[Image above] In the past 100 years, the ceramics and glass field has expanded enormously, from its traditional industries, such as structural clay products, to advanced applications, such as electronics. Credit: PxHere
By Laurel Sheppard
“Ceramics is…the art of producing from natural inorganic materials with the aid of heat a bewildering number and variety of articles with an extremely wide range of usefulness and beauty.”
This definition of ceramics was given by Lawrence E. Barringer, ACerS past president (1916) and engineer in charge of the Insulation Engineering Division of the General Electric Company, during theSeventh Annual Edward Orton, Jr., Memorial Lecture. His table on the classification of ceramics (below), which appeared in the August 1939 issue of the ACerS Bulletin, provides some insight into the state of the industry at the time.
These classifications mirrored the Society’s eight Divisions in the 1930s, which consisted of Art, Enamel, Glass, Materials and Equipment, Refractories, Structural Clay Products, Terra Cotta, and White Wares. But fast forward almost a century, and Barringer would likely be amazed at how his “bewildering” number of products is now dwarfed by the advanced applications seen today, as illustrated through the newer ACerS Divisions.
While the traditional ceramic industries are still reflected through several of the current 11 ACerS Divisions, including the Manufacturing, Refractories, and Structural Clay Products Divisions, the other Divisions demonstrate how the applications for ceramics have skyrocketed beyond the traditional uses, encompassing advanced sectors such as bioceramics, electronics, and energy.
Today we will take a closer look at some of the advanced ceramic applications and developments represented by these newer divisions. Many of these examples come from previous Bulletin articles and Ceramic Tech Today posts, in addition to several articles that I wrote while working as associate editor at ASM International’s technical publication, Advanced Materials & Processes (AM&P).
Bioceramics
The Bioceramics Division was established in 2017, but developments in this field had begun much earlier. Bone-inspired synthetic hydroxyapatite came on the scene in the 1950s when it was used as an inert scaffold for filling bone defects. Then, three decades after Barringer’s lecture, ACerS Distinguished Life Member Larry Hench and colleagues at the University of Florida discovered bioactive glass, the first material to form an interfacial bond with host tissue after implantation.
Termed 45S5 Bioglass, Hench’s discovery launched the modern field of bioceramics, with Bioglass particulate in clinical use since 1985 for middle ear bone replacement and for providing a more stable ridge for denture construction following tooth extraction, among other applications.
Other materials saw applications in the dental and medical field, as discussed in my article “Cure it with ceramics,” published in the May 1986 issue of AM&P. The article discussed alumina for tooth implants and dental crowns; glass-ceramics for dental crowns and middle-ear prosthetics; calcium phosphate cement for repairing teeth and bone; Kyocera’s ceramic vertebral spacers (Bioceramic P); and alumina-silicate glass spheres doped with radiation for treating liver cancer, developed at the University of Missouri-Rolla by ACerS Distinguished Life Member Delbert Day. More recently, silicon nitride has been considered for dental applications and spinal implants.
Today, many hip replacements incorporate ceramics for the head and liner components. For example, CoorsTek offers a line of alumina matrix composite products while Kyocera offers some zirconia-based options.
For more information on bioceramics and bioactive glasses, see the cover story of the December 2020 Bulletin. Other recent advances are highlighted here.
Cements
The Cements Division was established in 1971, after Geoffrey J. C. Frohnsdorff, manager of research and development for the American Cement Corporation (Riverside, Calif.), met with the Society’s Committee on Programs and Meetings to develop a symposium on cements for the 72nd ACerS Annual Meeting.
Today, the cement industry is facing the challenge of decarbonization to make its processes more sustainable, as discussed in the November 2023 episode of ACerS podcast Ceramic Tech Chat. The development of cement substitutes and new forming methods are two ways the industry is working to tackle emissions, as demonstrated at the Division’s recent annual meeting, 14th Advances in Cement-based Materials. A recent special issue of Buildings provides more details on new additives and admixtures for concrete.
Electronics
The Electronics Division was established in 1958; the first multilayer ceramic capacitors made from polycrystalline barium titanate were produced in the early 1950s. By the 1980s, ceramics had made their way into a wide variety of electrical and electronic circuity, as evidenced by my article “Ceramics for sensors,” published in the September 1986 issue of AM&P. The article discussed developments based on a session devoted to the topic held at the 88th ACerS annual meeting. An example of the materials and devices highlighted in the article are
- Titania sensors for oxygen detection;
- Tin oxide thin films for gas sensors;
- Barium titanate and composites of V2O3 with elastomers for thermistors;
- BaTiO3/BaSnO3 multifunctional sensors for temperature, relative humidity, and acetylene or ethylene gases;
- Zirconia air-fuel ratio sensor with heater for three-way catalytic converters; and
- LiTaO3 or PbTiO3 thermal sensors for chemical processes.
Another article in the same issue of AM&P looked at hermetic ceramic packages, including lead-zinc-borate glasses for integrated circuit packages, ceramic dual-in-line ceramic (Cerdip) packages, and multilayer ceramic packages using an alumina substrate.
