Mechanical Properties Of Porous Titanium Research Articles

Dynamic deformation behavior and mechanical properties of porous titanium: Coupling effect of high temperature and high strain rate

Porous titanium exhibits excellent mechanical properties and clarifying its dynamic deformation behavior with the rate-temperature effect can offer the significant insights for the structural design of materials. This article delves into the coupling effect of rate and temperature, as well as the local deformation mechanisms of porous titanium subjected to high-temperature and high-strain-rate conditions (−823 K and −8000/s, respectively). A dynamic balance formula for rate-temperature competition has been introduced for application in high-temperature and high-strain-rate conditions. The local relative deformation observed at the end face exceeds 300% than other regions, while the degree of end surface densification reaches 61.5%.

The Effect of Space Holder Size on the Mechanical Properties of Porous Titanium.

The Effect of Space Holder Size on the Mechanical Properties of Porous Titanium.

Advanced composite material: effect of composite SiC on compressive strength and hardness of porous titanium

Porous titanium is an excellent bone-implant biomaterial. This article uses SiC as a reinforcing agent to compound into porous titanium materials to improve the mechanical properties of porous titanium as medical materials. Porous titanium with different SiC(0–7.5wt.%) content was prepared by the conventional powder metallurgy method. Results revealed that SiC significantly improves porous titanium's densification and sintering properties. Moreover, when the SiC content is 3wt.%, the compressive capacity of porous titanium reaches 191.1Mpa. Likewise, the addition of SiC significantly improves the hardness and strength.

Dual effects of acid etching on cell responses and mechanical properties of porous titanium with controllable open‐porous structure

This study was focused on dual effects of 20 wt % hydrochloric acid etching treatment on cell responses and mechanical properties of a porous titanium with controllable open-porous structure. The results show that the acid etching induced the formation of a rough surface on the porous titanium, resulting in a remarkable improvement of the MG-63 osteoblasts adhesion and proliferation on the porous titanium. The surface roughness is found to be mainly dependent on the etching time. As increasing etching time, the surface roughness exhibited a noticeable rise. After etching for 90 min, the best cell response was achieved on the rough surface with a roughness value of 3.7 mm. However, the acid etching treatment displayed a negative effect on the porous titanium strength, and the yield strength was reduced down to 106 MPa as the etching time increased to 150 min. Taking both the cell responses and strength into account, an optimal etching time was determined as 60 min by experiments.

Influence of the Compaction Pressure and Sintering Temperature on the Mechanical Properties of Porous Titanium for Biomedical Applications

In the present work, the use of porous titanium is proposed as a solution to the difference in stiffness between the implant and bone tissue, avoiding the bone resorption. Conventional powder metallurgical technique is an industrially established route for fabrication of this type of material. The results are discussed in terms of the influence of compaction pressure and sintering temperature on the porosity (volumetric fraction, size, and morphology) and the quality of the sintering necks. A very good agreement between the predicted values obtained using a simple 2D finite element model, the experimental uniaxial compression behavior, and the analytical model proposed by Nielsen, has been found for both the Young’s modulus and the yield strength. The porous samples obtained by the loose sintering technique and using temperatures between 1000 °C −1100 °C (about 40% of total porosity) are recommended for achieving a suitable biomechanical behavior for cortical bone partial replacement.

Preparation and Properties of Titanium Obtained by Spark Plasma Sintering of a Ti Powder⁻Fiber Mixture.

Porous titanium is a functional structural material with certain porosity, which is prepared from titanium powder and titanium fiber. In order to study the porosity, phase structure, microstructure, sintering mechanism and mechanical properties of porous titanium obtained by spark plasma sintering of a Ti powder–fiber mixture at different sintering temperatures, a spherical titanium powder (D50 of 160 μm) was prepared via plasma rotating electrode processing, and titanium fiber (average wire diameter of fiber of 110 μm) was prepared by drawing, and they were mixed as raw materials according to different mass ratios. Porous titanium with a fiber–powder composite porous structure was prepared by spark plasma sintering at sintering temperatures of 800 °C, 900 °C and 1000 °C under a sintering pressure of 20 MPa. The results showed that there were no new phases occurring in porous titanium with porosity of 1.24–24.6% after sintering. Titanium fiber and titanium powder were sintered using powder/powder, powder/fiber and fiber/fiber regimes to form composite pore structures. The mass transfer mechanism of the sintered neck was a diffusion-dominated material migration mechanism during sintering. At higher sintering temperatures, the grain size was larger, and the fiber (800 °C; 10–20 μm) was finer than the powder (800 °C; 10–92 μm). The stress–strain curve of porous titanium showed no obvious yield point, and the compressive strength was higher at higher sintering temperatures. The results of this paper can provide data reference for the preparation of porous titanium obtained by spark plasma sintering of a Ti powder–fiber mixture.

