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Collaboration may lead to additively produced ceramics for hypersonic travel

Published on April 10th, 2018 | By: April Gocha  ctt

  We’ve seen trends in faster flight heat up over the past few years—including both efforts to travel at supersonic (Mach 1–Mach 5) and hypersonic (>Mach 5) speeds.

   For instance, NASA has been public about its plans to develop a series of X-planes that use a host of new technologies to develop and test entirely new aircraft designs.

   Just recently, NASA announced that it will start building one of its concept X-planes that can travel at supersonic speed sans the supersonic boom. Engineered to redirect supersonic shockwaves coming off the plane, the aircraft design prevents the loud boom noise that has historically accompanied—and prevented—supersonic travel.

    Plus there are plenty of indications that even faster hypersonic planes are now in development, or perhaps even already built. Other countries are speeding towards hypersonic travel, too—China reportedly is making significant progress towards realizing its goals to lead the world in hypersonic technologies.

   The ability to travel faster is good news for reducing travel time. But aircraft that travel at such fast speeds pose an engineering challenge because of the high temperatures their materials must withstand.

 

Additively manufactured ceramic matrix composites are enabling new possibilities for commercial
jet engines today by enabling higher operating temperatures, but when it comes to supersonic and hypersonic
speeds, even ceramic matrix composites can’t take the heat.

 

Cold Sintering of Ceramics

   Penn State-Led Team Makes Strides in
The cold sintering process (CSP) can sinter ceramics at temperatures of less than 300°C—saving energy and enabling a new form of material with high commercial potential.



   A schematic illustration showing the co-sintering of ceramics and 2D materials using cold sintering processing, as well as a TEM image and an energy dispersive spectroscopy (EDS) map of a cold-sintered 99ZnO-1Ti3C2Tx nanocomposite. The MXene nanosheets are distributed homogeneously along the ZnO grain boundaries. (Image credit: MRI/Penn State.)
   Researchers have created a nanocomposite of ceramics with a two-dimensional material that opens the door to new designs of nanocomposites with a variety of applications, such as solid-state batteries, thermoelectrics, varistors, catalysts, chemical sensors and more. Sintering is a method that uses high heat to compact powder materials into a solid form; ceramic powders are typically compacted at temperatures of 800°C or higher. A sintering process developed by a team of researchers at Penn State, called the cold sintering process (CSP), can sinter ceramics at much lower temperatures—less than 300°C—saving energy and enabling a new form of material with high commercial potential.

Seven Common Causes of Refractory Failure

Careful collaboration between end users and refractories material suppliers can minimize the risk of failure and improve reliability.

 

Technique can densify most materials in seconds


One flash spark plasma sintering to rule them all

    Researchers at San Diego State University (San Diego, Calif.) have developed a flash spark plasma sintering technique that can densify all kinds of materials, regardless of their electrical conductivity, in a matter of just seconds.
    The research builds off the scientists’ previously developed sintering technique, which we reported about on CTT about a year ago. That flash spark plasma sintering technique, or flash hot pressing, could consolidate silicone carbide powder up to full density in just seconds withth the help of a specially designed tooling die. The San Diego State team’s new work is the next step forward for the technique.

Building a ceramic microelectronic manufacturing plant

Kyocera:

    “More powerful mobile devices, larger televisions, autonomous and electric vehicles, wearables, virtual reality, and the Internet of Things (IoT)—these technologies drive innovation and efficiencies in the electronics industry and in semiconductors themselves. Ceramics serve a crucial role in enabling these developments, whether in the manufacturing, use, or application of advanced semiconductors.” That was the introductory paragraph of the cover story,written by Kyocera International’s Arne Knudsen, from the April 2018 issue of the ACerS Bulletin.

Utilizing the Cold Sintering Process for Flexible–Printable Electroceramic Device Fabrication


Abstract
Conventional thermal sintering of ceramics is generally accomplished at high temperatures in kilns or furnaces. We have recently developed a procedure where the sintering of a ceramic can take place at temperatures below 200°C, using aqueous solutions as transient solvents to control dissolution and precipitation and enable densification (i.e., sintering). We have named this approach as the “Cold Sintering Process” because of the drastic reduction in sintering temperature and time relative to the conventional thermal process. In this study, we fabricate basic monolithic capacitor array structures using a ceramic paste that is printed on nickel foils and polymer sheets, with silver electrodes. The sintered capacitors, using a dielectric Lithium Molybdenum Oxide ceramic, were then cold sintered and tested for capacitance, loss, and microstructural development. Simple structures demonstrate that this approach could provide a cost-effective strategy to print and densify different materials such as ceramics, polymers, and metals on the same substrate to obtain functional circuitry.

