Mechanical Characterization of Dense Hydroxyapatite Blocks

2006 ◽  
Vol 514-516 ◽  
pp. 1083-1086
Author(s):  
Cláudia M.S. Ranito ◽  
Fernando A. Costa Oliveira ◽  
João P. Borges

Bioactive dense HAp ceramics possess a unique set of properties, which make them suitable as bone substitute. However, both physical and mechanical properties of HAp have to be evaluated in order to produce new materials that match the bone stiffness. This paper highlights the influence of both porosity and grain size on the four-point flexural strength and the indentation fracture toughness of pure dense HAp blocks sintered at 1300°C. Both discs and rectangular bars were produced by uniaxial pressing at 40MPa and sintered in static air at temperatures between 1150 and 1325°C for 1 h in order to assess the densification behaviour of the P120S medical grade HAp powder used. After sintering, both the density and the open porosity were measured. In addition to FT-IR, XRD and SEM, the mechanical properties of the dense HAp blocks, including Young´s modulus, flexural strength, Vicker´s hardness and fracture toughness, were characterized and whenever possible these properties were compared to those reported for cortical bone. Pressureless sintering to full density at temperatures below 1300°C does not occur for the stoichiometric powder used. The results obtained underline the importance of full mechanical characterisation of dense HAp so that new implant materials can be developed. There is a need to improve the microstructure and thus enhance mechanical strength of HAp ceramics, as it was found that flexural strength is closely related to the micropores present in the sintered samples.

Author(s):  
Gyeung Ho Kim ◽  
Mehmet Sarikaya ◽  
D. L. Milius ◽  
I. A. Aksay

Cermets are designed to optimize the mechanical properties of ceramics (hard and strong component) and metals (ductile and tough component) into one system. However, the processing of such systems is a problem in obtaining fully dense composite without deleterious reaction products. In the lightweight (2.65 g/cc) B4C-Al cermet, many of the processing problems have been circumvented. It is now possible to process fully dense B4C-Al cermet with tailored microstructures and achieve unique combination of mechanical properties (fracture strength of over 600 MPa and fracture toughness of 12 MPa-m1/2). In this paper, microstructure and fractography of B4C-Al cermets, tested under dynamic and static loading conditions, are described.The cermet is prepared by infiltration of Al at 1150°C into partially sintered B4C compact under vacuum to full density. Fracture surface replicas were prepared by using cellulose acetate and thin-film carbon deposition. Samples were observed with a Philips 3000 at 100 kV.


2000 ◽  
Vol 15 (7) ◽  
pp. 1505-1513 ◽  
Author(s):  
Y-S. Chou ◽  
J. W. Stevenson ◽  
T. R. Armstrong ◽  
J. S. Hardy ◽  
K. Hasinska ◽  
...  

The room temperature mechanical properties of a mixed conducting perovskite Sm1?xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phase, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of elastic modulus, microhardness, indentation fracture toughness, and biaxial flexure strength were measured. Young's modulus of 180–193 GPa and shear modulus of 70–75 GPa were determined. The biaxial flexure strength was found to decrease with increasing Sr content from ∼70 to ∼20 MPa. The drop in strength was due to the occurrence of extensive cracking. Indentation toughness showed a similar trend to the strength in that it decreased with increasing Sr content from ∼1.1 to ∼0.7 MPa m1/2. In addition, fractography was used to characterize the fracture behavior in these materials.


2006 ◽  
Vol 326-328 ◽  
pp. 1853-1856 ◽  
Author(s):  
Sang Ll Lee ◽  
Yun Seok Shin ◽  
Jin Kyung Lee ◽  
Joon Hyun Lee ◽  
Jun Young Park

This paper dealt with the fabricating process of liquid phase sintered (LPS) SiC ceramics containing the oxide additives of Al2O3 and Y2O3, in conjunction with the evaluation of their mechanical properties. LPS-SiC ceramics was sintered at the temperature of 1820 oC under an applied pressure of 20 MPa and a pressure holding time of 2 hour. A commercial SiC powder with an average size of about 0.3 μm was used as a starting powder. LPS-SiC ceramics with additive composition ratios of 1.5 and 2.3 (Al2O3/Y2O3) represented an excellent density of about 3.2 Mg/m3. LPS-SiC ceramics had a flexural strength of about 800 MPa and a fracture toughness of about 8.0 MPa⋅m0.5 at an additive composition ratio (Al2O3/Y2O3) of 1.5.


2016 ◽  
Vol 13 (2) ◽  
pp. 74-79 ◽  
Author(s):  
A. S. Bhattacharyya ◽  
P Kumar ◽  
N Rajak ◽  
R.P Kumar ◽  
A Sharma ◽  
...  

Nanoindentation is an effective way of finding mechanical properties at nanoscale. They are especially useful for thin films where elimination of the substrate effect is required. The mechanism is based upon depth sensing indentation based on Oliver and Pharr modeling. The load-depth curves as well as time on sample were analyzed. Indentation impulse was found to have significant contribution in the nature of failure zone during indentation. Fracture toughness was also related to time on the sample.


