High-Toughening Alumina Composites Weakened by Metastable Hexacelsian Interphases

2007 ◽  
Vol 345-346 ◽  
pp. 721-724
Author(s):  
Sang Jin Lee ◽  
Sang Ho Lee
Keyword(s):  
Laminated Composite ◽  
Crack Deflection ◽  
Alumina Matrix ◽  
Electronic Microscopy ◽  
Deflection Curve ◽  
Laminate Design ◽  
Alumina Composite ◽  
Alumina Composites ◽  
Load Deflection Curve ◽  
Work Of Fracture

New laminate design for improved toughness in hexacelsian-alumina composite is introduced. The composite is based on crack deflection in a weak interphase in the alumina matrix and hexacelsian interphase. The strength and toughness of the laminated composite were studied both qualitatively by electronic microscopy and measuring flexure strength. The metastable hexacelsian interphases had partially microcracks to provide crack deflection in the composite, and the crack deflection noticeably proceeded along the meta-stable hexacelsian interphase. Load-deflection curve for the laminate showed improved work of fracture of 2.23 kJ/m2.

Toughening of Ceramic Composite Designed by Silica-Based Transformation Weakening Interphases

2005 ◽  
Vol 287 ◽  
pp. 358-366
Author(s):  
Sang Jin Lee ◽  
Chung Hyo Lee ◽  
Jong Hee Hwang
Keyword(s):  
Phase Transformation ◽  
Ceramic Composite ◽  
Mechanical Test ◽  
Shape Change ◽  
Laminated Composite ◽  
Alumina Matrix ◽  
Cell Shape Change ◽  
Oxide Composites ◽  
Load Deflection Curve ◽  
Work Of Fracture

A new concept for achieving graceful failure in oxide composites is introduced. It is based on crack deflection in a weak interphase between a matrix and reinforcement (e.g. fiber), or in a laminated composite. The interphase can be phase transformation weakened by volume contraction and/or unit cell shape change. Microcracking induced by a displacive, crystallographic phase transformation in silica-based interphases resulted in increase in the toughness of the bulk composites. In the present study, mullite/cordierite laminates with b®a-cristobalite (SiO2) transformation weakened interphase, and alumina matrix fibrous monolith with metastable hexacelsian (BaAl2Si2O8) interphases were investigated for interphase debonding behavior. In mechanical test, the laminates showed step-wise load drop behavior dependent on a grain size of b-cristobalite. In particular, in the fibrous monolith design, the load-deflection curve showed unusual plastic-like behavior with reasonable work of fracture.

scholarly journals Zirconia–Alumina Composites Obtained by Centrifugal Slip Casting as Attractive Sustainable Material for Application in Construction

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 250
Author(s):  
Justyna Zygmuntowicz ◽  
Justyna Tomaszewska ◽  
Radosław Żurowski ◽  
Marcin Wachowski ◽  
Paulina Piotrkiewicz ◽  
...  
Keyword(s):  
Slip Casting ◽  
Sintering Process ◽  
Alumina Matrix ◽  
X Ray Diffraction ◽  
Casting Method ◽  
Zro2 Content ◽  
Stereological Analysis ◽  
Alumina Composite ◽  
Alumina Composites ◽  
Sintered Materials

This paper focuses on the possibility of adapting the centrifugal slip casting method to obtain zirconia–alumina composite materials in the form of finished tube-shaped products. These types of products, due to their unique properties, can be utilised, for example, in the transport of aggressive substances, even in extreme temperatures or corrosive conditions. The study reports on the two series of zirconia–alumina composites differing in the content of ZrO2—2.5 and 25 vol%. The fabricated and sintered materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and stereological analysis. Moreover, a life cycle assessment (LCA) was provided in accordance with the requirements of the ISO 14044 and EN 15805 standards. The obtained data clearly show that the centrifugal slip casting method allows obtaining samples with high density and extremely uniform distribution of the ZrO2 phase in the alumina matrix. The stereological analysis results proved also that the addition of ZrO2 is effective in reducing the growth of Al2O3 grains during the sintering process. The phase analysis carried out by means of XRD showed that during the sintering process, in the case of composites with a lower ZrO2 content (2.5 vol%), the monoclinic to tetragonal transformation of ZrO2 was total, while for samples containing 25 vol% ZrO2, the monoclinic phase remained in a small amount in the final product.

