World's most heat resistant material found

December 25, 2016

London, Dec 25: Scientists have identified materials that can withstand temperatures of nearly 4,000 degrees Celsius, an advance that may pave the way for improved heat resistant shielding for the faster-than-ever hypersonic space vehicles.heat

Researchers from Imperial College London in the UK discovered that the melting point of hafnium carbide is the highest ever recorded for a material.

Tantalum carbide (TaC) and hafnium carbide (HfC) are refractory ceramics, meaning they are extraordinarily resistant to heat. Their ability to withstand extremely harsh environments means that refractory ceramics could be used in thermal protection systems on high-speed vehicles and as fuel cladding in the super-heated environments of nuclear reactors.

However, there has not been the technology available to test the melting point of TaC and HfC in the lab to determine how truly extreme an environment they could function in. The researchers developed a new extreme heating technique using lasers to test the heat tolerance of TaC and HfC.

They used the laser-heating techniques to find the point at which TaC and HfC melted, both separately and as mixed compositions of both.

They found that the mixed compound (Ta0.8Hf0.20C) was consistent with previous research, melting at 3,905 degrees Celsius, but the two compounds on their own exceeded previous recorded melting points. The compound TaC melted at 3,768 degrees Celsius, and HfC melted at 3,958 degrees Celsius.

The findings may pave the way for the next generation of hypersonic vehicles, meaning spacecraft could become faster than ever.

"The friction involved when travelling above Mach 5 -hypersonic speeds - creates very high temperatures," said Omar Cedillos-Barraza, currently an Associate Professor at the University of Texas.

"So far, TaC and HfC have not been potential candidates for hypersonic aircraft, but our new findings show that they can withstand even more heat than we previously thought - more than any other compound known to man," said Cedillos-Barraza, who carried out the research as a PhD student at Imperial College London

"This means that they could be useful materials for new types of spacecraft that can fly through the atmosphere like a plane, before reaching hypersonic speeds to shoot out into space," he said.

"These materials may enable spacecraft to withstand the extreme heat generated from leaving and re-entering the atmosphere," he added.

Examples of potential uses for TaC and HfC could be in nose caps for spacecraft, and as the edges of external instruments that have to withstand the most friction during flight.

Currently, vehicles going over Mach 5 speeds do not carry people, but Cedillos-Barraza suggests it may be possible in
the future.

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
February 6,2020

Washington D.C., Feb 6: An international team of astronomers has found an unusual monster galaxy that existed about 12 billion years ago when the universe was only 1.8 billion years old.

The team of astronomers was led by scientists at the University of California, Riverside.

Dubbed XMM-2599, the galaxy formed stars at a high rate and then died. Why it suddenly stopped forming stars is unclear.

"Even before the universe was 2 billion years old, XMM-2599 had already formed a mass of more than 300 billion suns, making it an ultra massive galaxy," said Benjamin Forrest, a postdoctoral researcher in the UC Riverside Department of Physics and Astronomy and the study's lead author.

"More remarkably, we show that XMM-2599 formed most of its stars in a huge frenzy when the universe was less than 1 billion years old and then became inactive by the time the universe was only 1.8 billion years old," Forrest added.

The team used spectroscopic observations from the W. M. Keck Observatory's powerful Multi-Object Spectrograph for Infrared Exploration or MOSFIRE, to make detailed measurements of XMM-2599 and precisely quantify its distance.

The study results appear in the Astrophysical Journal.

"In this epoch, very few galaxies have stopped forming stars, and none are as massive as XMM-2599," said Gillian Wilson, a professor of physics and astronomy at UCR in whose lab Forrest works.

"The mere existence of ultramassive galaxies like XMM-2599 proves quite a challenge to numerical models. Even though such massive galaxies are incredibly rare at this epoch, the models do predict them."

"The predicted galaxies, however, are expected to be actively forming stars. What makes XMM-2599 so interesting, unusual, and surprising is that it is no longer forming stars, perhaps because it stopped getting fuel or its black hole began to turn on. Our results call for changes in how models turn off star formation in early galaxies," the professor stated.

The research team found XMM-2599 formed more than 1,000 solar masses a year in stars at its peak of activity -- an extremely high rate of star formation. In contrast, the Milky Way forms about one new star a year.

"XMM-2599 may be a descendant of a population of highly star-forming dusty galaxies in the very early universe that new infrared telescopes have recently discovered," said Danilo Marchesini, an associate professor of astronomy at Tufts University and a co-author on the study.

"We have caught XMM-2599 in its inactive phase," Wilson said, who led the W. M. Keck Observatory data acquisition
Co-author Michael Cooper, a professor of astronomy at UC Irvine, said this outcome is a strong possibility.

"Perhaps during the following 11.7 billion years of cosmic history, XMM-2599 will become the central member of one of the brightest and most massive clusters of galaxies in the local universe," he said.

"Alternatively, it could continue to exist in isolation. Or we could have a scenario that lies between these two outcomes," he stated.

The study was supported by grants from the National Science Foundation and NASA.

