materials engineering research colloquiummtrl.sites.olt.ubc.ca/files/2014/06/mercdec05.pdf · frank...

MERC 2005Materials Engineering Research Colloquium Materials Engineering Research Colloquium

December 2, 2005December 2, 2005

Department of Materials EngineeringUniversity of British ColumbiaVancouver BC CANADA

Materials Engineering Research Colloquium Schedule

December 2, 2005

Presenter Title

Session I: (10:00 am – 11:00 am)

Y. Zhang Metals Processing Continuous scrap melting in an oxy-fuel-fired rotary furnace

M. Tsui Ceramics Electrochemical deposition of calcium phosphate coating on coronary stent

L. Silva Biomaterials Nanomechanical characterization of cortical bone quality

Session II: (11:15 – 12:15)

G. Malkhuuz Hydrometallurgy Use of strong brine and HCL solutions to process sulphide

concentrates with an emphasis on nickel sulfides and associated gang

A. Chaudhary Metals Processing Modelling constitutive behaviour of aluminum alloys during DC casting at below solidus temperatures

J. Mitchell Metals Processing Determination of strain during hot tearing by image correlation

LUNCH (12:15 – 13:15)

Session III: (13:15 – 14:15)

S. Hedge Microstructural Engineering

High temperature oxidation behaviour of single crystal superalloy, CMSX-10

F. Xie Hydrometallurgy Catalytic leaching of silver ore with dissolved ferric cyanide

D. Mayne Hydrometallurgy Galvanic effect between chalcopyrite and pyrite in atmospheric leaching

MERC2005 December, 2005

Continuous Scrap Melting in an Oxy-Fuel-Fired Rotary Furnace

Yanjun Zhang Metals Processing Group; T.R. Meadowcroft and P.V. Barr

Frank Forward Building, Room 401 Department of Metals and Materials Engineering, University of British Columbia

Research Summary: Cheap hydrocarbon fuels will be the main energy source for high temperature melting in the future. However, the configuration of electric arc furnaces (EAF) is not optimal to efficiently utilize hydrocarbon energy inputs. Rotary melting furnaces (RMF) are common in the foundry industry. Although competitive with the EAF in terms of thermal efficiency, they remain batch processes with relatively low melting rates. Recently a new process for continuous scrap melting in an oxy-fuel-fired RMF has been proposed with sufficient melting capacity to replace the EAF in minimill steel operations. Model-generated results indicate that the process can save "at-source" energy by up to 50%. However, the process has not been physically demonstrated at any scale. The focus of the current work is to demonstrate the feasibility of the process at a bench-scale and gather data sufficient for validation of an improved mathematical model to be developed as part of the project. The validated model would then be used to predict the performance of an industrial-scale operation. In order to investigate the effects of oxygen and slag on thermal efficiency, two groups of trials have been performed for continuous melting copper at rates up to 25 kg/h. Copper, rather than iron or steel, was chosen for improved safety (Cu being relatively noble) while still offering a melting temperature at least approaching that of steel. As shown in Figure1 (a), the thermal efficiency increased almost linearly with increasing oxygen level, while it decreased with increasing of slag thickness (Figure 1 (b)). For the industrial-scale RMF fired with 100% oxygen, the thermal efficiency can be expected to be 70% or more due to the enlarged freeboard volume and surface area for heat transfer.

(a) (b)

Figure 1: (a) The thermal efficiency versus oxygen level (no slag was applied), (b) The effect of slag thickness on the thermal efficiency (the baseline oxygen level was 53.0%)


