菌丝体/膨胀珍珠岩建筑用保温隔热复合材料实验研究

选用不同片径的蘑菇菌丝体,分别以水玻璃、聚乙烯醇为黏结剂进行粘结,以模压成型工艺制备两种黏结剂下的纯菌丝板,对其进行热学和力学性能测试,确定最佳导热系数的菌丝片径大小为6~8目;以具有最佳导热系数片径的蘑菇菌丝与膨胀珍珠岩混合,以相同的工艺方法制备两种黏结剂下的菌丝体/膨胀珍珠岩复合保温材料,研究材料的密度、导热系数、抗折、抗压强度和膨胀珍珠岩所占比例(ω)之间的关系。结果表明:随着ω的增加,材料的密度、抗折、抗压强度逐渐降低,两种黏结剂相比,以水玻璃粘结的材料具有更小的密度、抗折、抗压强度;导热系数随着ω增加出现降低的趋势,且以水玻璃粘结的样品具有更小的导热系数,更适合于建筑隔热保温材料的应用。     

Effect of microstructures restoration on high temperature fatigue behavior of DZ125 superalloy

Combination of hot isostatic pressing (HIP) and rejuvenation heat treatment (RHT) technology was used to restore creep-damaged DZ125 directional solidified superalloy, and the influence of microstructure restoration on high temperature fatigue behavior of the samples was explored. The results show that the HIP+RHT process could effectively heal internal cavities and recover the degraded γ′ phase in creep-damaged DZ125 superalloy to cubic particles similar as in as-received sample. After restoration treatment, the stress concentration areas inside the sample eradicated with the healing of the internal cavities, and the fatigue source areas were limited only to near surface than initiating from inside as in the as-received and creep-damaged samples. As a result, the restored sample had higher crack initiation life and lower crack propagation rate compared to as-received and creep damaged samples. The TEM microstructure characterization near fatigue fracture showed that the restoration of the degraded γ′ phase eliminated tangled dislocation in creep damaged sample and produced evenly distributed dislocations in the γ channel with short curved line-like morphology, like the as-received sample, which effectively hindered the dislocations movement during subsequent deformation, and strengthen the fatigue resistant of alloy. Therefore, it can be concluded that the HIP-RHT process, through the combined effect of internal cavities healing and the restoration of the degraded microstructures, renders higher high temperature fatigue life than creep-damaged and even higher than as-received DZ125 superalloy.     

基于Simulink的振动压路机七自由度模型的动力学分析

通过牛顿运动定律对振动压路机建立了七自由度的力学模型和运动微分方程,阐述了运用状态空间法把压路机的微分方程转化为能方便用Matlab/Simulink仿真的模型,运用状态空间法建模简化了编程过程,提高了编程的质量和可靠性.介绍了Matlab/Simulink对压路机进行运动仿真的分析方法.通过仿真分析可得:与五自由度的压路机模型相比,七自由度的力学模型同样简单可行,而且还能对驾驶室和驾驶座进行动力学分析,分析的问题更加全面,为振动压路机设计和减振性能的研究提供理论指导.     

三明重工YZ18压路机在巴南高速公路路基施工中的应用

在巴南高速挖方路基和填方路基进行振动压实前,进行了大量的试验研究,确定振动碾压的压实方法、压实遍数、压实速度等实验数据,提高了该路基的压实度、整体强度和承载力,加速了路基的下沉降,减少了路基的工后沉降,达到了预期的目的。通过对YZ18压路机在高速公路巴南高速公路路基施工的应用情况进行分析,希望能在其他填方路基振动碾压时有一定的借鉴作用。     

In situ (α-Al2O3+ZrB2)/Al composites with network distribution fabricated by reaction hot pressing

