Papers by Author: Y. Shen

Abstract: In this paper, the coating was prepared by the slurry pack cementation on the surface of Fe-14Mn-6Si-5Ni alloy at 900°C for 10 h. A slurry pack cementation mixture was composed of Cr₂O₃ used as chrominizing source, pure Al powder as reducer, an activator of NH₄Cl and albumen (egg white) as cohesive agent. The microstructure, wear resistance and corrosion resistance of coating has been studied. The results showed that the microstructure of the coating is composed of solid solution with Al and Cr; the microhardness of coating with a value of 460 HV was 1.4 time than that of the matrix alloy, friction coefficient of the coating was 0.35, 1/2 of that of matrix alloy, and the rate of corrosion of coating was lower one order of magnitude than that of the FeMnSi based alloy.

Abstract: The electro-caloric energy conversions in single-crystal and polycrystalline barium titanate samples are investigated using differential scanning calorimetry (DSC). The DSC measurement reveals a refrigeration effect of 0.1 J/g under an electric field of 15 kV/cm at T=17.5 °C, which is related with the ferroelectric-to-ferroelectric transition in barium titanate. The thermodynamics calculation based on Maxwell’s relations leads to similar conclusion. Such EC effect shows relaxation with the heat release process more significant than the heat adsorption process when the applied field is changed, which is different with those occur near the ferroelectric-to-paraelectric transition temperatures. Furthermore, the electro-caloric energy conversion relation or the scaling relation between the maximum refrigeration effect ΔH and the applied field E, is found to follow a power law ΔH_max~E^b with b=1.72, which is significantly larger than those for EC effects related with the ferroelectric-to-paraelectric transitions.