Tapping Into Industry Expertise at Ceramics Expo 2017
The two-track, free-to-attend Conference @ Ceramics Expo runs for the duration of the event.
Wouldn’t it be great if you could go somewhere and network with dozens of industry experts, all in one place and at the same time? What if you could listen to these experts share their expertise, and then ask focused questions in order to get specific information that would help you and your business? This isn’t just a pipe-dream scenario: it’s what attendees of Ceramics Expo 2017 can expect during the Conference @ Ceramics Expo.
The two-track, free-to-attend conference runs for the duration of the event, which will be held April 25-27 in Cleveland, Ohio. (Read more about Ceramics Expo 2017.) Topics of discussion at the conference will range from industry trends and manufacturing improvements to specific end-use applications.
The opening plenary session, which will begin at 10:30 a.m. on Tuesday, April 25, will focus on “Forecasting Key Ceramic Markets to Understand Industry Trends.” Moderated by Mark Zupan, president of Alfred University, the panel will discuss several aspects of the industry, including ceramic matrix composites, ceramic coatings, bio-ceramics and bio-glasses, and refractories, as well as materials considerations such as thermal and electrical properties (e.g., dielectric, piezoelectric, ferroelectric, and semiconductor).
The industry will certainly continue to see end-user markets such as aerospace, energy and medical increasingly turning to ceramics to replace traditional materials. Two factors are in play here: end users are becoming more educated about ceramics and their properties/abilities, and ceramic materials/component manufacturers are developing products that address these specialized applications like never before.
“When people come to us, they’ve realized they need something to survive at a high temperature, or a high pressure, or maybe a very low temperature,” says Richard Clark of Morgan Advanced Materials, who will participate in the plenary session. “What we’re seeing more than anything is more people pushing toward specialized, niche applications where they want very tight tolerances or different designs than they wanted previously, something that requires a characteristic that can only be addressed by ceramic.”
All of this innovation and the associated intellectual property (IP) offers opportunities for growth, but also comes with some major challenges as well. “There is now an amazing amount of IP being generated, particularly from China,” says Clark. “You’re trying to innovate, but so is everyone else. Literally thousands of patents are being generated in fields that you would imagine would be new. Getting an IP position is really important.”
End-use sectors that are primed to provide growth include aerospace, medical, energy (renewable and traditional), electronics and automotive, among others. “What I think we’ll see more of is material combinations, like composite materials,” says Clark. “The good part is that the overall market is growing. There is more competition, but there’s also a bigger pie to share.”
Clark will be discussing the thermal characteristics of ceramics during Tuesday’s session. “For example, we’re developing some novel systems for electric vehicles that make the vehicle safer and also conduct the heat away,” he says. “Part of the development of ceramics is looking at new characteristics and how to apply them. How can we modify the thermal conductivity characteristics of ceramics so we can use ceramics to improve system efficiency as well as safety?”
CMCs Take Flight
Aerospace companies are exploring the potential of ceramic matrix composites (CMCs) in areas such as the leading edges of space vehicles. This is no small task, since temperatures can reach nearly 3,000°F as the craft goes back and forth through the atmosphere. Jet engine components are another application getting a lot of attention, as ceramics can provide superior strength while reducing weight to improve fuel efficiency.
“Two things are really important for aerospace applications,” says Shay Harrison, senior materials scientist with Free Form Fibers LLC. “One is strength. You get to take advantage of the silicon carbide [SiC] matrix’s high strength, high modulus properties. Another is lightweighting. When you compare densities, specific strengths between SiC/SiC CMCs and the typical superalloys that have been used, you save a lot of weight. When you combine that weight savings with the ability to go to higher temperatures with the SiC/SiC CMCs, you really start making a significantly positive impact on efficiencies.”
What is being done to help make CMCs a viable choice for these demanding applications? A panel moderated by Harrison will discuss “Evaluating Advances in CMC Processing and Manufacturing Technologies” beginning at 2:45 p.m. on Tuesday. For his segment of the session, Harrison will discuss materials and manufacturing approaches for the three main components of SiC/SiC CMCs: the fiber, the interface coating, and the matrix.
