Mechanical Properties of Highly Porous NiTi Alloys

AbstractNear-equiatomic porous nickel-titanium shape memory alloys (NiTi SMAs) are becoming one of the most promising biomaterials in bone implants because of their unique advantages over currently used biomaterials. For example, they have good mechanical properties and lower Young�s modulus relative to dense NiTi, Ti, and Ti-based alloys. Porous NiTi SMAs are relatively easy to machine compared to porous ceramics such as hydroxyapatite and calcium phosphate that tend to exhibit brittle failure. The porous structure with interconnecting open pores can also allow tissue in-growth and favors bone osseointegration. In addition, porous NiTi alloys remain exhibiting good shape memory effect (SME) and superelasticity (SE) similar to dense NiTi alloys. To optimize porous NiTi SMAs in bone implant applications, the current research focuses on the fabrication methods and surface modification techniques in order to obtain adjustable bone-like structures with good mechanical properties, excellent superelasticity, as well as bioactive passivation on the entire exposed surface areas to block nickel ion leaching and enhance the surface biological activity. This invited paper describes progress in the fabrication of the porous materials and our recent work on surface nanorization of porous NiTi scaffolds in bone grafts applications.

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Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽

10.3390/civileng2020029 ◽

2021 ◽

Vol 2 (2) ◽

pp. 523-540

Author(s):

Imed Beghoura ◽

Joao Castro-Gomes

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Pore Size ◽

Physical And Mechanical Properties ◽

Critical Parameters ◽

Porous Structures ◽

Foaming Agent ◽

Al Powder ◽

Highly Porous ◽

Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

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Microstructural evolution, mechanical properties, and oxidation performance of highly Ni-rich NiTi alloys with added V using vacuum arc melting

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2021.160263 ◽

2021 ◽

pp. 160263

Author(s):

K.J. Yuan ◽

Y. Wang ◽

L.J. Zheng ◽

H. Zhang

Keyword(s):

Mechanical Properties ◽

Microstructural Evolution ◽

Vacuum Arc ◽

Niti Alloys ◽

Arc Melting ◽

Vacuum Arc Melting ◽

Oxidation Performance

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Mechanical Degradation of Porous NiTi Alloys Under Static and Cyclic Loading

Shape Memory and Superelasticity ◽

10.1007/s40830-017-0120-5 ◽

2017 ◽

Vol 3 (4) ◽

pp. 476-484 ◽

Cited By ~ 2

Author(s):

Seyyed Alireza Hosseini

Keyword(s):

Cyclic Loading ◽

Mechanical Degradation ◽

Niti Alloys ◽

Porous Niti ◽

Static And Cyclic Loading

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Investigation of the Microstructure and Mechanical Properties of Highly Porous Calcium Aluminates

Sintering and Related Phenomena ◽

10.1007/978-1-4615-8999-0_38 ◽

1973 ◽

pp. 439-448

Author(s):

S. F. Hulbert ◽

C. N. Wilson ◽

J. E. Lemons

Keyword(s):

Mechanical Properties ◽

Microstructure And Mechanical Properties ◽

Calcium Aluminates ◽

Highly Porous

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Mechanical properties of cellulose aerogels and cryogels

Soft Matter ◽

10.1039/c9sm01028a ◽

2019 ◽

Vol 15 (39) ◽

pp. 7901-7908 ◽

Cited By ~ 12

Author(s):

Nela Buchtová ◽

Christophe Pradille ◽

Jean-Luc Bouvard ◽

Tatiana Budtova

Keyword(s):

Mechanical Properties ◽

Compressive Modulus ◽

Cellulose Materials ◽

Highly Porous

Compressive modulus of highly porous and lightweight cellulose materials prepared via dissolution–coagulation and different drying routes.

