What are Ceramics?

Ceramics encompass such a vast array of materials that a concise definition is almost impossible. However, one workable definition of ceramics is a refractory, inorganic, and nonmetallic material. Ceramics can be divided into two classes: traditional ceramics and advanced ceramics.

Traditional ceramics include clay products, silicate glass and cement
Advanced ceramics consist of carbides (SiC), pure oxides (Al2O3), nitrides (Si3N4), non-silicate glasses and many others.

In general, advanced ceramics have the following inherent properties:

• Hard (wear resistant)
• Resistant to plastic deformation
• Resistant to high temperatures
• Good corrosion resistance
• Low thermal conductivity
• Low electrical conductivity

However, some ceramics exhibit high thermal conductivity and/or high electrical conductivity.

The combination of these properties means that ceramics can provide:

• High wear resistance with low density
• Wear resistance in corrosive environments
• Corrosion resistance at high temperatures

Ceramics offer many advantages compared to other materials. They are harder and stiffer than steel; more heat and corrosion resistant than metals or polymers; less dense than most metals and their alloys; and their raw materials are both plentiful and inexpensive. Ceramic materials display a wide range of properties which facilitate their use in many different product areas.

• Aerospace: space shuttle tiles, thermal barriers, high temperature glass windows, fuel cells
• Consumer Uses: glassware, windows, pottery, Corning¨ ware, magnets, dinnerware, ceramic tiles, lenses, home electronics, microwave transducers
• Automotive: catalytic converters, ceramic filters, airbag sensors, ceramic rotors, valves, spark plugs, pressure sensors, thermistors, vibration sensors, oxygen sensors, safety glass windshields, piston rings
• Medical (Bioceramics): orthopedic joint replacement, prosthesis, dental restoration, bone implants
• Military: structural components for ground, air and naval vehicles, missiles, sensors
• Computers: insulators, resistors, superconductors, capacitors, ferroelectric components, microelectronic packaging
• Other Industries: bricks, cement, membranes and filters, lab equipment
• Communications: fiber optic/laser communications, TV and radio components, microphones

Edited By Peter Wray • September 7, 2012

 

 

Global requirement for medical device coatings by region, 2010-2017. Credit: BCC Research.

Next week ACerS will be holding its first Innovations in Biomedical Materials conference with aim of generating some synergy from representatives of the materials research, manufacturing and medical communities.

Some of the goals laid out for the conference are:

• Share and explain technical advancements
• Facilitate product innovations; and
• Identify potential new applications.

These aren’t pedestrian matters. It’s fair to say that there are a lot of people in the materials science community that think we are on the brink of bringing an enormous and amazing range of new applications (e.g., novel biocompatible materials, sensors, delivery systems and imaging systems) to the medical community.

Of course, the most important aspect is identifying new ways of improving the human condition through better healing methods, improved disease detection and treatments, advanced prosthetic devices, etc.

From a business perspective, there seems to be a huge opportunity. A lot of businesses are looking at demographics, treatment trends, engineering breakthroughs and so on, and are starting to make some estimates of how valuable this field is.

Even with current technologies, the market seems huge. For example, a recent report from Market Research.com valued the 2011 global medical ceramics market at $10.4 billion and estimates it will reach $13.1 billion by 2017. Ceramic technology developments have contributed heavily to the development of implantable electronic devices. The authors of the report noted that ceramic materials are “ideal for a range of medical implant applications, from artificial joints to implantable electronic sensors, stimulators and drug delivery devices.” The authors also highlight the role of alumina and zirconia for dental uses, orthopedic repair applications, implantable electronic devices and surgical and diagnostic instruments.

Here’s another window into the potential business opportunity: A BCC Research report issued earlier this year estimates that the global medical device coating market, alone, reached $5.4 billion in 2011 and predicts it will grow to $8 billion in 2017. The authors looked at a wide range of materials and related innovations, including alloys, ceramics, hybrids, energy-absorbing, micro- and nanomaterials, protective polymers and surface treatments. A separate BCC Research report places the North American market just for high-performance ceramic coatings (including thermal spray and chemical and physical vapor deposition technologies) at $1.4 billion in 2011, an amount researchers say should grow to $2.0 billion by 2016.

