Our Research
ADDITIVE ANALYTICS offer additive manufacturing consulting services applying advanced materials and metal 3D printing process development for application specific solutions. Applications include thermal management, electrical machines, antimicrobial and crashworthiness among others. ADDITIVE ANALYTICS has supported research in many sectors publishing extensively in academic journals.
Electrical conductivity of additively manufactured copper and silver for electrical machine applications
Abstract
Efficient electrical machines are critical in driving the next generation of green energy technologies for many industries including automotive, aerospace and energy. However, one of the primary requirements to enable this is compact and functionalised windings optimised for custom geometries, while reducing losses and increasing power density. As such, bringing together design optimisation principles and application specific materials through AM offers the ability for superior performance while reducing the weight of electrical machine components in a cost-effective manner. L-PBF is the most mature AM technology for metals however laser processing highly reflective and conductive metals like Cu and Ag is highly challenging. In this regard, this study reveals the L-PBF processing of high purity Cu, Ag and Cu-Ag alloys and the resultant electrical performance characteristics. The research is built on a standard 400W L-PBF system where six Cu and Ag material variants are investigated in four comparative studies characterising the influence of material composition, recoating, laser exposure and electropolishing. For Cu, densities of 73%, 75% and 88% are achieved with small enhancements in Cu purity negated by lower sample densities resulting in lower electrical performance. Additively manufactured Ag was found to comparatively outperform both Cu and Cu-Ag alloys in density and electrical performance. Additionally, hard recoating and single laser exposure strategies positively influenced the electrical performance by 2.8% and 2% respectively. Furthermore, electropolishing parameters for L-PBF Cu are also established which resulted in improved surface roughness. Finally, the study fabricates electrical machine proof of concept coil windings highlighting the potential for 400W L-PBF processing of Cu and Ag extending the current state of the art.
Abstract
The COVID-19 pandemic and associated supply-chain disruptions emphasise the requirement for antimicrobial materials for on-demand manufacturing. Besides aerosol transmission, SARS-CoV-2 is also propagated through contact with virus-contaminated surfaces. As such, the development of effective biofunctional materials that can inactivate SARS-CoV-2 is critical for pandemic preparedness. Such materials will enable the rational development of antiviral devices with prolonged serviceability, reducing the environmental burden of disposable alternatives. This research reveals the novel use of L-PBF to 3D print a porous Cobalt-Chromium-Molybdenum superalloy with potent antiviral activity (100% viral inactivation in 30 min). The porous material was conceived using a multi-objective surrogate model featuring track thickness and pore as responses. The regression analysis found the most significant parameters for Co-Cr-Mo track formation to be the interaction effects of scanning rate (Vs) and laser power (Pl ) in the order PlVs > Vs > Pl . Contrastively, the pore diameter was found to be primarily driven by the hatch spacing (Sh). The study is the first to demonstrate the superior antiviral properties of 3D printed Co-Cr-Mo superalloy against an enveloped virus used as biosafe viral model of SARS-CoV-2. The material significantly outperforms the viral inactivation time of other broadly used antiviral metals such as copper and silver, as the material’s viral inactivation time was reduced from 5 h to 30 min. As such, the study goes beyond the current state-of-the-art in antiviral alloys to provide extra protection to combat the SARS-CoV-2 viral spread. The evolving nature of the COVID-19 pandemic brings new and unpredictable challenges where on-demand 3D printing of antiviral materials can achieve rapid solutions while reducing the environmental impact of disposable devices.
