微镁处理对铸态低碳钢中夹杂物和组织的影响

在实验室条件下,对低碳钢进行微镁处理,以SEM-EDS和金相显微镜为表征手段,通过与空白样的对比,研究钢中夹杂物、组织的演变过程。结果表明:微镁处理使得夹杂物从Al_2O_3转变为Mg-Al-O复合夹杂物,并且其尺寸明显细化,密度显著增加。组织分析表明:Mg-Al复合夹杂物能够诱导晶内针状铁素体形核,并且在这些夹杂物附近的铁基体中存在贫锰区。理论分析认为这促进了晶内针状铁素体的形核,结晶核心起源于复合夹杂物中镁铝尖晶石的镁空位。     

高频MnZn功率铁氧体研究进展

Mn Zn铁氧体因具有高磁导率、高饱和磁通密度、低损耗而成为高频磁性元件的首选材料,其高频损耗的降低对开关电源的小型化和高效化有重要影响。介绍了高频Mn Zn铁氧体材料的损耗构成和控制机理,总结了国内外高频Mn Zn铁氧体材料研究和开发的发展现状,并对高频Mn Zn铁氧体材料的发展前景进行了展望。     

Optimum design of electromagnetic shielding rooms with minimum usage of absorbing materials

In this article, a novel method has been proposed to optimize the electromagnetic shielding rooms. This method is based on using minimum electromagnetic absorbing materials on the inner surface of the rooms. The positions of the absorbing materials are found optimally to produce a “best” performance for the shielding rooms. The ray‐tracing method is used to predict the shielding effectiveness (SE) of the electromagnetic shielding rooms with apertures. The performance of the proposed method is verified by a comprehensive example. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010.     

NOx adsorption behavior of LaFeO3 and LaMnO3+δ and its influence on potentiometric sensor response

NO_x adsorption behavior on LaFeO₃ (LFO) and LaMnO_3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO₂ was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NO_x species than LMO and was shown to be more active for NO_x surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO₂ decomposition mechanism to NO and O₂ for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NO_x sensing mechanisms were considered and predicted based on the types and quantities of surface species formed.     

基于初始磁导率的铁氧体裂纹检测

铁氧体是电子电路中广泛使用的抗干扰元件,生产中应力引发的内部缺陷裂纹严重影响其电气性能。其传统检测方法准确率低、速度慢,难以满足产品的快速检测需求。将基于初始磁导率的缺陷检测方法运用于铁氧体工件的检测,对检测传感器进行优化,使之能够在微小激励下获得准确的输出响应。对改进前后的传感器进行了对比实验,分别就其结构、尺寸、磁导率等参数进行了针对性分析,证明了该检测方法和参数优化的有效性。     

工业赤磷除铁工艺研究

采用双级逆流串联反应流程,对工业赤磷除铁工艺进行研究,讨论了影响除铁效果的主要因素,选最佳除工艺条件为：反应温度８８－９０℃,单级反应时间４．５－５．５ｈ,助剂Ｍ与工业赤磷的比例１：１２０,在此条件下,铁的去除率达到９８％以上,赤磷中含铁量降至０．００８％以下。     

An ultrahigh strength steel produced through deformation-induced ferrite transformation and Q&P process

In this work,DIFT technology and Q&P process were combined in order to introduce ultrafine-grained ferrite into the matrix of martensite and retained austenite to develop a new kind of advanced high strength steel,and two kinds of steels were investigated by this novel combined process.The newly designed process resulted in a sophisticated microstructure of a large amount of ferrite(about 5 m in diameter),martensite and a considerable amount of retained austenite for TRIP 780 steel.The ultimate tensile strength can reach about 1200 MPa with elongation above 16% for TRIP 780,that is much higher than the one solely treated by Q&P process.Tensile tests showed that both steels with the novel combined process achieved a good combination of strength and ductility,indicating that the new process is promising for the new generation of advanced high strength steels.     

Effect of Nb on the transformation kinetics of low carbon （manganese） steel during deformation of undercooled austenite

The hot compression tests using Gleeble 1500 were performed by varying the true strain up to 1.6 （80% reduction） in Nbfree and Nb-microalloyed steels. The effect of Nb addition on the transformation kinetics during deformation of undercooled austenite was investigated. It was found that as compared with Nb-free steel, the transformation incubation period of Nb-bearing steel was prolonged and the transformation kinetics curves parallelly moved to higher strain because of the solute Nb drag effect. Studies on kinetics also showed that the deformation-enhanced ferrite transformation （DEFT） of the two steels were composed of three stages, which can be expressed by the J-M-A equations individually. However, the parameter n related to the mode of nucleation and growth is somewhat different in the first and second stages of the two steels, and the same in the third stage for both the steels corresponding to the nucleation Of retained austenite.     

GIS中的快速暂态过电压的抑制机理

介绍GIS内隔离开关操作产生的快速暂态过电压（VFTO），利用微积分系统对VFTO进行测量，并分析其结果。研究了用铁氧体磁环抑制VFTO的可能性，并阐述其机制。     

超级铁精矿提纯与锶铁氧体预烧料试验研究

对武钢金山店的磁铁精矿进行提纯，得到了超纯磁铁精矿（TFe〉71．5％，SiO2〈0．5％）。以该超纯磁铁精矿与分析纯碳酸锶及添加剂为原料，通过对配比、预烧温度、保温时间等条件进行优化得到了性能较好的锶铁氧体预烧料。