Electrochemical deposition of calcium phosphate coating on coronary stent

Manus Tsui

Ceramics Group; Tom Troczynski Frank Forward Building, Room 106A

Department of Metals and Materials Engineering, University of British Columbia

Research Summary: Coronary artery disease (CAD) is a condition caused by thickening of the artery walls that supply blood to the heart muscle. Fatty deposits or plaques may build up inside the artery wall blocking the blood flow. When these arteries become blocked, the heart is deprived of oxygen and can become damaged. Severe cases can result in heart attack. CAD is the leading causes of death in North America, 54% of all cardiovascular deaths are due to coronary artery disease. Coronary stenting technique is widely used to battle CAD. Coronary stents are small metallic spring-like implantable device. When implanted, the stent act as a scaffold to keep the artery open. However, bare metallic stent may trigger inflammatory response that lead to restenosis- the artery becomes blocked again. A thin coating, such as hydroxyapatite (HAp) can provide a biocompatible environment between the stent and the artery. Calcium phosphate ceramics, especially hydroxyapatite, have gained much attention in clinically application due to their excellent biocompatibility. Among different methods for producing HAp coating, electrochemical deposition (ECD) was used to deposit a uniform thin film coating (0.5 µm) on coronary stents. XRD results demonstrated that hydroxyapatite was the main component of the coating deposited. In vitro stent expansion studies confirm that the thin film coating show good adhesion without detachment. The thin film HAp coating also exhibit a highly porous morphology, which is ideal for the next generation drug eluting stent technology. Future experiments will focus on quantitative analysis of adhesive strength, co-deposition technique, and drug eluting capability.

Figure Caption - SEM micrographs of stainless steel stent deposited with CaP via electrochemical deposition.


Nanomechanical Characterization of Cortical Bone Quality

Leandro De Macedo Soares Silva Biomaterials Group; Rizhi Wang and Thomas Oxland


Research Summary: Bone is a composite material composed of collagen, carbonated apatite mineral, water, and other non-collagenous proteins. The bone structure inside human body is under constant remodelling. The mechanical properties of bone and their dynamic changes during remodelling are crucial to the health and quality of life. Bone quality depends on three factors that will be investigated during this research, namely: mechanical properties characterization by Nanoindentation, measurement of the degree of bone mineralization by Quantitative Backscattered Electron Imaging (qBSEi), and measurement of the degree of cortical bone porosity also evaluated by Backscattered Electron Imaging (BSEi). The main objective of this work is to relate clinical evaluation of bone health to laboratory measurements of bone structure and properties.The understanding and combination of these three parameters enable a more reliable and accurate reading of clinical evaluative tools such as Peripheral Quantitative Computed Tomography (pQCT), largely used in bone health diagnosis. Fifteen human tibias were measured and the results will be presented along with a two-way repeated measures analysis of variance (ANOVA). The mechanical properties of bone are intrinsically dependent on the measurement conditions. The degree of mineralization also affects bone mechanical properties. The mechanical properties of bone greatly vary across the cortex and bone microstructure. Porosity appears as a great indicator of bone quality and can drastically decrease bone density. A correlation between clinical pQCT and BSEi willl be presented to better understand the diagnostics provided by pQCT.

a) Cross-section of the distal tibia; b) Detailed view cortical wall – anterior site; c) Detailed view of an individual osteon with five indents.


Use of strong brine and HCl solutions to process sulfide concentrates (with an emphasis on nickel sulfides and

associated gang)

Ganbold Malkhuuz Hydrometallurgy Group; Supervisor: David B. Dreisinger


Research Summary: The chloride processing of base metal sulfide concentrates has recently entered a period of renewed interest and investigation. Proper understanding of thermodynamic properties of aqueous chloride solution is required in order to utilize the specific properties for the leaching processes of sulfide minerals. Studies have recognized that the ionic activity (coefficient) would be the key quantity. Available data are limited dilute solutions and at lower temperatures. All hydrometallurgical processes operate at upper level of chloride concentration. Therefore, the current research is focused on two parts: thermodynamic measurements of MgCl2-HCl mixture and the dissolution behaviour of sulfide minerals. The activity coefficient is first estimated by a method known as Meissner's. These calculated data were very consistent with the references. Furhter, individual ionic activities are assigned and the effects of Al3+, Ca2+, Na+ cations on proton activity are estimated. Second, the emf measurement method is utilized to determine experimentally activity coeffcients beyond reference ionic strenghts and temperatures. The current work is in the middle of activity coefficient measurement experiments for the selected mixtures with the intention of moving on to the leaching tests.