Microstructure and Mechanical Properties of Porous Titanium Based on Controlling Young's Modulus

The Young's modulus of implant plays an important role in reducing stress shielding. A new method called titanium mesh stacked-forced-sintering (TMSS) was applied to porous titanium, which could easily control Young's modulus and balance the mechanical properties by different porosities, pore sizes and pore distribution. The results indicate that porous titanium has different structures in different directions. It has regular macro-pores in the cross section and irregular micro-pores in the longitudinal section. The stress-strain curve of porous titanium shows smooth and stable increase at plastic deformation along the axis direction. The Young's modulus obviously decreases, when increasing the porosity, decreasing nominal pore size, or changing pore distribution from regular to staggered at the same porosity. So the Young's modulus of porous titanium can be adjusted by these architecture factors to match the different bone tissues, and the appropriate pore sizes have the potential to induce bone tissue ingrowth. The match of mechanical properties and appropriate structures can effectively promote the fixation between the implant and the bone tissue in a long term.

Application of porous titanium in prosthesis production using a moldless process: Evaluation of physical and mechanical properties with various particle sizes, shapes, and mixing ratios

The prosthetic applications of titanium have been challenging because titanium does not possess suitable properties for the conventional casting method using the lost wax technique. We have developed a production method for biomedical application of porous titanium using a moldless process. This study aimed to evaluate the physical and mechanical properties of porous titanium using various particle sizes, shapes, and mixing ratio of titanium powder to wax binder for use in prosthesis production. CP Ti powders with different particle sizes, shapes, and mixing ratios were divided into five groups. A 90:10wt% mixture of titanium powder and wax binder was prepared manually at 70°C. After debinding at 380°C, the specimen was sintered in Ar at 1100°C without a mold for 1h. The linear shrinkage ratio of sintered specimens ranged from 2.5% to 14.2%. The linear shrinkage ratio increased with decreasing particle size. While the linear shrinkage ratio of Groups 3, 4, and 5 were approximately 2%, Group 1 showed the highest shrinkage of all. The bending strength ranged from 106 to 428MPa under the influence of porosity. Groups 1 and 2 presented low porosity followed by higher strength. The shear bond strength ranged from 32 to 100MPa. The shear bond strength was also particle-size dependent. The decrease in the porosity increased the linear shrinkage ratio and bending strength. Shrinkage and mechanical strength required for prostheses were dependent on the particle size and shape of titanium powders. These findings suggested that this production method can be applied to the prosthetic framework by selecting the material design.

Mechanical properties and pore structure deformation behaviour of biomedical porous titanium

Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were studied. Porous titanium with porosities varying from 36%–66% and average pore size of 230 μm was fabricated by powder sintering. Microstructural features were characterized using scanning electron microscopy. Uniaxial compression tests were used to probe the mechanical response in terms of elastic modulus and compressive strength. The mechanical properties of porous titanium were found to be close to the those of human bone, with stiffness values ranging from 1.86 to 14.7 GPa and compressive strength values of 85.16–461.94 MPa. The relationships between mechanical properties and relative densities were established, and the increase in relative density showed significant effects on mechanical properties and deformations of porous titanium. In a lower relative density, the microscopic deformation mechanism of porous titanium was yielding, bending and buckling of cell walls, while the deformation of yielding and bending of cell walls was observed in the porous titanium with higher relative density.

