The ubiquitous nature of materials, entering into almost every industry and activity, makes materials a key set of enabling technologies for a multitude of goals. Advanced alloys, ceramics, composites, and polymers are enabling technologies for, among other ends, high-performance aerospace and surface transportation. This supports both civil and military systems. Functional materials, such as diamond thin films, can provide enhanced physical and electronic characteristics for a wide range of applications in the manufacturing and electronics industries. In turn, this couples not just to economic goals, but to other goals, from environmental to space exploration. New materials are also key to many manufacturing developments, whether through improving existing products or through creating entirely new possibilities.
The following technology areas are addressed in the Materials category:
No single assessment of the performance of the United States could be appropriate across a range as broad as that represented in the technology sub-areas, and indeed, the international position of the United States in Materials is mixed. Although generally leading, there are some areas where the lead is shrinking or a lag has appeared. Some of these assessments are familiar, as the foreign lead in materials for semiconductor manufacturing, or the U. S. lead in polymer matrix composites. Others may be less familiar, as the good U. S. position in ceramic composites, where we do not yet lead the Europeans, but appear better positioned than the competition for the emerging market. Our long concentration on materials science has paid dividends. The specifics of the assessment are presented in the text of the section. The summary of the U.S. relative position and trends from 1990 to 1994 are shown in Figure 7.1.
Alloys contribute to job creation and economic growth through efficiencies in production of automobiles and aircraft, in construction, and in other industries where materials can be created for specialized applications. Alloys contribute to enhanced national security by allowing the creation of better quality and less expensive military equipment.
The United States has a slight overall lead in metals technologies, but there are important areas in which foreign firms are equal or slightly ahead. France, the United Kingdom, and Russia, for example, are all about equal to the United States in aluminum-lithium alloy technology. Russia is quite strong with capabilities very close to those of the United States in many areas of advanced metals, including titanium, aluminum, and superalloys. Russian high-strength titanium alloys, if performance claims are true, are equal if not superior to corresponding materials in the United States. France, at the forefront of European aluminum-lithium alloy technology, is being helped by cooperation with Russia. The United States retains a slight technology lead in high-purity titanium alloys, but French research for the next generation of aerospace-grade titanium alloys is approaching U.S. research in terms of goals and achievements. U.S. and European firms, driven primarily by their aerospace industries, have a technology lead in superalloys which are used in a variety of high-temperature and corrosive environments, ranging from jet engines to chemical processing plants. Japan recently completed a national-scale project to develop superalloy capabilities and further research is underway to match U.S. and European capabilities in producing state-of-the-art single-crystal superalloys for aerospace applications. Japan's production capabilities cannot yet match those of U.S. and European firms, but its focus on manufacturing should lead to improvements.
The United States was the first country to perform engine tests of intermetallic gas turbine blades and has a clear technology lead. German, French, and Japanese research has been comparable to that performed in the United States, but has generally focused more on research than on near-term applications development. The Japanese have developed an intermetallic for turbine blades, but its overall properties are behind those in the United States. Although the United States currently has the lead, both in technology and production capabilities, Europe and Japan are close enough that many industry observers expect the future market to be evenly split, with each country favoring indigenous production. Russia may have an advantage in its ability to weld advanced alloys, which can help in some applications of those alloys.
Ceramics contribute to job creation and economic growth in several ways. Their lower heat conduction helps engine efficiency, particularly for diesels, while ceramic coatings reduce friction between automobile engine parts, making automobiles more productive in world markets. In addition, to contributing to efficiency in production, ceramics contribute to improved environmental quality by improving fuel economy and reducing emissions. By reducing friction between parts and lowering the need for lubricants, ceramics also contribute the U.S. national security by reducing the need for logistical support, and thereby improving U.S. global power projection capabilities and effectiveness of warfighting in unconventional conflicts.
