工艺因素对C／C复合材料ICVI致密化的影响

以2D针刺碳毡为预制体、丙烯为前驱气体、氮气为稀释气体,在常压条件下研究了沉积温度、滞留时间和丙烯分压等工艺因素对致密化速度的影响。结果表明,三个工艺参数协同作用,对致密化具有相似的影响:参数取值较高时初期致密化速度也较快,结果导致预制体表层气孔的过早填充,不利于进一步的沉积,反之,则致密化速度较慢,但有利于预制体内部的沉积。

CLVD法制备C/C复合材料工艺探索研究

研究了采用化学液气相沉积法制备 C/ C复合材料的工艺过程 ,分析了不同预制件、温度、浸泡时间等工艺参数对致密速度、效果的影响 ,并总结出了一套快速高效的致密方法。

Analysis of elastic anisotropy of tight sandstone and the influential factors

Tight sandstone has a certain anisotropy. Using ultrasonic measurements of samples in three different directions and related matched experiments, this study systematically analyzes the pore structure and anisotropy of tight sandstone samples obtained from oil fields and compares results with those of shale. Results firstly show that the anisotropy of tight sandstone is mainly related to the compositional layering and thin interbedding which occur in different sedimentary environments. Tight sandstone has typical transverse isotropic medium characteristics, Young’s modulus increases in different directions with increasing confining pressure, Poisson’s ratio change is not obvious, anisotropic coefficients decrease with increasing effective pressure, and a certain linear relationship exists between ε, γ, and δ. This article finally summarizes anisotropy in different areas, thereby providing a foundation for the use of suitable appraisal models in different regions. This research can be used as an experimental reference for logging evaluation, seismic data interpretation, and fracturing develop of tight sandstones.

纳米三氧化二铝对陶瓷烧结温度的影响

采用在普通陶瓷坯料上涂抹一层纳米三氧化二铝的方法进行分组烧结试验。利用纳米颗粒的奇异特性提高坯料表面的扩散速率,降低烧结温度,提升烧结产物的致密化程度。实验中通过控制纳米添加剂的剂量以及工艺优化,取得最佳的增强、增韧效果。运用SME、XRD等检测手段分析不同晶型、不同形貌的纳米氧化铝对烧结温度的降低程度以及力学性能的改善状况,为陶瓷制备提供实验数据储备。实验结果表明:在陶瓷坯料表面涂抹纳米三氧化二铝涂层既可节省纳米材料又能大幅度降低烧结温度,是提高力学性能的行之有效的措施。

烧结条件对(α+β)-Sialon陶瓷组织与性能的影响

系统地讨论了两种不同的烧结方法对(α+β)-Sialon系统相形成、显微结构及性能的影响。实验结果表明:同样的烧结参数,热压烧结制备的(α+β)-Sialon具有较好的显微结构和强度,这是由于外加推动力加速了材料的烧结过程,提高了致密度,因而提高了材料性能。讨论了温度、时间和加热速率的影响。结果表明:最适宜的无压烧结和热压烧结温度分别为1750～1800℃和1700～1750℃,烧结时间分别为120 min和60 min。两种烧结方法的最佳升温速率均为15～20℃/min。

The fast rotation of companions of compact objects in close binary systems

We have performed Monte Carlo simulations of the rotation of single stars and companions of compact objects(The compact objects are white dwarfs(WDs) and neutron stars(NSs)) in close binaries.We present a comparison between the rotation of companions of compact objects and that of single stars.We find that the rotation of the companions of compact objects is on average faster than that of the single stars.According to the distribution of the orbital period and the rotation angular velocity,we find that the rotation of the companions of compact objects is mostly accelerated by stable mass transfer.Tidal forces of the compact object can also affect the rotation of companion.