Qiu Guibao

Preparation and Compressive Properties of Magnesium Foam

Abstract As a new structural and functional material, metal foam has been proven to obtain excellent properties when compared with dense ones. In the present paper, the powder metallurgy with a space holder technique was used to prepare magnesium foam. The porosity of the foam ranges from 38.90% to 57.50%, when the elastic modulus decreases from 8.50 GPa to 3.30 GPa, and the initial yield stress decreases from 24.90 MPa to 9.40 MPa. The magnesium foam has lower yield stress and longer stress platform, so it can be used as good cushioning energy absorbing materials.

Structures and Properties of TiMn2-5x(V4Fe)x(x=0.30, 0.35) Hydrogen Storage Alloys

Abstract Structures and electrochemical properties of TiMn2-5x(V4Fe)x(x=0.30,0.35) alloys were investigated. The results of XRD analysis show that the alloys are mainly composed of body centered cubic (bcc) phase, whose lattice parameters are enhanced with the increase of V and Fe content. The SEM images of the alloys show that there are some colonies in the matrix phase. The proportion of colony to the matrix decreases with increasing of V and Fe content. The electrochemical measurements show that TiMn0.25(V4Fe)0.35 alloy has unfavorable activation performance until temperature reaches 327 K, while TiMn0.50(V4Fe)0.30 alloy shows better activation performance, but passivation phenomenon was found in the process of charging at low temperature, which can be eliminated by heating to high temperature. The PCT curves of alloys show that the TiMn0.50(V4Fe)0..30 alloy has a good comprehensive performance, with a favorable plateau pressure at room temperature and wide plateau. The enthalpy and entropy in hydrogen desorption of TiMn0.50(V4Fe)0..30 alloy were also calculated and they are −36.1 kJ/mol, −126.9 J/(mol·K), respectively.

Preparation of Titanium Foams with Uniform and Fine Pore Characteristics Through Powder Metallurgy Route Using Urea Particles as Space Holder

Titanium powder particles were used as the matrix and powdery urea particles as the space holder to fabricate porous titanium by powder metallurgy technology. And titanium foams with porosity of 42.7–56.2% were prepared successfully. The uniform distribution of the tiny urea particles in the matrix made the titanium foams have homogeneous and connected pore structure. Pore morphology and compressive behavior of the resulting foam have been studied. The pore structure is composed of large pores and small pores distributed on the hole wall, and these small pores are mostly interconnected. Porous regions contained some micro-pores increasing the connectivity of pores. The mechanical behavior was investigated by compressive test, the foams delineated a relatively stable plateau region and the yield strength and Young’s modulus vary in the range of 93.85–276.52 Mpa and 1.53–3.21 GPa respectively. The results manifested that the processed foams is an ideal medical implant, impact energy absorbing and filterability material.

Titanium Foam for Cancellous Bone Implant Prepared by Space Holder Technique

Open-cell titanium(Ti) foams with 75.5% porosity were manufactured by powder metallurgy route using acicular carbamide particles as space holder. The TG and DSC curves of carbamide were measured to optimize the heat treatment during carbamide removal. X-ray diffraction studies of carbamide before and after removed to ensure that the foams produced featured no contamination. The compressive strength and Young’s modulus of Ti foams were 11.1 MPa and 0.32 GPa, respectively. This kind of open-cell the foam is expected to be a potential substitute biomaterial for cancellous bone, due to its mechanical properties well match that of cancellous bone.

An Empirical Equation to Predict the Porosity of Titanium Foams

Structural control is an interesting but less studied subject in titanium foam production using space holder technique. In this paper, an empirical equation was reported to predict the porosity of pure titanium foams. The empirical equation is P = 0.9S C + 0.011, where P and Sc represent porosity and spacer content, respectively. Results indicate that porosity is always lower than spacer content by approximately 10%. The porosities obtained from this method are also always lower than 90%.

Effects of Rare Earth Er2O3 on Microstructure and Mechanical Properties of Titanium Foams by Powder Metallurgy

Titanium foams containing different content of rare earth Er2O3 were prepared by conventional powder metallurgy using carbamide particles as a space holder. The porosity of titanium foams was measured by Archimedes’ method, simultaneously microstructure was observed by SEM and the mechanical properties were investigated by compressive tests. The effects of Er2O3 on microstructure and mechanical properties of titanium foams were investigated. The results indicated that, when the doping content of rare earth is less than 0.75wt..%, the mechanical properties increase with increasing doping content. However, the mechanical properties slightly reduce with the doping content further increased. In addition, it was found that there is no correlation between the titanium framework density and rare earth Er2O3 in terms of quantitative analysis.