The major area of Japanese materials strength is in ceramics. Japanese ceramic fibers and powders are believed by industry experts to be the highest quality in the world. Ube's "Tyranno" fiber and Nippon Carbon's "Nicalon" and "Hi- Nicalon" are considered the best silicon carbide fibers available for use in ceramic composites. Japan currently ranks first in the world in applying monolithic ceramic components such as turbocharger rotors to automotive engines. The willingness of Japanese automakers to incorporate ceramic parts into their production automobiles has given Japan valuable experience in real world applications. Kyocera and NGK Spark Plug, which began introducing ceramic turbochargers for use in Japanese automobiles in the late 1980s, are now mass producing turbochargers and ceramic exhaust valves. Although German companies are developing similar ceramic valves, they have not begun using them on a production scale. Japan has also applied ceramics to machine tool parts such as bearings, rollers, and tool inserts. The technology necessary to produce these components provides Japanese firms with the basic building blocks for eventual production of components for more demanding applications such as cruise missile engines, auxiliary power units, and industrial and aircraft gas turbine engines. Japanese firms benefit from active government support as well as from spin-off capabilities flowing from their dominance of electronic ceramics. Japan's lead in ceramics is directly attributable to a focus on monolithic ceramics, whereas other countries, such as the United States, have allocated more resources to developing ceramic composites for comparable structural applications.
The metal-matrix composites use metal rather than plastic as the matrix. Usually the metal is in the form of a powder which is combined with the reinforcing fibers in a mold, where the combination is subjected to heat and pressure to fuse the part together. Metal matrix composites (MMC's) have advantageous properties of higher strength, stiffness, wear resistance and elevated temperature properties, and are especially applicable for high-temperature uses such as in jet engines. Many metal matrix-composites can be machined on the same apparatus used for traditional metals and some can be welded. Matrix materials include nickel, superalloys, titanium alloys, aluminum alloys, magnesium, copper, intermetallics, and steels. Fibers include, silicon carbide (SiC), refractory metal wires, and carbon fibers, among others.
Metal matrix composites have the potential to significantly affect future propulsion systems, as well as airframes. One metal matrix composite being investigated is fiber-reinforced titanium which is about three times stronger for a given weight than nickel superalloy at temperatures up to 1500[[exclamdown]]F.
Ceramics are attractive as composite matrix materials in aerospace applications because they offer increased turbine inlet temperatures while lowering overall weight. Unfortunately, at this time ceramics are brittle, costly, and difficult to manufacture. The high brittleness of purely ceramic parts which makes them extremely prone to impact damage may be overcome by using ceramic matrix composites.
There are two types of composites. In one, fibers are uniformly mixed with the matrix and a material with isotropic properties is created. A second type of composite involves aligning fibers in a specific direction in order to create materials with much greater strength in a direction of greatest loads. While composite materials offer numerous advantages in weight and fuel efficiency, their application has been rather limited to date in the commercial world. One reason is that the cost of manufacturing composites remains substantially higher than metals due to the large amount of hand labor, and the weight savings do not always justify their use. However, if the production process were to be more automated, the manufacturing cost of composites could become competitive with metals.
Composites are key to making lighter cars, an important part of meeting the PNGV goals of improved fuel efficiency without sacrificing safety which would make the new generation of U.S. automobiles more competitive on world markets. Composites contribute to the efficiency and competitiveness of the aerospace industry for the same reasons. New composites are already being introduced for surface (non- structural) parts of buildings, and will probably be used for structural elements in the future, contributing to the health of the U.S. construction industry in the U.S. and to competitiveness of U.S. construction companies on world markets. The ability of composites to reduce weight while maintaining strength is a contributor to enhancing national security and warfighting capabilities as well. It allows improvements in global power projection capabilities through the creation of lower-weight equipment.
Europe and Japan are slightly behind the United States in composite technology. European firms lead in developing and using ceramic matrix composites (CMCs), although they rely on the high-quality, low-cost ceramic fibers available from the Japanese. France is the world leader in CMC technology with applications in nozzle flaps for the M-88 gas turbine engine for the Rafale. Japan has focused primarily on monolithic ceramics and is significantly behind European and U.S. efforts in CMCs. Despite the current European lead in CMC research, the United States has excellent long term prospects. Europe's lead is based largely on the R&D efforts of the French firms Societe Europeane Propulsion (SEP) and Aerospatiale on silicon carbide/silicon carbide composites aimed primarily at military and aerospace applications, although they continue to rely on reinforcing fibers from Japan. However, industry estimates predict that the major sectors for CMC applications will be in industrial applications such as radiant burners and heat exchangers. The United States--with CMC programs aimed at developing industrial applications--would gain the most from such a scenario, while France would likely need a substantial redirection of research strategy.