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
July 3,2020

Mumbai, Jul 3: In yet another move to keep Chinese technologies companies at bay, the Centre has cancelled the 4G upgradation tender for BSNL as it has decided to come up with fresh specifications for the upgrade process, sources said.

The Department of Telecommunications (DoT) is likely to issue a fresh tender in the next two weeks.

People in the know said that the fresh tender may not allow Chinese companies to participate and that the new tenders that will be floated in the next two weeks will emphasise on Make in India.

As the border tussle with China escalated last month and around 20 soldiers lost their lives, the government had last month asked both BSNL and MTNL not to use equipment of Chinese makers in their upgrading process to 4G facilities.

Huawei and ZTE are the major Chinese telecom equipment makers working with Indian telecom companies and they would be the hardest hit by the decision.

The impact may be felt in terms of the much-awaited 5G trials in the country. After much deliberation, the Centre last December decided to allow Huawei to take part in the 5G trials.

The cancellation of tender for BSNL's 4G upgradation comes after the Centre on Monday banned 59 Chinese apps including TikTok, WeChat and UC Browser.

A statement by the Ministry of Electronics and IT said that the decision was taken since "there is credible information that these apps are engaged in activities which are prejudicial to sovereignty and integrity of India, defence of India, security of state and public order".

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
March 25,2020

In an unprecedented crisis despite Prime Minister Narendra Modi assuring the continuation of essential services like food and groceries, online marketplaces like Flipkart and Amazon along with delivery platforms like Bigbasket, Grofers and FreshToHomes hit a major blockade on Wednesday as local authorities shut warehouses and sent delivery boys back, even harassed them.

Millions of people across cities were left helpless at homes as essential items like fruits and vegetables, dairy and milk, meat and fish etc did not reach their doors despite placing orders well in advance. Later, the orders went dry.

While Grofers' warehouse in Faridabad was closed by the local law enforcement agencies, Bigbasket complained that the police stopped its delivery partners and "some of them were even beaten up by for no fault of theirs".

"We are not operational due to restrictions imposed by local authorities on movement of goods in spite of clear guidelines provided by central authorities to enable essential services. We are working with the authorities to be back soon,' Bigbasket tweeted.

In a statement to IANS, Bigbasket said that it will help to have better coordination between the Centre and state, and between the state and local police to "ensure that our delivery vans and bikes don't get stopped by the police. Bigbasket and bb daily are not taking new orders".

Furious people stormed the social media platforms, writing their plight to NITI Aayog CEO Amitabh Kant on Twitter.

"Sir, all e-commerce are down. Believe me I tried everything (Grofers, Bigbasket, Flipkart, Amazon, Big Bazaar), no delivery till 31st March or Server Down or No Service. Need to think how we can enable them through digital India," tweeted one user.

Kant tweeted back to Bigbasket: "They should give me specifics - State & location. I will act on it by getting in touch with concerned authorities & sorting it out. Govt guidelines exempt them. We will ensure that citizens are not impacted".

Kant also responded to Grofers: "Cold storages & Warehouses as well as delivery of all essentials goods including food, pharma thru E-Commerce are exempted under MHA order. I have spoken to CS & DGP, Haryana . They have taken immediate action to ensure that supply chains efficiently function for the citizens".

The subscription-based hyperlocal delivery startup FreshToHome sent messages to its customers, saying that despite the government declaring food delivery as essential, "we are facing hardships in continuing our operations".

"Please bear with us as we are working hard to unblock local authority hurdles," said the FreshToHome team.

Reports later surfaced that the Department for Promotion of Industry and Internal Trade (DPIIT) has initiated talks with the state Chief Secretaries asking them not to restrict movement of people engaged in home delivery of essential items, mentioned in the list of exempted items circulated by the Home Ministry.

Meanwhile, Flipkart said it has temporarily suspended its operations and services - including grocery items. The marketplace has decided to halt all orders from March 25 for all three supply chains -- groceries, non-large goods and large items.

"Flipkart has temporarily suspended orders as we assess the possibilities of operating in the lockdown. We are prioritising the safety of our delivery executives and seeking the support of the local governments and police authorities to meet the needs of our customers as they stay home during this lockdown," Rajneesh Kumar, Chief Corporate Affairs Officer, Flipkart, said in a statement.

E-commerce giant Amazon said the company has to "temporarily stop taking orders and disable shipments for lower-priority products.

"For all pending customer orders on lower-priority products, we are reaching out to customers and giving them a choice to cancel their orders, and receive a refund for prepaid items," said the company.

Witnessing a surge in demand, supermarket chain Biz Bazaar entered the fray, with launching doorstep delivery services in major cities like Delhi, Mumbai, Bengaluru and Gurugram.

However, within no time, Big Bazaar was flooded with calls, forcing the company to issue a statement, saying that "In light of the recent announcement, we are receiving an unprecedented number of requests for doorstep delivery. There could be a delay due to the restrictions on movements".

Already battling massive surge in demand, the online delivery platforms faced other issues too, including zero access to several high-rises across the country which have gone under complete lockdown with all entry and exit gates locked.

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.