Novel Processing of Porous Titanium Composite for Producing Open Cell Structure

2007 ◽  
Vol 539-543 ◽  
pp. 1004-1009 ◽  
Author(s):  
Makoto Kobashi ◽  
Naoyuki Kanetake
Keyword(s):  
Latent Heat ◽  
Volume Fraction ◽  
Cell Structure ◽  
Processing Condition ◽  
Physical And Mechanical Properties ◽  
Titanium Boride ◽  
Porous Titanium ◽  
High Porosity ◽  
Reaction Products ◽  
Open Cell

Processing technique to produce open-cell porous titanium composite was developed. One of the outstanding benefits of porous titanium composite is both physical and mechanical properties can be controlled widely by changing the metal/ceramic fraction and cell structures. In this work, porous titanium composite was fabricated by a chemical reaction between titanium powder and boron carbide (B4C) powder. The reactions between titanium and B4C generates a large amount of latent heat and, therefore, it was a combustion and self-propagating mode. Precursors were made by compacting the starting powder blend (Ti and B4C), and heated in an induction furnace to induce the reaction. The reaction was strongly exothermic and, therefore, the precursor was sintered by its latent heat when the Ti/B4C blending ratio was appropriate. The reaction products were titanium boride (TiB and/or TiB2) and titanium carbide (TiC). By controlling the Ti/B4C blending ratio, it was possible to control the volume fraction of reaction products in titanium matrix. The combustion synthesized titanium composite was porous and its cell structure was strongly affected by the processing condition of the precursor (porosity and Ti/B4C blending ratio). High porosity with open pores was obtained with small Ti/B4C ratios and high porosity of the precursor, while the cell structure was closed and spherical with high Ti/B4C ratio. The cell-wall size was varied from several tens of microns to about 500 microns by changing the combustion temperature.

Morphological Control of Porous Structure in Al-Ti Intermetallics Foam Manufactured by Reactive Precursor Process

2014 ◽  
Vol 794-796 ◽  
pp. 790-795
Author(s):  
Makoto Kobashi ◽  
Naoyuki Kanetake
Keyword(s):  
Melting Point ◽  
Porous Structure ◽  
Cell Structure ◽  
Exothermic Reaction ◽  
Combustion Reaction ◽  
Maximum Temperature ◽  
Reaction Products ◽  
Open Cell ◽  
Morphological Control ◽  
Novel Processing

In this paper, a novel processing method (reactive precursor method) to manufacture high-melting point porous Al-Ti intermetallics is investigated. Especially, morphological control of porous structure is focused. In the reactive precursor process, precursors are made by blending aluminum and titanium powders. The precursor is heated to ignite an exothermic reaction (so called “combustion reaction”) between the elemental powders. Pore formation is a well-known intrinsic feature of the combustion reaction, and we tried to control the pore morphology. Fundamentally, the closed-cell structure can be obtained when the maximum temperature during the reaction exceeds the melting point of the reaction product. By blending the exothermic agent powder in the precursor, the maximum temperature is increased and the reaction products are melted. The porosity is controlled by the maximum temperature. In contrast, an open-cell porous structure can be obtained when the maximum temperature is below the melting point of the reaction product. Microwave heating turned out to be an effective method to create an open cell structure. A powdery substance that does not react with other elemental powders (heat-absorbing agent powder) decreases the temperature during the reaction. Closed, open and bimodal-sized open pores have been achieved by the reactive precursor process so far.

Pore Scale Investigation of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Scale Model ◽  
Small Scale ◽  
High Porosity ◽  
Pore Scale ◽  
Open Cell

In this paper, a numerical model employing an approximately realistic three-dimensional (3D) foam structure represented by Weaire–Phelan foam cell is developed to study the steady-state heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. The conduction problem is considered in a cubic representative computation unit of the composite material with a constant temperature difference between one opposite sides of the cubic unit (the other outer surfaces of the cubic unit are thermally insulated). The effective thermal conductivities (ETCs) of metal foam/paraffin composites are calculated with the developed pore-scale model considering small-scale details of heat conduction, which avoids using adjustable free parameters that are usually adopted in the previous analytical models. Then, the reason why the foam pore size has no evident effect on ETC as reported in the previous macroscopic experimental studies is explored at pore scale. Finally, the effect of air cavities existing within solid paraffin in foam pore region on conduction capacity of metal foam/paraffin composite is investigated. It is found that our ETC data agree well with the reported experimental results, and thus by direct numerical simulation (DNS), the ETC data of different metal foam/paraffin composites are provided for engineering applications. The essential reason why pore size has no evident effect on ETC is due to the negligible interstitial heat transfer between metal foam and paraffin under the present thermal boundary conditions usually used to determine the ETC. It also shows that overlarge volume fraction of air cavity significantly weakens the conduction capacity of paraffin, which however can be overcome by the adoption of high conductive metal foam due to enhancement of conduction.

