Engineering topics

Sleugh, Andrew

Publications and source records attributed to Sleugh, Andrew.

5 records

DOE OSTI2023

Dynamic fracture processes in hydrogen embrittled iron

Mechanistic understanding of hydrogen embrittlement is critical to the transport and storage of hydrogen as a sustainable fuel. Experimental observation of dynamic fracture processes in hydrogen environments has been challenging. Here, in-situ transmission X-ray microscopy is used to image polycrystalline iron foils that are concurrently strained and electrochemically charged with hydrogen. Using this technique, voids and microcracks down to ∼30 nm in size are identified at or near the crack tip and tracked as strain is increased. We observe both hydrogen-induced transgranular failure and hydrogen-induced intergranular failure with distinct fracture processes. We find that transgranular fracture occurs through the formation of sharp branched structures at the main crack tip that are reminiscent of slip band formation. This is followed by void growth and coalescence, and interaction with secondary cracks that lead to propagation of the main crack. Intergranular fracture is found to occur through void coalescence along grain boundaries, along with significant secondary cracking near the crack tip. The crack growth rate is greater for void-mediated intergranular failure than for slip-mediated transgranular failure. Additionally, the removal of hydrogen results in recovered ductility for a crack initially propagated under hydrogen charging.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Detection of voids in hydrogen embrittled iron using transmission X-ray microscopy

Hydrogen embrittlement remains a barrier to widespread adoption of hydrogen as a carbon-neutral energy source. Here, hydrogen embrittlement mechanisms are investigated across length scales in iron using transmission X-ray microscopy (TXM), digital image correlation (DIC), and notched tensile testing during in-situ electrochemical hydrogen charging. TXM reveals void size and spatial distribution ahead of a propagating crack. We find hydrogen charging leads to voids within ~10 μm of the crack tip and suppression of voids beyond this distance. Near the crack tip, voids are elongated in the direction of the crack and are smaller than voids in an uncharged sample. In the presence of hydrogen, these voids lead to quasi-cleavage fracture and a sharper crack tip. DIC shows localization and reduction of plastic strain with hydrogen charging, and tensile testing reveals a reduction in fracture energy and elongation at failure. Finally, these results are discussed in the context of hydrogen embrittlement mechanisms.

08 HYDROGEN↗

DOE OSTI2021

Rapid Open-Air Processing of Low-Cost Perovskite Solar Modules

We report an industrially relevant approach to both scalable and fast open-air perovskite photovoltaic (PV) module production. This work resolves some of the most formidable barriers to module-level scaling that the perovskite community has been facing. Key advances include scalable large-area spray deposition, new monolithic integration scribing techniques, advanced photoluminescence characterization, and reproducible high-throughput manufacturability. Our rapid spray processing techniques enabled the highest perovskite PV efficiency produced in open-air. Innovations in scribing techniques enabled the first single-source laser process to achieve perovskite module monolithic integration and technoeconomic analysis led to a comprehensive cost model for perovskite module manufacturing. We report significant progress in reducing perovskite manufacturing costs necessary to potentially compete with incumbent Si-based PV for utility-scale power generation.

cost modeling↗

DOE OSTI2021

Perspectives of Open-Air Processing to Enable Perovskite Solar Cell Manufacturing

We report high throughput open-air processing techniques for the scalable production of all device and barrier layers for perovskite photovoltaics (PV). This work discusses and resolves some of the most formidable barriers to module-level scaling that the perovskite community has been facing. Our advanced technoeconomic manufacturing analysis indicates that vacuum-based processes with high capital expenditures (CapEx) and low throughputs dominate the cost of production. Open-air fabrication methods offer low CapEx routes to manufacturing, but achieving reproducibility in ambient conditions with varying relative humidity has been a persistent challenge. The use of rapid processing methods with plasma curing to convert films from the solution-state enables reproducibility, moisture immunity, and the highest perovskite PV efficiency produced in open-air. These methods are readily translatable to in-line processing where layers are sequentially deposited without the need for lengthy post-annealing steps that reduce throughput and involve additional equipment. Significant progress is demonstrated in reduced manufacturing costs as perovskites contend as a commercially viable next-generation thin film PV technology.

14 SOLAR ENERGY↗

DOE OSTI2020

Rapid Open-Air Fabrication of Perovskite Solar Modules

We report on the open-air fabrication of perovskite solar modules with key advances including scalable large-area spray deposition, new monolithic integration scribing techniques, advanced photoluminescence characterization, and reproducible high-throughput manufacturability. Perovskite deposition with linear speeds of 12 m/min without a post-anneal are demonstrated with improved device performance, luminescent yield and >10X carrier lifetimes. Manufacturability using monolithic integration of series-connected modules is accomplished with a new indirect fiber laser ablation scribing method. A stable cell and module power output of 18.0% and 15.5%, respectively, was achieved with a subcell V oc > 1.06V. A comprehensive supporting technoeconomic analysis details the entire in-line manufacturing process from the glass substrate to the junction box of the encapsulated module. Here, the module manufacturing cost, balance of system costs and levelized cost of energy for a range of module efficiencies and lifetimes provides insights for the necessary tool speeds, efficiencies, and lifetimes for utility-scale energy generation.

14 SOLAR ENERGY↗