Of course, the materials world is much broader than ceramics. There are also polymers, metals, composites and hybrid materials that have to be factored in before the size of the entire market can really be captured. At the broadest level, a thorough market evaluation would even extend to devices such as laser-based devices and next-generation CT machines.

Biomedical materials is an exciting field to watch these days, and I have to admit that I’m really looking forward to providing some blog posts based on the presentations at next week’s meeting. Stay tuned.

Linked: http://ceramics.org/

Technical ceramics are favored in a wide range of electronics and engineering applications for their chemical and mechanical properties. Compared to metals, they are stronger in compression, especially at higher temperatures. Ceramics have a good thermal stability (i.e. a low coefficient of thermal expansion) and good thermal and electrical resistance. They are also hard, and have excellent dimensional stability.

As a result, the list of applications for technical ceramics is long and varied, including, for example: aerospace engine blades, rings and valve components, industrial pump bearings, cutting tools and die parts, medical instruments, and wide uses in the electronics industry as a substrate and in specialized vacuum components.

Ceramic-Metal Bonding

For many applications it is often necessary to join ceramic to metal to create the finished part.

Ceramic-metal bonding is one of the biggest challenges that has faced manufacturers and users over the years because of the inherent differences in the thermal expansion coefficients of the two types of materials. Various methods are available, including mechanical fasteners, friction welding, and adhesive bonding, but by far the most widely used and effective method for creating a leaktight, robust joint between ceramic and metal is by brazing. This starts with the chemical bonding metallization of the ceramic to create a wettable surface on which braze alloy will flow between the two components during the brazing process.

Morgan Advanced Ceramics is a worldwide designer and manufacturer of metallized ceramic components, producing custom parts for applications ranging from very small volume production runs of high-value components for special projects to high-volume manufacture of precision designs. Here are two examples.

Example 1: A Unique Engineering Challenge

ISIS, a world-class spallation neutron source based at the CCLRC Rutherford   Appleton Laboratory, Oxfordshire, UK commissioned a series of highly specialized metallized ceramic components from Morgan Advanced Ceramics as part of a major expansion project to build a Second Target Station (TS-2).

The components are a fundamental part of instrumentation, monitoring the intensity of the extracted proton beam (EPB). Ceramic vacuum tubes used in the first target station were sealed with Indium wire, but experience proved that these became unreliable if disturbed. Metallized ceramic offered a solution that provides a 100% reliable vacuum seal within the very tight tolerances of the design

There were two key challenges: first, to come up with a design and a manufacturing process that would produce a robust, high integrity vacuum seal (leak rate 10^-8mbar l/s) across a large component (200 mm diameter); second, to solve the problem of the differences in thermal coefficient between the alumina ceramics of the tube and its mild steel flanges. A very tight specification was set for the physical dimensions and cleanliness of the components because of the nature of the project.

The ISIS assembly is 158 mm long with two nickel-plated mild steel flanges 240 mm in diameter, insulated from each other by a preformed diamond ground alumina ceramic insulator. To ensure hermetic integrity of the assembly, the ceramic is brazed in a hydrogen/nitrogen furnace at 850°C to two flanges made of nickel iron cobalt steel, chosen because it provides the best thermal expansion match to the ceramic. This process is achieved by applying a moly-manganese coating, which is sintered at 1,400°C, then electroplating a layer of nickel. The ceramic/metal-brazed subassembly is then welded to the mild steel flanges with a stainless steel interface and machined to the final dimensions.

The order from ISIS was for 13 components, supplied by the end of 2006. As is usually the case with this sort of project, neither time nor budget was available to produce a prototype to refine the process, so the experience and expertise of the specialist team were relied on to get it right first time. Problems were solved as they arose and all the components were delivered.

Example 2: Precision and Consistency

For another customer, Morgan Advanced Ceramics manufacturers metallized ceramic components forvacuum electronic devices used in continuous wave and pulsed radar systems, such as those for fighter aircraft.

Here the challenge is to push the performance envelope of the materials to meet the industry’s demand for higher frequencies. This means smaller components with the same physical properties as their larger cousins, and calls for very high precision engineering and close quality control to ensure consistency throughout production.

