Engineering Commons^™

Environmental Effects On Corrosion Properties Of Alloy 22, Mano Misra

Publications (YM)

This document presents detailed technical report for four Subtasks that were conducted independently. All four Subtasks investigated environmental effects on corrosion properties of Alloy 22. The four Subtasks that were investigated are as follows: Subtask 1: Experimental Determination of Parameters for the General Corrosion Model. Subtask 2: Corrosion under Dust Deposits Containing Hygroscopic Salts. Subtask 3: Heated Electrode Approach for the Study of Corrosion Under Aggressive Conditions. Subtask 4: Effect of Hydrogen Permeation on the Stability of the Passive Film of Alloy 22.

The Role Of Silicon Content On Environmental Degradations Of T91 Steels, Ajit K. Roy, D. Maitra, Pankaj Kumar

Mechanical Engineering Faculty Research

T91 grade steels showed a gradual enhancement in tensile ductility at ambient temperature due to an increase in Si content from 0.5 to 2.0 weight percent (wt.%). However, the ultimate tensile strength was reduced only above 1.5 wt.% Si. The corrosion potential became more active in an acidic solution with increasing temperature. The cracking susceptibility in a similar environment under a slow-strain-rate (SSR) condition was enhanced at higher temperatures showing reduced ductility, time to failure, and true failure stress. Cathodic potentials applied to the test specimens in SSR testing caused an enhanced cracking tendency at 30 and 60°C, suggesting hydrogen …

Tensile Deformation Of A Nickel-Base Alloy At Elevated Temperatures, Ajit K. Roy, Anand Venkatesh, Vikram Marthandam

Mechanical Engineering Faculty Research

The results of tensile testing involving Waspaloy indicate that the failure strain was gradually reduced at temperatures ranging between ambient and 300 °C. Further, serrations were observed in the engineering stress versus strain diagrams in the temperature range of 300-600 °C. The reduced failure strain and the formation of serrations in these temperature regimes could be the result of dynamic strain aging of this alloy. The extent of work hardening due to plastic deformation was reduced at temperatures above 300 °C. A combination of ductile and intergranular brittle failures was seen at temperatures above 600 °C. γ′ was detected at …

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 14, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

This report shows the work done for this period in accordance to cooperative agreement of University of Nevada system for the Task 019 “Subsurface Corrosion Research on Rock Bolt System, Perforated SS Sheets and Steel Sets for the Yucca Mountain Repository”, the overall objective of which is to conduct corrosion research and predict the durability of rock-bolts and other underground metallic roof supports. We are performing oxidation tests using Thermogravimetric Analyzer (TGA), and Potentiodynamic and immersion tests to determine the corrosion rates of rock bolts.

In this quarter specifically we have accomplished the following:

Potentiodynamic tests were performed to determine …

Fundamental And Applied Experimental Investigations Of Corrosion Of Steel By Lbe Under Controlled Conditions: Kinetics, Chemistry Morphology, And Surface Preparation, John Farley, Allen L. Johnson

Transmutation Sciences Materials (TRP)

Advanced nuclear processes and facilities (e.g., transmutation of nuclear waste, fast reactors, and spallation neutron sources) impose special demands on materials, which must withstand high temperatures, high radiation fields, and chemical corrosion. Proposed schemes for transmuting nuclear waste require a nonmoderating coolant such as lead-bismuth eutectic (LBE) or liquid sodium. While LBE corrodes most steels, small amounts of oxygen in the LBE greatly reduces the corrosion rate, and could ideally re-grow a damaged oxide layer in situ. The protective oxide layer would thus be self-healing. However, a fundamental understanding of the role of oxygen and passivating oxide layers is presently …

Effect Of Silicon Content On The Corrosion Resistance And Radiation-Induced Embrittlement Of Materials For Advanced Heavy Liquid Metal Nuclear Systems, Ajit K. Roy

Transmutation Sciences Materials (TRP)

The beneficial effects of Si on both the metallurgical and corrosion properties of Cr-Mo steels have previously been demonstrated at UNLV. Therefore, additions of Si ranging from 0.5-2.0 weight percent (wt%) was attempted in this investigation to explore Si effect on both the high temperature tensile properties and corrosion behavior of T91 grade steel. Corrosion studies in the presence of molten LBE could not be performed due to a lack of proper experimental facilities at UNLV. Therefore, detailed corrosion studies involving Si-containing T91 grade steels were performed in an aggressive aqueous solution of acidic pH. Further, significant efforts have been …

Theoretical Modeling Of Protective Oxide Layer Growth In Non-Isothermal Lead Alloy Coolant Systems, Yitung Chen, Taide Tan, Jinsuo Zhang, Jichun Li