Figure 1. Reference data (only available) for the activity coefficients of MgCl2-HCl mixture against calculated values by Meissner's method


Modelling constitutive behaviour of aluminum alloys during DC casting at below solidus temperatures

Alankar Chaudhary

Metals Processing Group; Dr. Mary A. Wells AMPEL Building, Room 411


Research Summary: In the DC casting of aluminum alloys, during primary and secondary cooling non-uniform temperature distribution occurs within the casting body and consecutively thermal stresses are generated in the casting. Thermal contraction and solidification shrinkage so produced may develop excessive stresses and strains which may cause defects in ingot geometry (i.e. hot tearing, butt curl, butt swell, or rolling face pull-in). In order to understand the development of such defects and optimize the design of casting process to avoid or minimize occurrence of such defects, mathematical modelling is extensively used for DC casting. Development of thermomechanical models for the Direct Chill (DC) casting of light metals requires knowledge of the constitutive behaviour of the material under thermomechanical conditions that are typical of those experienced during DC casting. This talk reviews the thermomechanical conditions experienced during DC casting and the use of empirical equations, one internal state variable based model and two internal variable based models to predict the high and low temperature constitutive behaviour of aluminum alloys. Experimental data for uniaxial compression tests on aluminum alloy AA5182 has been fitted against the empirical equation and one state variable model. Results demonstrate the limited applicability of emprical equations. It has been concluded that internal state variable equations may be used to better explain the constitutive behaviour. Effect of orientation and location of specimen in the as-cast ingot, on deformation behaviour has also be discussed for which more experiments are in progress.

1. Figure Showing uniaxial compression test on Gleeble 3500 (Left), Typical Stress-Strain response of AA5182 (Right)


DETERMINATION OF STRAIN DURING HOT TEARING BY IMAGE CORRELATION

Jason Mitchell

Metals Processing Group; Dr. Steve Cockcroft Frank Forward Building, Room 401b


Research Summary: Hot tearing refers to cracks that frequently occur within the mushy zone during cooling from the liquid to solid state during shape and ingot casting. Both ferrous and non-ferrous alloys may be affected, and there is some evidence to suggest those with long freezing ranges are more susceptible. Due to the nature of this defect the economic impact is often significant and can result in an immediate productivity loss. It is therefore important for industry to be able to better predict the susceptibility of various alloys to hot tearing. Various theories have been proposed and several different types of experimental methods have been developed to interpret the properties of alloys in the semi-solid state. However, many of these techniques do not produce good quantitative data (i.e. strain) that can be used to calibrate a thermal-mechanical computer simulation of casting. Existing experimental methods often measure strain indirectly by means of a load train frozen into the end of the casting which moves at a specified loading rate. However, local strain at the hot tear initiation site would be more valuable for computer model calibration. Under development is a new hot tearing test which localises strain to promote hot tearing to occur in only one region of the casting. Images of this region captured during solidification will be correlated with each other and used to determine strain accumulated during hot tearing. Image capture tests were recently conducted at The University of Queensland, Australia, using an existing hot tear rig. The images have been correlated with one other to determine strain using a commercial software package. Temperature data was also collected during testing allowing alloy fraction solid data to be compared with strain accumulation during hot tearing. Preliminary results will be presented at MMRC 2005.

Figure - Hot tear and associated strain contour map in Al-0.5% Cu alloy.


High temperature oxidation behaviour of single crystal superalloy, CMSX-10

Subray Hegde

Microstructure Engineering Group; Ainul Akthar, Roger Reed) AMPEL-124A


Research Summary: The continuous quest of gas turbine designers to increase the turbine inlet temperature is limited by the high temperature capabilities of the superalloys with which turbine components are made. Over 30 years, there have been tremendous improvements in the high temperature properties of superalloys. Historically, the research work in the area of superalloy designing was focused in increasing the mehcanical properties; predominantly creep resistance. And, the surface protection, though important, received little attention. As a consequence, the new generations of the superalloys are showing lower corrosion resistance as against better mechanical properties when compared to the previous generation alloys. Hence, the oxidation/corrosion study has gained importance in the industry. In the present work the high temperature oxidation behaviour of one such new generation nickel base single crystal superalloy, CMSX-10 has been examined. A series of isothermal oxidation tests of the alloy was carriedout in a thermogravimetric analyser at temperatures ranging from 800'C to 1250'C for 100hrs. The plot of mass gain v/s time at various temperatures shows a transition from parabolic to sub-parabolic growth. Also, mass gain (after 100hrs of oxidation) v/s temperature curve shows an unusual behaviour (fig). The scanning electron micoscopy and XRD analysis of the specimens provided insight into the observed anomaly.

