槽波透射勘探技术在寺河矿的精准应用

在井下综采工作面一侧巷道内激发槽波,另一侧巷道中接收通过采面透射的槽波。利用煤层与岩层的物理力学差异,分析在煤层中激发和接收到的槽波,以此来探查综采工作面中地质构造、煤体破碎区、应力集中区的位置,从而为后期探测地质构造参数、煤体破碎区注浆、应力集中区消突等工作的顺利进行提供基础数据,提高后期工程实施的针对性。     

A variational approach for free vibrating micro-rods with classical and non-classical new boundary conditions accounting for nonlocal strengthening and temperature effects

Abstract

Transverse vibration of a circular cross sectional micro-rod subjected to a new kind of boundary constraints with elastic torsional springs is presented based on nonlocal elasticity. A nonlocal strengthening beam model is utilized and the effect of temperature changing is taken into consideration. The variational method and Hamilton’s principle are applied to derive the governing equation of motion and corresponding boundary conditions. A higher-order partial differential equation that is a typical characteristic of nonlocal strengthening model is developed, and the boundary conditions contain not only classical conditions but also non-classical higher-order conditions. Unlike previous studies which were only concerned with some conventional boundary constraints, we consider more general boundary conditions named elastic torsional spring supports. Such boundary conditions are between the simply supported and clamped ones, and they are closer to the actual constraints of existing engineering structures. Natural frequencies of micro-rods with new boundary constraints are determined via an eigenvalue method and compared with other results in the literature. It is shown that the nonlocal scale factor, thermal parameter, rigidity parameter and torsional spring coefficient play significant roles in free vibration of micro-rods. The research can provide a reference for a large class of boundary conditions ranging from simply supported to clamped micro-rods.     

氮对镀锡钢板的强化作用

通过物理化学相分析研究了3种不同氮含量镀锡板中固溶氮、化合氮的含量,结合相关理论计算了镀锡板中氮的固溶强化和析出强化对强度的贡献。结果表明:随着总氮含量从0.0021%提高到0.0103%,钢中化合氮含量下降10.1%,但是AlN析出相中的氮的含量上升10.7%。氮在提高镀锡板强度方面发挥重要作用,钢中总氮含量提高0.0082%,其对屈服强度的贡献值提升约30 MPa。     

ZK60镁合金表面滚压强化试验研究

试验研究了ZK60镁合金表面滚压加工中工艺参数对试件表面粗糙度、表面形貌、表面残余应力和表层显微硬度的影响,结果表明滚压力和重复滚压次数对试件的表面粗糙度、表面形貌以及表面残余应力和表层硬度影响程度较大,滚压速度影响较小。对精车ZK60镁合金试件进行滚压加工,试件表面粗糙度R a、R z最大减小了50.3%和48.1%;残余压应力最大可达-54.55 MPa;显微硬度从试件表层到内部基体材料逐渐降低,表层硬度值最大为92.83 HV 0.25,比基体材料硬度提高了15.32%。     

7050铝合金双级双峰时效强化机理

本文系统地研究了7050铝合金双级双峰时效微观组织对强度和硬度的影响。 结果表明，7050铝合金的双级时效出现了双峰现象。 第二峰的硬度和强度均略高于第一峰。 透射电子显微镜（TEM）观察表明，第二峰值的硬度和强度的增加是由于一定数量的n相数量的增加引起的。 此外，n相和GP区的共同作用优于GP区单独的效果。     

Influence of the ZrB2 content on the anti-oxidation ability of ZrB2-SiC coatings in aerobic environments with broad temperature range

ZrB₂-SiC coatings with different ZrB₂ contents were prepared by liquid phase sintering. The oxidation processes of coatings were explained according to TG results of ZrB₂-SiC coatings and powders tested from 298 K to 1773 K. Results show that, increasing ZrB₂ content made the weight of the samples changed from weight-loss of 10.04% to weight-gain of 0.14%, while the fastest weight-loss regions were narrowed, whose inflection points reduced from 1310℃ to 1050℃. Increasing ZrB₂ content made the relative oxygen permeability of the ZrB₂-SiC/SiC coatings reduced from 40%–60% to -10%-5%. Increasing ZrB₂ content enhanced high-temperature stability of coatings, making final weight of samples changed from weight-loss of 0.16% to weight-gain of 0.11% after oxidation at 1773 K for 200 h. The peeling and dispersion of Zr-oxides formed Zr-B-Si-O compound glass layer, presenting enhanced stability, dispersion strengthening and pinning effect of Zr-oxides, which were responsible for the excellent anti-oxidation protective effect of coatings in a broad temperature region.     

