- THE MAGAZINE
Nanophase and NanocompositeThere are two main classes of nanosized materials: nanophase and nanocomposite. Nanophase materials provide closer control of product properties. Nanophase ceramics (nanoceramics), for example, are stronger and more ductile than conventional ceramics. They can also be sintered at lower temperatures, increasing the range of possible substrates and lowering processing costs. Nanophase materials are generally monolithic pure materials, such as titanium oxide.
In nanocomposite ceramics, a tiny ceramic particle will be entrapped in another particle. An example of a nanocomposite is nanometer-sized silicon carbide inside of alumina. Nanocomposite ceramics can exhibit wear resistance, chemical inertness, corrosion resistance and thermal insulating properties.
ApplicationsNanophase materials, including nanoceramics, have the potential to become another materials revolution. Nanophase material properties can be manipulated to provide a designer with the specific material needed to build a product that is strong and can withstand wide temperature variations, while having special optical, electrical or magnetic properties. The ability to manufacture a nanocrystal ceramic material at lower temperatures is a great advantage that could result in economical production of flawless, high-precision ceramics using techniques similar to those in the powder-metal industry.
Nanostructured materials are being developed and used for diverse applications that exploit their magnetic, optical, electronic, catalytic and other properties. The unique properties of nanocrystalline ceramics have opened a wide range of applications, including durable ceramic parts for automotive engines, cutting tools, ultrafine filters, flexible superconducting wire and fiber-optic connector components. Some of the other potential and current applications are shown in Table 1.
U.S. MarketsThe market for nanosized materials has been slowly picking up in the latter part of the 1990s. According to a Business Communications Co., Inc. (BCC) study, “Fine and Nano Ceramic Powders,” the 1998 market is estimated to be 2.2 million pounds worth $42 million. This is projected to increase to 6.5 million pounds worth $156 million by the year 2003. Nanocrystalline iron oxide and alumina are expected to remain the market leaders, with shares of about 40% and 29%, respectively, during the projected period. Other nanoceramic powders such as barium titanate, ceria, zirconia and zinc oxide are expected to double their market shares from 1998 to 2003.
Table 2 presents the major markets for nanoceramic powders according to various advanced ceramic applications, i.e., electronic, structural and chemical processing/environmental, and Figure 1 shows the share of each market segment. In 1998, the combined electronic/magnetic/optic applications constituted 50% of the total market, followed by structural/mechanical applications with 33.3%. However, by the year 2003, structural/mechanical applications are expected to pick up more growth to reach $60.5 million with a market share of 38.8%, due to increased usage as abrasives in chemical mechanical polishing (CMP) applications.
Among the electronic/magnetic/optical applications, magnetic application is expected to have the most dramatic growth due to increased application of nanocrystalline iron oxides as contrast agents for MRI (magnetic resonance imaging) procedures. Another application is iron oxide nanocrystals in the more established ferrofluid market. Among the structural/mechanical applications, significant growth is expected in the usage of nanocrystalline oxides for industrial polishing applications, particularly in the semiconductor industry, where ultrafine abrasive particles are needed for the chemical mechanical polishing of dielectric and metallic layers deposited on silicon wafers.
Currently, amorphous silica is the predominantly used abrasive material, although alumina is also used for CMP. Several companies involved in this area are investigating other oxides as well, including nanocrystalline ceria, zirconia and titania. Besides polishing applications in the semiconductor industry, nanocrystalline abrasives are also used to obtain high quality finishes on magnetic recording disks and heads and optical fibers. Nanocrystalline alumina is expected to account for about three-quarters of the total abrasive market, with other materials such as ceria and zirconia generating the remainder.
International CompetitionOverall, the most serious competitors to U. S. producers of nanocrystalline materials are companies based in Japan and Germany. The Japanese were quick to recognize the technological importance of small particles and launched concerted development and commercialization efforts in the 1960s that were continued in the following decades. A number of Japanese companies have thus developed large-scale and cost-effective ultrafine and nanocrystalline powder production facilities.
An area receiving a great deal of attention is the development of ultrafine particles for magnetic recording media. Based on this early focused effort, the Japanese now completely dominate the magnetic recording tape industry in terms of submicron and nanocrystalline particle production. There are three major Japanese companies producing oxide and metallic magnetic nanocrystalline powders for incorporation into magnetic tapes—Dowa Mining, Kanto Denka Kogyo and Toda Kogyo. The Japanese are also major producers of nonmagnetic particles, such as titania and alumina, and have succeeded in marketing these materials in the U. S. at very competitive prices.
Although the Japanese were quick to jump on the bandwagon, the Germans—companies such as Degussa and Wacker Chemie—were the true leaders in nanostructured materials technology, as they were among the pioneers of vapor-phase processing methods to produce nanocrystalline particles in the 1930s and commercialized the production of nanoscale fumed silicas in the next decade. Today the Germans remain important players in this industry.
Editor’s Note: This article is based on a recently completed BCC study “Fine and Nano Ceramic Powders,” published in May 1999. A copy of the table of contents of this study including the introduction is available gratis. Contact: Dr. Thomas Abraham, BCC Inc., 25 Van Zant St., Norwalk, CT 06855, USA; (203) 853-4266, ext. 313, fax: (203) 853-0348; e-mail: firstname.lastname@example.org.