Mechanical properties of porous titanium with different distributions of pore size

To satisfy the mechanical and biological requirement of porous bone substitutes, porous Ti with two different pore sizes designed in advance was fabricated by the space-holder sintering process. Mechanical properties of the porous Ti were explored via room temperature compressive~tests. The pore sizes and shapes are uniform throughout the specimens with porosities ranging from 36% to 63%. The compression strength and the elastic modulus are in the range from 94.05 to 468.57 MPa and 2.662 to 18 GPa, respectively. It is worth noting that the relationship between the compressive strength and the porosities is completely linear relation beyond the effect of pore size distributions on the mechanical properties. The value of the constant C achieved from the Gibson-Ashby model suggests that the pore sizes affect the yield strength of the porous Ti and the values of density exponent (n) for porous Ti with two different pore sizes are higher than 2, which suggests that the deformation mode of the porous Ti with a porosity ranging from 36% to 63% is mainly buckling of the cell struts.

Microarc oxidized TiO2 based ceramic coatings combined with cefazolin sodium/chitosan composited drug film on porous titanium for biomedical applications

Porous titanium was prepared by pressureless sintering of titanium beads with diameters of 100, 200, 400 and 600μm. The results indicated that the mechanical properties of porous titanium changed significantly with different bead diameters. Plastic deformations such as necking phenomenon and dimple structure were observed on the fracture surface of porous titanium sintered by beads with diameter of 100μm. However, it was difficult to find this phenomenon on the porous titanium with a titanium bead diameter of 600μm. The microarc oxidized coatings were deposited on its surface to improve the bioactivity of porous titanium. Furthermore, the cefazolin sodium/chitosan composited films were fabricated on the microarc oxidized coatings for overcoming the inflammation due to implantation, showing good slow-release ability by addition of chitosan. And the release kinetic process of cefazolin sodium in composited films could be possibly fitted by a polynomial model.

Formability and mechanical properties of porous titanium produced by a moldless process

Tailor-made porous titanium implants show great promise in both orthopedic and dental applications. However, traditional powder metallurgical processes require a high-cost mold, making them economically unviable for producing unique devices. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering. The formability of the mixture, the dimensional changes after sintering, and the physical and mechanical properties of the sintered porous titanium were evaluated. A 90:10 wt % mixture of Ti powder and wax binder was created manually at 70°C. After debindering, the specimen was sintered in Ar at 1100°C without any mold for 1, 5, and 10 h. The shrinkage, porosity, absorption ratio, bending and compressive strength, and elastic modulus were measured. The bending strength (135-356 MPa), compression strength (178-1226 MPa), and elastic modulus (24-54 GPa) increased with sintering time; the shrinkage also increased, whereas the porosity (from 37.1 to 29.7%) and absorption ratio decreased. The high formability of the binder/metal powder mixture presents a clear advantage for fabricating tailor-made bone and hard tissue substitution units. Moreover, the sintered compacts showed high strength and an elastic modulus comparable to that of cortical bone.

Mechanical properties of open-cell metallic biomaterials manufactured using additive manufacturing

An important practical problem in application of open-cell porous biomaterials is the prediction of the mechanical properties of the material given its micro-architecture and the properties of its matrix material. Although analytical methods can be used for this purpose, these models are often based on several simplifying assumptions with respect to the complex architecture and cannot provide accurate prediction results. The aim of the current study is to present finite element (FE) models that can predict the mechanical properties of porous titanium produced using selective laser melting or selective electron beam melting. The irregularities caused by the manufacturing process including structural variations of the architecture are implemented in the FE models using statistical models. The predictions of FE models are compared with those of analytical models and are tested against experimental data. It is shown that, as opposed to analytical models, the predictions of FE models are in agreement with experimental observations. It is concluded that manufacturing irregularities significantly affect the mechanical properties of porous biomaterials.

Effect of sintering neck on compressive mechanical properties of porous titanium

In order to study the role of sintering neck in porous titanium with helical pores, the effect of size and position of sintering neck on compressive mechanical properties of porous titanium single cell was studied by using numerical simulation method. The results show that the compressive mechanical properties of the porous titanium unit cell are determined by the helical pore structure and sintering neck. Contribution coefficient of sintering neck is approximately 3.5 times larger than that of helical pore structure. With the increase of the relative diameter of sintering neck, compressive yield stress and elastic modulus of the cell are constantly increased. The sintering point of C1 is the most important sintering position. Under the same condition, increasing the size of sintering neck at C1 is much effective to the increasing of compressive properties.

