Microstructures and corrosion of intermediate level wasteforms fabricated using novel thermal techniques

Simulant intermediate level waste materials received from Sellafield, 3 produced using Joule heating techniques, and 3 from plasma furnace methods, were characterised and subjected to leaching tests for up to 14 weeks to assess their potential as a waste matrix. Each wasteform was used to simulate a combination of waste surrogates such as plutonium contaminated material, site ion exchange plant waste, high metal content waste, Magnox sludge, asbestos, or pile fuel cladding. Five samples were characterised as glass composite materials, containing a crystalline and glassy portion, with the sixth being characterised as a glass. XRD and EDX analysis were used to identify the crystalline components, revealing a wide array of phases over the six samples such as pigeonite, anorthite, diopside, Cerium-Lanthanum silicate, proto and clino hypersthene, augite, and two glasses from liquid-liquid phase separation. ICP-OES analysis and pH were used to analyse the leachant, and SEM-EDX surface scans and depth profiles for analysis of the wasteform, post corrosion. Results revealed several of the wasteforms to be more than adequate for safe disposal, showing protective corrosion layers or durable crystalline components. However, not all wasteforms were suitable; in particular glass encapsulated metals should not be used as a waste matrix due to the susceptibility of the metal/metal oxide portion to chemical attack.Open Acces

Cold Micro Metal Forming

This open access book contains the research report of the Collaborative Research Center “Micro Cold Forming” (SFB 747) of the University of Bremen, Germany. The topical research focus lies on new methods and processes for a mastered mass production of micro parts which are smaller than 1mm (by forming in batch size higher than one million). The target audience primarily comprises research experts and practitioners in production engineering, but the book may also be of interest to graduate students alike

Solidification study of commercial magnesium alloys

In this thesis, the solidification behaviors of AZ9ID, AM60B and AE44 commercial magnesium alloys have been studied experimentally by differential scanning calorimeter (DSC) and optical microscopy. The effect of different cooling rates on the transition temperatures and microstructures were analyzed. It was found that the effect of cooling rate on the solidus temperature is more significant than on the liquidus. The solidus temperature decreases clearly with increasing cooling rates, but for the liquidus temperature there is slightly increasing trend. The latent heat of solidification was also calculated and found that it increases when the cooling rate increases. Thermodynamic calculations were made using FactSage along with VLGM database and were compared with the experimental findings as well as with the literature data. Thermodynamic calculations were also utilized to understand the microstructures as well as the phase distribution. The microstructural details of as-cast and post-DSC samples have also been investigated using optical microscope. Finally, relationships between cooling rate and transition temperature as well as between cooling rate and latent heat of solidification have been established based on the general power law. Using these relationships it is possible to predict the transition temperatures and latent heat of solidification of these alloys at high cooling rate

Iron rich low cost superalloys

An iron-rich low-cost superalloy was developed. The alloy, when processed by conventional chill casting, has physical and mechanical properties that compare favorably with existing nickel and cobalt based superalloys while containing significantly lower amounts of strategic elements. Studies were also made on the properties of Cr(20)-Mn(10)-C(3.4)-Fe(bal.), a eutectic alloy processed by chill casting and directional solidification which produced an aligned microstructure consisting of M7C3 fibers in a gamma-Fe matrix. Thermal expansion of the M7C3 (M = Fe, Cr, Mn) carbide lattice was measured up to 800 C and found to be highly anisotropic, with the a-axis being the predominant mode of expansion. Repetitive impact sliding wear experiments performed with the Fe rich eutectic alloy showed that the directionally solidified microstructure greatly improved the alloy's wear resistance as compared to the chill cast microstructure and conventional nickel base superalloys. Studies on the molybdenum cementite phase prove that the crystal structure of the xi phase is not orthorhombic. The crystal structure of the xi phase is made up of octahedra building elements consisting of four Mo and two Fe atoms and trigonal prisms consisting of four Fe and two Mo atoms. The voids are occupied by carbon atoms. The previous chemical formula for the molybdenum cementite MoFe2C is now clearly seen to be Mo12Fe22C10

Energy. A continuing bibliography with indexes, issue 26, 1 April - 30 June 1980

This bibliography lists 1134 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System from April 1, 1980 through June 30, 1980

A study of graphite morphology control in cast iron

The objectives of the research project were to gain a deeper understanding of the factors influencing the graphite morphology in cast iron; particularly the role of different solute elements in relation to the industrial manufacture of compacted graphite iron. A number of melt treatment processes were assessed for their abilities to produce low nodularity compacted graphite microstructures over a range of casting section thicknesses. In this respect, the magnesium-titanium method was found to be superior to treatment using cerium Mischmetall and calcium additives; and very promising results were obtained with methods using zirconium as a major constituent of the treatment alloy. Scanning electron microscopy, secondary ion mass spectrometry and X-ray microanalysis were used to study the structural characteristics of different cast iron microstructures and the elemental distributions of important solutes between the phases. This information was used to clarify the role of the main solute elements in graphite morphology control and to assess current graphite growth theories

Metallurgical Process Simulation and Optimization

Metallurgy involves the art and science of extracting metals from their ores and modifying the metals for use. With thousands of years of development, many interdisciplinary technologies have been introduced into this traditional and large-scale industry. In modern metallurgical practices, modelling and simulation are widely used to provide solutions in the areas of design, control, optimization, and visualization, and are becoming increasingly significant in the progress of digital transformation and intelligent metallurgy. This Special Issue (SI), entitled “Metallurgical Process Simulation and Optimization”, has been organized as a platform to present the recent advances in the field of modelling and optimization of metallurgical processes, which covers the processes of electric/oxygen steel-making, secondary metallurgy, (continuous) casting, and processing. Eighteen articles have been included that concern various aspects of the topic

Energy: A continuing bibliography with indexes, supplement 16, January 1978

This bibliography lists 1287 reports, articles, and other documents introduced into the NASA scientific and technical information system from October 1, 1977 through December 31, 1977