67 research outputs found
Lightweight vitreous carbon material: approaches to making open-pore cellular structure
Cellular vitreous carbons with the open-pore structure are attractive materials in some aerospace applications, such as the super-lightweight structural materials or sandwich core materials in the thermal protection systems. Cellular vitreous carbon (or VC foam) with the open-pore structure can be synthesized by pyrolysis of cellular precursor structures made from some types of resins, such as epoxy or phenolic resins. Several approaches elaborated at RPMI, Belarus can be applied to create the precursor resin foams. The replication approach ensures perfect open-pore structure with the porosity of >90% and high hydraulic permeability. The sacrificial template approach ensures lower porosity and hydraulic permeability, and higher specific strength. In the approach with the deformable space-holder granules in the sacrificial template, the foam porosity can be controlled in a wider range. The paper compares different methods of making the precursor resin foams and properties of VC structures synthesized by pyrolysis of these precursor foams
Nickel foams with oxidation-resistant coatings formed by combustion synthesis
A combustible mixture containing aluminum, titania and boron oxide powders was deposited onto the open-cell nickel foam structural elements. Heating the sample ensured formation of a protective coating based on titanium boride and alumina over the nickel foam struts via the combustion synthesis reaction. Oxidation rate of the resultant composite foam was remarkably lower compared to the bare nickel foam, the stressβstrain behavior changed and was dependent on the coating thickness, and the original open-cell structure was retained
Porous titanium manufactured by a novel powder tapping method using spherical salt bead space holders: characterisation and mechanical properties
Porous Ti with open porosity in the range of 70β80% has been made using Ti powder and a particulate leaching technique using porous, spherical, NaCl beads. By incorporating the Ti powder into a pre-existing network of salt beads, by tapping followed by compaction, salt dissolution and βsinteringβ, porous structures with uniform density, pore and strut sizes and a predictable level of connectivity have been produced, showing a significant improvement on the structures made by conventional powder mixing processes. Parts made using beads with sizes in the range of 0.5-1.0 mm show excellent promise as porous metals for medical devices, showing structures and porosities similar to those of commercial porous metals used in this sector, with inter-pore connections that are similar to trabecular bone. The elastic modulus (0.86GPa) is lower than those for commercial porous metals and more closely matches that of trabecular bone and good compressive yield strength is retained (21MPa). The ability to further tailor the structure, in terms of the density and the size of the pores and interconnections has also been demonstrated by immersion of the porous components in acid
ΠΡΠΎΡΠ½ΠΎΡΡΠ½ΡΠ΅ ΠΈ Π³ΠΈΠ΄ΡΠ°Π²Π»ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ²ΠΎΠΉΡΡΠ²Π° ΠΎΡΠΊΡΡΡΠΎΡΡΠ΅ΠΈΡΡΠΎΠ³ΠΎ ΠΏΠ΅Π½ΠΎΡΡΠ΅ΠΊΠ»ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄Π°, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ°Π·Π½ΡΠΌΠΈ ΠΌΠ΅ΡΠΎΠ΄Π°ΠΌΠΈ
