Conference @ Ceramics Expo: I Want It All!
The free-to-attend sessions during the Conference @ Ceramics Expo offer in-depth information and insights on a plethora of topics for both manufacturers and end users.
The Conference @ Ceramics Expo always makes me feel like a kid in a candy shop. These free-to-attend sessions offer in-depth information and insights on a plethora of topics for both manufacturers and end users of high-tech ceramic and glass components. There’s so much to see!
Ceramics Expo will be held May 1-3 in Cleveland, Ohio. Details regarding the expo and new features at this year’s event can be found in “Ceramics Expo 2018: All Eyes on Cleveland.” While the conference will have a special focus on materials in 2018, it will again cover the industry in two tracks: manufacturing and applications.
I had the chance to chat with a few of the presenters who are lined up to participate. During these conversations, I discovered that the breadth of issues that will be covered during the conference will be truly exciting.
Ensuring Biomedical Component Quality
Materials such as hydroxyapatite, tricalcium phosphate and bioglasses are widely used in bone grafting applications. Whether bone is lost due to disease, accident or surgical intervention, these materials help facilitate new bone growth in skeletal defects that are too large in volume to heal naturally. After the ceramic material is placed in a bone void adjacent to the skeletal tissue, the bone grows into the ceramic pores, which facilitate the deposition of de novo bone. Once the defect has been bridged by that new bone, the ceramic scaffold resorbs over time—from months to as long as decades, depending on the material—through the body’s natural metabolic process.
As Ian Dunkley, Ph.D., a senior R&D engineer with Medtronic, explains, the properties required of these materials can be quite different from those commonly associated with ceramic components. “There’s no requirement for any real strength, just enough for handling by the surgeon so the ceramic doesn’t crumble into pieces,” he says. “Designing a bone graft substitute to withstand mechanical loading after implantation would actually be a very challenging activity, since the ceramic is going to disappear in time.”
On Wednesday morning, Dunkley will discuss materials characterization, including key properties such as biocompatibility, chemical formulation, and porosity that are necessary for these applications, as well as how those properties help ensure that the materials will be accepted in the body, cause no harm, and then be resorbed once their function is no longer needed. Since these materials are placed within living tissue, it is vital that they meet all relevant regulatory and quality control requirements. The process of ensuring the finished components’ effectiveness, quality and safety—from raw materials through all needed manufacturing steps—is as complicated as you’d think.
Medtronic undertakes ongoing risk management to ensure that finished components safely and properly perform their specified roles. The company considers how each product is designed, manufactured, and used in order to ensure devices are properly produced and function safely and effectively.
“We document each step of the process, assigning a probability and severity of any plausible failure mode,” explains Dunkley. “We evaluate all options that can eliminate or mitigate this risk, and reduce it to as low as reasonably possible in the design phase. We then demonstrate through rigorous testing protocols that our design actually delivers the desired functionality well in advance of product release. Each design, manufacturing step, and product use condition decision requires validation and verification testing that ensures the end product is safe and effective when used as instructed.”
In terms of the raw ceramic (and other) materials, component manufacturers must think beyond the various materials characterization analyses that are required and understand how each material’s properties affect the overall production process. “Raw materials are often variable in how they’re delivered,” says Dunkley. “Perhaps in other industries, it’s not too concerning, because you might be permitted to tweak your manufacturing parameters to account for that variability. However, the challenge we have in manufacturing implantable materials is to anticipate the full range of raw material variability we will encounter over a product lifetime during the development phase.
“This information is needed in order to create robust production processes from the outset. We can’t just start turning knobs and adjusting parameters outside of what we have previously qualified to account for any unexpected changes to our raw materials, because we can’t always predict how such changes might affect other product characteristics. In cases where raw material properties have drifted outside qualified values, the result can be the initiation of costly new verification and validation testing to ensure the end product meets safety and efficacy requirements.”
Progress through Disruption
A disruptive technology is defined by the Cambridge English Dictionary as one that “overturns a traditional business model, which makes it much harder for an established firm to embrace.” Flash sintering could represent such a technology to the ceramic industry, replacing traditional processes for joining dissimilar materials in applications ranging from orthodontics to electronics.
