镍基高温合金真空感应熔炼脱氮的研究

研究了采用CaO坩埚真空感应熔炼镍基高温合金过程中的脱氮行为.试验表明在精炼过程中加Al对脱氮有促进作用;加Ti则对脱氮有明显不利影响;提高熔炼时的真空度是促进脱氮的有力措施.     

渣浆泵用WC/铁基表面复合材料的研究

针对承受严重冲蚀磨损的渣浆泵过流件，采用型负压铸渗工艺制备了WC／铸铁基表面复合材料，分析了复合层的微观组织，检测了复合材料的冲蚀磨损性能，并用于渣浆泵过流件受磨损面的局部复合，结果表明，WC／灰铸铁基表面复合材料具有良好的微观组织结构和优异的抗冲蚀磨损性能，抗冲蚀磨损性是Cr15Mo3高铬铸铁的2．7倍，砂芯负压铸渗工艺可进行大面积异型曲面的复合。     

Structure and properties of cathodic vacuum arc deposited NbN and NbN-based multi-component and multi-layer coatings

Binary Nb-N coatings, ternary Ti-Nb-N and Zr-Nb-N, and multi-layer TiN/NbN coatings consisting of up to 100 alternating TiN and NbN layers, were deposited onto WC-Co substrates, using two different vacuum arc deposition (VAD) systems: with and without magnetic guiding of the metal plasma flow. Binary Nb-N coatings were fabricated by deposition of metal plasma produced by a Nb cathode in a background of reactive nitrogen gas at different pressures, P. Ternary coatings were fabricated at co-deposition of plasmas originating from two different cathode materials. Multilayer coatings were fabricated by alternatively depositing plasmas of Ti and Nb in reactive nitrogen gas. The crystalline coating structure, phase composition, hardness and critical load for coating failure were studied.For binary Nb-N coatings fabricated using both deposition systems, the phase composition, the Vickers hardness, HV, and the critical load strongly depended on the deposition pressure. Using VAD with magnetic plasma guiding, the highest HV of ∼ 42 GPa was measured for coatings deposited at low nitrogen pressure. These coatings contained a hexagonal β-Nb₂N phase and had a relatively low critical load. The highest critical load and HV ∼ 38 GPa were obtained for coatings consisted of a single phase NaCl-type cubic δ-NbN structure, deposited at a higher nitrogen pressure. The structure and properties of Nb-N coatings deposited using VAD without magnetic plasma guiding had a similar correlation with the deposition pressure, however, their hardness values were lower.Ternary Ti-Nb-N and Zr-Nb-N coatings fabricated by both deposition processes had a single phase cubic NaCl-type structure and the hardness higher than that of the binary nitrides TiN, ZrN and NbN. The hardest coatings, HV ∼ 51.5 Pa, deposited with magnetic plasma guiding had a single-phase cubic δ-(Ti,Nb)N structure and a Ti:Nb ratio of ∼ 50:50 (at.%).Multilayer coatings TiN/NbN consisting of 20-40 alternating TiN and NbN layers with total thickness of 4-5 μm increased the life time of cemented carbide cutting inserts at turning tough Ni-base alloys by 2-7 times relative to uncoated cutting tools, while conventional vacuum arc deposited TiN coatings were not effective in machining of these alloys.     

低密度超细银包铝复合软导线的制备工艺研究

采用磁控溅射真空镀膜技术制备银包铝复合线坯,通过后续不退火多道次拉拔,制备低密度的超细银包铝复合软导线。结果表明,磁控溅射处理时,银镀层厚度随走线速度加快而变薄,随溅射电流增加而增厚;拉拔加工要求银镀膜层厚度大于1.3μm,道次变形量宜小于7%;随银镀层厚度增加,制备的10μm超细丝的密度和抗拉强度均增大。将φ15μm的纯铝芯材采用优选条件溅射镀银膜,经拉拔加工制得φ10μm的银包铝复合软导线,其密度为4.87 g/cm~3,抗拉强度286 MPa,复层表面均匀致密无缺陷。     

