汽轮机末级叶片激光熔覆的研究

以Nb、Ti、Si合金粉末(at%61:21:18)为原料,在汽轮机末级叶片材料Ti-6Al-4V(TC4)合金表面进行激光熔覆,应用OM、XRD、SEM、EDS和EMPA等方法分析了涂层的显微组织,测试了涂层的显微硬度。结果表明:激光熔覆涂层的组织是在共晶连续固溶体(Nb,Ti)ss弥散分布着Nb3Si和Ti5Si3颗粒,涂层的显微硬度在HV960-1000之间,比基体合金提高了近3倍。     

基于激光熔覆的船用柴油机结构件修复技术研究

对激光熔覆技术进行了总体介绍;就该技术应用于船用柴油机结构件修复的可行性及技术难点进行了分析。通过激光熔覆技术在船用柴油机气缸及曲轴磨损修复中的实际应用,展示了该技术的绿色再制造特质及广阔的应用前景。     

汽轮机末级叶片激光熔覆镍基合金研究

利用激光熔覆技术在汽轮机末级叶片材料Ti-6Al-4V(TC4)上制备出原位自生TiC陶瓷颗粒增强Ni基复合材料涂层。应用OM、XRD、EDS和SEM方法分析了涂层的组织结构,测试了涂层的显微硬度。结果表明:涂层中存在γ-Ni、β-Ti固溶体及TiC为主的陶瓷相,涂层与基体冶金结合良好,且无气孔和裂纹缺陷,涂层显微硬度值较基体提高了近3倍。     

基于激光熔覆的机体修复前后再加工工艺

基于某大功率高速柴油机机体主轴承孔激光熔覆修复前后再加工工艺展开技术研究。在工艺试验基础上探究激光熔覆对机体已加工部位热影响规律,制定修复后再加工工艺方案,并指出该方案存在的技术问题及解决途径。     

叶片激光三维熔覆与钎焊合金片工艺质量的比较研究

为克服钎焊合金片与基体结合不牢固的缺点,采用半导体激光器在汽轮机叶片进汽边熔覆专用钴基合金.对比了激光熔覆和钎焊合金片叶片的断面组织结构、显微硬度分布以及激光熔覆层和钎焊Stellite合金片与基体之间的结合强度.结果表明:激光熔覆层与基体呈冶金结合,在拉伸试验中结合区没有断开,其平均抗拉强度达699 MPa,熔覆层组织均匀无缺陷,从熔覆层到基体硬度呈阶梯式分布;而钎焊试样钎焊层有气孔,厚薄不均匀,从合金片到基体硬度差异较大,拉伸试样最小抗拉强度仅为206MPa;激光熔覆层与叶片基体的结合强度至少为钎焊Stellite合金片工艺的3倍以上.     

核阀零件激光熔履层耐磨性的研究

应用5kW横流CO2激光器在核阀阀瓣密封面上熔覆Co基自熔合金,采用预置粉末法进行多道扫描。研究了激光熔覆和等离子喷焊2种工艺形成的涂层对抗擦伤磨损性能的影响。结果表明：激光熔覆层的组织细密均匀,气孔、夹杂物少,稀释率低,其抗擦伤磨损性能明显高于等离子喷焊和堆焊工艺,随着载荷增大,这种耐损性的差距将进一步拉开。     

瓦锡兰基于机器人的激光熔覆技术可延长发动机活塞寿命

正Wartsila services下属Quanti Serv公司新推出的大缸径活塞修补翻新技术可将焊接时间压缩至最短,减少对基体材料的冷热冲击,并将代替老的镀铬技术。Quanti Serv公司主管Ole Pyndt Hansen指出:"较之常规的镀铬工艺,除了其环境效益外,新的涂料将     

20G钢管表面激光熔覆非晶合金复合涂层的耐腐蚀性能试验研究

利用激光熔覆技术在20G钢表面熔覆合金涂层,分析了激光熔覆层的微观组织,利用高温腐蚀试验和烟气模拟腐蚀试验测试激光熔覆层的耐腐蚀性能。结果表明：细小晶粒与有较高韧性的非晶相夹杂并弥散于金属间化合物的复合组织具有良好的抗高温腐蚀、抗烟气腐蚀性能,可应用于垃圾焚烧锅炉受热面,改善其表面的耐腐蚀性能。     

用熔覆工艺修复铝活塞缺陷的方法研究

本文介绍了用熔覆工艺修复铝活塞的方法,重点分析了熔覆材料,熔覆工艺参数对其效果的影响,并通过试验和实验验证了该方法的有效性和实用性。     

球墨铸铁的镍基合金激光熔敷试验

用千瓦级横流ＣＯ２激光器对球墨铸铁进行了镍基合金的激光熔敷试验，阐述了激光熔敷工艺，熔敷层组织结构及硬度特点，结果表明，球墨铸铁可以进行大面积、无裂纹的镍基合金激光熔敷。     

Solar energy availability in greenhouses as affected by condensation on cladding materials

To investigate the solar radiation transmission through cladding materials covered with condensation on their inner surface a new experimental set-up was constructed. Transmittance experiments were carried out on vertical glass plates and polyethylene films covered with condensation without and with runoff for several incidence angles in the horizontal plane using perpendicularly polarized radiation. It was observed that condensation on a glass plate slightly decreased the solar radiation transmittance when compared with the dry state. The reduction in transmittance increased from 0.8% at normal incidence to 8.5% at an incidence angle of 60°. Results for polyethylene pointed out that condensation affected the solar radiation transmission and so the available solar energy in the greenhouse much more than in a glasshouse. At normal incidence, a transmittance reduction of 20.8% with respect to the dry state was obtained. For higher incidence angles, the transmittance reduction decreased gradually to 7.2% at an incidence angle of 60°. For both glass and polyethylene, it was observed that the start of runoff gave rise to a transmittance increase of up to 2% when compared with the phase of condensation without runoff.     