The United States pioneered research in polymer matrix composites (PMCs) in the 1960s and continues to lead the world in this technology. PMCs are attractive for a number of applications--including civil and military aircraft, industrial equipment, and automotive components--due to their excellent strength-to-weight ratios and design flexibility. While manufacturing costs continue to limit the wide-scale introduction of PMCs into advanced applications, industry experts believe a growing acceptance in the automotive and commercial aerospace industries will offset shrinking military markets. The Japanese are ahead in some manufacturing processes, such as co-curing and tooling; and European companies have made important advances in compression moldings and tape-laying processes. Europe is using advanced polymeric composites to a limited degree in primary structural components for new aircraft such as France's Rafale fighter, Sweden's Gripen fighter, the Euro 2000 fighter, and the Airbus 330/340 civil transport.
The United States, Europe and Japan are all actively developing metal-matrix composites, largely for use in the aerospace industry, and there is currently no clear leader in this field. U.S. and French firms have a slight technological lead in the quality of finished products, but British and Japanese companies have performed notable research on the processing of metal-matrix composites. Currently, the only commercial systems using metal-matrix composites are satellite frames, but these materials have significant potential in turbine disks for jet engines, where they can lower the weight of the engine components by as much as 50 percent. The United States and Britain have led recent efforts to incorporate these materials into jet engines.
The United States and France pioneered carbon-carbon composites research, and remain the technology leaders. Carbon-carbon composites, because of their ability to withstand high temperatures and high stresses, were originally developed for use in missile nozzles and re-entry vehicles, but they are seeing increased application in low- technology applications such as aircraft brakes. Because use has been limited by high processing costs, much of the current research is geared toward developing more efficient processing methods. Although a French team at the Center for Aerospace Studies recently developed a manufacturing method which could reduce the cost of finished materials. Japanese companies are the world leaders in carbon-carbon weaving technology. Germany's efforts have been waning in the past few years, with BASF, one of the largest manufacturers, selling their composites division. U.S. and French firms are likely to maintain their lead in carbon-carbon composites over the Japanese, who perform good research, but lack the applications opportunities that have driven other efforts. Japan has successfully manufactured carbon-carbon products used for the OREX, a materials test bed reentry vehicle for the HOPE space plane, and has manufactured prototype carbon- carbon leading edge, nosecap, and flat panel components also intended for HOPE.
Foreign firms are generally ahead of the United States in technology for electronic and photonic materials-- particularly in technology for producing silicon wafers for microelectronic devices. Japanese and European firms are now producing state-of-the-art eight-inch wafers and are ahead in work on larger-diameters. MITI is funding 70 percent of a seven-year, $180 million project to standardize on a 16-inch wafer for future production. The project includes the nine Japanese companies and two German firms that together control 90 percent of the current world market, and could consolidate foreign control over this technology sector. Firms in other regions, such as Korea and Taiwan are trying to establish independent silicon wafer production facilities and developing wafer technology to support their semiconductor industries. Some larger wafer size will likely become the de facto standard.
Japan and Europe are roughly equal to the United States in gallium arsenide (GaAs) wafer technology--the leading alternative to silicon as a semiconductor substrate material. Companies in all three regions are working to improve GaAs wafers by lowering defect densities or forming an insulating layer that could extend applications. GaAs substrates, however, are facing competition from silicon which has a much larger market and is much cheaper. Japan trails the United States and Europe in another alternative material, silicon germanium.
There are two basic classes of photonic materials: electronic materials with controllable and appropriate optical properties for optical-electronic transducers (GaAs and GaAlAs), and silica glasses for long-distance transmission of optical signals. Because they allow faster computing and transmission of information over wider bandwidths, photonic materials make a particularly important contribution to harnessing information technology by allowing distributed access to information ranging from multi-media entertainment to medical diagnostics.
