Scientists have synthesised a bi-functional catalyst made of nanocarbon material that can make rechargeable zinc-air batteries used in making electric vehicle propulsion more efficient and durable.

India is looking for alternatives to lithium-based batteries, and zinc, sodium and aluminium batteries are under fast-paced research. Metal-air batteries, where air is the cathode, are gaining ground, but the research is still nascent. The efficiency of such batteries, particularly zinc-air, is dependent on the cathode material. Binary metals are essential for achieving bifunctionality in electrocatalysts to be rendered as cathode materials in rechargeable zinc-air batteries.

The major hindrance is that the active metal centres are more likely to etch out if not properly bound to the substrate. This leads to uncertainty in the metal-active units, which impede the catalysts.

Scientists at the Indian Institute of Nano Science and Technology, Mohali, an autonomous institute of the Department of Science and Technology (DST), have developed an efficient bifunctional electrocatalyst. “This material could be further used as a cathode catalyst, impacting high power in both liquid and solid-state rechargeable zinc-air batteries,” says a DST press release.

New way of making steel alloy powder

Researchers at the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, have developed a manufacturing process for steel alloy powder that can help produce efficient cooling channels for pressure die casting. This can improve the service life and quality of cast parts, and reduce the number of rejections during the casting process.

Pressure die casting is used to manufacture devices ranging from medical to industrial. Manufacturing of die tools with efficient cooling channels through conventional processes has been challenging. In conventional manufacturing, the die tools are designed with compromised straight-line cooling channels.

The ARCI team has developed an additive manufacturing process for a steel alloy powder (called AISI H13) which can act as a tool for efficient cooling channels or conformal cooling channels (CC) for pressure die casting. “Such CC systems show great promise to substitute conventional cooling systems as the former can provide more uniform and efficient cooling effects and thus improve the production quality and efficiency significantly. The additive manufacturing process offers the freedom to give any desired shape to the cooling channels so that they can carry out the cooling efficiently,” says an ARCI press release.

Iron aluminide coatings for corrosion resistance

A team of scientists at the Centre for Engineered Coatings (CEC), International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), has developed low-cost iron-based intermetallic powders that can be used as corrosion-resistant coating for materials exposed to harsh environments like the high temperature in thermal power plants, where oxidation, corrosion, and wear-and-tear take place simultaneously. The coatings showed four times more corrosion resistance in the aqueous corrosive media than mild steel.

Wear and corrosion cause major damage over a range of service temperatures. Hence, the need to protect the component surface for economic viability. Such a surface coating on a turbine blade can enhance the service life.

At present, thermally sprayed chromium carbide-nickel chromium powder and tungsten carbide-cobalt (cermet) coatings are widely used for superior wear and high-temperature oxidation resistance in thermal power plant turbine blades, aerospace engine blades, landing gear shafts, and steel rolls in the paper industry. This is mainly attributed to their hardness, toughness, and corrosion resistance under exposure to nearly 550 degrees C in the case of tungsten carbide-cobalt coatings and up to 850 degrees C for chromium carbide-nickel chromium coatings. However, the powders are expensive due to the presence of cobalt and nickel. Besides, chromium is toxic. The replacement of these coatings with simple iron-based coatings with novel microstructural constituents is very promising. In this regard, iron-based solid phases involving two or more metallic or semi-metal elements (intermetallics) can play a major role owing to their hardness and better corrosion resistance. However, their deployment is restricted by low ductility. ARCI has addressed this by synthesising iron-based intermetallic powders and used them for depositing the coatings using detonation spray coating (DSC) technique.

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Besides, ARCI has developed gas atomised iron aluminide powder and deposited it on mild steel substrates through DSC, without any cracks or spalling. The coatings demonstrated four times more corrosion resistance in the aqueous corrosive media than mild steel.

The coatings show improved corrosion resistance when chromium and aluminium are in a solid solution with iron than in the iron-rich phases. The coatings demonstrated 30-40 per cent more wear resistance than mild steel under the solid particle erosion mode, implying they can be used for high-temperature erosion resistance applications. For further studies, ARCI has joined hands with NTPC to apply this technology to enhance the life of the power company’s boilers.

Virus-proofing aquaculture

Scientists at the Agharkar Research Institute (ARI) have developed a handy peptide-based diagnostic tool that detects an aquaculture pathogen known as the White Spot Syndrome Virus (WSSV).

Infection caused by the WSSV in the shrimp Penaeus vannamei results in huge loss of crop. This high-value superfood is susceptible to a wide range of viral and bacterial pathogens and the probability of infection is high. Improved nutrition, probiotics, disease resistance, quality control of water, seed and feed, immuno-stimulants and affordable vaccines play an important role in enhancing production. Technologies for early and rapid detection of pathogens in the field will help fish and shell-fish farming, which provides significant export revenue, with the country being a leading supplier to the US.

To provide a handy self-use diagnostic for WSSV, Dr Prabir Kulabhusan, Dr Jyutika Rajwade and Dr Kishore Paknikar developed a lateral flow assay using gold nanoparticles for easy visualisation of the results. Instead of using poly- or mono-clonal antibodies in assay development, the ARI scientists selected 12 amino acids containing peptides from a phage display library through bio panning. This was a time- and cost-saving approach, eliminating the need for immunisation of laboratory animals to obtain the antisera. With the use of peptides, cold-chain requirements for storage are reduced and the assay becomes production-friendly.