Alumina Ceramics

Biomedical and Clinical Applications

Andrew J. Ruys

• Publisher: Woodhead Publishing
• Year: 2018
• ISBN:
  9780081024430
• Topic: Tecnología e ingeniería
• Subtopic: Ciencias de los materiales

Alumina Ceramics: Biomedical and Clinical Applications examines the extraordinary material, Alumina, and its use in biomedicine and industry. Sections discuss the fundamentals of Alumina Ceramics, look at the various industrial applications, and examine a variety of medical applications. Readers will find this to be an invaluable and unique resource for researchers, clinical professionals, engineers, and advanced level students. Alumina ceramics are a leading biomaterial used for specialist medical applications, such as bionic implants and tissue engineering, and the only biomaterial commercially viable for use as bearings for orthopedic hip replacements. As such, this book is a timely resource on the topics discussed.

• Provides a unique and thorough review of Alumina ceramics
• Written by one of the world's leading experts in bioceramics and advanced industrial ceramics, especially alumina
• Targeted to researchers in the materials, clinical and dental fields
• Enables the non-expert with an overview of the underlying alumina technology, major challenges, major successes and future directions

1

Introduction to alumina ceramics

Abstract

This 16 chapter/180,000 word book is a comprehensive overview of alumina ceramics, defined as dense Al₂O₃ ceramics in the purity range 85%–100%. Alumina powder technology (e.g., abrasives), low purity alumina ceramics (below 85% pure), porous alumina ceramics, and alumina-matrix ceramic composites are beyond the scope of the book. The fledgling alumina ceramics industry began in the 1950s. It is 35 years since the last book dedicated to alumina ceramics was published, at which time the alumina ceramics industry was still quite rudimentary, with a primary focus on refractories and electrical insulators. Thus this book represents a major update on alumina ceramics. In 2018, the two most commercially significant applications for alumina are: (1) alumina feedthroughs in bionic implants, a $25 Billion industry (pacemaker, bionic ear, bionic eye, deep brain stimulator, and 10 other bionic implant types); (2) alumina electrical substrates in the semiconductor and microelectronics industry—SOI substrates are a $50 Billion industry, the thick-film alumina microelectronics industry is comparable in scale. Alumina bearings have revolutionized the hip replacement industry, reaching global dominance in 2015, and now capturing 55% of the global market of 1.3 million hip replacements a year. Alumina lightweight body armor, first trialed in 1965, has changed the world. Ceramic body armor has been deployed on a massive global scale since 1996, for the first time in history military/security personnel of all ranks are protected against the munitions of the day, an extraordinary humanitarian and egalitarian advancement. Alumina wear-resistant ceramics dominate the global $500 Billion mining industry, uniquely combining low cost with extreme wear resistance, and they are also important in textile manufacturing, papermaking, food processing, pumps, seals, and general engineering, and many other industries. Alumina continues to play an important role in the $50 Billion refractories industry, and has many other important applications such as dental technology, tissue scaffolds, oxygen sensors, architectural ceramics, aerospace ceramics, and machining tools. This book begins with a look at alumina refining (bauxite and the Bayer process), and then an overview of alumina processing, structure, and properties. It then comprehensively overviews all the applications for alumina ceramics discussed above, as well as many more minor applications.

Keywords

Alumina ceramics; Review; Overview; Monograph; Bionics; Orthopaedics; Electrical ceramics; Wear resistant ceramics; Armor ceramics; Refractories

1.1 Introduction to alumina ceramics

The word “alumina” conveys images of a pearly white ceramic. However, alumina ceramics are much more than that. In the biomedical sector, alumina ceramics have delivered important life-saving and life-enhancing technologies to millions of people in the world in the last few decades. Moreover, in the industrial sector, alumina underpins some of the world's largest industries: mining and mineral processing ($500 billion), semiconductors ($500 billion), and refractories ($50 billion).

1.1.1 Live-saving alumina technologies

Implantable bionic pacemaker (Chapter 8): All cardiac pacemakers use an alumina feedthrough, a key enabling platform technology that made the bionic implant possible. Millions of implantable bionic pacemakers have kept arrhythmia sufferers alive in recent decades (the great majority since the turn of the century), and more still since the advent of the implantable bionic defibrillator and pacemaker/defibrillator.

Alumina ceramic lightweight body armor (Chapter 11): Millions of body armor insert plates have protected lives in recent decades, the great majority since the turn of the century when ceramic lightweight body armor went mainstream.

Many lives have been saved as a result, and I consider myself fortunate to have been able to serve the community by being active in both these technology sectors in my long career.

1.1.2 Life-enhancing alumina technologies

Orthopedics (Chapters 6 and 7): Alumina bearings bring greatly enhanced implant longevity to about 700,000 or so hip replacement recipients a year, i.e., 55% of the 1.3 million hip replacement recipients, the half who are lucky enough to receive the “deluxe” alumina version of the hip replacement, rather than the regular CobaltChrome hip replacement, and its problems with 2 trillion polyethylene wear particles released per year, and cobalt and chromium release into the joint cavity through galvanic corrosion and fretting wear.

Other bionics (Chapters 9 and 10): While it is the pacemaker that saves lives, all bionic implants use an alumina feedthrough. Today there is a wide range of bionic implants on the market that treat drug-resistant Parkinson disease, dystonia, obsessive-compulsive disorder (OCD), depression, chronic pain, sensorineural deafness, blindness, and incontinence, to name but a few of the 25 or so significant disease states now treated by bionic implants.

1.1.3 Community enhancing

Mining industry (Chapter 12): As a low-cost highly wear-resistant ceramic, alumina has significantly enhanced the economic viability of the $500 billion mining and mineral processing industry, one of the world's largest industries.

Textile industry (Chapter 12): This is a significant employer in developing countries, where the affordability of alumina and the longevity it brings to textile processing equipment is of significant economic and social importance.

In addition, alumina is important in many other large global industries such as electronics, and refractories.

One of the most unique aspects of the global alumina industry is how little interaction is there between those involved in each market sector. There are a number of large global markets for alumina, but those involved in each market have virtually no interaction with those from the other markets. This is much more pronounced for those involved in the biomedical applications (orthopedic bearings, feedthroughs for implantable bionics, lightweight body armor, dental implants, and tissue scaffolds) than for those involved in the industrial applications (wear-resistant linings, refractories, microchips, insulators, and electrical feedthroughs). Those involved in the industrial applications are commonly aware of the other industry sectors, and even to some extent, the biomedical sectors. However, in my long career in bioceramics and industrial ceramics since the 1980s, in which I have had an involvement in all of the above sectors, I have never come across such a book or review that has overviewed all biomedical and industrial applications in one document.

The most recent monograph written on alumina, the 1984 book of Dorre and Hubner [1], came the closest to achieving this. However, the rudimentary world of alumina in 1984 is so far removed from the world of alumina today, that this excellent book written 35 years ago has mainly historical value today. Bionics did not feature in the 1984 book at all, and lightweight body armor received only a very brief mention. Orthopedics covered several pages by virtue of the fact that the principal author Erhard Dorre was a pioneer in orthopedic alumina. Dorre was from Feldmuhle, the German company that pioneered the commercialization of the alumina hip...