Research

Abstract: Functional Strontium Phosphate Coated Magnesium Alloys for Orthopaedic Use

This project aims to develop a functional strontium (Sr)-release surface upon magnesium-based orthopaedic implants to suppress the rapid degradation rate of Mg, facilitate new bone formation and ultimately shorten healing process. The project will establish theunderstanding of the formation mechanisms of Sr-releasing coatings, and determine the critical release rate of Sr to activate bone cell responses. The project is significant for the development of practical, bone-favourable and degradation-inhibiting surfaces for magnesium implants, which are in demand and can bring significant patient benefits. The project will forge new and important collaborations and provide an output for biomedical technology locally and internationally.

The project is supported by ARC Linkage project LP150100343 'Functional Strontium Phosphate Coated Magnesium Alloys For Orthopaedic Use'. Visit the project's grant page on the ARC website for more information.

Abstract #1: High-Throughput Discovery of New Corrosion Inhibitors

The generation of new corrosion inhibitor leads requires the experimental testing of many hundreds of chemicals under varying conditions (concentration, pH, etc) on multiple different metal samples with perhaps thousands of synergistic inhibitor combinations, a virtual impossibility by standard corrosion techniques. I developed a high-throughput method that allows for 88 simultaneous corrosion inhibitor tests in 24 hours on a single metal plate (Corrosion Science, 2012, 58, 327). Leads generated by this technique are then analysed further by electrochemistry and also incorporated as a pigment in a coating for further electrochemical & salt spray testing (New Journal of Chemistry, 2020, 44, 7647-7658). Successful inhibitors or inhibitor combinations, discovered by these methods, have been patented.

Publication highlights

• White, P. A., Collis, G. E., Skidmore, M., Breedon, M., Ganther, W. D., Venkatesan, K., Towards materials discovery: assays for screening and study of chemical interactions of novel corrosion inhibitors in solution and coatings. New Journal of Chemistry, 2020, 44, 7647-7658.
  
• Taheri, P., Milosev, I., Meeusen, M., Kapun, B., White, P., Kokalj, A., Mol, J. M. C., On the importance of time-resolved electrochemical evaluation in corrosion inhibitor screening studies. NPJ Materials Degradation, 2020, 4, 12.
  
• White, P. A.; Smith, G. B.; Harvey, T. G.; Corrigan, P. A.; Glenn, M. A.; Lau, D.; Hardin, S. G.; Mardel, J.; Markley, T. A.; Muster, T. H.; Sherman, N.; Garcia, S. J.; Mol, J. M. C.; Hughes, A. E. A new high-throughput method for corrosion testing. Corrosion Science, 2012, 58, 327.
  
• Harvey, T. G.; Hardin, S. G.; Hughes, A. E.; Muster, T. H.; White, P. A.; Markley, T. A.; Corrigan, P. A.; Mardel, J.; Garcia, S. J.; Mol, J. M. C.; Glenn, A. M., The effect of inhibitor structure on the corrosion of AA2024 and AA7075.  Corrosion Science 2011, 53 (6), 2184.
• White, P. A.; Hughes, A. E.; Furman, S. A.; Sherman, N.; Corrigan, P. A.; Glenn, M. A.; Lau, D.; Hardin, S. G.; Harvey, T. G.; Mardel, J.; Muster, T. H.; Garcia, S. J.; Kwakernaak, C.; Mol, J. M. C, High-throughput channel arrays for inhibitor testing: Proof of concept for AA2024-T3. Corrosion Science, 2009, 51 (10), 2279.

Patents

• Methods for Inhibiting Corrosion. US Patent 2020/0040465A1
  
• Soluble Corrosion Resistant Sol-Gel. US Patent 2019/0241752A1
  
• Polymeric Agents and Compositions for Inhibiting Corrosion. International Patent WO 2017/152240 A1
• Compositions for Inhibiting Corrosion. International Patent WO 2016/154680 A1
• Recovery of Precious Metals. US Patent 2003/0154822 A1

Abstract #2: Australian War Graves project

Project duration: 03/2022 - 03/2023

RMIT’s RDF Team is working with the Department of Veterans’ Affairs’ Office of Australian War Graves (OAWG) to help ensure that commemorative bronze plaques and lettering on marble & granite headstones remain in good condition and are legible for the maximum time. OAWG is responsible for the care & maintenance of these commemorations in perpetuity. RMIT will work with OAWG to examine both fabrication & exposure conditions to provide guidance to enhance the life of these important memorials.

Abstract: Next Generation Corrosion Inhibitors for Protection of Galvanised Steel and Cold Rolled Steel

Corrosion has a significant economic impact with losses in the magnitude of billions of USD annually in transportation, manufacturing and infrastructure. In this project, new corrosion inhibitors for galvanised and cold rolled steel are being screened experimentally and quantum chemically described using density functional theory and classical methods. A database is generated for computational model building to identify lead structures for the development of new highly effective inhibitors.

The project was conducted in conjunction with BASF Coatings.

