Johnson Matthey Technology Review - Volume 69, Issue 3, 2025

Research on building energy efficiency has increased significantly over the past twenty years, creating a complex and fragmented landscape that complicates a thorough comprehension of the field’s development and present condition. This study utilises a mixed-method approach that integrates bibliometric analysis and systematic literature review to investigate the building energy efficiency research environment from 2003 to 2023. We examined 1458 papers from the Scopus^® database, concentrating on publication trends, collaborative networks, research themes and emerging issues. Research on building energy efficiency has expanded significantly, exhibiting a compound annual growth rate of 15.3% in publications. Artificial intelligence, the internet of things and improved materials are crucial catalysts of contemporary advancements. Collaborations among academics, industry and policymakers have increased, promoting more applied research. This two-part paper presents the inaugural complete, longitudinal examination of the building energy efficiency research environment, elucidating its evolution, present condition and prospective trajectories.

This is Part II of a study utilising a mixed-method approach that integrates bibliometric analysis and systematic literature review to investigate the building energy efficiency research environment from 2003 to 2023. China, the USA and European nations are prominent contributors to building energy efficiency research. The emphasis of research has transitioned from individual building elements to comprehensive, systems-oriented methodologies. We delineate research gaps and emerging trends, providing a framework for researchers, policymakers and practitioners to progress in the domain of building energy efficiency.

Electrical discharge machining (EDM) is a highly effective and widely utilised unconventional manufacturing technology primarily used to produce complicated forms in materials that are challenging to machine. This versatile manufacturing approach finds applications in producing diverse items such as surgical instruments, aerospace components, automotive parts, dies and moulds. Despite its manifold advantages, this method presents notable drawbacks, including relatively modest material removal rates (MRR), significant tool wear rates (TWR), electrode wear ratio (EWR) and notable surface roughness (SR). The current paper examines numerous approaches used by researchers to enhance the functionality of EDM and the scope for upcoming research. The effects of various circuit and non-circuit characteristics on performance metrics like MRR, TWR and SR are listed. The impact of different electrode material, dielectrics and their alterations on machining performance are carefully examined. Furthermore, the paper elucidates a range of advanced EDM iterations developed to enhance performance through cutting-edge technologies. It delves into research findings concerning the environmental sustainability of EDM. It also examines various theoretical models that have been put out to describe EDM’s spark generation and material removal processes. The review’s final section provides a summary of the potential areas for EDM research in the future. The investigation has shown that material removal in EDM is a complicated process. The correct electrode and dielectric material must be chosen and their properties must be adjusted to fit the type of workpiece material for it to be effective. The choice of circuit parameters is also affected by the type of workpiece material. The effectiveness of EDM in machining metal matrix composites (MMCs), ceramics and nanomaterials requires more investigation.

This review is focused on ‘frustrated Lewis pair’ (FLP) hydrogenations. Following a discussion of the conceptual discovery and initial efforts to exploit the finding for metal-free hydrogenations, the scope of substrates that are susceptible to FLP hydrogenations are considered. The further advancement of FLPs to enantioselective reductions are discussed. Applications of the concept in transfer hydrogenation, and the reductions of carbon dioxide and main group substrates are also presented. Finally, the utility of the concept of FLPs in several heterogeneous catalysis systems is considered. The review concludes with an outlook for the future of FLP reductions.

Slurry erosion is a mechanically induced wear observed in various industries transiting the mixture of liquid and erodent particles, either naturally or affectedly. The equipment and pipelines need frequent monitoring and slurry erosion prediction to check the severity of erosion for implementing preventive measures to minimise the damage of erosion wear. Experimental investigation and online condition monitoring are very high priced and provide a fair idea about the extent of slurry erosion wear; nevertheless, precise prediction of slurry erosion wear requires in situ operating conditions. To minimise expenditure on slurry erosion testing or monitoring and accurate slurry erosion prediction, tribological modelling of slurry erosion wear by mathematical approach or computer-based simulations has proved to be an excellent approach by numerous researchers to foresee the slurry erosion wear and control its severity. Several authors in the past have aligned their efforts in this direction. This two-part review is an attempt to estimate the progress in the variety of tribological modelling (primarily mathematical models) of slurry erosion for its forecasting, monitoring and to suggest the apt approach for the modelling of slurry erosion wear, especially for hydroturbine components. This article covers the research studies pertaining to mathematical wear models for solid particle erosion recommending a commencing approach for slurry erosion wear modelling.

This article is Part II of a review of the progress in the variety of tribological modelling (primarily mathematical models) of slurry erosion for its forecasting, monitoring and to suggest the apt approach for the modelling of slurry erosion wear, especially for hydroturbine components. There is a discussion of mathematical modelling, irregularly shaped erodent particles and computer-simulation based models. Future scope and conclusions of this research are presented.

Solar power is the primary renewable energy solution for alleviating power shortages in developing areas. Leveraging this energy faces constraints arising from specific environmental conditions. Challenges in solar tracking systems include maintaining accuracy under varying environmental conditions, such as changes in sunlight, weather shadows and ensuring reliable performance while minimising energy consumption and mechanical wear. To address these challenges, solar tracking technology is employed. Solar trackers are pivotal in optimising power generation from photovoltaic panels, offering a range of drive types and control strategies to enhance efficiency. This review aims to explore various solar tracking systems to improve the efficiency of solar power generation. We compare the tracking approaches, performance, advantages and disadvantages of different tracking systems. Additionally, this review presents and categorises various types of solar tracking systems according to the technologies and methods of operation, focusing primarily on image processing-based solar tracking systems. Utilising image processing technology in solar tracking systems provides innovative approaches to enhance energy generation from photovoltaic panels. These techniques enable precise detection of the sun’s position, even under challenging environmental conditions, ultimately enhancing efficiency and reliability.