For example, the smallest part made in this way is a cylinder with an internal diameter of just 0.2 in. The internal surface is metallized to a very tight thickness tolerance, within 0.007-0.0012 in. The metallization process used is based on molybdenum-manganese (MoMn) refractory ink systems developed in-house by Morgan Advanced Ceramics and is matched to specific high purity alumina ceramic bodies to ensure consistent high strength bonds. The glass phases in the MoMn metallization bond with the glass phases in the ceramic to form the bond. The metallized surface receives a secondary coating of nickel to seal and improve wettability for later brazing.

Conclusion

Advanced ceramics are meeting the needs for higher performance critical components in a wide variety of applications. Through a detailed understanding of ceramic-metal bonding techniques, such as the metallization process, designers and manufacturers are better able to devise these key components.

By Steve Deiters

Porous stone diffusers have been used to disperse high volumes of fine bubbles in very dense gas patterns in a wide variety of applications for literally hundreds of years. Applications range from oxygen transfer in wastewater treatment plants, to disinfection of potable water with ozone, stripping of volatile organic compounds in manufacturing processes and groundwater remediation sites, and many others.

Ceramic fine bubble diffusers come in a variety of shapes and sizes ranging from domes and discs that operate in a vertical format to tubular or rod styles designed for use in a horizontal format. Materials of construction for ceramic diffusers range from the original porous slag to silica and the high performance fused aluminum oxide materials of today. The evolution of ceramic diffusers has been driven by the need for consistent operation and higher degrees of compatibility with a wide variety of hostile operating environments.

Typical ceramic tubular diffuser and ceramic dome fine bubble diffusers of varying porosities for industrial applications.

The most widely found use for ceramic diffusers is in biological treatment applications that require high mass transfer rates of oxygen interfacing with liquid, such as wastewater treatment. They are also used for the disinfection of potable water with ozone gas. Such systems have been in use in Europe for quite some time but have been slow to evolve in the United States. That is partially due to the slow acceptance of new technology in the U.S. and the expense of replacing existing infrastructure.

Ceramic dome diffusers installed on a conversion header in an existing system originally designed for horizontal format diffusers. From previous operation a reddish patina formed on the header pipes from mineral content in water source.

Non-Traditional Applications

As with all devices and hardware used in process technologies, improvements in the technology set the stage for alternative application that before had no easy solutions. One problem solved with ceramic fine bubble diffusers is the treatment of groundwater contaminated with volatile organic hydrocarbons. VOCs can originate from a variety of sources ranging from gas stations with deteriorating underground fuel tanks to industrial or military sites where hydrocarbons, solvents, and other contaminants have percolated down and found their way into the water table.

The more traditional approach for groundwater remediation involves pumping the groundwater from the contaminated plume into a tank for treatment. Once the VOCs have been volatilized and removed, the water is pumped back into the ground in a closed loop basis. This approach tends to be capital and manpower intensive, but the simplicity of design makes it desirable for many applications.

An approach gaining increasing acceptance in recent years is the instu treatment of groundwater contaminated with hydrocarbons. This is achieved by identifying the extent of the contaminated groundwater plume by sinking wells and testing the groundwater. Once the size and extent of the plume is established the well casings can be used in the treatment process.

Ceramic tubular diffusers are horizontal format devices by design and typically are installed parallel to the bottom of a vessel. For insitu groundwater applications the tubular diffusers are rotated and used as a lance that is inserted into a well casing. The exterior of the diffusers are then packed with media and sealed using application specific packing materials to maximize the efficiency of the process. The diffuser is connected to the gas source such as air, oxygen, ozone or others as required for a successful remediation process.

The function of the system is based on the natural movement and flow of the groundwater water coming in contact with the active area of the gas diffuser. The media provide an added benefit by slowing the rise rate of the bubbles in this type of installation. The number of wells required is driven by the severity of the remediation requirement, size of the contaminated plume, and the extent that it has travelled.

Ceramic diffusers can also be used for pH adjustment in wastewater treatment applications. This is accomplished by using commercially available sources of carbon dioxide and interfacing the gas with the flow in a trough or a tank.

