#sintering

Scientists just found a way to 3D print one of the hardest metals on Earth

Tungsten carbide-cobalt (WC-Co) is widely valued for its extreme hardness, but that same strength also makes it very difficult to shape and manufacture. Current production methods consume large amounts of costly material while delivering relatively modest yields. As a result, researchers have been searching for a more efficient and economical way to produce these exceptionally tough materials. WC-Co cemented carbides are essential for applications that demand strong resistance to wear and high hardness, including cutting and construction tools. Traditionally, these materials are produced through powder metallurgy. In this process, powders of WC and Co are compressed under high pressure and heated in sintering machines to form solid cemented carbide. While this method produces very durable final products, it uses significant quantities of expensive raw materials and generates inefficient yields.

'Permanently wet' coating method could transform wastewater treatment by helping bacteria survive better

Living bacteria embedded in coatings could clean wastewater, capture carbon and generate biofuels—but only if they survive the manufacturing process. Researchers at the University of Surrey and the University of Warwick have developed a method that keeps bacteria submerged throughout coating formation, increasing the number of surviving cells by around 500 times compared to conventional approaches. The research, published in ACS Applied Materials & Interfaces, addresses a persistent problem with the technology of biocoatings—thin layers of polymer that contain living bacteria. Most sewage treatment already depends on bacteria to break down organic matter and process nitrates and ammonia, but those bacteria are grown in large open tanks that are expensive, space-hungry and slow to respond to changes in load.

How to train your catalyst, one atom at a time

How do you keep a copper catalyst from losing its oomph? Just add a dusting of platinum, says a new study published in Nature Materials. A team of researchers, including scientists at the Department of Energy's SLAC National Accelerator Laboratory, investigated a class of metal nanoparticles used as catalysts in major industrial processes. They found that adding a trace amount of platinum to copper nanoparticles greatly reduced an effect known as "sintering," which causes these catalysts to degrade over time. The problem of 'sintering' At peak performance, metal nanoparticles—which include copper, silver, and gold—increase manufacturing throughput by a thousandfold, enabling efficient production of everything from plastics, fertilizer, and fuels to medicine manufacturing and fuel cell operation.

Researchers have demonstrated a new technique that uses lasers to create ceramics that can withstand ultra-high temperatures, with applications ranging from nuclear power technologies to spacecraft and jet exhaust systems. The technique can be used to create ceramic coatings, tiles or complex three-dimensional structures, which allows for increased versatility when engineering new devices and technologies. "Sintering is the process by which raw materials -- either powders or liquids -- are converted into a ceramic material," says Cheryl Xu, co-corresponding author of a paper on this research and a professor of mechanical and aerospace engineering at North Carolina State University. "For this work, we focused on an ultra-high temperature ceramic called hafnium carbide (HfC). Traditionally, sintering HfC requires placing the raw materials in a furnace that can reach temperatures of at least 2,200 degrees Celsius -- a process that is time-consuming and energy intensive.

Sintered salt (NaCl)

Processing The salt has been compacted (20MPa) and sintered for four hours at 785 degrees C Applications A sintered preform of salt can be used as a preform in the investment casting of open celled metal foams. The preform can then be washed out. Sample preparation The sample has been sputter-coated with gold Technique Scanning electron microscopy (SEM) Length bar 140 μm Further information The interconnectivity of pores in the reticulated aluminium foam was found to be strongly dependent on the degree of sintering of the salt. The sintering occurs by a non-densifying mechanism but the necks grow progressively wider with time. Four hours provides sufficient interconnectivity for the salt to be readily washed-out. Contributor J A Curran Organisation Department of Materials Science and Metallurgy, University of Cambridge