scholarly journals Non-linear analysis of laminated composite doubly curved shallow shells

2006 ◽  
Vol 28 (1) ◽  
pp. 43-55
Author(s):  
Dao Huy Bich
Keyword(s):  
Laminated Composite ◽  
Governing Equations ◽  
Shallow Shells ◽  
Approximate Analytical Solutions ◽  
Linear Buckling ◽  
Non Linear ◽  
Vibration Problems ◽  
Doubly Curved ◽  
Analytical Expressions ◽  
Load Deflection Curve

This paper deals with governing equations and approximate analytical solutions based on some wellknown assumptions to the non-linear buckling and vibration problems of laminated composite doubly curved shallow shells. Obtained results will be presented by analytical expressions of the lower critical load, the postbuckling load-deflection curve and the fundamental frequency of non-linear free vibration of the shell.

Experimental Study on Mechanical Properties of Rubber Used for Damping Bearing

2011 ◽  
Vol 189-193 ◽  
pp. 1132-1136 ◽  
Author(s):  
Yong Xu Zhao ◽  
Wen Jun Hu ◽  
Jun Mei ◽  
Niu Wei ◽  
Jian Jun Xie
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Three Dimensional ◽  
Middle Part ◽  
Loading Conditions ◽  
Deflection Curve ◽  
Rubber Bearing ◽  
Components Analysis ◽  
The Impact ◽  
Load Deflection Curve

After testing on T-type rubber bearing under tensile, compression and shear mechanical properties under different temperature in this paper. Obtained load deflection curve and destructive mode under different loading conditions at -40 and normal temperature of rubber components. Analysis the impact of temperature and the loading conditions that effect on load-elongation and destructive mode of T-type damping rubber structure. It showed that T-end rubber bearing has different kinds of deformation under different force-giving methods. Under compression, the stress pattern of the rubber bearing is three-dimensional and middle rubber bear the greatest force. Under tensile loading, the middle part of the rubber contract and the side with smaller lateral section has greater shrinkage; moreover, damage occurred in the area with stress concentration and weak strength. Under shearing action, extrude faces appeared with crinkle and damage occurred in the middle part of extrude faces. At the low temperature-40 , rubber support still has great elastic properties. The low temperature has a big effect on tensile properties and has little effect on damage properties.

scholarly journals Effect of Equivalent Load Distribution on the Accuracy of Mapping the Reinforcement Load Deflection Curve in LTP

2020 ◽  
Vol 10 (17) ◽  
pp. 6127
Author(s):  
Beata Gajewska ◽  
Marcin Gajewski
Keyword(s):  
Load Distribution ◽  
Load Transfer ◽  
Single Case ◽  
Soft Soil ◽  
Triangular Distribution ◽  
Deflection Curve ◽  
Measurement Results ◽  
Equivalent Load ◽  
Load Deflection Curve ◽  
Best Fit

The formulations of tasks modelling embankments on soft soil, improved with columns and with reinforced load transfer platform (LTP), differ significantly. One of these differences is the distribution of equivalent load modelling part of the load carried by the LTP reinforcement and soft soil. This article analyses the influence of the nature of the load-modelling linear function, i.e., inverse triangular, uniformly distributed and triangular, as well as intermediate distributions. In total, 41 distributions of equivalent load were considered, and the results of the obtained deflection functions were compared with the measurement results of reinforcement deflection for 5 cases of experimental research available in the literature. A measure of the accuracy of mapping the reinforcement deflection curve was proposed as a relative error in relation to the deflection curve resulting from experimental measurements. Based on the analysis of the mapping error, it was determined that among the three commonly used distributions, the inverse triangular distribution shows the best fit in most of the analysed cases. However, not in every single case this is the distribution leading to a solution that best describes the behaviour of the geosynthetic reinforcement.

