The study on novel physical properties of structural ceramics or ceramic composites could make them more conducive to be function‐ and structure‐integrated materials. Herein, titanium nitride‐alumina (TiN–Al2O3) duplex ceramics were prepared and the dielectric spectra of the ceramics were studied from 10 MHz to 1 GHz. Negative permittivity appeared when TiN content exceeded 40 wt% due to the induced plasmonic state of massive delocalized electrons in connected TiN grain networks. Meanwhile, alternating current conduction behaviors of the duplex ceramics were discussed with percolation theory. Furthermore, the analysis of reactance by equivalent circuit models indicated that negative permittivity ceramics exhibited inductive character. This work realized negative dielectric behaviors in TiN–Al2O3 duplex ceramics and would promote the study of electromagnetic functionalization in wave shielding or attenuation for structural ceramics.

The applications of magnesium (Mg) alloys as biodegradable orthopedic implants are mainly restricted due to their rapid degradation rate in the physiological environment. In this study, Si–CaP micro-arc oxidation (MAO) coatings were prepared on a Mg–Zn–Ca alloy by a second-step MAO process at different voltages in order to decrease the degradation rate and increase the bioactivity of the alloy. The microstructure and morphology of the samples were characterized using XRD, FT-IR SEM and EDS. The degradation behaviours of samples were evaluated using electrochemical techniques, and immersion tests in simulated body fluid (SBF). The results indicate that the morphology of the Si–CaP coatings changed significantly with the increase in Ca/P ratio as the second-step voltage increased. The Si–CaP containing coating produced at 450 V could significantly decrease the degradation rate of Mg and caused a slow increase in pH of the SBF solution. The haemolysis test concluded that the coating C3 did not cause a haemolytic reaction. The corrosion resistance of Mg alloy was greatly improved with the Si–CaP coatings, and the Mg alloy with Si–CaP coating prepared at 450 V had the best corrosion resistance, which indicates that the Si–CaP coatings are promising for improving the biodegradation properties of Mg-based orthopedic implants. Haemolysis tests indicated that the Si–CaP coating prepared at 450 V conforms to the given standard (YY/T0127.1-93).