Ceramic fine bubble diffusers can create a large volume of bubbles for interfacing with resultant surface area interfacing with liquids to perform a variety of tasks

Some installations with a need for pH adjustment may also have access to flue gas, an acidic by-product of combustion in manufacturing or facility heating processes. A side stream of flue gas can be pumped to the diffusers and works in conjunction with solenoids or actuated ball valves and a pH controller to achieve the targeted level of pH adjustment prior to discharge. In those cases, handling of dangerous chemicals and their ongoing cost is eliminated and a previously wasted by-product of operation is put to use in what could be considered a “green” application.

Fine bubble diffusers have also been used for boosting levels of dissolved oxygen in wastewater or process streams prior to discharge to municipal systems or streams. The final dissolved oxygen level is typically driven by prevailing local, regional, or national enforcement guidelines.

Retrofits

Ceramic diffusers can offer a viable hardware alternative when upgrading systems. Many older installations often had tubular or rod style diffusers which were the diffuser of choice for many years. The major stumbling block to system upgrades is the need to reformat the piping manifold and headers from a system that was designed for horizontal format diffusers (tubular style) to one that can accommodate vertical format (dome style) diffusers.

One solution to the problem uses the existing manifold and header system with tubular replacement header adaptors fabricated to accept multiple ceramic dome diffusers. The existing tubular diffuser is removed and the adaptor “header” is threaded into place with the vertical format connections located at the 12 o’clock position for final installation. The changeover can literally be accomplished in hours rather than weeks or months.

About the Author: Steve Deiters is president of Diffused Gas Technologies Inc. of Lebanon, Ohio. The company is a manufacturer of fine and coarse bubble air/gas diffusers and systems used in the water and wastewater treatment industries. He has held marketing, project management, and technical positions with pollution control equipment manufacturers such as Pollution Control Inc. and Clow Waste Treatment Division as well as capital equipment manufacturers serving the process and electronics industries.

Morgan Technical Ceramics is promoting its range of striped tubes for the defence sector with an innovative design, offering lower frequency and increased drive for applications where high acoustic transmitting properties are required.

Ideal for a variety of defence uses including anti-submarine warfare, torpedo decoy and countermeasure, the striped tubing can achieve typical frequencies of 12-15 kHz for a two inch tube and guarantees higher, stronger acoustic signals underwater. The key to the product’s success lies in its revolutionary striped design.

In contrast to a standard tube, which has three main resonance modes (length, wall and circumferential), Morgan Technical Ceramics’ innovative striped tubes have one main resonance – the circumferential mode. In 99 per cent of cases, circumferential mode (low frequency) is chosen for underwater transmission applications to allow the signal to move further away from the source.

Having focused and refined performance through the circumferential mode, the striped tubing features segments which are equally distributed around the circumference, and the space in between the positive and negative electrodes is generally greater than the wall thickness. As the distance between the electrodes is much larger, this allows a user to apply a much higher voltage, and thus achieve a higher acoustic output. If a strong, acoustic signal is needed from a standard tube, its wall thickness limits the higher vibrations achievable.

The striped tube range is available from 12.70 mm (1/2”) to 101.60 mm (4”) diameter tubes with lengths ranging from 10 mm to 75 mm (under ½” to 3”); Morgan Technical Ceramics can also make the product in 152.4 mm (6”) to 202.8 mm (8”) diameter tubes with lengths of up to 75 mm (3”). Larger or smaller sizes are available on request, dependant on available tooling.

The striped tubes are generally manufactured from PZT401 and PZT807 which are hard PZT materials for increased robustness and longevity but this offers low sensing properties. If a striped tube is required for receive/sensing, rather than transmission, Morgan Technical Ceramics can offer an alternative striped tube product made from a softer material such as PZT5A1 which is more sensitive. Applications for this would be more confined to commercial purposes, such as for bore hole investigation, oil exploration and drill navigation.

In receive/sensing mode a standard tube will see uniform pressure on OD/ID and voltage output will be proportional to the D33. In a striped tube, the same happens but the voltage is proportional to the D31 which is much lower than D33.

Richard Carus, product sales manager – Piezo Components for Morgan Technical Ceramics, said: “We work closely with our clients in the defence and security industries to listen and really understand their challenges. The launch of the striped tube range reflects our commitment to radical innovation and to bringing to life the products that our clients want and need. We believe that this ethos to work for our customers is what allows us to retain our position as leader in the design and manufacture of electro ceramic products for the security and defence markets.”