Abstract
The COVID-19 pandemic emphasises the need for antiviral materials that can reduce airborne and surface-based virus transmission. This study aims to propose the use of additive manufacturing (AM) and surrogate modelling for the rapid development and deployment of novel copper-tungsten-silver (Cu-W-Ag) microporous architecture that shows strong antiviral behaviour against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The research combines selective laser melting (SLM), in-situ alloying and surrogate modelling to conceive the antiviral Cu-W-Ag architecture. The approach is shown to be suitable for redistributed manufacturing by representing the pore morphology through a surrogate model that parametrically manipulates the SLM process parameters: hatch distance, scan speed and laser power. The method drastically simplifies the three-dimensional (3D) printing of microporous materials by requiring only global geometrical dimensions solving current bottlenecks associated with high computed aided design data transfer required for the AM of porous materials. Findings – The surrogate model developed in this study achieved an optimum parametric combination that resulted in microporous Cu-W-Ag with average pore sizes of 80 mm. Subsequent antiviral evaluation of the optimum architecture showed 100% viral inactivation within 5 h against a biosafe enveloped ribonucleic acid viral model of SARS-CoV-2. Research limitations/implications – The Cu-W-Ag architecture is suitable for redistributed manufacturing and can help reduce surface contamination of SARS-CoV-2. Nevertheless, further optimisation may improve the virus inactivation time. Practical implications – The study was extended to demonstrate an open-source 3D printed Cu-W-Ag antiviral mask filter prototype. Social implications – The evolving nature of the COVID-19 pandemic brings new and unpredictable challenges where redistributed manufacturing of 3D printed antiviral materials can achieve rapid solutions. Originality/value – The papers present for the first time a methodology to digitally conceive and print-on-demand a novel Cu-W-Ag alloy that shows high antiviral behaviour against SARS-CoV-2.
Abstract
On-demand additive manufacturing offers great potential for the development of functional materials for the next generation of energy-efficient devices. In particular, novel materials suitable for efficient dissipation of localised heat fluxes and non-uniform thermal loads with superior mechanical performance are critical for the accelerated development of future automotive, aerospace and renewable energy technologies. In this regard, this study reports the L-PBF processing of high purity Cu, Ag and novel CuAg alloys. The materials were analysed for their relative density, mechanical and thermal performance using X-ray computed tomography, destructive tensile testing and laser flash apparatus, respectively. It was found that while Ag featured higher failure strains, Cu in comparison showed a 109%, 17% and 59% improvement in yield strength (σyσy), Young’s modulus (E) and ultimate tensile strength. CuAg alloys, significantly outperformed Ag, Cu and all commercial Cu materials when it came to mechanical performance offering significantly superior performance. The yield strength, Youngs modulus and ultimate tensile strength were 105%, 33% and 94% higher in comparison to Cu. When it came to thermal performance, L-PBF Ag was found to offer a 70% higher thermal diffusivity in comparison to Cu despite the variation in density and porosity. CuAg alloys however only showed a 0.8% variation in thermal performance despite a 10–30% increase in Ag. Overall, the study presents a new understanding regarding the AM and performance of Cu, Ag and CuAg alloys.
Abstract
In this study copper-silver (CuAg) structures with varying Ag content were fabricated by in situ alloying and L-PBF AM. Powder morphology, distribution and elemental analysis were conducted using SEM and dynamic imaging for CuAg10, CuAg20 and CuAg30 atomised powder. The resultant pore defect morphology and distribution for each as built and annealed CuAg alloy structure was investigated and reported using X-ray Computed Tomography (XCT) and 3D visualisation. The atomic crystal structure for each as built and annealed CuAg alloy is reported through X-Ray Diffraction (XRD) analysis. Yield strength, Young’s Modulus, failure strain and Ultimate Tensile Strength (UTS) of AM CuAg structures are reported and sample fracture surfaces were analysed using SEM and Energy Dispersive X-Ray (EDX) techniques. Increased Ag content from CuAg10% to CuAg30% is shown to decrease the number of pore defects by 87% and 83% for as built and annealed samples with average pore size decreasing by 40% and 9.5%. However, the annealing process was found to increase the porosity by up to 164%. Furthermore, the annealing process resulted in atomic lattice contractions resulting in increased yield strength, Youngs Modulus and Ultimate Tensile Strength (UTS) for CuAg30%.