Abstract: Developing Functional Coating Systems for Bio-metal for Orthopaedic Implants

The desirable mechanical properties and superior biocompatibility of magnesium (Mg) and its alloys has placed them in the research frontier in materials for biomedical applications. However, their clinical applications are significantly restricted by the high degradation rate in physiological environment. In order to tackle such a limitation, functional polymeric coating systems will be developed to address rapid degradation as well as to reduce other clinical issues such as wear resistance, infection and low bone-inductivity.

The project was conducted in conjunction with Surface Engineering for Advanced Materials ARC Training Centre (SEAM).

Abstract: Development of a Robotic Electrochemical Testing Facility

Corrosion poses significant challenges to the transportation, manufacturing and infrastructure sectors. For this reason, it is imperative to prevent and control corrosion using corrosion inhibitors. A corrosion inhibitor protects a metal by restricting cathodic or anodic activity on the metal surface. Its exact performance depends on its exact molecular chemistry. Due to this dependence on molecular structure, there are literally tens of thousands of possible inhibitors so high throughput screening methods are required to select the best. In this work, a fully electrochemical robotic system will be developed for the purpose to select and design the best performing corrosion inhibitors. The robotic facility will carry out more than 100 electrochemical tests per day.  

The project was conducted in conjunction with BASF Coatings.

Dr Ernane de Freitas Martins

Abstract: Multi-scale QM/MM + NEGF Formalism to Address Electrified Metal/Water/Corrosion Inhibitor Interfaces

The use of molecular modelling to investigate the performance of corrosion inhibitors can provide significant gain to the proposal of new and more efficient inhibitors. Although its use has increased over the last few years, the most commonly used models still do not consider some important aspects, such as solvent effects and the stability of the proposed inhibitors when a potential is applied. To address these gaps, we propose using a new approach that combines density functional theory (DFT), non-equilibrium Green's functions (NEGFs), and a quantum mechanics/molecular mechanics (QM/MM) method to include a realistic number of solvent molecules. Our project’s end goal is the best characterisation thus far of the metal/solvent/corrosion inhibitor interface.

The project was conducted in conjunction with the Catalan Institute of Nanoscience and Nanotechnology (ICN2, Spain).

Kai Rui Wang

PhD abstract: Developing an Agar System for Studying Microbiologically Influenced Corrosion of Ferrous Pipes in Soil

Risks of leakage and contamination are incurred by the corrosion of buried steel water pipelines, which cause health and safety hazards to the communities that potable water is delivered to. As much of the corrosion originates from the outer pipe surface, monitoring soil-to-steel interactions is crucial to understanding the physical and chemical mechanisms that cause corrosion. It was found that semi-solid agar could be a good analogue for simulating clay-based soil conditions for corrosion testing; however, a more systematic study needs to be carried out to investigate the metal-bacteria-environment interactions present in microbiologically influenced corrosion situations. Detailed studies are currently being performed to analyse such interactions in the novel semi-solid agar system. The system as an analogue of soil, if validated, would allow significant advancements to laboratory-based research of corrosion in a soil environment, thus allowing the scientific community to better combat MIC for pipelines buried underground.

Project Publications

• K. Wang, A. Spark, I. Cole, and L. Ward (2019). ‘Effects of electrochemical techniques on carbon steel in agar’, Corrosion & Prevention; 23-27 November 2019, Melbourne, Australia. Paper ID 45. p 1-11.
• A Spark, K. Wang, I. Cole, D. Law, and L. Ward (2020). ‘Microbiologically influenced corrosion: a review of the studies conducted on buried pipelines’, Corrosion Reviews, 38(3), 231-262. DOI: 10.1515/corrrev-2019-0108.

Jakeria Mohd. Rafiuddin

PhD abstract: Corrosion Inhibition Studies of Aluminium Alloys 6XXX Series and Mechanisms of Film Formation

Corrosion protection of high-strength AA6xxxx alloys by film-forming small molecules such as 2mercaptobenzimidazole (2MBI) in a corrosive environment are potentially a useful contribution to the corrosion literature. 2MBI has been reported to interact with metal surfaces by S & N moieties from its five-membered ring structure, and promptly forms an inhibitor film. The produced film could hinder the diffusion of ions and reduce water adsorption on metal surfaces. However, time-dependent-dependent studies of 2MBI film growth in saline solution over AA6xxxx alloys, changes to barrier properties of inhibitor-induced film against ionic diffusion, alteration of bonding environments from the metal-coating interface to the coating-electrolyte interface, and consequent changes in coating structure aligned with mechanical properties have been minimally reported in the available literature. The aim of this PhD project is to highlight these critical issues and develop a methodology to systematically answer the relevant research questions on film-forming mechanisms. Results of electrochemical & complementary surface analysis techniques have indicated that 2MBI could adsorb over AA6xxxx in saline solution in the form of a film from as early as 30 mins, then become stabilised after 90 mins with a continuous but inhomogeneous structure. The adsorbed film maintains a higher inhibition efficiency (97%) by reducing current density, which drops gradually with time (Fig 1). The 2MBI-induced film appears to be complex with the coexistence of aluminum oxide & inhibitor constituents (Fig 2). During longer periods, the complex film becomes porous & defective with a gradual drop in inhibition efficiency & barrier properties (Fig 3). High-resolution AFM imaging coupled with nano-indentation has revealed changes to inhibitor film stiffness over time (Fig 4). The film stiffens both in the early stages of growth and again after 90 mins. Distribution of oxide inside the film structure is thought to play a key role in this regard. Chemical analysis of inhibited treated saline solution in the presence of AA6xxxx has revealed time-dependent inter- & intramolecular changes to 2MBI.