GREENVILLE, S.C.–(BUSINESS WIRE)–Aug. 16, 2012– AVX Corporation (NYSE:AVX), a leading manufacturer of advanced passive components and interconnect solutions, announced today that the major automotive supplier Robert Bosch GmbH, has joined the AVX “Solutions for Hope” Project.

We are very pleased to have Bosch, one of the world’s premier electronics suppliers to the automotive sector participate in our project said Peter Collis Vice President of the tantalum products.

The “Solutions for Hope Project,” established in July 2011, works with leading OEMs such as Motorola Solutions, Intel, and HP to deliver a “closed-pipe” process for delivering conflict-free tantalum material from the Democratic Republic of Congo (DRC) in accordance with the Organization for Economic Cooperation and Development(OECD) due diligence guidelines and incorporating the independently-validated Electronic Industry Code of Conduct (EICC) and the GLOBAL e-SUSTANABILITY INITIATIVE (GeSI) Conflict-Free Smelter (CFS) program.

The “Solutions for Hope Project” remains the only project to exclusively utilize EICC/GeSI validated Conflict-Free Smelters for processing tantalum ore into capacitor-grade materials.

AVX is the first in its industry to validate a closed tantalum pipe process, assuring all products contain only conflict-free tantalum in accordance with the principles of the Dodd-Frank legislation and the current OECD guidelines.

“AVX will continue its leading role by working with a growing list of major electronics companies like, Robert Bosch GmbH in the Solutions for Hope program. This program demonstrates that verifiably conflict-free tantalum material can be mined and shipped in a manner that is reliable, sustainable and expandable, allowing the DRC to be utilized as a trusted regional source for responsible minerals,” said Bill Millman, Tantalum Divisional Director of Quality and Technology.

For further information on this project, please contact Bill Millman at AVX: +44 (0) 1803 697211 or conflict.free@eur.avx.com

COSTA MESA, CA–(Marketwire – August 10, 2012) – Ceradyne, Inc. (NASDAQ: CRDN) announced that it has acquired a minority interest with an option to acquire all of Tempe, Arizona-based Graphite Machining Services and Innovations, LLC (GMSI). GMSI has developed a proprietary method of applying a chemical vapor deposited (CVD) silicon carbide ceramic coating on precision machined graphite shapes. The resultant product is used in the manufacture of Light Emitting Diodes (LEDs) for the rapidly growing solid state lighting market.

GMSI’s expertise and technology have been focused on the precision machining of ultra-high quality graphite shapes since its founding in 1984. The demand for state-of-the-art components for use in the MOCVD (Metal Organic Chemical Vapor Deposition) process in the manufacturing of LEDs has led to GMSI’s shift in technology and manufacturing capacity to serve the LED and other semiconductor markets.

This acquisition of GMSI will not materially affect Ceradyne’s 2012 financial performance.

Mr. David Reed, president of Ceradyne’s North American Operations, commented: “We are excited about this relatively small but high technology investment in GMSI. It fits very well with our diversification strategy, coupled with our interest in building out Ceradyne’s advanced technical ceramics portfolio. Furthermore, the market for efficient, environmentally friendly LED lighting systems is expected to grow very rapidly over the next ten years.”

Mr. Reed further stated, “The GMSI facility in Tempe is absolutely first class and GMSI’s president, Peter Guercio, and his partners, Rex Dillman and Dale Beeck, are excellent additions to Ceradyne’s entrepreneurial, technology-driven culture.”

Peter Guercio, GMSI’s president, commented: “The relationship with Ceradyne is perfect. It is clear to us with the growth opportunities we see ahead that we will need the resources of a larger technology operation. Ceradyne and its advanced technical ceramic focus is the ideal partner. We are looking forward to our growth in the burgeoning LED markets.”

About Ceradyne, Inc.
Ceradyne develops, manufactures, and markets advanced technical ceramic products and components for defense, industrial, energy, automotive/diesel, and commercial applications.