等离子堆焊技术在电站阀门中的应用

在介绍等离子粉末堆焊技术的原理及特点的基础上,阐述其与其它堆焊方式对比的优越性。通过堆焊Co基合金的方式显著提高了阀门密封面耐磨损、耐腐蚀性能及高温性能,延长了使用寿命,节省贵重材料,并降低了产品成本。     

Feasibility assessment of the alumina-forming duplex stainless steels as accident tolerant fuel cladding materials for light water reactors

Previously, the Fe-based alumina-forming duplex stainless steels (ADSSs) were developed for the application of accident tolerant fuel (ATF) cladding materials for light water reactors (LWRs). The on-going research activities focusing on the feasibility assessment of ADSS alloys for ATF cladding are summarized. A long-term corrosion behavior in simulated LWR environment and short-term corrosion resistance in steam environment at temperature range of 800°C to 1200°C were performed, and the results showed excellent corrosion resistance of ADSS alloys. The tensile properties of ADSS alloys were evaluated at room temperature to 550°C, which showed much higher strength compared with other Fe-based alloys. After accelerated thermal aging at 425°C for 1000 hours, strength of ADSS alloys was increased and the elongation was decreased. However, the elongation of aged ADSS alloys was still greater than 15% because of the presence of ductile austenite phase. Meanwhile, because of the neutron absorption by Ni, Cr, and Fe, the use of ADSS alloys as ATF cladding would have detrimental effects on the fuel cycle length. Nonetheless, it was assessed that the neutronics penalty could be readily overcome by adopting thinner fuel cladding and slightly higher fuel enrichment. Finally, the fabrication of thin-walled tube was introduced. Overall, it has been shown that ADSS alloys could be considered as candidate alloys as ATF cladding materials.     

排水泵站中水泵的节能措施

水泵是排水泵站能源消耗的重要设备,通过优化选型,运用机械技术手段水泵工况点调节采取节能措施进行科学化管理,减少水泵泵内损失,提高水泵节能潜力。     

16V240ZJB型柴油机喷油泵出油阀接头断裂原因分析及改进措施

通过分析 ,指出造成喷油泵出油阀接头断裂的主要原因 ,并从加工、热处理、组装等方面提出了相应的改进措施 ,取得了明显的效果     

激光固溶17-4PH的机理与性能研究

采用扫描电子显微镜(SEM)、显微硬度仪和能量色散谱仪(EDS)分别对经激光固溶处理后的17-4PH材料强化层的显微组织、显微硬度及元素含量进行了分析.结果表明:激光固溶时效后,17-4PH材料的表层平均显微硬度比基体提高了约40%,接近420 HV0.2;表层存在高密度的位错马氏体组织,且马氏体组织中含有Cr、Ni及Cu等合金元素;激光固溶层的耐磨损性能及抗气蚀性能都有一定程度的提高.根据阿伦尼乌斯定律以及菲克第二定律分析了激光固溶的机理,证明:Cu在激光作用下可以在短时间内完全溶入奥氏体,完成固溶过程.     

Characteristics of force acting on adjustable axial flow pump blade

The internal three-dimensional turbulent flow of adjustable axial-flow pump arrangement was simulated, and the force acting on the blade surface was calculated under different operating conditions. Based on the calculated results, finite element method (FEM) was adopted to analyze stress and strain distributions of the adjustment blade in different operations. Hydraulic moment, centrifugal moment and friction moment which must be conquered by adjusting the blades were also calculated. __________ Translated from Journal of Shanghai University (Natural Science), 2007, 13(3): 314–319 [译自: 上海大学学报]     

Thermal-hydraulic analysis of UO2 and MOX fuel considering different cladding materials at various burnup levels in pressurized water reactor

Thermal analysis of fuel elements with UO₂ and mixed-oxide (MOX) fuels at different fuel burnup levels has been performed analytically and by simulation using ANSYS. Results showed that UO₂ incurred a lower fuel temperature than MOX under all conditions. Higher fuel element temperatures were obtained for higher levels of burnup for UO₂ fuel. For MOX fuel, higher temperatures were obtained for low and high burnup fuel. Radial temperature, thermal gradient, and thermal heat flux were determined across reactor pressure vessel (RPV), demonstrating the highest value at the center of the RPV. The maximum linear power density was determined for UO₂ and MOX, showing that using UO₂ fuel at 2 at% burnup rendered the highest allowable linear power density. Furthermore, the transient analysis showed that there was a small rise in fuel temperature for a decrease in mass flow rate from 100% to 60% followed by a rapid increase in temperature for further reduction in flow rate.