Flash sintering is accomplished through the application of an electric field to a ceramic material during a sintering process. When a set voltage is applied across the material in question at a set furnace temperature, the result is an exponential conductivity increase that occurs quite rapidly (thus the term flash).
According to David Pearmain, flash sintering business manager with Lucideon, technology currently in development enables rapid sample processing while reducing furnace temperatures. In addition, because the sintering happens so quickly, grain growth is somewhat retarded. With dense samples of different controllable grain sizes, this can enable the manipulation of the materials’ end properties as well.
“If you could sinter directly onto a metal substrate because the furnace temperature is low enough that you’re not destroying, affecting or poisoning the substrate in any way, think of what further research areas become possible,” says Pearmain. “For example, can you increase the bond strength? It’s been shown that if you sinter composite materials with flash sintering more quickly than in a conventional process, the buildup of mechanical stresses is reduced. On top of that, you’ve got the flash processing and the grain size control manipulating the porosity to get better thermal conductivity.”
Andre Prette, technical manager in Advanced Materials & Processing for Lucideon, will detail flash sintering research in model thermal barrier coating systems on Thursday. In aerospace applications, for example, flash sintering could potentially both enable direct bonding and the use of new materials. Aerospace manufacturers currently are somewhat limited in terms of material choice for thermal barrier coatings due to the need to rectify thermal mismatch issues. Flash sintering could alleviate those issues and give manufacturers the opportunity to use a thermal barrier coating with a more suitable thermal conductivity.
Flash sintering could become “disruptive” to the ceramic industry in a wide range of applications, according to Pearmain. The process has been shown to reduce sintering times for ceramic tile to mere seconds (vs. tens of minutes), while a 25% increase in fracture toughness of zirconia and alumina disks for orthodontic components has been achieved.
The reduction in required temperature is an important consideration that could provide opportunities for new processes. “If you have a process that can operate at 600, 700 or 800°C, you don’t need that 1,200 or 1,500°C kiln anymore,” explains Pearmain. “You need an entirely new economic review in terms of parameters such as refractory wall size, energy in, and so on. Flash sintering is very much a disruptive technology because it may require a reimagining of the materials that go in to be optimized for flash, then the rapid processing with flash, and then the properties and production rates that you can achieve as a result.”
Another application under development could enable manufacturers to vastly simplify surface repair issues. In sanitaryware, for example, “normally you would have to send the entire piece through an up to 36-hr re-glaze process,” says Pearmain. “We’ve developed a flash solution that can sinter the surface glaze, and the consequence of that would be huge. You don’t need your re-fire kiln, which is of considerable length in the factory space, and flash would be an energy-efficient process. The other big benefit is you can produce to order because you know what batch you’re getting out.”
While the adoption of a disruptive technology can be daunting (after all, who needs more disruption in their life?), the benefits can be extensive. How should ceramic manufacturers begin the process of considering a disruptive technology for their operation? Pearmain suggests thinking beyond performance and productivity benefits to long-term considerations relating to not only ROI but the company’s status in the industry and its ability to draw top talent. He will be part of a panel discussion on Wednesday afternoon focusing on various issues involved with adopting disruptive technologies.
Replacing Traditional Materials
Ceramics are feasible replacement materials for metals and plastics in applications ranging from electronics and automotive to alternative energy and nonferrous metallurgy. Properties that can make ceramics attractive in these sometimes harsh environments include low coefficients of thermal expansion (leading to higher dimensional stability), high corrosion and electrical resistance, high mechanical strength and stability (even at high temperatures), high wear resistance, and lower density (resulting in less weight).
For example, silicon nitride is finding increasing use in electronics applications due to its mechanical strength and stability, flexibility, machinability, and high resistance to thermal shock. Mark DiPerri, business development manager in the Advanced Materials Business Division of Toshiba America Electronics Components, Inc., will address some of these benefits on Wednesday afternoon.