The paper reports on comparative studies of mechanical strength and hydraulic permeability of open-cell vitreous carbon foams manufactured by different methods. Vitreous carbon foam were manufactured either by infiltration of the epoxy precursor resin into a layer of pore-forming removable granules or by replication of a structure of polyurethane foam template with the phenolic precursor resin followed by pyrolysis of the precursor resins in neutral gaseous environment. It was stated that the vitreous carbon foams manufactured by the replication method had higher hydraulic permeability compared to the vitreous carbon foams manufactured by infiltration, but had poorer mechanical strength at similar cell diameter and within similar relative densities range. Recommendations for the use of the studied foams in various areas have been proposed.ΠΡΠΎΠ²Π΅Π΄Π΅Π½Ρ ΡΡΠ°Π²Π½ΠΈΡΠ΅Π»ΡΠ½ΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΡΠ½ΠΎΡΡΠΈ ΠΈ Π³ΠΈΠ΄ΡΠ°Π²Π»ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠ½ΠΈΡΠ°Π΅ΠΌΠΎΡΡΠΈ ΠΎΡΠΊΡΡΡΠΎΡΡΠ΅ΠΈΡΡΠΎΠ³ΠΎ ΠΏΠ΅Π½ΠΎΡΡΠ΅ΠΊΠ»ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄Π°, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΠΎΠ³ΠΎ ΡΠ°Π·Π½ΡΠΌΠΈ ΠΌΠ΅ΡΠΎΠ΄Π°ΠΌΠΈ. ΠΠ΅Π½ΠΎΡΡΠ΅ΠΊΠ»ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄ ΠΏΠΎΠ»ΡΡΠ°Π»ΠΈ ΠΈΠ½ΡΠΈΠ»ΡΡΡΠ°ΡΠΈΠ΅ΠΉ ΠΏΠΎΠ»ΠΈΠΌΠ΅Ρ-ΠΏΡΠ΅ΠΊΡΡΡΠΎΡΠ° Π² ΡΠ»ΠΎΠΉ ΠΏΠΎΡΠΎΠΎΠ±ΡΠ°Π·ΡΡΡΠΈΡ
ΡΠ΄Π°Π»ΡΠ΅ΠΌΡΡ
Π³ΡΠ°Π½ΡΠ» ΠΈ Π΄ΡΠ±Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΡΡΡΠΊΡΡΡΡ Π²ΡΡΠΎΠΊΠΎΠΏΠΎΡΠΈΡΡΠΎΠ³ΠΎ ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΊΠ°ΡΠΊΠ°ΡΠ° ΠΏΠΎΠ»ΠΈΠΌΠ΅Ρ-ΠΏΡΠ΅ΠΊΡΡΡΠΎΡΠΎΠΌ Ρ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠΈΠΌ ΠΏΠΈΡΠΎΠ»ΠΈΠ·ΠΎΠΌ ΠΏΡΠ΅ΠΊΡΡΡΠΎΡΠ° Π² Π½Π΅ΠΉΡΡΠ°Π»ΡΠ½ΠΎΠΉ Π³Π°Π·ΠΎΠ²ΠΎΠΉ ΡΡΠ΅Π΄Π΅. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΎ, ΡΡΠΎ ΠΏΡΠΈ Π±Π»ΠΈΠ·ΠΊΠΎΠΌ Π΄ΠΈΠ°ΠΌΠ΅ΡΡΠ΅ ΡΡΠ΅Π΅ΠΊ ΠΈ Π² Π±Π»ΠΈΠ·ΠΊΠΎΠΌ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½Π΅ ΠΎΡΠ½ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΠ΅ΠΉ ΠΏΠ΅Π½ΠΎΡΡΠ΅ΠΊΠ»ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠΉ Π΄ΡΠ±Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΠΎΠ»ΠΈΠΌΠ΅ΡΠ½ΠΎΠ³ΠΎ ΠΊΠ°ΡΠΊΠ°ΡΠ°, ΠΏΡΠ΅Π²ΠΎΡΡ
ΠΎΠ΄ΠΈΡ ΠΏΠΎ Π³ΠΈΠ΄ΡΠ°Π²Π»ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΠ½ΠΈΡΠ°Π΅ΠΌΠΎΡΡΠΈ ΠΏΠ΅Π½ΠΎΡΡΠ΅ΠΊΠ»ΠΎΡΠ³Π»Π΅ΡΠΎΠ΄, ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΠΉ ΠΈΠ½ΡΠΈΠ»ΡΡΡΠ°ΡΠΈΠ΅ΠΉ, Π½ΠΎ ΡΡΡΡΠΏΠ°Π΅Ρ Π΅ΠΌΡ ΠΏΠΎ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΡΠΎΡΠ½ΠΎΡΡΠΈ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Ρ ΡΠ΅ΠΊΠΎΠΌΠ΅Π½Π΄Π°ΡΠΈΠΈ ΠΏΠΎ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Π½ΡΡ
ΠΏΠ΅Π½ΠΎΠΌΠ°ΡΠ΅ΡΠΈΠ°Π»ΠΎΠ² Π² ΡΠ°Π·Π»ΠΈΡΠ½ΡΡ
ΠΎΠ±Π»Π°ΡΡΡΡ
Open Celled Porous Titanium
Among the porous metals, those made of titanium attract particular attention due to the interesting properties of this element. This review examines the state of research understanding and technological development of these materials, in terms of processing capability, resultant structure and properties, and the most advanced applications under development. The impact of the rise of additive manufacturing techniques on these materials is discussed, along with the likely future directions required for these materials to find practical applications on a large scale
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