抗氧化行为;利用扫描电镜分析了样品在800℃和1000℃恒温氧化后的表面形貌。研究结果表明:经球磨50h制备的细颗粒碳化硼掺杂石墨材料在1000℃氧化时,有优良的自愈合抗氧化性能。其抗氧化机理为:均匀分散的细颗粒B4C可以在氧化时迅速形成连续的、均匀的保护膜覆盖在基体表面,从而有效地抑制氧气进入和基体反应。 相似文献
7.
采用静态氧化实验与XRD,FSEM测试技术对电弧熔炼制备的NbMoTaWV难熔高熵合金的高温氧化行为进行研究。结果表明:1000℃及1200℃下NbMoTaWV由于氧化层开裂严重失去保护性,氧化增重遵循直线氧化规律;1400℃下生成的熔融态氧化物释放氧化层的生长应力,填补Mo, V氧化物挥发留下的孔洞,使氧化层对氧气能够起到一定的阻隔作用,氧化增重遵循抛物线氧化规律。在NbMoTaWV的氧化过程中,氧气扩散进入基体内部后率先与扩散层中的Nb和Ta发生氧化反应,生成针棒状氧化物,之后与其他合金元素发生氧化反应,W的氧化物固溶在Nb和Ta氧化物中,颗粒状的Mo和V混合氧化物在高温下挥发。 相似文献
8.
9.
经研究致密的Sic-AIN-Y2O3复相陶瓷的氧化行为后发现,陶瓷材料的表面在空气中氧化的反应物随着温度的高低而变化。800℃、20h氧化试验后,试样表面无任何变化;1100℃氧化20h,表面形成了极少量的SiO2,但两者均无增重,1250℃和1320℃氧化30h后,试样的重量和表面发生较明显的变化,形成了SiO2与a-Al2O3;1370℃氧化试验30h后,陶瓷表面的氧化产物SIO2与a-Al2 相似文献
10.
研究了热压AIN-SiCw复合材料在1200℃~1400℃的氧化行为,分析了晶须掺量对复合材料氧化产物,氧化过程及强度的影响,结果表明,复合材料的氧化符合抛物线规律,氧化产物为Al2O3莫来石及铝硅酸盐玻璃相,晶须掺量的变化对复合材料的氧化并无显著影响。 相似文献
11.
12.
13.
14.
Takahiro Kondo 《Science and Technology of Advanced Materials》2013,14(1):780-804
AbstractVarious types of zero, one, and two-dimensional boron nanomaterials such as nanoclusters, nanowires, nanotubes, nanobelts, nanoribbons, nanosheets, and monolayer crystalline sheets named borophene have been experimentally synthesized and identified in the last 20 years. Owing to their low dimensionality, boron nanomaterials have different bonding configurations from those of three-dimensional bulk boron crystals composed of icosahedra or icosahedral fragments. The resulting intriguing physical and chemical properties of boron nanomaterials are fascinating from the viewpoint of material science. Moreover, the wide variety of boron nanomaterials themselves could be the building blocks for combining with other existing nanomaterials, molecules, atoms, and/or ions to design and create materials with new functionalities and properties. Here, the progress of the boron nanomaterials is reviewed and perspectives and future directions are described. 相似文献
15.
16.
D.V. Shtansky Y. >Yamada-Takamura T. Yoshida Y. Ikuhara 《Science and Technology of Advanced Materials》2013,14(4):219-225
The mechanism and the crystallography of the nucleation and growth of cubic boron nitride (c-BN) films deposited on 〈100〉-oriented silicon substrate by RF bias sputtering have been studied by means of cross-sectional high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Both methods provide experimental information showing no sp2-bonded BN layer formation in the subsurface region of c-BN phase. This is clear evidence for layer-by-layer homoepitaxial growth of cubic boron nitride without graphitic monolayers in the near-surface region of the film. The turbostratic boron nitride (t-BN) consists of thin sub-layers, 0.5–2 nm thick, growing in such a way that a sub-layer normal is almost parallel to the growth direction. t-BN also comprises a large volume fraction of the grain boundaries with high interface energies. The present result and the finding by Shtansky et al. [Acta Mater. 48, 3745 (2000)], who showed that an individual sub-layer consists of parallel lamellae in both the hexagonal +h-BN) and rhombohedral (r-BN) configurations, demonstrate that high intrinsic stress in the films is due to the complex structure of sp2-bonded BN. The crystallography of c-BN films indicates heteroepitaxial nucleation of cubic phase on the graphitic BN structural precursor. The present results are consistent with stress-induced c-BN formation. 相似文献
17.
D. V. Shtansky Y. Yamada-Takamura T. Yoshida Y. Ikuhara 《Science and Technology of Advanced Materials》2000,1(4):1046
The mechanism and the crystallography of the nucleation and growth of cubic boron nitride (c-BN) films deposited on 100-oriented silicon substrate by RF bias sputtering have been studied by means of cross-sectional high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Both methods provide experimental information showing no sp2-bonded BN layer formation in the subsurface region of c-BN phase. This is clear evidence for layer-by-layer homoepitaxial growth of cubic boron nitride without graphitic monolayers in the near-surface region of the film. The turbostratic boron nitride (t-BN) consists of thin sub-layers, 0.5–2 nm thick, growing in such a way that a sub-layer normal is almost parallel to the growth direction. t-BN also comprises a large volume fraction of the grain boundaries with high interface energies. The present result and the finding by Shtansky et al. [Acta Mater. 48, 3745 (2000)], who showed that an individual sub-layer consists of parallel lamellae in both the hexagonal (h-BN) and rhombohedral (r-BN) configurations, demonstrate that high intrinsic stress in the films is due to the complex structure of sp2-bonded BN. The crystallography of c-BN films indicates heteroepitaxial nucleation of cubic phase on the graphitic BN structural precursor. The present results are consistent with stress-induced c-BN formation. 相似文献
18.