Microstructure Formation Mechanism for Ca(Zr,Hf) | Chapter 4 | Chemical and Materials Sciences: Research Findings Vol. 4

The binary phase diagram of ZrO2-CaO includes the eutectic of the CaZrO3 phase and the CaO-stabilised ZrO2 phase. In this study, Ca(Zr_1-xHfx)O3/(Zr_1-xHfx)O2 (x=0, 1/3, 0.5) eutectic film was prepared by rapid solidification process using high power laser irradiation method. CaCO3 of 99.9% purity, ZrO2 and HfO2 of 98% purity powders were used as starting materials. The coating process was performed in an electric furnace at 1300°C. Solidified film with fine lamellar structure was obtained. When the Zr site was substituted with Hf, the lamellar spacing increased with the amount of substitution. Separate from the solidification film prepared by laser irradiation, a rapidly solidifying sample with x=0.1 composition was prepared using an optical floating zone apparatus. The melt of the sample was free-falling onto a copper dish. No film-like rapidly solidified sample was obtained. Hf ion was homogeneously solid-soluble in both phases of CaZrO3 and ZrO2. This study attempted to prepare eutectic solidification coatings for CaHfO3/HfO2 eutectic under the same conditions as for CaZrO3/ZrO2 eutectic coatings. No eutectic structure was obtained.

 

Author (s) Details

Shunkichi Ueno
College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan.

Please see the book here:- https://doi.org/10.9734/bpi/cmsrf/v4/5468

Structural Changes in UHMWPE Reactor Powders during Sintering under Different Conditions| Chapter 9 | New Trends in Physical Science Research Vol.3

The change in the structure of the ultra-high-molecular-weight polyethylene (UHMWPE) nascent reactor powder during sintering at various temperatures and pressures was examined using the DSC method to elucidate the effect of processing parameters on the structure. Scanning electron microscopy revealed that the primary morphological units of the UHMWPE reactor powder investigated are crystalline lamellae. Because the heat flux dH/dT (where H is the melting enthalpy and T is the sample temperature) is proportional to the mass fraction of lamellae melting at a given temperature, data on the thickness distribution of the lamellae could be obtained by analysing the shape of the polymer melting peak on the DSC curves. The structure of UHMWPE has not yet been subjected to such scrutiny. The proportion of thick (>15 nm) and thin (10 nm) lamellae in compacted samples and those sintered at a temperature of 130oC (lower than the equilibrium melting temperature of an infinitely long polyethylene crystal T0 = 142oC) is found to be virtually identical. Significant variations in the composition of the lamellae of various thicknesses have been observed in the samples sintered at temperatures above the T0 of PE with subsequent cooling under various circumstances. At the same time, their melting points remained unaltered when the samples were heated from 130°C to 145°C while under pressure.

Author(s) Details:

L. P. Myasnikova,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

A. K. Borisov,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

Yu. M. Boiko,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

A. P. Borsenko,
A. A.Galkin Physical-Technical Institute, str. R. Luxemburg 72, Donetsk, 83114, Ukraine.

V. F. Drobot’ko,
A. A.Galkin Physical-Technical Institute, str. R. Luxemburg 72, Donetsk, 83114, Ukraine.

V. M. Egorov,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

E. M. Ivankova,
Institute of Macromolecular Compounds, 31 Bolshoy pr., St. Petersburg 199004, Russia.

E. I. Radovanova,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

V. A. Marikhin,
IOFFE Institute, 26 Polytechnicheskaya, St. Petersburg 194021, Russia.

Please see the link here: https://stm.bookpi.org/NTPSR-V3/article/view/6828