Project Publications

• Jakeria, M.R., R.J. Toh, X.-B. Chen, and I.S. Cole (2022). ‘Evolution and stability of 2-mercaptobenzimidazole inhibitor film upon Al alloy 6061’, Journal of Applied Electrochemistry, p. 1-24, DOI: 10.1007/s10800-022-01687-w.
  
• Jakeria, M., L. Ward, and I. Cole (2021). ‘Long term durability studies on the corrosion inhibition effect of 2-mercaptobenzimidazole (C3H4N2S) on AA6022: Mechanism of film formation and influence of IMPs’, Surfaces & Interfaces, 25: p. 101164. DOI: 10.1016/j.surfin.2021.101164.
  
• I.S. Cole, L. Ward, and M.R. Jakeria (2019). ‘Influence of azole derivatives on corrosion inhibition of AA6022’, Corrosion & Prevention 2019, 25-28 November 2019, Melbourne, Australia.
  

PhD abstract: Study of Quorum Sensing (QS)-Driven Inhibitors for Mitigating Microbially Influenced Corrosion of Carbon Steel

Microbiologically influenced corrosion (MIC) is a process by which microorganisms initiate, facilitate, or accelerate the electrochemical corrosion reactions of metallic components. Several studies report that MIC accounts for 20-40% of the total cost of corrosion. For example, MIC in oil & gas pipelines can result in significant production loss & serious environmental effects. Biofilm formation caused by surface microorganisms upon metal components is known to play a vital role in MIC. The QS system plays a significant role in controlling the expression of some bacterial enzymes, e.g. catalase regulates biofilm formation and thus the MIC rate for metal. As such, avoiding biofilm formation via inhibiting QS is a sound potential strategy for mitigating MIC of metal. This PhD aims to elucidate the mechanistic role of QS both in biofilm formation & corrosion of carbon steel, a prevalent engineering material for construction of pipelines, with Pseudomonas aeruginosa as a model organism.

Qiushi Deng

PhD abstract: Rapid Discovery of Next-Generation Inhibitors for Galvanised Steel

Great momentum has been gained in the development of corrosion inhibitor technologies to mitigate corrosion of metallic materials, in particular for zinc & galvanised steel. Corrosion inhibitors are crucial to ensuring the integrity, durability, and safety of many metallic structures. The use of metallic salts as corrosion inhibitors has been broadly explored since the early stages of corrosion science owing to their ability to passivate the metal surface and generate protective films. However, increasing environmental concerns and the pursuit of more cost-efficient techniques has shifted the focus toward organic alternatives due to their many advantages, including i) cost effectiveness, ii) pronounced inhibiting effect, and iii) flexibility to different applications with non-toxic nature. Unfortunately, candidate molecules acting as effective corrosion inhibitors are rich in diversity of chemistry and structural complexity, and their inhibition behaviour also depends on the existing form of molecules (i.e. de/protonation) and the metal’s surface condition (i.e. surface charge & presence of oxides). Given these challenges, this project aims to design a sound strategy to explore high-efficiency organic inhibitors from a large variety of candidate molecules in an attempt to reveal their inhibition mechanism from the viewpoint of inhibitor structural change, molecular evolution, and interfacial metal charge. The expected finding of this project is an improved understanding of the protection mechanism of organic inhibitors from a molecular viewpoint, which will form a concrete basis for the design & preparation of new inhibitor molecules of engineering relevance.

This project is conducted in conjunction with BASF Coatings.

Project Publications

1. Q. Deng, S. Jeschke, B.J. Murdoch, S. Hirth, P. Eiden, J.N. Gorges, P. Keil, X.B. Chen, I. Cole (2022). ‘In-depth insights of inhibitory behaviour of 2-amino-4-methylthiazole towards galvanised steel in neutral NaCl solution’, Corrosion Science, vol. 199, 110206. 10.1016/j.corsci.2022.110206.
   
2. M.S. Song, Q. Deng, R.J. Toh, I. Cole, X.B. Chen (2022). ‘Permanganate, molybdate and vanadate conversion coatings’ in ‘Conversion coatings for magnesium and its alloys’, Springer, Cham, 2022. DOI: 10.1007/978-3-030-89976-9_5.

Karim Gamaleldin

MRes abstract: Rapid Evaluation Assessment of Corrosion Inhibitors

My MRes concerns the development of rapid screening techniques for evaluating a wide range of potential inhibitors for 5xxx aluminium alloy systems. The use of corrosion inhibitors for the protection of these alloys is well established. While various inhibitors have been developed and assessed for the protection of marine-grade Al alloys, the most common practice for many decades has been the addition of chromate-based pigments to paint films. Chromates are recognised as extremely robust and effective inhibitors, however, there is increasing awareness of their toxicity and associated environmental hazards. This has led to the search for alternative inhibitors that are less toxic, more affordable, and effective at low concentrations.

