Effect of Fluoride Additives on Mechanical Properties in Hydroxyapatite/Alumina Composites

2006 ◽  
Vol 43 (1) ◽  
pp. 48-54
2008 ◽  
Vol 591-593 ◽  
pp. 436-440
Author(s):  
João Marcos K. Assis ◽  
Francisco Piorino Neto ◽  
Francisco Cristóvão Lourenço de Melo ◽  
Maria do Carmo de Andrade Nono

A comparative study between alumina added niobia ceramics and two alumina zirconia composites from nanostructured TZP (7% and 14% weight) was made. On this composites the zirconia were yttria stabilized and the alumina were submicron structured. As sintering aid a mixture of magnesia, niobia and talc were used on all samples. The sintering was performed at 1450 oC during 60 minutes. The characteristic grain size and shape of an alumina and zirconia powders, aggregates and agglomerates were characterized. The sintering ceramics were evaluated through hardness, fracture toughness and 4 point bending test. Weibull statistic was applied on the flexural results. Although the fracture toughness result from ZTA were lower, and seems to be affected by the liquid fase, the hardness and Weibull modulus were higher than alumina niobia. The grains size and the homogeneity of its distributions on the microstructure of this ceramics was correlated to these higher values. The results from these alumina zirconia composites showed a potential to apply as a ballistic armor material.


2018 ◽  
Vol 53 (13) ◽  
pp. 1815-1826
Author(s):  
Sheng Cai Tan ◽  
Jimmy KW Chan ◽  
Kian Ping Loh

This paper aims to investigate the effect of co-milling-assisted exfoliation of graphite into polyethylene and alumina matrices on the mechanical properties of the composites. Tensile mechanical properties of composite materials based on polyethylene reinforced with graphite and graphite-derived fillers at 0–0.75 wt% loading were investigated, while hardness and flexural properties of alumina composites with 0.25 wt% loading of the same additives were assessed. Exfoliated graphite, applied at 0.25–0.75 wt% in pre-exfoliated form or in a co-milling-assisted fashion, has been demonstrated to be effective in enhancing the tensile strength of polyethylene composites. Similar enhancement in hardness and flexural properties was observed in alumina composites with 0.25 wt% loading of the exfoliated graphite. Co-milling-assisted exfoliated graphite nanoplatelets additive introduction has been found to effect a more desirable mechanical properties enhancement in the composites investigated in this study.


2014 ◽  
Vol 17 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Xia Liu ◽  
Yu-Chi Fan ◽  
Jian-Lin Li ◽  
Lian-Jun Wang ◽  
Wan Jiang

2014 ◽  
Vol 11 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Igor Danilenko ◽  
Serhii Prokhorenko ◽  
Tetyana Konstantinova ◽  
Leonid Ahkozov ◽  
Valerii Burkhovetski ◽  
...  

The use of ceramic instead of metallic parts in devices that operate in aggressive conditions increases the service life of machines and equipment for chemical, metallurgical and other industries. The wear resistant zirconia/alumina composites were sintered from nanopowders obtained by co-precipitation technique. In the case of addition of 1wt% of alumina in zirconia ceramics the wear resistance increased by approximately 30%.The formation of complex multilevel composite structures, such as Al3+ ion segregation on zirconia grain boundaries and intracrystalline alumina inclusions in zirconia grains, increased the fracture toughness values of composites obtained from co-precipitated nanopowders and consequently decreased the volume loss of ceramic material.In this study, we investigated the effect of nanopowders synthesis methods and alumina concentration on composite structure, fracture toughness and tribological behavior of 3Y-TZP/alumina ceramic composites and searched correlation between structures and mechanical properties.


1992 ◽  
Vol 274 ◽  
Author(s):  
Takashi Fujii ◽  
Hironobu Muragaki ◽  
Hiraku Hatano ◽  
Shin-Ichi Hirano

ABSTRACTSimultaneous additions of lanthanum aluminate(LAL) and Al2O3 to Ce-TZP (12mol% CeO2-ZrO2) lead to the in-situ formation of lanthanum- β-alumina(LBA) platelets (∼1.0.μ m in width and 5 ∼10 μ m in length) in the Ce-TZP matrix during sintering. The composites showed a fracture toughness(SEPB method) of 9.5 MPa · m0.5 and fracture strength of 960 MPa. which are remarkably improved from Ce-TZP sintered body (8.5 MPa · m0.5 and 560 MPa).The composites also exhibit the no degradation by hydrothermal treatment.


2013 ◽  
Vol 39 (2) ◽  
pp. 1835-1840 ◽  
Author(s):  
S.M. Naga ◽  
E.M. Abdelbary ◽  
M. Awaad ◽  
Y.I. El-Shaer ◽  
H.S. Abd-Elwahab

1994 ◽  
Vol 365 ◽  
Author(s):  
Steven A. Jones ◽  
James M. Burlitch ◽  
Ersan Üstündag ◽  
Jeannie Yoo ◽  
Alan T. Zehnder

ABSTRACTNickel-alumina composites have the potential to be high performance materials. Alumina, with its excellent oxidation resistance, combined with a ductile phase such as nickel may provide a tough material with a lower density and higher Young's modulus, overall, a higher specific modulus than typical Superalloys. Dense, interpenetrating Ni-Al2O3 composites were synthesized using a displacement reaction between NiO and aluminum. The resulting composites were characterized in terms of their mechanical properties such as hardness, flexure strength, fracture toughness and elastic constants. The synthesis, characterization, and mechanical properties, as well as the effect of the interpenetrating microstructure on the toughening mechanisms and other properties will be discussed.


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