Plane Orientation (plane + orientation)

Distribution by Scientific Domains

Selected Abstracts

Thick Nb-Doped Bismuth Titanate Film with Controllable Grain Orientation

Weiwu Chen
In the current work, we reported a potential approach to obtain thick ceramic films with controllable grain orientation based on magnetic alignment and polymerization techniques. The slurry containing 40 vol% Bi4Ti2.96Nb0.04O12 (BINT) ceramic powder, monomer, initiator, and catalyst was drop coated on a Pt substrate and then moved into a vertical 10 T magnetic field. In 1,2 min, the ceramic particles were aligned by a strong magnetic force in slurry and then in situ locked by polymerization on the substrate. After sintering at 1000C, a BINT ceramic film (50,80 ,m in thickness) with a highly a/b plane orientation was obtained. Theoretically, the grain orientation in the films can be easily controlled by adjusting the magnetic field direction. This approach is readily applicable to other materials with a non-cubic structure and is expected to facilitate the fast preparation of grain-oriented thick films. [source]

Templated Grain Growth of Barium Titanate Single Crystals

Paul W. Rehrig
BaTiO3 single crystals were grown via templated grain growth (TGG), which is a process in which a single-crystal "template" is placed in contact with a sintered polycrystalline matrix and then heated to migrate the single-crystal boundary into the matrix. Millimeter-sized, stoichiometric single crystals of BaTiO3 were produced by heating polycrystalline matrix with a relative density of 97% and a Ba/Ti ratio of <1.00, which was bonded to a BaTiO3 single crystal, at temperatures above the eutectic temperature. Growth rates of 590,790, 180,350, and 42,59 ,m/h were observed for {111}-, {100}-, and {110}-oriented single-crystal templates, respectively. Lower-surface-energy facets were formed for {111}- and {100}-oriented templates, whereas {110} crystals maintained a {110} growth front, which indicated that this plane orientation was the lowest-energy surface in this system. SrTiO3 also was shown to be a suitable substrate for TGG of BaTiO3. [source]

Analytical and experimental studies on fatigue crack path under complex multi-axial loading

ABSTRACT In real engineering components and structures, many accidental failures are due to unexpected or additional loadings, such as additional bending or torsion, etc. Fractographical analyses of the failure surface and the crack orientation are helpful for identifying the effects of the non-proportional multi-axial loading. There are many factors that influence fatigue crack paths. This paper studies the effects of multi-axial loading path on the crack path. Two kinds of materials were studied and compared in this paper: AISI 303 stainless steel and 42CrMo4 steel. Experiments were conducted in a biaxial testing machine INSTRON 8800. Six different biaxial loading paths were selected and applied in the tests to observe the effects of multi-axial loading paths on the additional hardening, fatigue life and the crack propagation orientation. Fractographic analyses of the plane orientations of crack initiation and propagation were carried out by optical microscope and SEM approaches. It was shown that the two materials studied had different crack orientations under the same loading path, due to their different cyclic plasticity behaviour and different sensitivity to non-proportional loading. Theoretical predictions of the damage plane were made using the critical plane approaches such as the Brown,Miller, the Findley, the Wang,Brown, the Fatemi,Socie, the Smith,Watson,Topper and the Liu's criteria. Comparisons of the predicted orientation of the damage plane with the experimental observations show that the critical plane models give satisfactory predictions for the orientations of early crack growth of the 42CrMo4 steel, but less accurate predictions were obtained for the AISI 303 stainless steel. This observation appears to show that the applicability of the fatigue models is dependent on the material type and multi-axial microstructure characteristics. [source]

Patient motion correction for multiplanar, multi-breath-hold cardiac cine MR imaging

Piotr J. Slomka PhD
Abstract Purpose To correct for spatial misregistration of multi-breath-hold short-axis (SA), two-chamber (2CH), and four-chamber (4CH) cine cardiac MR (CMR) images caused by respiratory and patient motion. Materials and Methods Twenty CMR studies from consecutive patients with separate breath-hold 2CH, 4CH, and SA 20-phase cine images were considered. We automatically registered the 2CH, 4CH, and SA images in three dimensions by minimizing the cost function derived from plane intersections for all cine phases. The automatic alignment was compared with manual alignment by two observers. Results The processing time for the proposed method was <20 seconds, compared to 14,24 minutes for the manual correction. The initial plane displacement identified by the observers was 2.8 1.8 mm (maximum = 14 mm). A displacement of ,5 mm was identified in 15 of 20 studies. The registration accuracy (defined as the difference between the automatic parameters and those obtained by visual registration) was 1.0 0.9 mm, 1.1 1.0 mm, 1.1 1.2 mm, and 2.0 1.8 mm for 2CH-4CH alignment and SA alignment in the mid, basal, and apical regions, respectively. The algorithm variability was higher in the apex (2.0 1.9 mm) than in the mid (1.4 1.4 mm) or basal (1.2 1.2 mm) regions (ANOVA, P < 0.05). Conclusion An automated preprocessing algorithm can reduce spatial misregistration between multiple CMR images acquired at different breath-holds and plane orientations. J. Magn. Reson. Imaging 2007;25:965,973. 2007 Wiley-Liss, Inc. [source]