Traditionally, the development of an inhibitor system for a particular application can be extremely time consuming, particularly if a systematic study using various analysis techniques is applied to a large, diverse range of potential inhibitors. Testing times can range from hours (electrochemical testing) to weeks (weight loss experiments, pitting studies), and even years (outdoor exposure field trials). This project aims to use the droplet corrosion test method for the first time with 44 structurally related chemical compounds as corrosion inhibitors to rapidly evaluate their performance.

Shrinivas Kulkarni

PhD abstract: Optimising the Surface Condition of Additively Manufactured Implants

I started my PhD in August 2020. This is focused on environmentally assisted corrosion (EAC), specifically the stress corrosion cracking (SCC) of additively manufactured (AM) passive metals in a physiological environment. The performance of an implant in the human body is mainly controlled by two characteristics: mechanical environmental functionality and bio-compatibility. The most widely used alloys in such implants are stainless steel 316L (SS316L) and titanium-aluminium 6wt%-vanadium 4% (Ti6Al4V). Samples of SS316L and Ti64 will be produced using Selective Laser Melting (SLM) and Electron Beam Melting (EBM) AM processes. Surface characteristics including roughness and AM process-related defects including porosity, cracks, and segregation will be explored. The aim is to establish the relationship between surface/microstructure and the total life of commercial implant materials when subject to environmental assisted cracking and fatigue. The implants will be subjected to corrosion testing in both NaCl solution and simulated body fluid. Furthermore, these samples will be subjected to stress corrosion cracking and fatigue testing, and the results will be analysed for the stress concentration factor at pits and the lifetime of the implant.

References

[1] M. Talha, Y. Ma, P. Kumar, Y. Lin, and A. Singh, “Role of protein adsorption in the bio corrosion of metallic implants – A review,” Colloids and Surfaces B: Biointerfaces, vol. 176. Elsevier B.V., pp. 494–506, Apr. 01, 2019, doi: 10.1016/j.colsurfb.2019.01.038.

[2] A. Bandyopadhyay, B. V. Krishna, W. Xue, and S. Bose, “Application of Laser Engineered Net Shaping (LENS) to manufacture porous and functionally graded structures for load bearing implants,” J. Mater. Sci. Mater. Med., vol. 20, no. S1, pp. 29–34, Dec. 2009, doi: 10.1007/s10856-008-3478-2.

[3] X. Z. Zhang, M. Leary, H. P. Tang, T. Song, and M. Qian, “Selective electron beam manufactured Ti-6Al-4V lattice structures for orthopedic implant applications: Current status and outstanding challenges,” Current Opinion in Solid State and Materials Science, vol. 22, no. 3. Elsevier Ltd, pp. 75–99, Jun. 01, 2018, doi: 10.1016/j.cossms.2018.05.002.

José María Castillo Robles

PhD abstract: A Multiscale Approach to Bias-Dependent Electrochemical Processes at Metallic-Aqueous Interfaces: Corrosion Inhibitors

Corrosion is a pre-eminent problem in industry, causing compounding financial losses and environmental problems. To prevent the corrosion process, toxic inorganic compounds such as chromates are often used as pigment additives or conversion coatings. Over the last few years, these are increasingly being replaced by more environmentally friendly inorganic and organic compounds. These organic compounds (corrosion inhibitors) have lone pair electrons and are thus good donors of charge, preventing cathodic and anodic reactions. While many chemicals are being studied for this purpose, the fundamental mechanisms determining corrosion inhibitor performance are still far from understood. We use a multiscale approach to address this problem, specifically investigating the interactions of a database of 28 compounds with aluminium surfaces in the presence of an aqueous electrolyte. We are using first-principles methods to obtain insight into the corrosion processes taking place at the molecular level, which will aid us in designing more efficient and sustainable corrosion inhibitors.

An innovative approach for modelling electrochemistry processes from first principles is through a setup consisting of two electrodes acting as charge reservoirs, which are kept at different potentials and are separated by an aqueous electrolyte. This setup is widely used to simulate electronic transport in nano-devices, where electrodes held at different potentials are connected to a nano-device through which an electric current is established. The method, first described in the context of density functional theory (DFT) in [1] and now implemented in the TranSIESTA code [1,2] (part of the open-source SIESTA software [3,4]), is now a standard for simulation of electronic transport in electronic nano-devices.  To enable the use of realistic electrolyte solutions, we will apply the hybrid quantum mechanics/molecular mechanics (QM/MM) approach [5], in which the system is split into quantum and classical regions according to the chemical processes of interest. This domain decomposition allows us to include in the QM region a reduced number of atoms (the metallic surface + the adsorbed molecules) with the remaining atoms (aqueous solution) modelled in the MM region.

José María Castillo Robles is cotutelle with the Autonomous University of Barcelona (UAB) & the Catalan Institute of Nanoscience and Nanotechnology (ICN2, Spain).