真空离子液-气相渗硼的研究

介绍了用自制的无毒无腐蚀的有机渗硼剂——硼酸三甲酯对排气阀热嵌模进行真空离子液-气相渗硼，经检测，整个化合物层和扩散层中含有B和Fe2B，并呈高度弥散分布状态，起到了抗重载热冲击、抗热磨损、抗反复低周循环热疲劳的良好作用，能大大提高热镦模的使用寿命。     

Influence of Annealing on Photocatalytic Performance and Adhesion of Vacuum Cold-Sprayed Nanostructured TiO2 Coating

Composite powder was prepared using primary nanoTiO₂ powder and polyethylene glycol (PEG). The nanoTiO₂ coating was deposited through vacuum cold spray using both the composite powder and the primary nanopowder. The influence of annealing on the coating adhesion and photocatalytic activity was investigated. The coating adhesion was evaluated through erosion test by water jet. The photocatalytic performance of the coatings was evaluated through photodegradation of phenol in water. Results showed that annealing of the coating at a temperature from 450 to 500 °C yielded both higher activity and better adhesion. The adhesion of the coating deposited using the composite powder was better than that using the primary nanoTiO₂ powder. It was found that the TiO₂ coating, resulting from the composite powder, presented much higher activity than that deposited with the primary nanopowder. The better activity is attributed to the existence of large pores resulting from the stacking of composite powder, which benefits the reactants’ transportation through the porous coating. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

基于PCS7流化床干燥器建模与控制策略的设计

对流化床干燥器工艺过程中给料单元、换热单元、空气输送单元和物料输出单元进行了建模与控制策略的设计。设计的目的是在保证过程控制系统单元稳定的情况下,优化出口物料的湿度以更优的效果达到工艺的要求。控制方案利用了先进PID控制与模型预测控制（MPC）的协同控制。利用西门子SIMATIC PCS7过程控制系统进行了仿真研究。结果表明控制效果良好,系统稳定,被干燥的湿物料能够快速达到稳定的状态。     

汽轮机组真空度过低原因探析与解决措施

重点讨论了凝汽系统和真空系统两方面的内容,说明了可能导致汽轮机真空度降低的原因,并给出了有针对性的解决措施,很好地解决了这个问题。     

土体加固对筒型基础承载特性的影响研究

为正确评估软体地基加固对提高筒型基础承载力的影响,建立考虑土体渗流~应力耦合效应的三维数值模型,模拟了筒顶负压抽水的土体加固过程,分析了筒内土体加固对筒型基础承载特性的影响。研究结果表明:在负压加固作用2.5 d后,筒顶沉降趋于平缓,孔隙负压扩散范围广,筒内土孔隙比下降幅度大,加固效果较好。此时,筒土之间接触更为紧密,极端荷载下筒顶脱开率大幅下降。在单一加载情况下,土体加固提高竖向设计承载力42.6%,水平设计承载力129.2%,抗弯设计承载力69.6%,竖向极限承载力4.4%,水平极限承载力61.3%,以及抗弯极限承载力99.1%。在复合加载情况下,土体加固前后V~M、V~H、V~H~M包络线存在一定的差异,未加固土体筒基的包络曲线分布在加固后的筒基外侧。通过试验数据对计算模型进行验证,吻合良好。这意味着现有的筒型基础设计仍有较大的优化空间。     

基于增益调整型模糊PID的脉动真空灭菌器控制系统

针对目前脉动真空灭菌器控制效果不好而产生湿包的问题,结合Chien-Hrones-Reswicks整定算法,提出用模糊变增益PID的控制策略,控制器输入取控制舱内温度的偏差e和偏差变化率△e;根据实际操作经验,加入模糊规则,输出取PID控制器2个参数的调整值,从而实现PID参数的在线自整定;在MATLAB/SIMULINK环境下进行了仿真实验,进行了传统PID控制与模糊变增益PID控制动态性能的仿真比较,结果表明采用模糊变增益PID控制策略可明显提高脉动真空灭菌控制系统的动态性能.