基于短时间温升试验和参数估计模型预测稳定温度

电机在稳定运行状态下的绕组温度是反映电机性能的重要参数。通常,检测机构依据GB/T1032-2012中规定的方法进行温升试验,至少需要持续3小时,甚至达到6小时。短时间内求取电机稳定温度能够提升检测机构温升检测试验的效率,节约检测机构大量的电力成本和人工成本。同时,根据预测温度能够监测绕组温度,避免绕组的绝缘漆损坏而导致电机烧毁。通过研究均匀纯铜的指数发热规律、创新实时带电测量绕组温度的装置和基于线性逼近方式建立参数估计模型的方法,搭建了在短时间高精度预估电机温度的系统。在对不同功率段电机进行现场温升实验验证中,结果表明系统能够高效准确的预测电机的稳定温度。     

颗粒强化钛基复合材料的氧化特性

研究了以ＴｉＣ颗粒增强的钛基复合材料的氧化特性。指出ＴｉＣ增强的钛基复合材料在６５０℃以上高温有着其它耐热钛合金不可比拟的高温抗氧化性能；ＴｉＣ／Ｔｉ的反应界面层有利于氧原子的扩散，使复合材料在６５０℃以下的氧化初期氧化速度较快；但在６５０℃以下经长时间保温，其氧化特性和其它耐热钛合金相似。     

基于高精度Fuzzy控制算法的校直机液压伺服系统的仿真与应用研究

模糊控制器以其结构简单、鲁棒性强、不需要被控对象的数学模型及粗调快速等优点被广泛应用于工业控制系统。但是,常规模糊控制器也存在控制精度不高、"调节死区"等问题。本文通过对普通模糊控制器的改进,研究出一种高精度模糊控制策略,并将其应用于校直机液压伺服控制系统。最后对控制系统进行了仿真研究,取得了较为满意的效果。仿真结果表明,与常规的模糊控制算法相比,该控制算法具有超调小,响应快等优点。     

Evaluation of Process Capability in Gas Carburizing Process to Achieve Quality through Limit Design Concept

NUMEROUS INDUSTRIAL APPLICATIONS requirea hard wear-resistant surface called the case,and arelatively soft,tough inside called the core.There arefive principal methods of case hardening:?Carburizing?Nitriding?Cyaniding or carbonitriding?Flame hardening?Induction hardeningThe first three methods change the chemicalcomposition,carburizing by the addition of carbon,nitriding by the addition of nitrogen and cyaniding bythe addition of both carbon and nitrogen.The last twomethods do n…     

Oxidation Performance of Fe-Al/WC Composite Coatings Produced by High Velocity Arc Sprayed at 650 ℃

Fe-Al intermetallics with remarkable high-temperatureintensity and excellent erosion,high-temperatureoxidation and sulfuration resistance are potential lowcost high-temperature structural material.ProducingFe-Al/WC composite coating by high velocity arcspraying(HVAS)on structural materials would notonly obviate the problems faced in fabrication of thesealloys into useful shapes,but also allow the effectiveuse of their outstanding high-temperature performance,which might thus promisingly mak…     

Indentation method for fracture resistance determination of metal/ceramic interfaces in thick TBCs

The indentation technique has been used to measure the adhesion of plasma- sprayed ceramic coatings on metals intended for thick thermal barrier coating ( TTBC) applications. This approach provides the adhesion value as the critical strain energy release rate,Gc, of the interface, which also takes into account any residual stresses. The theoretical background of the method is outlined, and specific examples are reported with respect to the effect of substrate temperature on the metal/ceramic adhesion of thick TBCs.     

Oxidation performance of Fe-Al/WC composite coatings produced by high velocity arc sprayed at 800 ℃

Fe-Al/WC intermetallic composite coatings were prepared by high velocity arc spraying (HVAS) technology on 20G steel and the oxidation performance of Fe-Al/WC composite coatings was studied. The results demonstrate that the kinetics curve of oxidation approximately follows the logarithmic law and the oxidation velocity of Fe-Al/WC composite coatings is less than that of 20G steel after 5 h. The composition of oxidized coating is mainly composed of Al2O3, Fe2O3, Fe3O4 and FeO. These phases distribute unevenly. The protective Al2O3 film firstly forms and preserves the coatings from further oxidation.     

New developments in cold spray based on higher gas and particle temperatures

In cold spraying, bonding is associated with shear instabilities caused by high strain rate deformation during the impact. It is well known that bonding occurs when the impact velocity of an impacting particle exceeds a critical value. This critical velocity depends not only on the type of spray material, but also on the powder quality, the particle size, and the particle impact temperature. Up to now, optimization of cold spraying mainly focused on increasing the particle velocity. The new approach presented in this contribution demonstrates capabilities to reduce critical velocities by well-tuned powder sizes and particle impact temperatures. A newly designed temperature control unit was implemented to a conventional cold spray system and various spray experiments with different powder size cuts were performed to verify results from calculations. Microstructures and mechanical strength of coatings demonstrate that the coating quality can be significantly improved by using well-tuned powder sizes and higher process gas temperatures. The presented optimization strategy, using copper as an example, can be transferred to a variety of spray materials and thus, should boost the development of the cold spray technology with respect to the coating quality. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

高速电弧喷涂镍铝打底层结构与性能研究

高速电弧喷涂技术是近年来发展起来的新型热喷涂技术，该技术具有优势，高效，低成本等特点，本文实验研究了高速电弧喷涂镍铝打底涂层的组织结构和力学性能，涂层的界面结合强度大于40MPa，显微硬度平均值为210HV，表面粗糙度表征参数Ra值为13．11um，涂层孔隙率为2．26％，涂层主要由镍铝合金和镍，铝氧化物组成，高速电弧喷涂镍铝涂层结合强度高，涂层组织致密，是优良的打底涂层。     

Al2O3/Cu复合材料的内氧化制备及性能研究

采用高能球磨制备出亚稳态的Cu-1%Al（质量分数）合金粉,再将Cu2O粉与其一起进行高能球磨,然后将复合粉末压坯在N2保护炉中同时进行氧化和烧结,制备出Al2O3/Cu复合材料。分析了分别采用湿法球磨和干法球磨时的合金化效果,讨论了模压压力对材料性能的影响。结果表明,对于Cu-Al混合粉来说,采用湿法球磨容易产生分层,采用干法球磨具有良好的合金化效果;在本试验条件下,750MPa为最佳的模压压力,但烧结后材料的电导率还是偏低,因此有必要进行后续的处理来进一步提高材料的性能。