Effect of Particle Size on Bulk Density and Strength Properties of Uranium Dioxide Specimens

Abstract

Fused uranium dioxide was separated into fractions of varying particle size by air separation. Specimens of the nominal size of l / 8 by 1/4 by 11/* in. were formed by hydrostatic pressing, firing, and lapping. Specimens prepared from the 0 to 5 p fraction were the strongest and most dense. The room-temperature density was about 92y0 of theoretical and the room-temperature flexural strength was about 12,000 Ib. per sq. in. When tested at 1000°C., the strength was about 18,000 lb. per sq. in. The flexural strength of specimens decreased and their density decreased as the starting particle size was increased. The crystallization of the urania fragments which had occurred during the firing treatment was observed.

Review and Statistical Analysis of the use of Ultrasonic Velocity for Estimating the Porosity Fraction in Polycrystalline Materials

“…(3) and (5) into Eq. (1) allows velocity to be expressed as: (6) lConcerning the relationship between Poisson's ratio and porosity fraction, most of the limited stUdies of Poisson's ratio show it decreasing with increasing porosity fraction less rapidly than for elastic modulus [3].…”

“…As examples concerning key properties of technologically-important materials, porosity fraction has been shown to affect (1) the strength, toughness and modulus of structural and refractory materials such as Steel [1], Tungsten [2], SiC [3], Si3N4 [3], and A1203 [3], (2) the strength of nuclear fuel materials such as U02 [4][5], (3) the thermal shock behavior and strength of porcelain-based ceramics [6-7J, (4) the dielectric and elastic properties of piezoelectric materials such as PZT [8], and (5) the critical current density, diamagnetic response, and modulus of superconducting ceramics such as YBa2Cu307_x [9-11J. In such cases where physical properties are directly dependent on porosity fraction, the measurement of porOSity fraction becomes important in the quality assurance process for the material.…”

Thermal Properties of UO2 by Molecular Dynamics Simulation

“…Dimensions of a sintered pellet were 10.663 mm in height x 4.227 mm in diameter. Density of the pellet was 10.53 g/cm 3 and its theoretical density was 96.08%.…”

“…In this temperature range, the thermal expansion values agreed with MD results and reported studies of bulk expansion measurements and lattice expansion obtained from high temperature X-ray diffraction measurement. [2][3][4][5] The reference data given by Conway et al and Burdick and Parker are bulk expansion values. 2,3) The data of Conway is in high temperature region and the data of Burdick and Parker is in low temperature region.…”

“…[2][3][4][5] The reference data given by Conway et al and Burdick and Parker are bulk expansion values. 2,3) The data of Conway is in high temperature region and the data of Burdick and Parker is in low temperature region. The reference data given by Baldock et al is a lattice expansion value.…”