ResearchSpace

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Welcome to ResearchSpace, the institutional repository of the CSIR. ResearchSpace is an open access electronic archive collecting, preserving and distributing scholarly digital materials created by the CSIR.

Recent Submissions

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Laser surface alloying of a novel Nb11.2Cr22.2 Co22.2Ni22.2Cu22.2/TiN/VC composite coating: A preliminary parametric study

(2024-12) Alabi, A; Popoola, A; Popoola, O; Mathe, Ntombizodwa R

A preliminary investigation was conducted to choose process parameters for laser surface alloying of a novel high-entropy alloy-based composite coating on a steel substrate. The chosen ranges for laser power, scanning speed and powder feed rate are 1500 to 2500 W, 0.4 to 0.8 m/min ute and 0.14 to 0.24 g/minute, respectively. The study examined the effect of powder feed rate and scanning speed on the properties of single beads. B eads' geometrical properties were measured, from which dilution percentage and aspect ratio were calculated. The correlation between microstructure and hardness value was also investigated. The highest combination of desired properties was achieved at 1500 W, 0.4 m/minute and 0.14 g/minute parameter settings. The bead deposited at the optimal condition resulted in dilution percentage, aspect ratio, and hardness value of 80.16%, 14.47, and 447.47 ± 6.60 HV0.3, respectively. It hardness profile across deposited layer interface revealed that hardness values decreased across bead-heat affected zone-substrate interface in the order: 447.47 ± 6.60 HV0.3 > 339 ± 36.93 HV0.3 >155.3 ± 1.01 HV0.3. Scanning electron microscopy revealed excellent bead-substrate melt pool mixing, resulting in good interfacial bonding, cracking, and pore-free microstructure.

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Acoustic device for recording and tracking rock hazards on the mining face

(2024-09) Greeff, Heinrich; Pienaar, M; Hanekom, Johan WL

To enhance personnel safety and operational efficiency in underground mining, this project introduces an innovative acoustic device for recording and tracking rock hazards on the mining face. This system combines advanced acoustic analysis with an ultra-wideband (UWB) location system to interpret sounds produced during rock mass sounding and scaling. The location system is georeferenced to the mine’s local coordinate system using available survey pegs. By integrating these technologies, each acoustic data point includes a spatial XYZ coordinate which facilitates tracking of loose rock locations throughout the mining excavation process. This dual-sensory approach advances previous methods by leveraging the innovation of acoustic technology and tailoring algorithms to specific rock types, enhanced by the tracking function so that rock hazards encountered underground can be mapped and communicated to the operational team. The collected data offers a systematic approach to hazard identification and enhances mine designs and operational strategies by providing insights into the dynamic response of the rock mass during excavation under different mining conditions. This project offers a new approach to proactive hazard management, potentially transforming how mines are operated and mine designs monitored to ensure safety and efficiency.

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On the existence of a family of ideal aircraft configurations

(2024-09) Huyssen, Reinhard J; Spedding, GR

The bulk of fossil fuel in aviation is consumed in the domain of fixed-wing subsonic flight. Environmental concerns put strong incentives on the industry to improve flight efficiency. Best flight efficiency can only be attained if an aircraft design is based on its ideal configuration. Already since the middle of the previous century, the industry became entrenched in the tube-and-wings configuration, here referred to as the Current Dominant Configuration (CDC). It is widely speculated that better arrangements of wings and bodies exist, and many research initiatives are dedicated to the exploration of alternatives. These are typically done for specific types of aircraft, mostly for the airline industry. Yet, new aircraft developments keep employing the CDC as if proposed alternatives are ignored. Here a hypothesis is tested which suggests that a single family of aircraft configurations exists which is ideal for the majority of economically significant flight objectives within this domain. To organise the aircraft design space into families of configurations, a hypothetical Ideal Wing is introduced as a common basis from which all configurations evolve by inflation to provide practical flyers with volume for their payload. While the most prominent configurations, including the CDC, appear to disqualify as candidates for the proposed ideal configuration, the one which qualifies, has not been seriously examined in human aviation, although it is familiar. Termed the Natural Dominant Configuration, as it appears in natural flyers, it certainly merits further exploration.

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Assessing the nanomechanical, wear and thermal stability of Ti-Al-Si-V alloys produced via laser engineered net shaping (LENS) in-situ alloying

(2024-12) Raji, SA; Popoola, API; Pityana, Sisa L; Tlotleng, Monnamme

Titanium aluminide (TiAl) intermetallic alloys are highly recognized because of their lightweight qualities and are particularly useful for replacing heavier Nickel-based (Ni-based) superalloys in high- temperature components. This study fossed on the investigation of the nanomechanical, wear, and thermal stability of intermetallic Ti-Al-Si-V alloys fabricated by in situ alloying with elemental metal powders using the laser engineered net shaping (LENS) technology. The impact of Vanadium (V) feed rate was examined both before and during the annealing heat treatment, which involved 60mins at temperatures of 1200 and 1400°C, and furnace cooling (FC) conditions. After heat treatment (1200°C and 1400°C), it was discovered that V addition enhances the Ti-Al-Si-V alloy's nanomechanical properties. According to the nanoindentation results, the mechanical characteristics of the heat-treated samples were typically better than those of the as-deposited alloy and were equivalent to the qualities of commercially available TiAl alloys. The alloy that was heat-treated at a temperature of 1200°C exhibited better tribological and thermal stability. Lastly, the as-deposited sample performed better in terms of tribological and thermal stability aspects than the sample that was heat-treated at 1400°C.

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The use of amino acids in gold leaching; the FTIR and DFT approach

(2024-09) Tapfuma, A; Akdogan, G; Luckay, RC; Lopis, Anton S

The drive towards environmentally benign gold mining, often referred to as ‘green mining’, has gained momentum as a response to the escalating environmental concerns linked to cyanide usage in gold processing. Recently, amino acids have emerged as promising gold-leaching lixiviants, offering advantages over the conventional cyanide methods. However, the bulk of research has predominantly focused on glycine, the first member of the alpha-amino acid group, leaving other amino acids unresearched. In a novel approach, this study shifts the focus to the use of alanine in gold leaching and associated gold-alanine complexation at both experimental and computational levels, coupled with dissolution work. Experimental analyses through Fourier Transform Infrared Spectroscopy (FTIR) showed that alanine, in either its neutral or deprotonated state, effectively bonds with gold through donor electrons from nitrogen (N) and oxygen (O) at the amine and carboxylic end, respectively. In addition, the complexes of deprotonated alanine, compared to neutral (zwitterion) alanine, exhibited higher characteristic peak shifts during complexation. Furthermore, quantum computational calculations revealed that deprotonated alanine formed the most stable gold complex compared to the neutral amino acid, characterized by the N-Au-N bonding. The complexation of gold and deprotonated alanine exhibits the larger complexation energy compared to the neutral form, as revealed by the computational analyses. The third part of the study involved the dissolution of gold using both the deprotonated and neutral molecules, and the results showed that gold dissolution was more pronounced using the deprotonated molecule. This study showed that the gold dissolution is connected to the complexation as shown by FTIR and DFT, and this can be seen in high gold dissolution corresponding to a high peak shift at deprotonation pH and high complexation energy for the gold with the deprotonated alanine compared to the neutral alanine. Lastly, the study suggests that deprotonated alanine can be a possible lixiviant to leach gold from secondary gold sources such as tailings.