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Situ Composite (situ + composite)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Synthesis, Microstructure, and Mechanical Properties of a Novel Ti2AlC/TiC/Al2O3In Situ Composite

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2006
D. L. Zhang
This paper describes a novel process for synthesizing a Ti2AlC/TiC/Al2O3in situ composite. This route utilizes TiO2, carbon, and Al powders as raw materials, and involves high-energy mechanical milling and powder sintering. The Ti2AlC/TiC/Al2O3 bulk in situ composite produced has a phase composition of Ti2AlC,20 vol% TiC,35 vol% Al2O3 with fine Al2O3 particles (size: 0.5,15 ,m) embedded in a Ti2AlC/TiC matrix. The Ti2AlC grains exhibit a nanometer scale lamellar structure, and most of the Al2O3 grains contain fine cubic TiOmC1,m precipitates (size: 10,200 nm). The average hardness and bending strength of the composite are in the ranges of 11,12.5 GPa and 380,440 MPa, respectively. Here we have demonstrated that the mechanical performance (mainly hardness and bending strength) of the composite is directly correlated with the size of the Al2O3 particles present in the as-fabricated in situ composite. [source]

Synthesis and Magneto-mechanical Properties of Ce-TZP/La M-Type Hexaferrite Composite

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002
Takashi Kojima
An in situ composite composed of ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP) and La{Co0.5Fe0.5(Fe0.9Al0.1)11}O19 was synthesized from a powder mixture of Ce-TZP, La(Fe0.9Al0.1)O3, Fe2O3, Al2O3, and CoO. The dense Ce-TZP dispersed with platelike La{Co0.5Fe0.5(Fe0.9Al0.1)11}O19 crystals as a second phase were formed after sintering from 1250° to 1350°C. The saturation magnetization of the insitu composite Ce-TZP/La{Co0.5Fe0.5(Fe0.9Al0.1)11}O19 was proportional to the mass fraction of the hexaferrite second phase in Ce-TZP. The coercivity of the composite with a 20 mass% of second phase decreased from 9.14 to 2.52 kOe (from 728 to 201 kA/m) after the pulverization of the composite. The susceptibility (,) increased by 15%,25% under uniaxial stress on the composite. The change of the susceptibility (,,/,) value increased with decreasing the mass fraction of the second phase in the composite. The ,, was found to increase linearly with applied stress and abruptly change on cracking, which is expected for the application in fracture sensing of the composite. [source]

Texture Development in Silicon Nitride,Silicon Oxynitride In Situ Composites via Superplastic Deformation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2000
Rong-Jun Xie
Silicon nitride,silicon oxynitride (Si3N4,Si2N2O) in situ composites have been fabricated via either the annealing or the superplastic deformation of sintered Si3N4 that has been doped with a silica-containing additive. In this study, quantitative texture measurements, including pole figures and X-ray diffraction patterns, are used in conjunction with scanning electron microscopy and transmission electron microscopy techniques to examine the degree of preferred orientation and texture-development mechanisms in these materials. The results indicate that (i) only superplastic deformation can produce strong textures in the ,-Si3N4 matrix, as well as Si2N2O grains that are formed in situ; (ii) texture development in the ,-Si3N4 matrix mainly results from grain rotation via grain-boundary sliding; and (iii) for Si2N2O, a very strong strain-dependent texture occurs in two stages, namely, preferred nucleation and anisotropic grain growth. [source]

Thermal properties of biaxially deformed in situ composites

POLYMER ENGINEERING & SCIENCE, Issue 8 2004
Youngwook P. Seo
The thermal properties of biaxially blown poly(etherimide) (PEI) films containing a thermotropic liquid crystalline polymer (TLCP) were studied using differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction and dynamic mechanical thermal analysis. The effects of the compatibilizer and thermal annealing on the thermal properties of biaxially oriented TLCP films were investigated. Though the compatibilizer (poly(ester imide)) improved deformation of the TLCP phase (poly ester amide) and adhesion between the matrix and the TLCP phase, which improved mechanical properties, it did not significantly affect the thermal properties of the in situ composite films. The film degradation behavior corroborated the role of the compatibilizer. Since a relatively small amount of TLCP (10 wt%) was added to the matrix and the matrix PEI was amorphous, the effect of annealing on the TLCP structure was not obvious. By the same token, while the effect of the deformation in the circumferential direction (a change in the blow-up ratio) was manifest in mechanical property improvements, its effect on the thermal properties was not obvious. All films showed similar thermal expansion behaviors, regardless of the thermal history and of the compatibilizer addition. Thus, there is an optimum amount of the compatibilizer required to obtain optimal mechanical properties for in situ composite films without causing a deterioration of their thermal properties. Polym. Eng. Sci. 44:1419,1428, 2004. © 2004 Society of Plastics Engineers. [source]