Thermal properties of pressureless melt infiltrated AlN-Si-Al composites

Thermal properties of AlN-Si-Al composites produced by pressureless melt infiltration of Al/Al alloys into porous a-Si3N4 preforms were investigated in a temperature range of 50-300 °C. SEM and TEM investigations revealed that the grain size of AlN particles was less than 1 μm. In spite of sub-micron grain size, composites showed relatively high thermal conductivity （TC）, 55-107 W/（m·K）. The thermal expansion coefficient （CTE） of the composite produced with commercial Al source, which has the highest TC of 107 W/（m·K）, was 6.5×10-6 K-1. Despite the high CTE of Al （23.6×10-6 K-1）, composites revealed significantly low CTE through the formation of Si and AlN phases during the infiltration process.

Interpenetrated Magnesium-Tricalcium Phosphate Composite:Manufacture,Characterization and In Vitro Degradation Test

Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium- tricalcium phosphate （Mg-TCP） composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration （CAMI） technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 μm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg-TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test.

Recent progress in porous Mg-based foam preparation approaches:effect of processing parameters on structure and mechanical property

Porous metals are a class of cellular materials with lightweight and unique mechanical,electrical,thermal,physical and acoustic characteristics.Magnesium and magnesium alloy foams have exhibited excellent advantages.In particular,open-cell Mg-based foams(porous Mg/Mg alloy foams)have been used for bioresorbable implants,CO_(2)trapping systems,filters,heat exchangers,absorbent panels and many other applications.While significant progress has been taken in producing porous Mg-based foams with good structure-property relations,but with a large number of different processing parameters,different mechanical properties and pore morphologies of each porous Mg-based foam,it is essential to understand the individual effects of each aspect of the parameters.Therefore,the present article summarized the effects of available processing parameters on the structure and mechanical properties of the porous Mg-based foams.Finally,the future perspectives to enhance the structure and properties of porous Mg/Mg alloy foams were discussed.