Current Google Scholar profile including contact details.

PhD abstract: Functionalized Carbon Materials for Corrosion Inhibitors & Energy Storage Applications

Broadly, the research work concerns functionalized carbon materials for corrosion resistance coatings on metal alloys. Newly design organic molecules were synthesised and functionalized with graphene oxide for improved inhibition efficiency and stable corrosion resistance in aggressive environments. The long-term stability of organic inhibitor molecules is useful as conventional inorganic alternatives can fail in aggressive environments. However, some organic inhibitor molecules cause damage to the environment if they are made from non-biodegradable organic molecules. Heterocyclic compound-functionalized graphene oxide and imidazole-functionalized graphene oxides act as ‘green’ inhibition coating materials for Mg alloys, mild steel, and titanium as they are biodegradable.

This project was conducted in conjunction with RMIT University (Melbourne) & Central University of Gujarat (India)

Chathumini Samarawickrama - ALUMNUS

Current LinkedIn profile including contact details.

MRes abstract: Study of Mechanisms of Film-Forming Behaviour of Corrosion Inhibitors for Commercial Grade Aluminium Alloys

In today's society, corrosion protection of structural aluminium alloys in the aerospace, marine, automotive, and construction industries is of paramount importance. This is commonly achieved via corrosion-inhibiting compounds. However, constraints such as potential health issues associated with exposure to conventional chromate-based corrosion inhibitors has led to the development of low-toxicity corrosion inhibitors for a wide range of industries. Since then, much work has been carried out to evaluate inhibitor performance and their mechanisms of action, but only a few studies have elucidated the precise film-forming characteristics of particular inhibitors. Therefore, this study presents key aspects of the film-forming behaviour of the selected inhibitors and the test methods used to evaluate the inhibitor-induced films in chloride solution. This study also aims to provide significant insights into film tenacity, influence of the molecular structure, and film stability in the absence of inhibitors to provide a deeper understanding of film-forming and film-breakdown mechanisms. This study focusses on two inhibitors known for their high corrosion inhibition efficiency for protection of aluminium AA2024-T3 alloy, namely 2-mercaptobenzothiazole and Na-mercaptopropionic acid. During this work, a wide range of electrochemical methods were utilised in conjunction with various surface analysis methods to understand inhibitor-induced film formation. (For the citations & images behind the above-described work, see my abstract included with the Corrosion and Inhibition subteam’s research.)

This project was conducted in conjunction with BASF Coatings.

Dr Milan Patel

Abstract: Multiscale Modelling of Selective Laser Melting

RMIT is participating in a CSIRO-NTU Singapore-led project to develop cutting-edge simulation models of additive manufacturing – specifically the Selective Laser Melting process. This project will combine high-definition continuum fluid dynamics at the part scale, which models powder melting & melt pool tracking, with phase-field modelling at the grain scale that predicts solidification rate and finished-part microstructure. ‘Live’, bidirectional data exchange between these two sub-models permits the most accurate predictions of both the behaviour of the SLM process & the microstructure of the finished part to be obtained from one simulation platform.

All coding is performed using open source platforms, allowing for rapid technology transfer to industry partners. Enquiries should be addressed to dayalan.gunasegaram@csiro.au.

Dr Xiangdong Li

Abstract: A Spatiotemporally Solved Predictive Model for COVID-19 Transmission in Indoor Spaces

Since the outbreak of the COVID-19 pandemic, indoor spaces have been the major venue for the disease to spread from person to person.

Spatiotemporally solved predictive models that can comprehensively account for various engineering and clinical/epidemiological factors (e.g. building design, HVAC layout, occupant movement, SARS-CoV-2 variants and stage of infection, the extent of personal protective equipment (PPE), and immunisation) are highly demanded in the global fight against COVID-19.

Supported by the Victorian Higher Education State Investment Fund (VHESIF) and in collaboration with partners from the healthcare, commerce, and manufacturing sectors, RMIT University is developing such a comprehensive predictive platform that holistically integrates the above factors into a single model. By combining the latest computational fluid dynamics (CFD) techniques, epidemiological models, and clinical/virological data for COVID-19 variants, the platform can generate high-resolution, quantitative ‘risk maps’ for COVID-19 infection in indoor spaces (Figure 1).

This capability is critical to the development of effective prevention & protection strategies. The predictive platform also provides a universal theoretical framework to develop fit-for-purpose predictive models for other airborne diseases such as influenza, measles, tuberculosis, etc.

The project was conducted in conjunction with the Victorian Higher Education State Investment Fund.

Neil Wilson

PhD abstract: Conformal Tooling via Hybrid Manufacturing

Conformal tooling is an advanced technology used to construct moulds for the mass manufacture of parts with complex shape. Its development continues across the industrialised world due to its promise in producing moulded parts at lower cost. It achieves this by significantly reducing manufacturing cycle time, i.e. the time required to complete a single moulding cycle from material injection to extraction of the part from the tool, and also by improved quality of the moulded parts due to closer control of mould cavity temperature throughout the moulding process.