Photonic materials are also widely used for military applications. These include: communication and navigation, laser radar, electronic warfare, guidance and control of smart weapon systems and unmanned vehicles, sensors (including: sonar, gyro, and focal plane arrays), and simulation and training. In all of these applications the key components involve sensors and detectors, laser arrays, and communication networks.
Russia is the world leader in advanced propellants, with work in advanced oxidizers and other key technologies taking place earlier than similar work in the United States. The French possess equivalent technology to that of the United States in high-energy density solid rocket propellant capabilities having produced comparable motor case materials, nozzles, and propellants. The French have an impressive R&D effort, which has produced energetic propellants and composite motor case materials, both of which are now being used on new generations of weapons systems. However, the French-- paralleling similar decisions by both the United States and Japan--have chosen to use older technology in the development of the Ariane 5 boosters. The technology used for these boosters was developed from solid rocket motors on the Ariane 3 and 4 and on French ballistic missiles. Japan is several years behind the United States in solid rocket technology, primarily in motor case materials and propellants. Japan developed and manufactured HTPB binders and propellants approximately eight to ten years after the United States based on original technology for composite propellants obtained under license from the U.S. company, Morton Thiokol. Currently, the performance that the Japanese obtain from their HTPB propellant is comparable to similar products in the United States. The Japanese prefer the reliability of HTPB-based propellants and probably will not pursue more energetic propellants for boosters because of the associated hazards.>
The United States has been a leader in the development of and use of high performance concrete (HPC), with compressive strengths above 10 ksi. Several other countries are moving aggressively to exploit HPC technology, including Canada, France, Japan, Norway and Sweden. In France, for example, designers routinely use HPC with strengths from 8 to 14 ksi in bridges and buildings. In addition to HPC, several countries, including Britain, France, Germany and Sweden are making significant advances in chemical-resistant concrete and high-precision concrete construction. Strengths to 100 ksi may soon be possible and are currently being studied in France.
In France, high performance surface dressing for asphalt pavements is being used, and requires special equipment for its placement. High-performance asphalt (HPA) is also the focus of interest in Germany where hot-mixed rubberized asphalt and reclaimed asphalt pavements are widely being used. Work in Sweden and Britain is producing pavers and blocks utilizing fly ash that may prove commercially viable.
Although the United States established an early lead in the development and introduction of high-performance steel (HPS) with yield points up to 100 ksi, the rest of the world has recently caught up and taken the lead. In catching up, steel makers in Japan and Europe have used new technology to overcome two of the major problems in manufacturing the new class of quenched and tempered steels: high energy consumption because of repeated heating, cooling and reheating; and fabrication requiring great care so that welded joints have the same desirable properties as the parent material. Japan is currently the world leader in weldable and fire-resistant HPSs. Over the past few years, Japanese and European producers have reported significantly improved mechanical properties for steels produced using special thermomechanical controlled processing (TMCP), and they have installed the facilities to produce these steels. In the United States the first production facility will not be installed at least until 1995.
Currently, the United States enjoys a leading role in advanced-composites technology, essentially based upon defense work. Large scale research efforts in Europe and Japan are now being accelerated and threaten to undercut the United States' leading role within the next decade. There is a large potential market for advanced composite materials (ACM) in the rehabilitation of our highway infrastructure, but ACM are not economically viable in most civil applications at current cost levels. New, more affordable processes for manufacturing composite structures for civilian infrastructure are being developed in the United States and several are being funded, in part, by ARPA. Unlike the United States there are a number of composite bridges in England, Europe and Japan. Japan is far ahead of the United States in the development of this new market.
Signatures are those characteristics by which these systems may be detected, recognized, and engaged. The modification of these signatures can improve survivability of military systems, leading to improved effectiveness and reduced casualties as demonstrated in the Persian Gulf conflict.
