Two kinds of aqueous precursor solutions are used to synthesize Mn–Zn ferrite powders: (i) nitrate (NO) precursor—derived from solutions of Mn(NO3)2, Zn(NO3)2, and Fe(NO3)3; and (ii) acetate (AC) precursor—derived from solutions of Mn(CH3COO)2, Zn(CH3COO)2, and Fe(NO3)3. The composition of the powders synthesized from the precursor AC is very uniform, whereas powders derived from the precursor NO have Mn and Zn segregated on the particle surfaces. In addition, the powders synthesized from precursor AC are solid spherical particles with fine porosity, whereas many hollow and fragmented particles are observed in the powder derived from precursor NO. Overall, the properties of Mn–Zn ferrite cores prepared from the precursor AC are superior to those prepared from the precursor NO. The reasons for the differences are explained and described in detail. The AC precursor powders synthesized by spray pyrolysis produced Mn–Zn ferrite cores with good magnetic properties.

Laser surface cladding was carried out on a Mg-Al-Zn system ZM5 magnesium alloy with a mixture of Al and nano-Al2O3powders. The microstructure, chemical composition analyses of the cladding coating were studied by scanning electron microscopy(SEM), energy dispersive X-ray analysis(EDAX).Both the coating and substrate were identied by microhardness tester. The laser cladding showed very good bonding with the magnesium alloy substrate. The Al2O3particles partially or completely melted during laser irradiation and re-solidified with irregular shapes in the size range of 5–60 µm along with a few islands as large as 500 µm, within the grain-refined Mg-rich dendritic matrix. The improvement in microhardness after cladding was attributed to the presence of ultra-hard Al2O3particles, increased solid solubility of Al and a very fine dendritic microstructure as a result of rapid solidification induced by laser cladding process. And corrosion resistance of the cladded coating was enhanced compared to that of the as-cast substrate after immersion tests.

An attempt has been made to fabricate Ni-base alloy layer on the surface of TC2 titanium alloy substrate by laser repair cladding technology for repairing the worn surface of TC2 alloy after in service. Laser cladding is carried out by melting the preplaced Ni-base alloy powder using a continuous wave CO2 laser and using Ar as shielding gas. Microstructure and chemical composition of the cladding coating was revealed by optical microscope (OM), scanning electron microscope (SEM), together with the energy dispersive X-ray spectroscope (EDS). A clad layer with low dilution and metallurgically bonding coating to the substrate could be obtained. A significant improvement in microhardness is achieved in the cladding layer and at the interfacial region. The results showed that laser repair cladding is highly promising technology to restore damaged Ti alloy parts.

Laser cladding has been taken into consideration for repairing K418 Ni-based superalloy material with CoCrNiW powder.Composition of cladding materials was revealed by energy dispersive X-ray spectrum(EDS). The characteristic microstructure of the cladding layer and interface were investigated by using an optical microscope and scanning electron microscope(SEM).Cladding coatings were obtained for different process parameters, and a detailed study of the effects of these parameters has been carried out by SEM. Metallurgical bonding between the cladding layer and substrate materials was obtained.Effect of heat input on cladding cracking susceptibility has been studied to obtain optimum condition for crack-free welds. Variations in cracking susceptibility as a function of heat input is discussed with reference to metallurgical characteristics of the clads. The corresponding microstructure induced by different heat input was discussed in this paper too.

Nonlinear simulation of efficiency is given to the large -orbit nonwiggler free electron lasers,where the relativistic electron beam is guided by an axial magnetostatic field under the absence of wiggler.The influences of the initial parameters are discussed. It is found that 19% may be achieved for the efficiency of TE2,2,22 mode at the wavelength of 2 mm under the guide of several thousands gauss.