Processing of diamond/alumina composites for low wear applications

1992 ◽  
Vol 7 (11) ◽  
pp. 3010-3018 ◽  
Author(s):  
May-Ying Chu ◽  
Bharat Bhushan ◽  
Lutgard C. De Jonghe
Keyword(s):  
Magnetic Thin Film ◽  
Alumina Matrix ◽  
Low Friction ◽  
Coated Materials ◽  
Vacuum Atmosphere ◽  
Rigid Disks ◽  
Alumina Composites ◽  
Low Wear ◽  
Wear Tests ◽  
Economical Alternative

A simple hot-pressing procedure for fabricating composites of diamond particulates in an alumina matrix at moderate applied pressures is described. Dense composites with up to 33 vol. % diamond particles are made by pressure-sintering at applied stress of 35 MPa in vacuum atmosphere. Preliminary wear tests of these composites on magnetic thin-film rigid disks show a low friction comparable to that of single crystalline diamond. Diamond/alumina composites can be an economical alternative to diamond or diamond coated materials for abrasion resistant applications.

Calculated Deflected Contours and Load-Deflection Curves for Tires

1968 ◽  
Vol 41 (4) ◽  
pp. 977-987
Author(s):  
S. D. Gehman
Keyword(s):  
Approximation Method ◽  
Elliptic Integrals ◽  
Deflection Curve ◽  
Load Axis ◽  
Incomplete Elliptic Integrals ◽  
Load Deflection Curve

Abstract The tire contour equation is derived for a flexible tire body with radial cords and a complete circumferential deflection, corresponding to the case of a radial-ply tire or a tire inflated inside a constraining cylinder. Equations are derived to calculate the load on a single cord in the deflected region using parameters of the un-deflected contour. It is then shown how the reasoning and equations can be generalized for a tire body with any cord path having a complete circumferential deflection so that the load-deflection curve for a single cord can be calculated. A new approximation method is described so that the integrals involved in these calculations can be evaluated in terms of incomplete elliptic integrals of the first and second kind with any desired accuracy. Finally, a procedure is given for summing cord loads in the usual spot deflection of a tire so that the load-deflection curve for a flexible tire body can be calculated from contour parameters of the undeflected tire. An illustrative calculation is included. Although the load-deflection curve for a single cord is convex toward the load axis, that for the tire is concave because more cords are involved as deflection progresses. A calculated contour does not exist beyond a limiting deflection, at which, presumably, buckling starts above the bead.

Fracture Behaviour of Pressureless Sintered Nickel-Reinforced Alumina Composites

2005 ◽  
Vol 290 ◽  
pp. 324-327 ◽  
Author(s):  
Alessio Beverina ◽  
Antonio Javier Sanchez-Herencia ◽  
N. Hernández ◽  
Rodrigo Moreno
Keyword(s):  
Colloidal Stability ◽  
Sintering Temperature ◽  
Fracture Behaviour ◽  
Slip Casting ◽  
High Dispersion ◽  
Nickel Aluminum ◽  
Alumina Matrix ◽  
Concentrated Suspensions ◽  
Alumina Composites ◽  
Flowing Atmosphere

Nickel-reinforced alumina composites have been manufactured by aqueous slip casting and pressureless sintered under flowing atmosphere of argon with 0,36 and 1% of oxygen in order to force interfacial reactions leading to the formation of a nickel-aluminum spinel. Colloidal stability of concentrated suspensions of alumina with 5, 10 and 15 vol% of nickel has been studied in terms of zeta potential, rheometry and packing density. The processed composites show a high dispersion of the nickel into the alumina matrix and green densities of 60-70 %th. The effect of sintering temperature and atmosphere on the mechanical behaviour of the composites has been investigated through Vickers indentation and fractographic SEM observations.

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