Ming Lv

Effect of Ca/P Molar Ratio and Heat Treatment on Thermal Decomposition and Reconstitution of Hydroxyapatite

Stability of hydroxyapatite(HA) structure is influenced by preparation conditions and afterwards heat treatment. In this paper, the powders with different Ca/P molar ratio were calcined to investigate the influence of Ca/P and heat treatment on thermal decomposition and reconstitution of HA. The results show that the Ca/P has little change even calcined at a high temperature of 1500°C. The Ca/P molar ratio close to 1.67 is beneficial to form high purity HA. HA gradually releases its OH- ions in the temperature range of 800-1200°C. The decomposition takes place at about 1200°C and will become more and more severe with the increase of temperature. Cooling with slow rate and post-heat treatment in wet atmosphere are beneficial to both the rehydration and the recovery of HA from the decomposition products (TTCP and α-TCP).

Experimental and Numerical Investigation on the Residual Strength of Laminates with Central and Edge Notch

Abstract: In this paper, experimental and finite element methods are integrated to carry out the research about residual strength of composite laminate structure with central and edge notch. First, the specimens with central and edge notch and the fixtures used in compression tests were designed and manufactured, and the tensile and compression residual strengths with different notch size were measured. Then, finite element analysis model of specimens with central and edge notch were established to predict the residual strength based on the average stress criterion and Hoffman criterion, the effect of the notch size on the residual strength is evaluated, the results were compared and found that the average stress model has higher prediction accuracy and notch size has a significant influence on the residual strength of composite laminate structure with central and edge notch.

Hydrothermal synthesis, sintering behavior and oxide ionic conductivity of Na-doped lanthanum silicate

Lanthanum silicates are promising candidates for SOFC electrolytes for their high oxide ionic conductivity at moderate temperatures. One of the main limitations of lanthanum silicate materials resides in the difficulty in preparing dense ceramics. In this work, a hydrothermal method has been developed for the synthesis of Na-doped lanthanum silicates, with a chemical formula of NaLa9(SiO4)6O2. Experimental results show that the synthesis is strongly dependent on the experimental parameters, including temperature, reaction time and pH value. Under the optimal synthesizing conditions, high-crystalline NaLa9(SiO4)6O2 nanoparticles with 74.7xa0nm in diameter and narrow size distribution can be obtained. The obtained fine powders show good sintering activity and can be pressureless sintered to 94.8xa0% of theoretical density at 1500xa0°C. Furthermore, the sintered bodies of NaLa9(SiO4)6O2 show ionic conductivity of 1.01xa0mS/cm at 700xa0°C, with an activation energy of 0.84xa0eV.Graphical Abstract