Ce-TZP和Ce-TZP/Al_2O_3层状复合材料受载裂尖的相变特性

用云纹干涉法研究了带直通切口的Ｃｅ ＴＺＰ（Ｔｅｔｒａｇｏｎａｌ ＺｉｒｃｏｎｉａＰｏｌｙｃｒｙｓｔａｌ）和Ｃｅ ＴＺＰ／Ａｌ２Ｏ３层状复合材料三点弯曲梁的相变过程．实验发现１６００°Ｃ／３ｈ烧结１２％ｍｏｌＣｅＯ２稳定的Ｃｅ ＴＺＰ在室温下就具有强烈的自催化效应，直通切口前缘的相变区呈树枝状，Ｃｅ ＴＺＰ／Ａｌ２Ｏ３层状复合材料的自催化相变被Ａｌ２Ｏ３层抑制，切口前缘的相变区变短，且相变区的覆盖面积减小．文中最后对Ａｌ２Ｏ３层改变Ｃｅ ＴＺＰ相变区及力学性能的原因进行了讨论．     

Crack tip superblunting: experiment,theory and numerical simulation

Experimental revelation ofsuperblunting along plane strain predominant crack tip segment is reported here for modified polyproplene. As elucidated by a heuristic model of progressive circumferential cold-draw, the formation of superblunting crack tip depends critically on the ratio between the cold-draw propagation speed and the loading speed, and contributes significantly to the material toughening, especially for the improvement in impact toughness. Detailed numerical calculations are conducted based on a hyperelastic-viscoplastic and anisotropic damage constitutive model at finite deformation. The simulated results recapitulate the essential features of crack tip superblunting. The project supported by the National Natural Science Foundation of China     

The effect of T-stress on crack–inclusion interaction under mode I loading

A closed-form solution has been developed to predict the effect of T-stress on the crack–inclusion interaction. As validated by several numerical examples, the approximate solution has satisfactory accuracy for different inclusion shapes and modulus ratios between inclusion and matrix under different T-stress levels. Thus the role of T-stress in crack–inclusion interaction can be predicted quantitatively.     

Reactive Core-Shell Bottlebrush Copolymer as Highly Effective Additive for Epoxy Toughening

Herein,we designed a core-shell structured bottlebrush copolymer (BBP),which is composed of rubbery poly(butyl acrylate) (PBA)core and an epoxy miscible/reactive poly(glycidyl methacrylate) (PGMA) shell,as an epoxy toughening agent.The PGMA shell allows BBP to be uniformly dispersed within the epoxy matrix and to react with the epoxy groups,while the rubbery PBA block simultaneously induced nanocavitation effect,leading to improvement of mechanical properties of the epoxy resin.The mechanical properties were measured by the adhesion performance test,and the tensile and fracture test using universal testing machine.When BBP additives were added to the epoxy resin,a significant improvement in the adhesion strength (2-fold increase) and fracture toughness (2-fold increase in Klc and 5-fold increase in Glc)compared to the neat epoxy was observed.In contrast,linear additives exhibited a decrease in adhesion strength and no improvement of fracture toughness over the neat epoxy.Such a difference in mechanical performance was investigated by comparing the morphologies and fracture surfaces of the epoxy resins containing linear and BBP additives,confirming that the nanocavitation effect and void formation play a key role in strengthening the BBP-modified epoxy resins.     

高性能摩阻材料用酚醛树脂

通过冲击强度、红外光谱、热分析、刹车片试验等手段研究了稀土和亚麻油对酚醛树脂的改性作用,结果表明,稀土离子将酚羟基封锁减少了酚羟基对其邻位上亚甲基的影响,提高了树脂的耐热性,亚麻渍的烷基链起到内增韧的作用,改善了树脂的脆性。通过稀土和亚麻渍的双改性,合成出高性能摩阻材料用酚醛树脂。     

纳米颗粒对陶瓷材料力学性能的影响

纳米材料是当今社科研究的热点,对陶瓷材料采用纳米颗粒复合的方法可大大改善其力学性能。本文介绍了纳米复合陶瓷的各种强韧化机理,简述了其制备工艺,对纳米复合陶瓷的内在强韧化机理和最佳制备工艺作了进一步探索。同时给出了我们的部分分散实验结果。     

ABS树脂研究进展

聚(丙烯腈-丁二烯-苯乙烯)三元共聚物即ABS树脂具有优异的机械性能、热稳定性能、耐化学性能、美学性能和加工性能等因而被广泛应用。本文综述了国内外ABS树脂的生产工艺和制备方法,指出了连续本体聚合法具有优势,但仍要与乳液聚合法长期竞争、共存,并重点阐述了ABS树脂的增韧改性用橡胶品种及其增韧机理,最后讨论了仪器化冲击试验机在高分子材料尤其是在ABS领域中的应用状况及前景,指出将显微技术与仪器化冲击手段结合可深层次地评价树脂材料的动态断裂过程与机理。     

具有大倾斜角的纤维桥联分析

将基体作为纤维在垂直和水平方向的弹性支承,考虑基体剥落与纤维拉出的完全耦合,基于基体的支承刚度和破坏条件,利用杆件非线性弯曲模型和有限元法,分析了具有大倾斜角的层间短纤维的桥联力与层间裂纹张开位移的关系·数值算例表明,桥联纤维的弯曲变形是局部的,主要是拉伸,在基体剥落与纤维拉出的影响下,韧性较好的芳纶短纤维桥联张开位移较大,可以在桥联中产生较大的能量耗散和增韧作用     

动态压力下固井防窜增韧剂研究与性能评价

调整井固井过程中地层压力时刻处于波动状态,这导致了严重的水窜;此外,储层改造时水泥环破裂将造成环空窜流.针对调整井固井存在的上述问题,首先,通过优选防窜增韧材料进行复配研究,制备出了一种动态压力下固井防窜增韧剂.然后,针对动态压力下水窜的特点,采用自主研制的新型水窜评价装置对防窜增韧改性水泥浆的防水窜性能进行评价.此外...     

新型锆合金设计与强韧化研究进展

空间活动构件尤其舱外活动件要在空间低温、交变温度、辐照、严重摩擦磨损和冷焊等苛刻环境下长期运转,其寿命与精度已成为航天器能否在轨长期服役的关键环节之一.锆及锆合金具有中子吸收截面小,良好的耐腐蚀和抗辐照特点,因此被广泛应用于核工业和化工业当中,其具有作为空间飞行器活动构件材料使用的发展潜力.但由于纯锆的抗拉强度较低,不能直接作为结构材料使用.实现强韧化并突破制备技术的瓶颈成为将其应用于空间活动构件的关键环节.本文从理论与实验两方面讨论了锆合金结构特点,成分设计与优化,组织性能关系等问题,针对空间活动构件的服役环境,提出了可作为空间活动构件使用的锆系合金材料的最佳体系与成分.