Preparation and Characterization of Macroporous Pumice-Porcelain Composite Foams

2008 ◽  
Vol 368-372 ◽  
pp. 1513-1515
Author(s):  
Zhen Jiang Wu ◽  
Yun Fa Chen ◽  
Yeon Tae Yu
Keyword(s):  
Raw Materials ◽  
Cell Structure ◽  
Volume Density ◽  
Ceramic Foam ◽  
High Porosity ◽  
Sem Images ◽  
Open Cell ◽  
Ceramic Foams ◽  
Porcelain Stone ◽  
Composite Foams

The open-cell macroporous ceramic foams can be used to air and water decontamination after loading catalyst. A new kind of ceramic foam was prepared using pumice, porcelain stone, quartz as main raw materials and polyurethane sponge as template. During the process, the polyurethane sponges were immersed in the powder slurry while submerged to fill all the pores, which makes it uniformly coating the sponge. Then the samples were dried at 80°C, and then sintered at 1050°C -1200°C for 2h in air. The ceramic foams present high porosity from 75% to 90%, higher compassion strength from 10 MPa to 50MPa and lower volume density from 0.15g/cm3 to 0.32g/cm3. The SEM images revealed the open-cell structure in the product.

scholarly journals Post-Processing of Cold Sprayed Ti-6Al-4V Coatings by Mechanical Peening

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1038
Author(s):  
Niroj Maharjan ◽  
Ayan Bhowmik ◽  
Chunwai Kum ◽  
Jiakun Hu ◽  
Yongjing Yang ◽  
...  
Keyword(s):  
Surface Integrity ◽  
Volume Fraction ◽  
Aerospace Industry ◽  
Metal Alloys ◽  
High Porosity ◽  
Post Processing ◽  
Premature Failure ◽  
Additive Manufacturing Technology ◽  
Hammer Peening ◽  
Compressive Residual Stresses

Cold spray is an emerging additive manufacturing technology used in the aerospace industry to repair damaged components made of expensive metal alloys. The cold sprayed layer is prone to surface integrity issues such as high porosity and inadequate bonding at the substrate-coating interface, which may cause premature failure of the repaired component. This study explored the use of mechanical peening as a post-processing method to improve the surface integrity of the cold sprayed component by modifying mechanical properties near the surface. Two mechanical peening processes, deep cold rolling (DCR) and controlled hammer peening (CHP), were utilized to improve cold sprayed Ti-6Al-4V coating on the Ti-6Al-4V substrate. Experimental results indicate that DCR and CHP increase the strength of the bond between the coating and substrate due to introduction of compressive residual stresses. In addition, porosity is also reduced by as much as 71%. The improvement is attributed to both the compacting effect of peening processes and the increment in the volume fraction of deformed regions.

Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Thermoplastic and Thermosetting Nanocomposites: A Review

2008 ◽  
Vol 16 (8) ◽  
pp. 483-500 ◽  
Author(s):  
Jianqing Zhao ◽  
Yi Fu ◽  
Shumei Liu
Keyword(s):  
Processing Condition ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
Physical And Mechanical Properties ◽  
Molecular Geometry ◽  
Surface Hydrophobicity ◽  
Dielectric Constants ◽  
Great Promise ◽  
Wide Range ◽  
Oligomeric Silsesquioxane ◽  
Mechanical Strengths

Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have been successfully incorporated into thermoplastic and thermoset polymers via copolymerization, grafting, blending, surface bonding, or other transformations. A great promise in the development of a wide range of POSS-containing nanocomposites with diversely improved properties has been displayed. Thermal properties, viscoelastic properties, mechanical strengths, dielectric constants, surface hydrophobicity and flame-retardancy of the nanocomposites are easily varied to target properties by adjusting POSS structure, crosslink density, processing condition, etc. Investigations on the effects of POSS molecular geometry, composition, and concentration on physical and mechanical properties of resultant POSS-modified thermoplastic and thermosetting nanocomposites have been carefully reviewed in this article.

Effect of Processing Parameters on Properties of Wheat-Straw Boards with FRW

2011 ◽  
Vol 250-253 ◽  
pp. 947-950
Author(s):  
Xiao Dong Zhu ◽  
Feng Hu Wang ◽  
Yu Liu
Keyword(s):  
Wheat Straw ◽  
Processing Condition ◽  
Fire Retardant ◽  
Physical And Mechanical Properties ◽  
Processing Parameters ◽  
Resin Content ◽  
National Standard ◽  
Appearance Time ◽  
Uf Resin ◽  
Peak Value

This paper explored the effect of MDI, UF and FRW content on the mechanical and fire retardant property of straw based panels with surface alkali liquor processing. In order to manufacture the straw based panel with high quality, low toxic and fire retardant, the interface of wheat-straw was treated with alkaline liquid under the optimal treating condition: alkaline liquid concentration was 0.4-0.8%, alkaline dosage was 1:2.5-1:4.5, alkaline-treated time was 12h-48h.The physical and mechanical properties of wheat-straw boards after treated could satisfy the China national standard. And the variance analysis of the fire retardant property of straw based panel showed that TTI, pkHRR and peak value appearance time were not affected by the MDI, UF and FRW content significantly. The results of orthogonal test showed that the optimized processing condition was MDI content as 4%, UF resin content as 7% and the FRW content as 10%.

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