Abstract
Functionally graded thickness (FGT) is an innovative concept to create light-weight structures with better material distribution and promising energy absorption characteristics suitable for vehicle crashworthiness applications. Accordingly, this paper suggests innovative circular tubes with in-plane thickness gradient along their perimeter and assesses their crashworthiness behaviour under lateral loading. Three different designs of circular tubes with thickness gradient were considered in which the locations of maximum and minimum thicknesses are varied. Selective laser melting method of additive manufacturing was used to manufacture the different tubes. Two different bulk powders including titanium (Ti6Al4V) and aluminium (AlSi10Mg) were used in the manufacturing process. Quasi-static crush experiments were conducted on the laser melted tubes to investigate their crushing and energy absorption behaviour. The energy absorption characteristics of the different FGT tubes were calculated and compared against a uniform thickness design. The results revealed that the best crashworthiness metrics were offered by FGT titanium tube in which the maximum thickness regions were along the horizontal and vertical directions while the minimum thickness regions were at an angle of 45° with respect to the loading direction. The results reported in this paper provide valuable guidance on the design of FGT energy absorption tubes for lateral deformation.
Abstract
In this study the relationship between L-PBF process parameters, associated pore defects and resulting tensile properties of additively manufactured (AM) pure (99.9 %) silver structures are investigated using X-ray Computed Tomography (XCT) and 3D visualisation analysis. Yield strength, Young’s Modulus, failure strain and ultimate tensile strength are reported. Furthermore, fracture surfaces of the samples are analysed using optical microscopy and Scanning Electron Microscopy (SEM) to investigate fracture surface porosity content and surface roughness is analysed using digital microscopy. Pore defect distribution, morphology and resultant pore surface area are reported, and average pore size calculated in relation to process parameters variations. It was found that sample yield and ultimate tensile strengths of pure silver have a direct correlation with energy density at the powder bed related to L-PBF process parameters selected. However, Youngs Modulus values were found to be dependent on the average porosity pore size rather than sample density or number of pores. The results reported in this work serve as a basis for further material development and mechanical property predictions utilising XCT analysis for pure silver and other nonstandard L-PBF materials.
Abstract
Implant infection is a serious complication resulting in pain, mortality, prolonged recovery, and antimicrobial resistance (AMR). Reducing the risk-of-infection associated with tissue implants require imminent attention, where pure silver (Ag) offers enormous potential. However, the printability, mechanical performance and antimicrobial resistance of additively manufactured (AM) pure Ag is unknown. This is critical as Ag is thought to play a vital role in the development of AM patient-specific infection resistant implants in the decade to come. The study therefore additively manufactured 99.9% pure-Ag and systematically investigates its mechanical performance. Two porous bone scaffolds at approximately 68 and 90% (wt.) porosity were fabricated and analysed with X-ray nanotomography (X-ray nCT) and the mechanical properties investigated. Furthermore, the antimicrobial efficacy of printed silver was tested against the common implant infection-causing Staphylococcus aureus and led to 90% and 99.9% kill in 4 and 14 h respectively. The study, therefore, is a first step towards achieving a new generation Ag-based AM infection resistant porous implants.
Abstract
Additive manufacture (AM) of metals and alloys using powder-bed fusion (PBF) often employs a 400 W (1060–1100 nm wavelength) fibre laser as the primary energy source. Highly reflective and thermally conductive materials such as pure silver (Ag) offer significant challenges due to insufficient laser energy absorption at the powder bed. This work pioneers the processing, analysis, and fabrication of 99.9% atomised Ag using L-PBF AM featuring a 400 W fibre laser system. Firstly, the pure silver powder is characterised for its morphology, size, shape, distribution. Laser-powder interaction is then investigated through single track fabrication to assess the feasibility of laser melting pure Ag. Varied process parameter single laser pass and single-track fabrication on both copper and steel build substrates are conducted and analysed with optical and scanning electron microscopy (SEM) techniques. The resulting L-PBF process parameters are then used to create pure Ag 3D structures and the effects of laser power, scan speed, hatch distance and layer thickness on material density is evaluated. Furthermore, SEM analysis of the 3D structures was conducted to identify optimum laser power, scan speed, hatch distance and layer thickness required to create dense pure Ag structures.