The ultrasonic and thermophysical properties of the platinum group metal nitrides (PGMNs) osmium nitride, iridium nitride and platinum nitride were scrutinised along <100>, <110> and <111> orientations at room temperature. In the present work, we evaluate the second, third and fourth order elastic constants (SOECs, TOECs and FOECs) of the PGMNs in the temperature span 0–500 K using the Coulomb and Born-Mayer potential model. At T = 0 K, the mechanical properties of the PGMNs were investigated for potential industrial applications. The ultrasonic wave velocity and other thermophysical parameters have been determined to evaluate the thermal performance of the chosen materials along the <100>, <110> and <111> orientations. The ultrasonic attenuation resulting from both the phonon-viscosity mechanism and the thermoelastic relaxation mechanism was calculated for three different orientations at room temperature. These calculated results were then analysed and compared with provided data on the selected materials and similar material types.

As a potential material for next-generation platinum channels, the Pt-5Au alloy offers promising advantages by significantly reducing processing costs while improving the quality of glass substrate production. This study investigates the possibility of enhancing the mechanical properties of the Pt-5Au alloy by introducing trace amounts of zirconium, leading to the formation of dispersion-strengthening phases. Using first-principles calculations, we systematically examined the mechanical and thermodynamic properties of four potential strengthening phases: Pt3Zr, PtZr, Pt3Zr5 and PtZr2. The calculation results of the enthalpy of formation (ΔH) and cohesive energy (Ecoh) of four potential strengthening phases show that they can all spontaneously perform and stably exist under 0 K and 0 Pa environment. Among them, Pt3Zr exhibits the most favourable properties, including outstanding toughness (Pugh’s ratio = 2.212), exceptional hardness (HV = 10.820 GPa) and thermodynamic properties closely aligned with those of the Pt-5Au alloy, making it the most suitable candidate for a dispersion-strengthening phase. This study provides a comprehensive analysis of the thermodynamic performance, mechanical performance and high-temperature performance of potential strengthening phases in the Pt-5Au alloy, offering theoretical guidance for optimising its composition and supporting the industrial application of platinum channels in the production process of high-performance glass substrates.

The isothermal section of the ternary systems gold-palladium-titanium and gold-rhodium-titanium at 1000°C was studied using the diffusion couple technique. These alloying systems are relevant for various technical applications, as functional materials for example high temperature shape memory alloys (HTSMAs), brazing filler metals, luxury items or biomedical implants. The research presents, for the first time, a comprehensive determination of phase relations and tie-triangles in these systems, identifying solid solubility of the various intermetallic compounds (IMC). The binary IMC of gold and palladium with titanium show a large solubility of the third alloying element, where gold and palladium replace each other at fixed titanium content. A complete solid solubility was observed between TiAu2 and α-Pd2Ti. The binary phases with B2 structure form a large single phase field with (β-titanium) that surrounds the phase field of Ti3Au. Moreover, this research sets the groundwork for further investigations into these alloys, recommending specific sample compositions for future studies to refine understanding of phase boundary definitions.

In pursuit of enhancing the high-temperature service performance of Pt-10Rh alloys, this study focuses on the preparation of two Pt-10Rh-based alloys through the incorporation of reinforcing elements zirconium and zirconium-yttrium. The investigation into the microstructure, mechanical properties and strengthening mechanisms of the alloys involved the utilisation of analytical tools such as an optical metallographic microscopy (OM), X-ray diffraction (XRD), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and tensile testing, coupled with first-principle computational analysis methods. The research results indicate the presence of Pt5Y precipitate phase and zirconium yttrium oxides in Pt-10Rh-0.5Zr-0.2Y alloy, but not detected in Pt-10Rh-0.5Zr alloy. It was found that adding a small amount of zirconium and yttrium elements to Pt-10Rh alloy can significantly enhance the mechanical properties at room temperature and 1300°C, especially the composite addition of zirconium and yttrium elements, which can also improve the high-temperature plasticity of the alloy. The strengthening mechanisms of zirconium and yttrium elements on Pt-10Rh alloy are mainly solid solution strengthening and second phase strengthening. The relationship between the mechanical properties of platinum-rhodium based alloys and their valence electron structure was discussed. The zirconium and yttrium reinforced platinum-rhodium based alloy studied in this work can replace Pt-10Rh alloy in certain fields.

Accurate measurement of glass transition temperature (Tg) and coefficient of thermal expansion (CTE) is of great significance in guiding the use and process performance of the materials. This manuscript measures the CTE and Tg of samples by the thermal expansion method and systematically researches the measurement factors affecting the Tg and the CTE, including the shape and size of the samples, the starting furnace temperature and the heat treatment process. The study shows that the sample shape and size, the starting furnace temperature and the heat treatment process all have an effect on the test results. At the same time, the placement of the sample and the data processing method will also make the test results deviate from the real value. Therefore, in order to accurately assess the thermal properties of the material, the size of the sample is specified to be 6 mm in diameter and 50 mm in length, while the initial temperature of the furnace during the CTE test should be lower than 35°C. In addition, test samples of the same glass grade should undergo the same heat treatment process to ensure the accuracy of the test results.