Numerous materials may be used in the creation of moulded parts, resulting in a potentially vast array of relevant client industries & products. The fundamental factors limiting the growth in scale and market penetration of conformal tooling are country specific, i.e. the presence of advanced manufacturing infrastructure, the availability of skilled multi-disciplinary toolmakers capable of incorporating the high-level additive manufacturing (AM) skillset, and simulation capability specific to the design of conformal tools. In Australia, the latter is only now becoming established in the form of specific design software components for use with conformal tooling, i.e. heat flux simulation, part deformation, heating/cooling fluid dynamics together with mould-filling fluid dynamics. These components alone do not deliver a generic methodology for the design of conformal tooling – for this purpose, generative design linkage modules are required that connect the modelling components. Such linkage modules promise conformal tooling design capability for use by non-expert users and are the focus of this thesis.

Well-designed conformal tooling demonstrates an optimal (i.e. uniform) temperature distribution (‘heat map’) along the inner surface of the tooling cavity. This is achieved by using additive manufacturing to include channels for heating/cooling fluid near both the mould’s cavity and core surfaces. Predictions of the required number, cross-sectional shape/size, pitch (inter channel distance & pattern), and distance between the channels & the cavity and tool surfaces must be reliably generated to achieve this homogenous heat map in a cost-effective manner, i.e. with the minimum of built prototypes. These typically multi-objective design calculations are conducted to a varying extent of accuracy by the current stable of process simulation software packages. However, none yet consider the varying heat map at the cavity face during the final material-filling stage of the injection process. This is now the subject of development within several software houses including Moldex, Altair, Siemens and nTopology. The research described in this thesis aims to achieve a manufacturer-independent (generic) software linkage module of this type, which is furthermore validated against experiments for both single-alloy and bi-metal combinations. We will also examine the effect of the air gap in cavity due to thermal shrinkage within the mould.

This project was conducted in conjunction with Romar Engineering Pty Ltd and CSIRO.

Ayush Ranjan

MRes abstract: Digitization of Workplaces to Ensure Safety from Airborne Pathogens

The COVID-19 pandemic has highlighted the importance of estimating & managing risk from airborne pathogens in indoor environments. The building services (HVAC) system, as well as the environmental disturbances generated by human movement & large electrical/electronic systems all influence transmission of contaminants inside a building. Therefore, it is imperative & timely to understand the impacts of these factors on contaminant transport to mitigate the risk of infection by airborne biological pathogenic contaminants. 

Four RMIT project teams are working on different aspects of this project:

1. Sensing team: Designing a digital model of a four different industry client buildings & installing multiple types of environmental sensors therein
   
2. Aerosol team: Building large-scale Computational Fluid Dynamics (CFD) simulations of the four buildings to compute infection risk maps based on their floorplans & HVAC details
   
3. Human Movement team: Tracking human-building interactions
   
4. System Integration team: Combining insights from other teams and simplifying them into generalised rules/guidance for facility managers to implement to reduce infection risk
   

As a part of the ‘System Integration team’ of this project, I will be (i) analysing combined datasets from different sensor types to generate insights into human-building interactions of relevance to reducing infection risk, and (ii) developing micro-scale CFD simulations (‘micro-cases’) from common building floorplans. These micro-cases will provide low-order infection risk maps that we will eventually ‘stitch together’ to produce low-order infection risk maps for an a priori unknown, real floorplan that predict how to reduce its inherent infection risk. Running & analysing infection risk maps from a large set of micro-cases CFD results will then help us develop a simple set of general rules that can be transmitted to building/facilities managers to reduce infection risk for a priori unknown, real floorplans.

This project is conducted in conjunction with the Victorian Higher Education State Investment Fund.

Omid Bafkar - ALUMNUS

Current LinkedIn profile including contact details.

Phd abstract: Study of Airflow Phenomena in the Human Respiratory System

Obstructive Sleep Apnoea (OSA) is a common disorder, and continuous positive airway pressure (CPAP) is usually the therapy of choice. CPAP is known to have problems with adherence with many patients eventually abandoning the device. However, the development of an optimal OSA treatment for a specific patient requires a thorough understanding of the responses of the patient to the tailored OSA treatments which in turn need numerously costly clinical trials and measurements.

Therefore, accurate predictions of the responses of the patient to the tailored OSA treatments are highly desired. We implement numerical modelling methods and techniques to understand airflow behaviour in various sleeping positions and conditions.

This aims to provide a technique that can help specialists provide better treatment solutions to their patients. 

Ethical approval was obtained for all human trials.

National Computational Infrastructure (NCI) facilities were used for some of this research.

This project was conducted in conjunction with Oventus Manufacturing Pty Ltd and CSIRO.

Dr Hong Yin

Abstract: Functional Nanoparticles for Sensing, Adsorption & Antimicrobial Applications

Heavy metal ions in water have posed severe environmental and health risks due to their high toxicity, high aqueous solubility, and difficulty participating in biological transformations to non-toxic end products.  Traditional water-monitoring equipment is heavy, costly, and normally only one or a few elements are detected at any one time. A cheap and multiplexed measurement using a portable device is urgently required to monitor water quality in rural and remote areas. This project will apply surface-functionalised fluorescent nanoparticles, such as quantum dots (QDs) and carbon dots (CDs), in a home-made portable device for detecting multiple heavy metal ions in a semi-quantitative way. 