“Imagine you go out in the morning when it’s -4°F, and you have to start your car,” he says. “You’re basically shocking the entire system. Even though the electronic components are packaged and may be protected, it’s still pretty cold in there. Silicon nitride can really handle thermal shocks tremendously well, much better than any of the other materials that we have today.”
Our society’s obsession with ever-smaller and/or more enabled electronic devices can also pose a temperature-related challenge. “One of the biggest changes in today’s electronics industry is the addition of intelligence to enhance smart devices,” says DiPerri. “Power densities are rising, as designers are being asked to provide smaller, more powerful, more efficient and lower-cost devices. And of course, when you make things smaller, you have to try to get the heat out.”
As you may have guessed, these challenges are also providing increasing opportunities for silicon nitride. “Silicon nitride is non-conductive,” explains DiPerri. “You can use silicon nitride to electrically isolate different structures or components from one another, simplifying the mechanical design while improving thermal management.”
Silicon nitride and silicon nitride-based materials such as sialon are finding increasing use in the nonferrous metallurgy industry as well. “These materials are non-wetting in molten nonferrous metals and will last for years if used properly,” says Tony Finoli, Ph.D., R&D manager for McDanel Advanced Ceramic Technologies, who will also discuss feasible advanced ceramic replacement scenarios on Wednesday. “They’re replacing more common refractories and even enamel-coated or refractory-coated cast iron for things like thermocouple protection tubes.”
These advanced ceramic materials are also enabling new technologies. For example, one traditional method of keeping aluminum molten within a holding furnace involves radiant heat provided by electrical heating elements in the roof of the furnace. However, immersion heaters are a much more effective way to heat molten metal vats. “When you have something such as silicon nitride or sialon that’s stable in the molten material, you’re actually able to use immersion heat,” explains Finoli. “The heater can be placed inside the molten metal with a protection tube made of silicon nitride-based material. It’s more efficient, maintains much better temperature uniformity, and lasts a long time.”
A similar concept can be effective in chemical processing industries. “The high corrosion resistance of certain ceramics allows them to be inside a bath of certain corrosive chemicals to keep them molten during processing,” says Finoli. “That technology wouldn’t be available if you didn’t have an advanced ceramic with properties that allow it to be in such a demanding application.”
Increasing adoption rates for silicon nitride and other advanced ceramics are being seen across a multitude of high-tech industries, and this advancement is only expected to continue. “At this point, the industry is seeing an increased interest in the use of silicon nitride for a lot of existing applications where the existing solutions out there just aren’t meeting the expectations of the vendors,” says DiPerri. “As the relationships between chemical compositions, microstructures and the mechanical properties of the ceramics get adjusted, we’re probably going to see other devices or other materials that will come along to offer solutions for thermal management and other challenges.”
To register for Ceramics Expo 2018 or for additional details, visit www.ceramicsexpo.com.
How can ceramic manufacturers help end users understand their products’ potential benefits?
“Be very familiar with your materials,” suggests Tony Finoli, Ph.D., R&D manager for McDanel Advanced Ceramic Technologies. “Know not only the advantages and properties that will help the materials survive in a certain application or present an advantage to the customer, but also be aware of the limitations of the ceramic so you can have an honest conversation with your customer or potential customer. Not only do you have to sell them on the benefits that the ceramic can bring, you also have to be able to clearly explain any changes that would need to be made to their processing conditions in order to optimize the performance of the ceramic. For example, ceramics have a much lower thermal shock resistance than metals, so we often need to talk to the customer about heat-up and cool-down rates and make sure that they’re able to control those rates so that they don’t break the ceramics when they’re used in the application.
“In addition to being familiar with your own product, you really have to be intimately familiar with the intended application. That involves having an open dialogue with the customer and often having to learn the jargon that is used in a variety of industries. This will enable you to be better prepared to explain the specific advantages and benefits that the ceramic can bring to the table. If you have a good relationship with your customer and you know the industry well, it’s easier to talk to them about the different options available to them and consequently arrive at the optimum solution to their processing problem.”