2

2.5

3

3.5

4

4.5

700 900 1100 1300

Temperature (Deg C)

Mas

s ga

in/A

rea

(mg/

cm s

q)

Variation of mass gain (after 100hrs of oxidation) with temperature showing the anomalous oxidation bhaviour of CMSX-10.


Catalytic Leaching of Silver Ore with Dissolved Ferric Cyanide

Feng Xie Hydrometallurgy Group; David Dreisinger


Research Summary: The silver extraction was usually much lower compared with that of gold during cyanidation process. This is mainly due to their different mineralogical characteristics as in some gold-silver ore silver may occurs dominantly as acanthite (Ag2S) other than nature metals or alloy (such as electrum). The low solubility of silver sulfide in weak cyanide solution results in obvious low silver recovery which sometimes could not be tolerated while treating the high grade silver ore or concentrates. A catalytic leaching process with dissolved ferric cyanide was investigated with the aim to raise the silver recovery during cyanidation process. Through the stoichiometry tests, the general chemistry of silver sulfide dissolution in ferric cyanide-cyanide solution was determined as Ag2S + 2Fe(CN)63- + 7CN- = 2Ag(CN)32- + CNS- + 2Fe(CN)64- . It also proved that the silver sulfide is nearly comlpetely dissolved after 48 hours leaching in 0.5g/l Fe(III) (in hexaferricyanide) ans 0.5g/l NaCN solution while less than 5% silver recovery was observed in absence of ferric cyanide. Catalytic and baseline leaching tests were conducted on several Veladero and Pierina ore samples to determine the improvement on silver recovery. The preliminary results indicate that the effect of ferric cyanide on silver and gold recovery is not obvious. By comprehensively analyzing the NaCN and lime consumption and the variation of the supernatant potential, it was speculated that most of the dissolved ferric cyanides had be consumed by reductive minerals such as sulfides. The possibility of the application the catalytic leaching process then should be well considered.

Figure 1 Ag extraction versa leaching time for baseline and catalytic leaching Figure 2 The effect of ferric cyanide addtion on Au and Ag recovery


Galvanic Effect Between Chalcopyrite and Pyrite In Atmospheric Leaching

Darren Mayne

Hydrometallurgy Group; David G. Dixon Frank Forward Building, Room 417


Research Summary: Chalcopyrite (CuFeS2) is the most abundant source of copper in the world. Historically, this mineral was processed by smelting to produce pure copper metal. However, due to increasing environmental regulations concerning sulphur dioxide emissions, lower grade ores, and difficulties in selling byproduct acid, there is a demand to develop a hydrometallurgical process to treat chalcopyrite. Sulphate-based leaching (more specifically ferric leaching) of chalcopyrite has been investigated due to the relative simplicity of the flow sheet. Unfortunately, chalcopyrite exhibits a passivating behavior, which drastically limits the overall extraction of copper in a reasonable residence time. The leaching behavior of this mineral can be viewed as an electrochemical cell, where copper oxidation and ferric reduction occur on the mineral surface. It has been found that the kinetics of reduction of ferric is much more rapid on pyrite than on chalcopyrite. Therefore, a galvanic couple can be formed between these two minerals, resulting in an overall increase in chalcopryite-leaching rate. Initial experiments conducted in stirred tank reactors have shown that complete extraction is possible in twenty-four hours. A study of the kinetics of the galvanic couple is the focus of the research. Parameters such as acidity, total iron, temperature, chalcopyrite:pyrite ratio, and solution potential are investigated on a variety of chalcopyrite sources.

Figure 1. Image of the stirred tank reactor used in the leaching experiments

materials engineering research colloquiummtrl.sites.olt.ubc.ca/files/2014/06/mercdec05.pdf · frank...

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