Other applied research in the nanostructures area includes tailored synthesis and surface modification of activated carbon adsorption materials and antimicrobial particles such as zinc oxide, silver, and magnesium hydroxide nanosheets for water purification and biomedical applications.

The project was conducted in conjunction with E-Micromaterial Technology Pty Ltd.

Dr Haiyan Li - AFFILIATE

Abstract: Bioactive Hydrogels for Tissue Regeneration

Tissue engineering provides a promising technology to address the critical gap between the growing number of patients on waiting lists for organ transplantation due to end-stage failure and the limited number of donated organs available for such procedures. One of the important factors in this technology – the tissue engineering scaffold – provides a means for the delivery of cells and/or growth factors to the site of damage and an appropriate template for new tissue formation throughout the construct. Among the different types of scaffold, injectable hydrogels have emerged as leading candidates for engineered tissue scaffolds due to their remarkable characteristics, including flexibility and versatility in fabrication, variety in composition, high moldability in shape, excellent biocompatibility, and similarity to the extracellular matrix.

The aim of our research is to fabricate injectable hydrogels with different features to meet various clinical applications, including injectable hydrogels with multilayer structures or macroporous structures, sequential delivery ability, bifunctional function, or a combination of the above. 

This project is funded as part of Haiyan Li's RMIT Vice Chancellor's Senior Research Fellowship.

Dr Shadi Houshyar - AFFILIATE

Abstract: Electrically Active Scaffold

Peripheral nerve injuries are the most common types of injuries affecting the nervous system. In the US alone, 20 million people suffer from peripheral nerve injuries costing ~$150 billion annually. A potential issue with current nerve guides is that they do not transmit electrical nerve impulses between the distal and proximal ends of an injured nerve, i.e. a synapse. Conductivity is a desirable property for a nerve guide being considered for peripheral nerve regeneration. Unfortunately, most conductive polymers reported for the fabrication of tissue engineering scaffolds are non-biodegradable and possess weak mechanical properties, and thus cannot be fabricated into 3D structures. This study will design a new nanocomposite material for the fabrication of nerve conduits, facilitating the growth and migration of neurons towards the targeted end of an injured nerve. This support and navigation of the scaffold lead to better sensory and motor function, which are highly in demand.

The second phase of the project is innovatively integrating an electrically conductive scaffold with a tailored wireless power transfer (WPT) receiver. This project will realise a WPT-stimulated electroconductive permeable nerve conduit that promotes nerve growth factors and aligned nerve regeneration for the recovery of sensory functions. These outcomes are essential for improving the quality of life for numerous patients suffering from peripheral nerve injuries.

This project is funded as part of Shadi Houshyar's RMIT Vice Chancellor's Research Fellowship.

Sabrina Beker - AFFILIATE

PhD abstract: Green Synthesis of Carbon Dots from Natural Resources as Potential Candidates for Nanobioremediation of Emerging Pollutants

A wide range of new & emerging pollutants (EPs) have been released into water bodies, mainly by human activities. Many of these EPs have been shown to be deleterious to the environment with some threatening the aquatic ecosystem.

Significant research & development is underway to develop new remediation technologies aimed at alleviating the environmental issues associated with EPs; however, the complete removal and efficient treatment of aquatic contaminants remains a huge challenge for water resource management. Advanced nanotechnology provides a promising alternative for increasing water treatment efficiency, especially carbon dots (CDs). CDs, which are fluorescent nanostructures in the size range of 2–10 nm, have attracted significant attention for their excellent physicochemical properties, low toxicity, chemical inertness, tunable fluorescence, good water solubility and potential applications in several fields of science and technology - particularly with respect to the environment. Recently, the conversion of natural resources into carbon-based dots has attracted major attention due to the environmental sustainability of the associated simple, economical and green synthesis.

Therefore, this research aims to synthesise CDs from green material and test them for their degradation of EPs in water. In particular, their ability to degrade industrial dyes and per- and poly-fluoroalkyl substances (PFAS) will be tested using the nanobioremediation technique developed in this study. In order to conduct a proper evaluation of the proposed nanobioremediation, an assessment of the impact of the CQDs on freshwater microbial community structure and the ecotoxicity of the CQDs will be conducted to minimise any adverse environmental impacts.

Sabrina Beker was supported by a Brazilian National Council for Scientific & Technological Development (CNPq) scholarship.