Transmutation Sciences Materials (TRP)

In advanced nuclear energy systems, lead alloys emerge as strong candidates for transmutation and advanced reactor systems as nuclear coolants and spallation neutron targets. However, it is widely recognized that corrosion of materials caused by lead alloys presents a critical barrier to their industrial use. A few experimental research and development projects have been set up by different groups such as at Los Alamos National Laboratory to study the corrosion phenomena in their test facilities and to develop mitigation techniques and materials. One of the central or main techniques under development is to use active control of oxygen thermodynamic activity …

Development Of Nanostructure Based Corrosion-Barrier Coatings On Steel For Transmutation Applications, Biswajit Das

Transmutation Sciences Materials (TRP)

Advanced transmutation systems require structural materials that are able to withstand high neutron fluxes, high thermal cycling, and high resistance to chemical corrosion. The current candidate materials for such structures are ferritic and ferritic-martensitic steels due to their strong resistance to swelling, good microstructural stability under irradiation, and the retention of adequate ductility at typical reactor operating temperatures.

In parallel, lead-bismuth eutectic (LBE) has emerged as a potential spallation target material for efficient production of neutrons, as well as a coolant in the accelerator system. While LBE has excellent properties as a nuclear coolant, it is also highly corrosive to …

Interaction Between Metal Fission Products And Triso Coating Materials, Clemens Heske

Fuels Campaign (TRP)

This project focuses on the chemical bonding and interface formation of metal fission products with the coating materials used in tri-isotropic (TRISO) fuel particles for gas-cooled reactors. By combining surface- and bulk-sensitive spectroscopic and microscopic methods, intermediate chemical phases at the interface, intermixing/diffusion behavior, and the electronic interface structure for different coating materials and metals are examined.

In detail, the project studies the interface formation of Pd, Cs, and Ag with SiC and pyrolytic carbon. Using SiC single crystals and highly-ordered pyrolytic carbon (HOPG) as substrates, interfaces are prepared under controlled conditions in an ultra-high vacuum environment and are studied …

Final Report: Phase Stability And Segregation In Alloy 22 Base Metal And Weldments, Jeffrey Lacombe

Publications (YM)

At the outset of this project, the design of the waste disposal containers relied heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr- Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, was the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it was conceivable that the desired performance characteristics (such as corrosion resistance) would …

Formation Of A Mineral Layer During Coke Dissolution Into Liquid Iron And Its Influence On The Kinetics Of Coke Dissolution Rate, M. Chapman, B. J. Monaghan, S A. Nightingale, J. Mathieson, Robert J. Nightingale

Faculty of Engineering - Papers (Archive)

The formation and development of the mineral layer that forms between coke and liquid iron during carbon dissolution has been characterised. Coke particles (-2mm, +0.5mm) were added to the top surface of an iron 2 mass% C melt at representative ironmaking temperatures, for periods of time between 2 minutes and 120 minutes, before being quenched. The quenched samples were then sectioned and the solidified coke-melt interfacial region analysed in the SEM. Analysis showed that a mineral layer was present at the interface at all experimental temperatures (1450-1550oC) from 2 minutes and persisted beyond 120 minutes. The mineral layer was found …

Kinetics Of Spinel Formation And Growth During Dissolution Of Mgo In Cao-Al2o3-Sio2 Slag, Sharon Nightingale, B. J. Monaghan

Faculty of Engineering - Papers (Archive)

The formation and growth of MgAl2O4 spinel crystals on a single crystal MgO substrate submerged in a 40% CaO, 40% SiO2 and 20% Al2O3 slag was directly observed using high temperature microscopy. This showed that the crystals initially form on the MgO surface, but may break off and be carried out into the liquid slag. Still pictures extracted from digitally recorded images were used to measure the size of these crystals at 1420, 1440 and 1460oC as a function of time. Growth of the crystals was found to follow the parabolic rate law, with rates increasing with temperature. An estimate …

Determination Of The Thermal Histories Of Coke In A Blast Furnace Through X-Ray Analysis, B. J. Monaghan, Robert J. Nightingale, V. Daly, E. Fitzpatrick

Faculty of Engineering - Papers (Archive)

A study has been undertaken to identify the source of coke fines sampled from the deadman area of the blast furnace. Using measurements of the coke crystallite dimension LC, it was established that some of the fines found in the deadman area of a blast furnace were not simply the degradation products of the lump coke in this area. The LC was measured using standard X-ray analysis techniques. The coke fines had a higher LC than the coke lump and therefore have experienced a higher maximum temperature than the associated coke lump. This finding has been interpreted as at least …