According to Harrison, the goal is to produce fiber that can operate at 2,700°F. The purity, density and length of the fiber are key elements that impact the effectiveness of the CMC, particularly at such a high temperature. “We’re utilizing laser CVD [chemical vapor deposition] to create what we’ve proven out to be a very high-purity, high-density fiber,” explains Harrison. “When you have impurities in your fiber, you start limiting the ultimate temperature that the fibers can operate in over an extended application lifetime. The other half of our big push is to be able to make continuous strands of silicon carbide fiber that are hundreds of feet long. We’ve done a demonstration where we’ve got a 32-ft continuous fiber, which, as far as we know, is the longest continuous SiC fiber that’s been made.”
The interface coating helps impart fracture toughness to the CMC. As Harrison explains, “If you’re going to put ceramics in a jet engine, you can’t have a bird hitting some component of the combustor and causing it to just shatter.” Instead, the interface coating helps the CMC avoid catastrophic failure. “As the cracks move through the composite, you don’t get monolithic ceramic behavior,” says Harrison. “It’s not shattering, like when you drop a plate or a glass. You’re getting graceful failure, where you actually improve the fracture toughness of the body.”
Boron nitride has been the go-to material in these interface coatings for decades, though work is ongoing to determine if it is truly the best option. “There’s still some work to do there,” says Harrison. “[Boron nitride] has its advantages, but it also has some weaknesses when it’s at high temperature and exposed to oxygen and moisture.”
The actual matrix of the CMC can be produced through different methods, including: melt infiltration, chemical vapor infiltration (CVI) and polymer infiltration and pyrolysis (PIP). Harrison will discuss the advantages and limitations of each method during his presentation. “CVIs are expensive and it takes a long time,” he says. “Melt infiltration can leave excess silicon present in the matrix, and the PIP conversion process can leave unreacted silicon oxide carbon-type of materials in there. There’s work to be done to improve each of those methods.”
Ceramic materials such as alumina, magnesia and silicon dioxide are vital components in sensors used for monitoring conditions in nuclear power reactors. “There aren’t a lot of materials that can be used inside a nuclear reactor,” says GE’s Jim Lustig. “Most polymers will break down from the heat, pressure, and neutron and gamma fluxes that are present in that environment.”
Ceramics also outshine polymers in sensors for area radiation monitoring. “There are some cases where, electrically, polymers would appear to be the preferred choice based on the electrical resistance properties, but ceramics are often chosen because ceramics can also be used to create hermetic seals,” explains Lustig. “A lot of what we do involves brazing ceramics to metal parts. At high temperatures, we’re able to bond that metal and ceramic together in a manner that allows virtually no gas through the seal, whereas almost all polymers allow some amount of gas permeation through them.”
Lustig will give a presentation on “Understanding Ceramic Material Behavior in High Radiation Flux Environments for Improved Insulation and Thermal Barriers” at 1:30 p.m. on April 26. Material selection is a key element that contributes to sensor success. “For example, magnesia has superior resistivity at high temperatures, so we have to use that for certain applications where alumina just loses too much insulation resistance as it goes up in temperature,” he explains. “In terms of how we use ceramics in braze/seal assemblies, we’ve discovered some things about ceramics that make how we specify our ceramics more durable in these environments. Properties like fine grain size and, to some extent, the purity of the ceramic affect whether that ceramic might swell and crack. If we don’t specify our ceramics properly, we’ll run into problems where it’ll allow gas to leak out of our detector in use due to radiation damage. We need to govern against that.”
Even properly selected ceramics can run into issues with contamination, however, and Lustig will discuss how GE prevents this problem. “One problem that ceramics have that polymers don’t in some of these low-current applications is moisture intolerance,” says Lustig. “We use a lot of mineral-insulated cable, and we have to do a lot of processing to make sure that there’s no moisture or other sources of contamination. Any small amount of moisture will significantly degrade the insulation resistance of the ceramic, especially in the powdered forms that they are in inside the cables.