Author(s):  
Muhammadin Hamid ◽  
Timbangen Sembiring ◽  
Kurnia Sembiring

Composite based on sugar palm stem powder has been made through conventional technique of mold and press from the sugar palm stem powder reinforced by matrix polyester resin, epoxy resin, and polyurethane resins. The composition of sugar palm stem powder were varied with 2;4;6;8 and 10% wt mass fraction also the 90;92;94;96 and 98 % wt mass fraction are enhanced by the polyester resin, epoxy resin and polyurethane resins in 300 MPa pressure treated with temperature of 120?C for polyurethane resin and temperature of 70?C for polyester resin and epoxy resin for 20 minutes. The test result of physical and mechanical properties generates 1.19 gr/cm³ of the density optimum number, 1.83% porosity, 2.83% water absorption, 80.47 kJ/m² impact strength, 80.42 MPa flexural strength, 5.95 MPa tensile strength and the result of SEM to see the surface structure of the sample which is homogenous. The study shows the mechanical properties and physical properties which meet the Standard JIS A 5905 : 2003, that is flexural strength >32 MPa and 0.3 – 1.3 gr/cm3 density.


Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1345 ◽  
Author(s):  
Özgür Sevgi Canarslan ◽  
Roberto Rosa ◽  
Levent Köroğlu ◽  
Erhan Ayas ◽  
Alpagut Kara ◽  
...  

α-β SiAlON/TiN composites with nominal composition of α:β = 25:75 were fabricated by microwave sintering. The effect of titanium nitride addition on the phases, microstructure, microwave absorption ability and mechanical properties (Vickers hardness and fracture toughness) of the SiAlON-based composites were studied. Finite Difference Time Domain (FDTD) software was used for the numerical simulation in order to assess the most suitable experimental setup. Sintering trials were performed in a single mode microwave furnace operating at 2.45 GHz and a power output of 660 W, for a reaction time of 30 min. SiC blocks were used as a susceptor to accelerate the microwave processing by hybrid heating, with reduced heat losses from the surface of the material of the α-β SiAlON/TiN composites. The optimum comprehensive mechanical properties, corresponding to a relative density of 96%, Vickers hardness of 12.98 ± 1.81 GPa and Vickers indentation fracture toughness of 5.52 ± 0.71 MPa.m1/2 were obtained at 850 °C when the content of TiN was 5 wt.%.


2017 ◽  
Vol 4 (10) ◽  
pp. 1697-1703 ◽  
Author(s):  
Shengyuan Peng ◽  
Jianhui Sun ◽  
Bo Cui ◽  
Xianfu Meng ◽  
Dandan Qin ◽  
...  

Hardness and indentation fracture toughness of La0.8Ti0.1Ga0.1Fe3CoSb12can be improved byin situformed Fe3Si, without sacrificing thermoelectric properties.


2016 ◽  
Vol 368 ◽  
pp. 158-161 ◽  
Author(s):  
Martin Fides ◽  
Alexandra Kovalčíková ◽  
Pavol Hvizdoš ◽  
Richard Sedlák ◽  
Roman Bystrický ◽  
...  

SiC based composite with 50 % of additives (Ti and NbC with ratio of 9:16) has been prepared. The microstructure, porosity, and chemical composition were studied using SEM equipped with EDS analyser. Local mechanical properties such a hardness and elastic modulus of individual components of the composite were investigated by nanoindentation using Berkovich indenter tip. Hardness and fracture toughness of studied material as a whole was evaluated by means of classic Vickers macroindentation. Indentation cracks were observed and their propagation was analyzed. It was shown that the present phases were distributed uniformly. Moreover, final density was satisfactory with porosity lower than 1 %. The individual constituents shown similar elasticity modulus (550 - 590 GPa). Hardness (HIT) exhibited very pronounced load-size effect. At 10 mN load, hardness was 42.33 GPa ± 1.1 GPa for SiC and 35.73 GPa ± 0.9 GPa for TiNbC, while at 500 mN the composite hardness was 27.61 GPa ± 0.505 GPa. It is in good agreement with macrohardness values, when 27.6 GPa and 25 GPa has been measured for 1 and 10 kg loads, respectively. Indentation fracture toughness was 3.3 MPa.m1/2 ± 0.22 MPa.m1/2. Electrical conductivity was measured by four point probes method and its value was 8.8×104 ± 0.3×104 Sm-1.


Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 750 ◽  
Author(s):  
Xinyi Chen ◽  
Xuedong Xi ◽  
Antonio Pizzi ◽  
Emmanuel Fredon ◽  
Xiaojian Zhou ◽  
...  

Ambient temperature self-blowing mimosa tannin-based non-isocyanate polyurethane (NIPU) rigid foam was produced, based on a formulation of tannin-based non-isocyanate polyurethane (NIPU) resin. A citric acid and glutaraldehyde mixture served as a blowing agent used to provide foaming energy and cross-link the tannin-derived products to synthesize the NIPU foams. Series of tannin-based NIPU foams containing a different amount of citric acid and glutaraldehyde were prepared. The reaction mechanism of tannin-based NIPU foams were investigated by Fourier Trasform InfraRed (FT-IR), Matrix Assisted Laser Desorption Ionization (MALDI-TOF) mass spectrometry, and 13C Nuclear Magnetic Resonance (13C NMR). The results indicated that urethane linkages were formed. The Tannin-based NIPU foams morphology including physical and mechanical properties were characterized by mechanical compression, by scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). All the foams prepared showed a similar open-cell morphology. Nevertheless, the number of cell-wall pores decreased with increasing additions of glutaraldehyde, while bigger foam cells were obtained with increasing additions of citric acid. The compressive mechanical properties improved with the higher level of crosslinking at the higher amount of glutaraldehyde. Moreover, the TGA results showed that the tannin-based NIPU foams prepared had similar thermal stability, although one of them (T-Fs-7) presented the highest char production and residual matter, approaching 18.7% at 790 °C.


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