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Expansion volume of alkali activated foamed cork composites from tungsten mining mud waste with aluminium

MATEC Web of Conferences ◽

10.1051/matecconf/201927403002 ◽

2019 ◽

Vol 274 ◽

pp. 03002

Author(s):

Imed Beghoura ◽

Joao Castro-Gomes ◽

Haroon Ihsan ◽

John Pickstone ◽

Nuno Estrada

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Physical And Mechanical Properties ◽

Mechanical And Thermal Properties ◽

Porous Structures ◽

Expansion Process ◽

Foaming Agent ◽

Al Powder ◽

Highly Porous ◽

Alkali Activated

Several mixes of alkali activated foams from tungsten mud waste (MW), grounded glass (GG) and metakaolin (MK) were developed incorporating expanded granulated cork (EGC). This study presents preliminary results of the expansion process obtained with the addition of aluminium (AL) powder as a foaming agent. 0.3 wt.%, 0.4 wt.% to 0.5wt.% of AL powder were added to the alkali activated matrix. The physical and mechanical properties of the obtained foams, the effects of the type and amount of the foaming agent added are presented and discussed. Highly porous structures were obtained, with overall expansion up to 68.2% when the AL powder was added. The size and distribution of pores are shown. The compressive strength of foams in the case of highly porous structures achieved of 1.2 MPa for the samples containing 0.5 wt.% of AL powder. Mechanical and thermal properties of the cured structure are good and can therefore be used for applications in acoustic panels and lightweight prefabricated components for thermal insulation purposes.

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Mechanical properties of highly porous PEEK bionanocomposites incorporated with carbon and hydroxyapatite nanoparticles for scaffold applications

Progress in Biomaterials ◽

10.1007/s40204-019-00123-1 ◽

2019 ◽

Vol 8 (3) ◽

pp. 211-221 ◽

Cited By ~ 3

Author(s):

Md. Nizam Uddin ◽

Puttagounder S. Dhanasekaran ◽

Ramazan Asmatulu

Keyword(s):

Mechanical Properties ◽

Bone Regeneration ◽

Pore Size ◽

Mechanical Tests ◽

Bone Diseases ◽

Filler Materials ◽

Test Results ◽

Micro Computed Tomography ◽

Carbon Particles ◽

Highly Porous

Abstract Bone regeneration is of great importance worldwide, because of various bone diseases, such as infections, tumors, and resultant fracture, birth defects, and bone loss due to trauma, explosion, or accident. Bone regeneration can be achieved by several materials and templates manufactured through various fabrication techniques. Uses of different materials and scaffold fabrication techniques have been explored over the past 20 years. In this research, polyetheretherketone (PEEK) was used to fabricate highly porous bionanocomposite foams for bone scaffolding. Melt casting and salt porogen (200–500 µm size) leaching methods were adapted to create an adequate pore size and the necessary percent of porosity, because pore size plays a vital role in cell implantation and growth. Porosity (75% and 85%) of the prepared scaffolds was adjusted by changing salt concentrations in the PEEK powder. Hydroxyapatite (HA) and carbon particles were used to improve cell attachments and interactions with the porous PEEK and to increase the mechanical properties of the scaffold materials. Carbon fiber (CF) and carbon nanotubes (CNTs) were uniformly dispersed into the PEEK powder before melt casting to enhance the mechanical properties and to observe the influence of the carbon particles on the properties of PEEK bionanocomposite foam. Compression test results of the fabricated bionanocomposites showed that HA and carbon particles are the potential filler materials for the enhancement of bionanocomposite mechanical properties. About 186% enhancement of compression modulus and 43% enhancement of yield strength were observed while incorporating only 0.5 wt% of CNTs into PEEK/HA bionanocomposites having 75% porosity, compared to PEEK/HA 20 wt% bionanocomposites. Micro-computed tomography (micro-CT) test results reveal that pore size and interconnectivity of the nanocomposite foams are in order and within the designed sizes. Mechanical tests proved that PEEK bionanocomposite foam has the potential for use in bone scaffolding and other biomedical applications.

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