A Study on Pore Structure and Mechanical Properties of Porous Titanium Fabricated by Three-dimensional Layer Manufacturing Process

A Study on Pore Structure and Mechanical Properties of Porous Titanium Fabricated by Three-dimensional Layer Manufacturing Process

Investigation of spacer size effect on architecture and mechanical properties of porous titanium

Abstract Titanium and its alloy foams have been receiving a growing interest for biomedical industry due to their biocompatibility and high potential in dental, spinal, joint and hip implant applications. Near net shape production and reproducibility of a product require a full understanding of the processing parameters’ effect on manufacturing and final properties. The shape complexity of titanium surgical implants, for example dental implants, necessitates a good control in compaction and sintering of metal skeletons containing macropores for near-net shape manufacturing. In this study, effects of processing parameters such as spacer powder size and amount on compaction, sintering and final structural properties were investigated. Commercially pure cellular titanium with porosities ranging between 35 and 75% and pore sizes between 100 μm and a few millimeters were produced via powder metallurgy with spacers. Architectural parameters of the foams, before and after sintering, were quantitatively characterized via X-ray computed microtomography. Addition of fine spacer powders enhanced compaction and densification of the foam structure. Pore walls were observed to get thicker during sintering. The use of coarser space holders resulted in thicker pore walls and a wider pore wall thickness distribution. The results indicated that strength and stiffness tend to increase with increasing pore size. Among the structural features that spacer size altered, pore wall thickness and pore face roughness were found to be the most dominant effects on strength and stiffness.

A numerical investigation of porous titanium as orthopedic implant material

Porous titanium is being developed as an alternative orthopedic implant material to alleviate the inherent problems of bulk metallic implants by reducing the stiffness to be comparable to bone stiffness and allowing complete bone ingrowth. However, a porous microstructure is susceptible to local permanent plastic strain and residual stress under cyclic loading which reduces damage tolerance and therefore limits their application as orthopedic implants. The mechanical properties of porous titanium are governed by the microstructural configurations such as pore morphology, porosity, and bone ingrowth. To understand the influence of these features on performance, the macroscopic and microscopic responses of porous Ti are studied using three-dimensional finite element models. The models are generated based on simulated microstructures of experimental materials at porosities of 15%, 32% and 50%. The results show the effect of porosity and bone ingrowth on Young’s modulus, yield stress, and microscopic stress and strain distribution. Importantly, simulations predict that the bone ingrowth reduces the stress and strain localization under cyclic loading so significantly that it counteracts the concentration condition caused by the increased porosity of the structure.

The Effect of Pressure and Pore-Forming Agent on the Mechanical Properties of Porous Titanium

Porous titanium compacts were fabricated by powder metallurgy using cold isostatic press with and without pore forming agents. Their microstructure and mechanical properties were investigated in this study. These alloy powders were sintered under 1300°C in vacuum of 10-3 Pa for 2h, followed by furnace cooling. Young’s modulus of sintered Ti could equal that of human’s dense bones. It was found that the strength of porous Ti enhanced by increasing the pressure or decreasing the amounts of pore forming agents. We prepared a porous pure Ti with 30wt.% NH4HCO3 as pore forming agents whose modulus was near to the human cortical bone, as compared in the range from 10 to 30GPa of Young’s modulus for human bone.

Caracterización mecánica de aleaciones porosas, base Ti, producidas mediante la técnica de sinterización con espaciador

The search of suitable materials for use as an implant involves more research of biomaterials, like titanium and its alloys. Regarding their mechanical properties, it must be guaranteed mechanical strength to support loads in use, as well as its stiffness must be similar to the bone. In this paper it have been measured several mechanical properties of porous titanium and Ti6Al4V alloy, produced by sintering powder metallurgy with space-holder method . The results show the relationship between porosity and mechanical properties and it is indicated in which cases it is presented a compromise between the stiffness and mechanical strength.

Porous titanium implants fabricated by metal injection molding

Sodium chloride (NaCl) was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM) method. The microstructure and mechanical properties of porous titanium were analyzed by mercury porosimeter, scanning electron microscope(SEM) and compression tester. The results show that the content of NaCl influences the porosity of porous titanium significantly. Porous titanium powders with porosity in the range of 42.4%–71.6% and pore size up to 300 μm were fabricated. The mechanical test shows that with increasing NaCl content, the compressive strength decreases from 316.6 to 17.5 MPa and the elastic modulus decreases from 3.03 to 0.28 GPa.