In situ (α-Al2O3+ZrB2)/Al composites with network distribution were fabricated using low-energy ball milling and reaction hot pressing. Differential thermal analysis (DTA) was used to study the reaction mechanisms in the Al–ZrO2–B system. X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDX) were used to investigate the composite phases, morphology, and microstructure of the composites. The effect of matrix network size on the microstructure and mechani-cal properties was investigated.The results show that the optimum sintering parameters to complete reactions in the Al–ZrO2–B system are 850℃ and 60 min.In situ-synthesizedα-Al2O3 and ZrB2 particles are dispersed uniformly around Al particles, forming a network micro-structure; the diameters of theα-Al2O3 and ZrB2 particles are approximately 1–3μm. When the size of Al powder increases from 60–110μm to 150–300μm, the overall surface contact between Al powders and reactants decreases, thereby increasing the local volume fraction of re-inforcements from 12% to 21%. This increase of the local volume leads to a significant increase in microhardness of thein situ (α-Al2O3–ZrB2)/Al composites from Hv 163 to Hv 251.     

1∶5滚动实验台轮轨力连续测量系统

轮轨作用力是评价铁道车辆安全性的主要指标.针对1∶5小比例滚动实验台,开发了轮轨力连续测量系统.首先使用有限元分析和应变实验,得到小比例轮对的最佳测点位置.根据测点的应变输出特性,提出小比例滚动台的轮轨力连续测量方案:轮轨横向力采用轮测法测量,再结合轴测法测量轮轨垂向力.在横向力测量中,一侧车轮采用简易余弦桥,另一侧车轮采用直流桥.研制了小比例测力轮对,静态试验结果说明简易余弦桥的测试精度较高.论文最后给出了1∶5滚动实验台轮轨力的测量结果.     

XGCF62钢板辊式淬火工艺开发与应用

依托国产中厚板辊式淬火机装备技术,通过理论模拟计算和工业试验进行了高品质锅炉压力容器板XGCF62淬火工艺及品种开发.应用有限差分方法,建立了中厚板淬火过程温度场计算模型,分析了不同辊式淬火工艺参数下钢板心部温度变化趋势;通过工业对比试验,研究分析了不同淬火工艺参数对淬后钢板金相组织和力学性能的影响.应用理论计算结果,在新钢厚板厂进行6～60 mm厚XGCF62钢板大批量淬火生产,淬后钢板板形良好,性能优异.     

行星滚柱丝杠副载荷分布及刚度计算

针对以往行星滚柱丝杠副刚度计算结果精度不足的问题,依据赫兹弹性接触理论,以滚柱为研究对象,对3种变形分别进行理论分析和计算:螺纹和滚柱之间的点接触螺纹槽的赫兹接触变形;丝杠和螺母分别与滚柱接触时的轴向变形;丝杠和螺母分别与滚柱接触时螺牙的变形.在分析行星滚柱丝杠副载荷分布规律的基础上,建立新的刚度数学模型.利用Matlab软件编写计算程序,得出行星滚柱丝杠副的轴向刚度曲线,并通过与试验数据进行对比,验证了该模型的正确性.     

316L粉末热等静压致密化过程数值模拟

为研究金属粉末热等静压（HIP）的致密化行为,采用Perzyna黏塑性流变模型,用有限元软件（MSC.Marc）实现316L粉末HIP过程的数值模拟.分析了粉末体在不同时刻的流动行为,同时研究不同阶段的致密化机制、压坯最终相对密度的分布及其变形.与试验结果对比表明：压坯的相对密度分布、变形趋势与试验结果符合得较好,尺寸...     

超细亚晶粒铝合金的强化机理

在室温下对经过时效处理的2024铝合金实施了等效应变为0.5的等通道转角挤压(ECAP)变形,将形变强化、时效强化和晶界细化强化有机结合,制备出超细亚晶粒铝合金,其硬度、屈服强度、伸长率分别约达100 HV,130 MPa和31%.分析探讨了超细亚晶粒2024铝合金的强化机理.研究结果表明,屈服强度的实测数值和理论计算...