Zeng Dechang

Study on Simulation and Experiment of the Magnetizer in Magnetic Flux Leakage Testing

As a type of research tool, the finite element method (FEM) has been widely used in engineering designs and other fields. In this paper, the magnetic circuit character of the magnetizer was studied using the finite element method and related experiments. For a type of permanent magnet multiloop magnetizer, the magnetic field distribution of the inner and 2 mm above the surface of the ferromagnetic bar was analysed with two important sizes varying. In the experiments, the high sensitive giant magnetic resistive sensor was employed. Changing the two parameters, the length index related with magnetization effect of the magnetizer was measured. The experimental results are qualitatively in agreement with the simulation. It is considered that this method will help in the parameter optimization of the device.

A Comparative Study of Spray-dried and Mechanically-mixed ZrB2-MoSi2 Composite Coatings Fabricated by Low Pressure Plasma Spray

Abstract The agglomerated ZrB 2 -MoSi 2 composite powder was prepared by spray drying and sintering. The spray-dried ZrB 2 -30wt%MoSi 2 (SZM) composite coating was manufactured by low pressure plasma spray (LPPS) using the agglomerated powder. For comparison, the mechanically-mixed ZrB 2 -30wt%MoSi 2 (MZM) composite coating was also prepared by LPPS. The composite powders and the coatings were characterized by X-ray diffraction and scanning electron microscopy. The flowability and the loose density of the agglomerated powders were measured by Hall flow meter and loose density instrument, respectively. Microhardness, porosity and oxidation behavior of the coatings were also investigated. The results show that when the spray-dried powder is sintered at 1200 °C for 1 h, its flowability and loose density are up to 25.8 s/50 g and 1.12 g/cm 3 , respectively. The distribution of MoSi 2 phase in SZM coating is much more uniform than that in MZM coating. Additionally, the SZM coating exhibits a high compactness and much better oxidation-resistance at 1500 °C compared to the MZM coating.