Preparation of Machinable Y-TZP/LaPO_4 Composite Ceramics by Liquid Precursor Infiltration

A machinable Y TZP/LaPO 4 composite ceramic was prepared by infiltrating LaPO 4 liquid precursor into Y TZP porous ceramic. Sintered Y TZP ceramic preformed with 35% (volume fraction) open pore volume was made by adding graphite (30%, volume fraction). The Y TZP/LaPO 4 composite ceramics containing different LaPO 4 contents were obtained by infiltration and pyrolysis cycles. The machinability and mechanical properties of materials were investigated. The results show that the machinable Y TZP/LaPO 4 composite ceramics containing 2 3% to 7.5% (volume fraction) LaPO 4 has good machinability as well as outstanding mechanical properties.

SiCp/Al Composites Fabricated by Modified Squeeze Casting Technique

A cost effective method was introduced to fabricate pure aluminum matrix composites reinforced with 20% volume fraction of 3.5 μm SiC particles by squeeze casting followed by hot extrusion. In order to lower volume fraction of the composites, a mixed preform containing pure aluminum powder and the SiC particles was used. The suitable processing parameters for the infiltration of pure aluminum melt into the mixed preform are： melt temperature 800℃, preform temperature 500℃, infiltration pressure 5 MPa, and solidification pressure 50 MPa. Microstructure and properties of the composites in both as-cast and hot extruded states were investigated. The results indicate that hot extrusion can obviously improve the mechanical properties of the composite.

Capillary infiltration of liquid silicon in carbon nanotubes:A molecular dynamics simulation

In this work,by simplifying the nanopores of porous C/C preform with single-walled carbon nanotubes(SWCNT)or double-walled carbon nanotubes(DWCNTs),the infiltration of liquid Si in the SWCNTs and DWCNTs was studied by molecular dynamics(MD)simulations.As a result,a quantitative relationship between tube diameter and liquid Si infiltration rate was established,which has been successfully ap-plied to reproduce the available experiment result.The obtained relationship indicates that the capillary infiltration of liquid Si at the nanoscale still conforms to the classic Lucas-Washburn law,however,the liquid Si infiltration quickly stops in small tubes with a diameter of less than 3 nm due to an obvious contraction of the tube wall.This work may provide theoretical guidance for pore structure optimization of porous C/C preform to fabricate high-density C/SiC composites.

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.