Performance of insulated FRP-strengthened concrete flexural members under fire conditions

This paper presents the results of fire resistance tests on carbon fiber-reinforced polymer (CFRP) strengthened concrete flexural members, i.e., T-beams and slabs. The strengthened members were protected with fire insulation and tested under the combined effects of thermal and structural loading. The variables considered in the tests include the applied load level, extent of strengthening, and thickness of the fire insulation applied to the beams and slabs. Furthermore, a previously developed numerical model was validated against the data generated from the fire tests; subsequently, it was utilized to undertake a case study. Results from fire tests and numerical studies indicate that owing to the protection provided by the fire insulation, the insulated CFRP-strengthened beams and slabs can withstand four and three hours of standard fire exposure, respectively, under service load conditions. The insulation layer impedes the temperature rise in the member; therefore, the CFRP–concrete composite action remains active for a longer duration and the steel reinforcement temperature remains below 400°C, which in turn enhances the capacity of the beams and slabs.     

碱铝硅酸盐玻璃化学强化关键影响因素概述

化学强化是一种玻璃机械强度增强方法,适用于异型、超薄、高碱、高膨胀玻璃增强,因新型超薄显示产品的屏幕保护玻璃发展需要,化学强化技术重新在碱铝硅酸盐玻璃品种掀起研究热潮。本文对化学强化本质及铝硅酸盐玻璃在屏幕保护玻璃应用进行了回顾,基于玻璃化学强化的高CS、DOL和低CT诉求,归纳总结了关键影响因素,第1,碱铝硅酸盐玻璃的成分及结构是基础,氧化铝有利玻璃网络孔隙增大创造交换通道,氧化钠或氧化锂是离子交换关键物质;第2,对于玻璃组成和结构设计,要求玻璃网络键合度R=O/Si或O/(Si+Al)满足2.15~2.40,碱金属氧化物质量分数大于13%且膨胀系数大于6×10^-6/℃;第3,在化学强化工艺方面,化学强化温度决定离子扩散系数,化学强化时间决定DOL,一步法仅能获得相对较大的CS,而DOL不很理想,只有两种离子参与交换的二步法才有利于CS和DOL同步提高。     

喷丸奥氏体耐热钢抗蒸汽氧化性的研究与使用现状

奥氏体钢内壁喷丸处理作为一种新的提高材料抗蒸汽氧化性的技术，在超超临界火电机组受热面管的使用越来越广泛和成熟。概述了传统奥氏体钢在蒸汽氧化过程中氧化皮的形成结构，材料临界Cr含量 对富Cr层形成的影响，以及氧化皮结构与临界Cr含量 的关系。奥氏体钢内壁喷丸处理提高抗蒸汽氧化性的机理为：喷丸在管子内表面形成一层微米级厚度的喷丸层，喷丸层中晶粒碎化、晶格畸变、位错增多，在蒸汽氧化过程中，为基体内的Cr原子向表面扩散提供短路通道，使喷丸层表面Cr浓度提高，以形成富Cr层，减小氧化速率，提高抗蒸汽氧化性。归纳得出国内外关于喷丸奥氏体钢与传统钢管在600~750 ℃温度范围内，抗蒸汽氧化性的顺序依次为：600~700 ℃温度下，喷丸SUPER304(S30432)>喷丸TP347H≈喷丸TP321H≈TP310HCbN(HR3C)>SUPER304≈TP347HFG>TP304≈TP347H>TP321H；700~750 ℃下，TP310HCbN(HR3C)>喷丸TP347H>喷丸TP321H。同时归纳了喷丸工艺中，各因素对喷丸效果的影响，喷丸层质量的金相和硬度评价方法，以及目前喷丸奥氏体钢的实际应用现状。最后分析了喷丸奥氏体钢关于加工、焊接以及使用寿命等仍需研究解决的问题，展望了喷丸工艺向马氏体钢的推广使用。     

汽车用钢弹性模量测试探讨

采用静态拉伸试验方法对系列汽车用钢材料进行测试，得到了汽车用钢材料的弹性模量，分析了强化方式、轧制方向、塑性变形等对材料弹性模量的影响。结果表明：强化方式影响材料的弹性模量，固溶强化的汽车用钢材料弹性模量最大；材料的弹性模量表现出各向异性特点，垂直于轧制方向的弹性模量最大；塑性变形降低材料的弹性模量。研究结果为工程设计、冲压模拟、碰撞模拟、回弹模拟等提供计算依据。