炉前包内冲废钢对灰铸铁组织和强度的影响

采用炉前包冲内冲废钢与孕育相结合的方法，研究了炉前包内冲废钢对灰铸铁组织和强度的影响。结果表明：冲废钢可以增加灰铸铁中初生奥氏体的数量，改变初生奥氏体枝晶的分布形态，强化灰铸铁孕育效果，有利于提高灰铸铁的强度。     

CHOICE OF FILLING MATERIALS AND TECHNIQUES IN XINQIAO PYRITE MINE

ＣＨＯＩＣＥＯＦＦＩＬＬＩＮＧＭＡＴＥＲＩＡＬＳＡＮＤＴＥＣＨＮＩＱＵＥＳＩＮＸＩＮＱＩＡＯＰＹＲＩＴＥＭＩＮＥ①ＺｈａｎｇＱｉｎｌｉ，ＷａｎｇＸｉｎｍｉｎＣｏｌｅｇｅｏｆＲｅｓｏｕｒｃｅ，ＥｎｖｉｒｏｎｍｅｎｔａｎｄＣｉｖｉｌＥｎｇｉｎｅｒｉｎｇ，...     

Ceramic coating on ceramic with metallic bond coating

The change in structure and adhesion strength of the interface by heating in air has been investigated for a plasma- sprayed alumina coating on a ceramic substrate with a 50Ni- 50Cr alloy bond coating. A veined structure composed of NiO, NiCr ₂O₄, and NiAl₂O₄ oxides grew from the bond coating into cracks or pores in the top coating and the alumina substrate after heating at 1273 K for 20 h in air. The NiAl₂O₄ spinel may have formed by the oxidization of nickel, which subsequently reacted with the alumina coating or the substrate. The mechanism of the penetration of the spinel oxides into the cracks or pores is not clear. The adhesion strength of the coating is increased to about 15 MPa after heating at 1273 K for 20 h in air, compared to an as- sprayed coating strength of only 1.5 MPa.     

晶化机制与激活能的晶化速率参比法确定

本文根据修正的Kissinger公式提出一种确定非晶材料晶化机制与激活能的最大晶化速率参比法。以Ar_(70)Cu_(30)非晶合金为例,研究了晶化机制与激活能及其与压力的关系。     

球磨过程中的碰撞行为分析

本文通过对行星球磨过程的分析，研究了行星球磨过程中的磨球碰撞行为，建立了球磨工艺参数与磨球运动速度。平均自由程及碰撞频率的理论关系。结果表明：随球磨转速提高，磨球运动速度和碰撞频率将增大，装料量一定时，提高球料比，磨球运动速率和平均自由程都将减小，碰撞频率增大，装料量和球料比一定时，磨球半径愈小，磨球运动的平均自由程减减小，碰撞频率增大。     

ZA22／Al2O3（F）复合材料室温拉伸强度的模拟研究

采用挤压法制备ＺＡ２２／Ａｌ２Ｏ３（Ｆ）复合材料，分别采用强度混合准则和神经网络模型研究了含Ｃｅ与不含Ｃｅ的ＺＡ２２／Ａｌ２Ｏ３（Ｆ）室温拉伸强度随短纤维体积分数Ｖｆ的变化情况，结果表明：强度混合准则能有效地预测复合材料的两个重要体积分数即最小体积分数Ｖｍｉｎ和临界体积分数Ｖｃｒｉｔ；而神经网络不仅能较准确地预测Ｖｍｉｎ和Ｖｃｒｉｔ，并且能够较好地描述复合材料强度随Ｖｆ的变化规律。     

高强度复合材料整铸辙叉前期研究

辙叉是线路上工作条件最为严峻的轨道部件之一。用高强度复合材料整铸的辙叉替代普通辙叉的研究具有重要意义。以ＰＤ３钢轨钢作为基体材料，在其表面熔合上一层新型具有更好耐磨性能的材质。新材料１、新材料２分别在ＰＤ３基础上把Ｖ的含量提高到０．１５％～０．２５％和０．３５％～０．４５％。采用合适的工艺措施，使新材料１、２与ＰＤ３轨道钢很好地熔合在一起。它们的σｂ、ａｋ、δ、τｂ均不低于ＰＤ３，而Ｈｖ却有了提高。     

软弱岩体Berger模型及井巷流变地压

在室内对硅藻岩进行了主要物理力学指标测定和蠕变试验的基础上，分析了软弱岩体的流变特性。根据Ｂｅｒｇｅｒ模型，建立了软弱岩体的流变状态方程和蠕变方程来分析支护前围岩移动规律和支护后流变地压的增长规律，同时还研究了软弱岩体的长期强度     

黏砂变形GFRP筋黏结性能研究

基于18个梁式试验、42个Losberg拉拔试验以及6个标准拉拔试验,对黏砂变形GFRP筋与混凝土之间的黏结性能进行了较系统的研究。研究表明:黏砂变形GFRP筋梁式试件和拉拔试件的破坏形态均可分为拔出破坏和劈裂破坏两种,黏结长度大于5倍直径的GFRP筋试件发生劈裂破坏,小于5倍直径的试件发生拔出破坏,而对于黏结长度为5倍直径左右的试件,两种破坏形态均有可能发生;GFRP筋与混凝土之间的黏结强度约为相应带肋钢筋的0.64～1.27倍;随着黏结长度和直径的增加,GFRP筋与混凝土之间的黏结强度有所降低;基于梁式试验、Losberg拉拔试验与标准拉拔试验得到的GFRP筋与混凝土之间的黏结强度无显著差异。最后,综合考虑GFRP筋直径、表面形态、黏结长度等因素影响,提出GFRP筋与混凝土之间黏结强度、锚固长度的设计建议。     

Size effect in RC deep beams: Experimental investigation and STM verification

An experimental program consisting of three groups of 11 specimens is carried out to investigate the possible causes of size effect, typically represented by a reduction in shear strength with an increase in the height of deep beams. It is well-known that deep beams behave very differently from shallow beams as arch action rather than flexure dominates the behaviour, after diagonal cracking has occurred. However, causes of size effect in deep beams remain unresolved. It is postulated that the factors influencing the strength of a compression member, i.e. the strut geometry and boundary conditions, govern the size effect. The experimental program provides experimental evidence for the hypotheses from strut-and-tie models. By properly configuring the loading and support plate dimensions, size effect in ultimate shear strength is significantly mitigated, even for beams with high h/b ratios and plain concrete web. Evenly-distributed web reinforcement is found to mitigate the size effect to some extent. Effects of out-of-plane actions on beam strength are also investigated and discussed. The modified STM incorporating the causes of size effect outperforms several other methods in accurately and consistently predicting the ultimate shear strengths.