冷挤压用材20CrMnTi热处理工艺研究

本文采用淬火回火和退火两种方法,研究了冷挤压用材20CrMnTi软化处理工艺,结果表明:20CrMnTi经淬火高温回火和球化退火两种方法处理,均可获得低硬度、高塑性的球状珠光体组织.淬火回火比退火获得的硬度低,球化效果好.     

群智感知中基于层次分析法的众包机制

针对节点移动性、社会性及复杂性给众包服务带来的挑战,研究了可信协作众包机制,提出基于层次分析法的服务节点发现和选择算法,定义服务质量因子、链路可靠性因子和区域热度因子等众包决策因子,实现基于分级激励的感知任务众包分配. 仿真实验进一步验证了所提方法的正确性和有效性.     

声幅变密度非常规情况下的定性解释

主要介绍青海油田声幅变密度测井在双层套管、快速地层、受地层物性影响等非常规情况下的固井质量评价。运用定性的方法去解释声幅变密度测井在非常规情况下的固井质量,并用青海油田的实例加以说明。     

南翼山中浅层油气解释及动态资料分析

南翼山构造位于柴达木盆地西部坳陷区茫崖坳陷亚区,从2001年10月开始,南翼山油田三、四油组(850～1600m)开始试注水,油层吸水状况良好。到2005年,南翼山浅层分Ⅰ+Ⅱ和Ⅲ+Ⅳ两套层系注水开发,加大了注水力度;随着注水量的不断加大油田含水率增长很快,油田不断的生产开发也使得南翼山地区测井曲线在中浅部储层段发生一定规律的变化特征。     

底板大体积混凝土浇筑裂缝控制

温度差是引起大体积混凝土裂缝的主要原因之一。在大体积混凝土基础工程中,优化混凝土配合比设计以控制温度差为目标,采用降低水泥用量,不仅使混凝土达到强度要求,而且未产生裂缝和渗漏,达到设计要求。     

添加剂对离心自蔓延高温合成陶瓷层组织结构与性能的影响

为了改善钢管内衬陶瓷层的韧性,在铝热剂中分别添加ZrO2,Al2O3,SiO2进行改性,采用离心自蔓延高温合成工艺制备了钢管内衬陶瓷层,研究了添加剂对陶瓷层形貌、结构和性能的影响.结果表明:加入ZrO2或Al2O3可以改变陶瓷层的组织结构,使Al2O3由树枝状晶变为等轴晶;加入SiO2可在Al2O3枝晶间隙形成网状Ca...     

Characterization and wear properties of nanoscaled TiN/TaN multilayer coatings

The structural, morphological, mechanical and tribological characterization of nanoscaled multilayer TiN/TaN coatings deposited by magnetron sputtering technology were investigated by low angle X-ray diffractometry, high angle X-ray diffractometry, atomic force microscopy, microhardness, pin-on-disc testing and 3-D surface profiler. The results show that the TiN/TaN coatings exhibit good modulation period and sharp interface between TiN and TaN layers. In mutilayered TiN/TaN coatings, TiN layers have cubic structure, but hexagonal structure emerged among TaN layers besides cubic structure as modulation period is beyond 8.5 nm. The mierohardness is affected by modulation period and the maximum hardness value of 31.5 GPa appears at a modulation period of 8.5 rim. The coefficient of friction is high and the wear resistance is improved for TiN/TaN coatings compared with those of TiN coating; the wear mechanism exhibits predominantly ploughing, material transfer and localized spallation.     

Microstructures and properties of graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites

Graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites were fabricated by perform squeeze-infiltration route. The effects of the volume of graphite particles on the microstructure, mechanical properties and tr/bological behavior were investigated under the conditions of constant size of graphite particle and volume of Al2O3 short fiber. The results reveal that the uniform distribution of the reinforced graphite particles and Al2O3 short fiber can be obtained by this technique, and they have strong bonding with the metal matrix. Increasing graphite volume results in decrease in hardness, the ultimate tensile strength whereas the Al2O3 short fiber makes contribution to the increase in hardness of the composite. The composite exhibits good wear resistance, small wear mass loss and low coefficient of friction as compared with the metal matrix. The wear mechanisms transit from oxidation wear, abrasion wear into delamination wear as the applied load is increased, and a film of lubricant covering almost entire surface of specimen, is found to be formed, which separates the wear surfaces from metal to metal contact and thus improves the tribological properties.     

热挤压对搅拌铸造Al—Si—Pb轴承合金磨损行为的影响

研究了干摩擦条件下铸态与热挤压态Al-Si-Pb轴承合金的磨损行为。研究结果表明：热挤压能有效改善铸态合金的组织，提高机械性能，显著降低气孔率。这些有利因素极大地提高挤压态Al-Si-Pb合金的耐磨性。光学观察与X射线光电子能谱分析（XPS）表明：含铅量超过15％的Al-Si-Pb合金在中等载荷下表现出几乎恒定的磨损率与较好的抗咬合性，其原因是因为在磨损过程中形成一层几乎覆盖整个麻醉损面的润滑膜，该膜是由含Al,Fe,Si,O,Pb等化合物混合组成。     

经激光表面熔凝处理的Mg-11Y-2.5Zn合金的显微组织和摩擦学性能

用X-ray衍射和激光共聚焦扫描显微镜对经激光表面熔凝处理的Mg-11Y-2.5Zn合金进行显微组织和相组成分析,并测量改性层硬度变化。研究结果表明,经激光表面熔凝处理后,改性层由熔化区和热影响区组成,熔化区的显微组织明显细化,硬度有所改善。研究了经激光表面处理和铸态Mg-11Y-2.5Zn合金的摩擦学性能,滑移速率为0.785m/s,载荷范围为20～320N。两者的摩擦因子无显著差异,但经激光表面处理的Mg-11Y-2.5Zn合金表现出较低的磨损率,归结于熔凝区的组织细化和硬度增加。SEM磨损表面形貌分析表明,激光表面熔凝处理的合金与未处理合金的磨损机制基本相同,轻微磨损阶段为磨粒磨损和剥层磨损,严重磨损阶段为表面热软化和熔化磨损。