“I’ll talk a bit about some of the best practices we have, in terms of how we maintain some of these purities and get good ceramic-to-metal adhesions. One of the problems you have with ceramics as you get up into these very high purities is that there’s no glassy phase to them. This makes it very difficult to make ceramic-to-metal seals, because there just isn’t anything to start that bonding process between the metal and ceramic.”
Is there a Ceramic in the House?
In addition to vast opportunities in the dental market (e.g., fillings, crowns, implants, orthodontics, etc.), the medical sector is increasingly taking advantage of ceramics’ unique properties for applications such as joint implants and coatings. On April 27 at 11:45 a.m., a panel of speakers will participate in a session focused on “Examining End-User Requirements of Ceramics for Medical Applications.”
“Monolithic ceramics are being used quite extensively in hip products, mainly in heads and liners as a bearing,” says Jason Langhorn of DePuy Synthes Joint Reconstruction, who will participate in the session. “The ceramics that are being used for those kinds of applications are zirconia-toughened alumina and, to a lesser extent, some stabilized zirconia materials like magnesia-stabilized zirconia.”
Biocompatibility is a key property that is helping ceramics build momentum in the orthopedics industry. “With most oxide ceramics, and with the silicon nitrides, what makes a ceramic viable is the fact that it’s biocompatible,” says Langhorn. “Since they have low bioactivity, typically they won’t react in vivo with soft tissues.”
Ceramics also benefit from high wear resistance properties, which is important as these implants are expected to see regular use for decades. “The amount of wear that you would get on a bearing surface because of its hardness is very low,” explains Langhorn. “The increased hardness with respect to a lot of the alloy materials that are used currently, [ceramics are] a lot harder. Your ability to be able to polish the surface to a much lower Ra—so a much higher shine—and the ability to resist scratching are huge for ceramics.”
Coatings play a part both on the implants themselves and on medical instruments. On joint implants, coatings provide protection by creating a hard, dense barrier that helps reduce ion release into the body’s soft tissue, which in some cases have been reported to lead to adverse tissue responses in some patients. The coatings can also enhance the performance of the joint components.
“A lot of those hard coatings for implants, either CVD [chemical vapor deposition] or PVD [physical vapor deposition] based, are typically put on implants to improve the wear against a polyethylene, which is used as a surrogate for cartilage in between two hard surfaces,” says Langhorn. “Improving the wear of polyethylene is done by making the mating surface harder, you can get a much better polish on a hard surface. It’s also less susceptible to things like scratching. Oxide ceramics also wet a lot easier; they’re much more hydrophilic than a cobalt chrome alloy, so you improve the wettability and you can potentially reduce the wear.”
When used on medical instruments, CVD and PVD-applied ceramic coatings increase wear performance, lengthening the safe useful life of the instrument. Certain coatings can also enhance surgeons’ ability to see what’s happening during surgery. “Gold colored titanium nitride-type coatings improve contrast and a surgeon’s visibility in a surgical environment, highlighting touch points for instruments,” Langhorn says. “With the bright white light needed in the OR, surgeons can get better contrast off a gold surface than a silver one.”
Fracture toughness and cost are the main challenges facing ceramics in medical applications; traditional metal alloy materials are less susceptible to catastrophic failure while also being less complicated to manufacture than ceramics. Work to address those issues is ongoing, as is a push to focus on testing standards from organizations such as International Organization for Standardization (ISO) and ASTM International.
“We need to continue to overcome materials and cost challenges,” says Langhorn. “We also need to improve upon standardized testing for ceramic materials in orthopedic applications through bodies like ISO and ASTM, with a goal to increasing FDA acceptance and approval for these applications. There’s certainly a lot of interest in orthopedics, and in the medical industry as a whole, to introduce ceramics. Designing around the fracture toughness issues and increasing competition in the orthopedic ceramics market to drive down cost are imperative to continue market acceptance and growth.”
To register for Ceramics Expo 2017 or for additional information, visit www.ceramicsexpousa.com.