Almost 40 years later, the electronics industry is now in the age of silicon. However, nonoxide ceramics are gaining interest, including gallium nitride (for small electronics) and silicon carbide (for vehicles). With the advent of quantum systems, synthetic diamonds have emerged to advance this technology. For more information on other emerging materials and techniques for quantum systems, see the June/July 2024 Bulletin.
Energy Materials and Systems
Before the Energy Materials and Systems Division was established in 2020, the Society had a Nuclear Division (established 1965) that was later renamed the Nuclear & Environmental Technology Division in 1994. This expansion to a more general energy Division recognized the increasing important of other clean energy topics besides nuclear, including batteries, fuel cells, solar panels, wind turbines, electrical systems, and hydrogen.
These energy technologies are critical for addressing climate change, and they contain many ceramic and glass materials. For example, wind turbine blades are made from glass fiber-reinforced composites, while solar panels rely on cover glass to protect the photovoltaic cells.
Despite the potential of these clean energy technologies to reduce greenhouse gases, disposing of them responsibly is a major issue. To learn more about recycling of wind turbine blades, see the January/February 2024 Bulletin cover story. Meanwhile, this CTT discusses a new way to recycle solar panels.
Carol Jantzen, the first woman president of ACerS, was a pioneer in radioactive waste immobilization, with a focus on glass. More recently, cermets are being investigated for nuclear waste containment.
Engineering Ceramics
The Engineering Ceramics Division was established in 1985 as an expansion of the previous Ceramic–Metal Systems Division (originally the Enamel Division). This renaming was driven by the significant broadening of the Division’s scope during the previous 10 years, according to Division chairman Frank D. Gac in the July 1985 Bulletin.
This point was emphasized a year later in the October 1986 issue of AM&P, which featured my article “Reliable ceramics for heat engines.” The article reported the results from several recent surveys, which found that engineered ceramics were a “hot” topic across various engineering groups.
- At the recent Society of Automotive Engineers annual meeting, 77% of attendees ranked ceramics technology high on the list of priority research.
- A survey of 200 auto design engineers found 66% selected advanced ceramics as one of the new materials that will have most vital applications for automobiles.
- More than 100 organizations were involved in structural ceramics research in the U.S. per a report by Technology Management Group.
The aerospace industry in particular makes expansive use of engineered ceramics, such as silicon carbide (SiC) and silicon nitride (SiN). Already in the 1980s, as reported by an article in the September 1986 issue of AM&P, the industry was using these materials in applications such as
- SiC whiskers/SiN composites for gas turbine rotors,
- Hafnium carbide-coated rocket nozzle and SiC-coated exit cone,
- Carbon fiber/ceramic composites for turbine rotors and nozzle flaps, and
- SiC/SiC composites for heat exchangers and turbine components.
Today, ceramics are also used for the turbine blades and vanes in aircraft engines and as thermal protection materials for spacecraft. In addition, oxide-oxide ceramic matric composites for rocket thrust chambers and SiCN reinforced with yttria-stabilized zirconia for electromagnetic interference shielding are being investigated. Other applications of ceramic and glass materials in aerospace are discussed in the December 2022 Bulletin cover story.
Most recently, research on ultrahigh-temperature ceramics, which were first reported in the late 19th century, is picking up again for use in emerging hypersonic and reentry vehicles. These and other materials are the focus of a new hypersonic materials training program run by ACerS and the United States Advanced Ceramics Association.
Glass & Optical Materials
As evidenced by Barringer’s classification table, the optical properties of glass have been recognized for a long time. For example, during the 1930s, George W. Morey discovered the outstanding optical properties of lanthanum-containing glasses, which include high refractive index with comparatively low dispersion and good transmission in the blue-violet spectral range. These compositions are still in use today for a wide variety of applications. Other developments in optical glass took place during the succeeding decades, but it wasn’t until 1990 that the Glass Division changed its name to the Glass & Optical Materials Division.
Since then, many other applications of optical glasses, glass-ceramics, and transparent ceramics have come to fruition. At the 2024 Glass & Optical Materials Division (GOMD) Annual Meeting, the application of these materials in photonic applications environmental monitoring, exoplanet discovery, and high-power laser systems were discussed. Additionally, the May 2024 Bulletin cover story overviews the growing market potential of chalcogenide glasses. For more information on optical and photonic ceramics, check out this review.
Classification conundrum
The “family tree” of ceramics has expanded so much that developing a modern classification table like Barringer’s would be a momentous task that likely would not include all materials and applications. But this expansion just demonstrates Barringer’s point that “…the term ‘ceramics’ is no longer confined to the very narrow meaning of the original Greek word from which it was derived…”
The industry’s expansion from “comprising all products fashioned from silicates or oxides” to also including carbides, nitrides, borides, and composites of many compositions is a list that grows longer every day. It will be exciting to see what materials and applications are developed in the near future. Stay tuned for new discoveries published in CTT and other ACerS publications!