ThermoOptical Measuring methods for the High Temperature Characterization of Refractories

Friedrich Raether1), Gerhard Seifert1), Jens Baber1)
Fraunhofer Center for High Temperature Materials and Design (HTL), Bayreuth, Germany, This email address is being protected from spambots. You need JavaScript enabled to view it.

Information on the high temperature material properties of refractories are the key for their successful application and for the development of new refractories. Due to the heterogeneous microstructure of refractories many standard methods for high temperature testing of materials are not applicable because the sample volume is too small. At HTL new measuring methods for the high temperature characterization of refractories are developed. These so-called ThermoOptical Measuring (TOM) methods aim at a full characterization of the thermal, mechanical and corrosion behavior of refractories at their operating temperatures. Especially a new measuring device, TOM_wave, is introduced. It measures thermal shock resistance, thermal diffusivity and other high temperature material properties by laser heating of samples in a furnace. In addition, a survey is given on the development of TOM devices for the high temperature investigation of other material properties. 

Water assists flash sintering to densify ceramic

   Sintering uses heat or pressure to compact individual particles together into a densified material. But while sintering has long been used to compact ceramics, the process is energy intensive, often requiring heating to very high temperatures for prolonged periods of time.So it’s no surprise that much research has been devoted recently to developing new varieties of sintering that consume less energy and fewer resources.

  Promisingisthe  technique  of flashing sintering, which uses an electric field to rapidly sinter ceramics at reduced furnace temperatures. Ever since its introduction by Rishi Raj and colleagues in 2010, much research has been done to explore the potential of flash sintering. Part of that research resulted not only in new and improved techniques, but lead to a better understanding of the flash sintering process itself.

Ceramic pump operates at 1174°C for thermal energy conversion

 Ceramic materials have outstanding properties-high temperature strength and melting points, extremely high hardness, high compressive strength, and dimensional stability. Depending on the specific material, they can be electrically conductive, thermally conductive or magnetic. That makes ceramics ideal for a number of applications, such as automotive parts that need heat-resistant characteristics and cutting tools for manufacturing that require excessive strength. The medical industry uses ceramic materials for bone and dental replacements. The aerospace industry uses ceramic materials in engines and missile nose cones to protect internal components from high heat. Ceramics contribute to environmental and solar energy industries in water treatment and power plant engines.
 

Graduate student Caleb Amy pours molten tin into a crucible. Credit: Georgia Tech

26.-29.9.2017 UNITECR 2017 in Santiago, Chile

 

  
Opening reception featured dancers representing the history and regions
of Chile—from Easter Island, the Mapuche people, Spanish settlers,
campesinos, and people from the northern regions, as well as
the Patagonia region in the south. Credit: ACerS


In September 2017, the refractories industry gathered  in Santiago, Chile, for the 15th Unified International Technical Conference on Refractories (UNITECR). The conference was organized and hosted by ALAFAR, the Latin American Refractories Association.
 Pablo Valenzuela, president of this congress said “I am most proud of two things. One, the Latin flavor in all the social matters, and two, the quality of the papers is really good.”
 The organizing committee was selective in the papers it accepted. Valenzuela says, “We didn’t want a competition [with previous UNITECRs] on quantity of papers, but on quality. We wanted new subjects, new investigations, and technological advances.”

OWENS CORNING TO ACQUIRE PAROC GROUP, A LEADING EUROPEAN MINERAL WOOL MANUFACTURER

    Owens Corning  announced that it has signed an agreement with CVC Capital Partners to acquire Paroc Group (“Paroc”), a leading producer of mineral wool insulation for building and technical applications in Europe, for an enterprise value of approximately €900 million. The transaction, which is subject to regulatory approvals and other customary conditions, is anticipatedto close in early 2018.
   Paroc is a leading European manufacturer of high-performance mineral wool insulation solutions for a variety of end markets. Paroc manufactures building insulation for thermal, fire and acoustic applications in residential and commercial construction. The company also manufactures technical insulation for HVAC systems; industrial processes; and the marine, offshore and original equipment manufacturer industries. Mineral wool products are customarily known as stonewool in Europe.

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