Jiajia Zhao

PhD abstract: Catalyst Development for CO₂ Hydrogenation & Mechanism Study

Concerns about record high (and still rising) atmospheric CO₂ concentrations is hastening the shift to the use of renewable fuels. One approach to mitigate this is CO₂ hydrogenation, i.e. the reaction of CO₂ & H₂ over a solid catalyst to produce carbon-neutral fuels including methane & methanol. Thermal- and photo-catalytic CO₂ conversion into hydrocarbons have been widely investigated as two promising CO₂ hydrogenation strategies. However, their cost-effective industrial applications will depend significantly on the design of efficient catalysts that are stable at relatively intense thermal-catalytic conditions or relatively mild photocatalytic conditions, whilst providing high conversion rate & selectivity. Supported plasmonic metals (e.g. Ru, Pt, Co, Ga, etc.) have demonstrated enhanced hydrocarbon formation by promoting H₂ dissociation and metal-support interaction. In addition, these metals can provide active sites by assisting with electron transfer during temperature- or light-driven reactions. The support material also plays an important role in stabilising metal particles and fine-tuning their electronic environment to improve reaction rate & selectivity, e.g. oxide supports such as ZrO₂ can provide adsorption sites for reactants or intermediates. The synergy amongst all the catalyst’s components is highly related to the reaction mechanism, and disclosing this mechanism via regulating the catalyst system is key to the rational design & optimisation of catalysts.

This project will design Ru/ZrO₂-based catalysts for CO₂ hydrogenation and investigate their reaction mechanism. A library of Ru/ZrO₂-based catalysts has been synthesised & characterised. Using a multi-reactor catalyst testing rig, catalysts have been screened in parallel for their performance at CO₂ hydrogenation. The results of this systematic investigation have been analysed together with insights obtained from in-operando PXRD characterisation and in-situ DRIFT. This synergistic approach is crucial to assembling credible reaction mechanisms for optimal CO₂ reduction using these catalysts, and will lead to further opportunities for carbon-neutral fuel production.

Dr Adam Truskewycz - ALUMNUS

Abstract: Nanoparticle Platforms for Environmental Remediation & Sensing

Release of heavy metals into the environment from industrial processes results in severe adverse social, environmental and human health problems. Many terrestrial and aquatic ecosystems contain persistent and undetected heavy metal concentrations which are unidentified due to the extensive cost associated with site sampling and expensive analytical measurements requiring trained scientific staff. On site detection of heavy metal contamination which is user friendly, cheap and rapid is therefore sought after to map out areas of concern and provide communities with information relating to the toxicity and suitability of their land and water resources for agricultural, potable and recreational use.

Nano-sensing of environmental pollutants is an emerging field of research possessing outstanding capacity for detecting low concentrations of pollutants (including heavy metals). This approach for pollution detection relies on a nanomaterial support which has fluorescent chemical functional groups attached to it which selectively bind the pollutant of interest. Upon binding, the fluorescence profile of the composite changes and can be measured. The concentration of heavy metal can be accurately associated with the amount of fluorescence output and heavy metal concentrations can be quantitatively determined.

Find out more about Adam:
Google Scholar
New team website

Bin Qian - ALUMNUS

Current LinkedIn profile including contact details.

Phd abstract: Development of Coumarins & Coumarin Composites as Optical Sensors for Cu²⁺ as Contaminants in Water & Soil

Copper contamination in soil and water is a major concern due to its direct impact on human health when present in excessive/inadequate amounts^[1,2] and form complexes with ligand, such as protein, molecules, enzymes, which possess electron rich centres to donate electrons, such as N, O, P, and S. Thus, the development of rapid and reliable sensing methods that are selective and sensitive to metals ions of interest, and that can be utilized in aqueous media is essential in allowing for rapid and readily available management of both nutrient- and contaminant-levels. By inviting molecular design and materials engineering, a series of fluorescent coumarin derivatives were designed, synthesized, and evaluated for their Cu²⁺ sensing performance in aqueous media to gain fundamental understanding of the structural requirements towards such molecular probes (Figure 1) using NMR, IR and MS, single crystal X-ray study of the probes and their Cu²⁺ complexes resulted in the insight understanding of the essential heteroatom ratio and configuration, and the optimum relative distances among the molecular moieties, rigidity of the structure and electron density with selective sensing^[1].

Meanwhile, aimed at the improvement of sensitivity and water solubility of previously developed Cu²⁺ - selective coumarin probes, SiO₂-coumarin nanohybrid was formulated via electrostatic attraction with negatively charged SiO₂ nanoparticles (SiO₂ NPs) and the selected coumarin in aqueous media at certain pH value. This material possessed the identical Cu²⁺ selectivity of the coumarin with lowered limit of detection and an extended linear detection range. The coumarin nanohybrids were also applied to determine Cu²⁺ concentration in aqueous soil extracts with >94% recovery rates when compared to standard soil analysis method - inductively coupled plasma-mass spectrometry (ICP-MS).

This project was conducted in conjunction with CSIRO.

References:

[1] Clemens, S.; Ma, J. F., Annual review of plant biology 2016, 67, 489-512.

[2] Giripunje, M. D.;  Fulke, A. B.; Meshram, P. U. Clean-Soil, Air, Water 2015, 43 (9), 1350-1354.

[3] Qian, B.; Váradi, L.; Trinchi, A.; Reichman, S.; Bao, L.; Lan, M.; Wei, G.; Cole, I. S.. Molecules 2019, 24 (19), 3569.