In many high performance applications, products made of advanced technical ceramics meet specifications that similar products made of metals, plastics or traditional ceramics cannot achieve. Advanced technical ceramics can withstand extremely high temperatures, combine hardness with light weight, are highly resistant to corrosion and wear, and often have excellent electrical capabilities, special electronic properties and low friction characteristics. Additional information about the Company can be found athttp://www.ceradyne.com.

Forward-Looking Statements
Except for the historical information contained herein, this press release contains forward-looking statements regarding future events and the future performance of Ceradyne that involve risks and uncertainties that could cause actual results to differ materially from those projected. Words such as “anticipates,” “believes,” “plans,” “expects,” “intends,” “future,” and similar expressions are intended to identify forward-looking statements. These risks and uncertainties are described in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2011 and its Quarterly Reports on Form 10-Q as filed with the U.S. Securities and Exchange Commission.

Ceramic Pumps for Pilot Plant Fluid Control

Fluid Metering’s valveless, ceramic pumps are designed for pilot plant fluid control. The sapphire-hard internal components of the pumps eliminate accuracy drift typical of pumping systems that rely on valves and elastomers (flexible tubing and diaphragms) to move fluid through the pump. The valveless rotating/reciprocation piston design eliminates the need for check valves, which can clog, leak or fail over time. The result is a maintenance free, drift-free fluid control that will hold an accuracy of 1 percent or better for millions of cycles. Flowrates can be infinitely controlled either mechanically and/or electronically via standard industrial control protocols. Flow control is viscosity-independent for added flowrate stability. Pump models are available to dispense as low as 5 µL per dispense up to 4 L per minute continuous metering.

Linked: http://www.flowcontrolnetwork.com

Authors of an new Early View story on the website of the Journal of the American Ceramic Society report about a solution they have found to some of the problem of shrinkage and deformation that occurs during sintering of large and complex parts composed of one type of bioactive glass.

The investigators, who are from the Department of Materials Science and Engineering, University of Erlangen-Nuremberg (Germany) and the BAM Federal Institute for Materials Research and Testing (Berlin), have been looking at how to improve the performance and production of 3D-printed “13-93″ bioactive glass and they say the addition of hydroxyapatite powder, creating a glass–ceramic composite for 3D printing, creates a finished product that retains more of the critical shape and dimensions during sintering than pure powders of the glass.

13-93, a silicate-based glass, isn’t new and several groups of researchers (such as Rahaman et al.) have generally documented that 13-93 is a good candidate material for non-load bearing uses in joint replacement and tissue engineering. The active interest in bioactive glasses, such as 13-93, is in large part due to the apparent ability of the material to accelerate the body’s natural healing process.

Different groups had experimented with using different processes to create green body structures using 13-93 powders and filaments, including fairly precise 3D fabrication and finishing methods, such as selective laser sintering. However, generally speaking, the larger and more complex the green body is, the more problematic sintering becomes. The authors of the JACerS paper report these types of parts “may deform significantly as a result of gravity, surface tension, intrinsic strain or temperature and density gradients. This complicates congruent or net-shape processing.”

The attractiveness of 3D processing is the promise of high-quality and easily reproducible shapes, pore size and distribution, etc.

The payoff in the German group’s work is that they found that a 13-93/HAp powder mix using 40 wt% of crystalline material provided the best combination of geometric stability and viscous sintering. They tested this formulation using the complex cellular cubic structure pictured above, and they were quite happy with the results. They note

“In this way, an overall axial shrinkage of about 20.5 ± 0.5% was obtained in all three dimensions. The diameter of cells was reproduced with an accuracy of 15 ± 5%, whereby the deviation is most probably related to surface effects induced by the printing process and manual powder removal. The ratio between individual cell diameters—the fingerprint of the specific structure—was reproduced with an accuracy of about 2%. … these data demonstrate very good reproduction of the 3D-printed part after sintering.”

Also, the addition of the HAp powder seems to not increase the propensity for crystallization of the bioglass, another problem that may change the properties that made the material desirable in the first place.

The authors suggest that other glass–ceramic composite candidates should be suitable for similar production methods.

More information can be found in “Sintering of 3D-Printed Glass/HAp Composites (doi: 10.1111/j.1551-2916.2012.05368.x).

Edited By Peter Wray • August 10, 2012

Linked: ACerS

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