Europe and Japan are behind in applied stealth technology as evidenced by U.S. aircraft programs such as the F-22, B-2, and F-117A. Most of the applied foreign low-observable work involves basic shaping, material coating techniques, and signature testing requirements. Europe has been led by France, Sweden, Germany, and the United Kingdom in various types and levels of low-observable applications. Applications on fighter aircraft have generally been at fundamental applied levels, primarily using absorbent coatings, limited structural shaping, and absorbent structure. Applications seem to be limited to the areas with highest signature return rather than application to an entire airframe. European firms are also working on stealth technology applications to cruise missiles and unmanned aerodynamic vehicles. Advanced Japanese fighters, like the FS-X, could deploy low-observable technology, but Japanese firms are probably better positioned as materials suppliers than as users.>
High-temperature superconductors are a relatively recent discovery. Providing the theoretical understanding of these materials could contribute to the goal of achieving world leadership in materials science. The losses in electric transmission could be reduced if high-temperature superconducting transmission lines became practical, providing less expensive power for job creation and economic growth. When the materials become commercially viable, their effects could also include cheaper magnetic levitation transportation systems, and better scientific infrastructure for those fields that use superconducting magnets.
Japan probably has a slight edge over the United States in superconductors based on a large and diverse research program emphasizing power as well as medical and electronics applications. Both are about equal in low-temperature superconductors (LTS) magnet technology, but each country has different areas of emphasis. Japan is ahead in applying LTS magnets to transportation applications such as magnetic levitation vehicles and magneto-hydrodynamic ship propulsion, whereas the United States has focused on magnets for high- energy physics including fusion research. Although LTS applications continue to be the mainstay of superconductor research, efforts on high-temperature superconductors (HTS) have continued and the development of wires, microwave devices, and magnetic field detectors is nearing the applications stage. Europe, led by Germany, trails the leaders by a few years. Russia has some capability, particularly in LTS for manufacturing wires and magnets. Much of this strength probably derives from work on fusion devices and particle accelerators.
Aircraft structures are essential to competitiveness in the aerospace industry, with impact on both commercial and military segments. The fibers of polymer matrix composites can be aligned, forming a material with anisotropic properties. If carefully designed for an application, such materials allow a lighter, smaller structure to replace larger, usually metal ones. So far, the application of such structures has been limited to those demanding the highest performance. These have usually been in the aerospace industry, frequently in military systems. Part of this limitation comes from the difficulty in fabricating complex structures from the materials. In the example of polymer matrix composites, this has been manifested as a difficulty in arranging the fibers in the pattern needed; the usual solution is expensive, because it is labor-intensive. For many applications, these problems are compounded by the difficulty of optimally designing with such materials.
Aircraft structures make a contribution to meeting job creation and economic growth by contributing to the success and competitiveness of the U.S. aircraft industry. They also contribute to meeting the U.S. warfighting capabilities by enhancing performance of military aircraft.
Japan lags Europe and the United States in computational structural mechanics for aircraft applications, and has relied heavily on Western-developed computational mechanical analysis tools to support most of its advanced aircraft structures programs. In the commercial sector, Mitsubishi Heavy Industries, Fuji Heavy Industries and Kawasaki Heavy Industries all use Dassault's CATIA 3-dimensional structural modeler. Japanese development of commercial codes is limited; integrated aero-structural-controls analysis and optimization approaches are still being explored at the research level. Although the major aircraft design and manufacturing firms are familiar with recent international development in the multidisciplinary optimization field, most of the interest is in obtaining and using U.S. and European techniques and software, including NASTRAN and CATIA.
The European aircraft production industry is slightly behind the innovative developments now entering applied engineering in the most advanced U.S. fighter and commercial aircraft acquisition programs. European aircraft computational mechanics activities have applied efforts of sophisticated technology in both military and commercial aircraft programs. Computer-aided engineering and manufacturing can permit designers and manufacturing engineers to meet in the preliminary design phase to integrate requirements and technology limitations early in the design cycle as well as throughout the development process. The result is an airframe optimized to the respective key performance specifications, whether as a military fighter or a commercial passenger aircraft. The benefits are avoidance of costly delivery delays and re-engineering work during the fabrication phase. The Eurofighter 2000 and the French Rafale have extensively used both U.S. and indigenous developed finite element analysis (FEA) and structural optimization software to advanced the airframe technology to state-of-the-art relative to mechanical performance and physical characteristics. The French have been using Dassault's CATIA design software package coupled with ELFINI FEA that has a demonstrated capability to handle the "paperless" design and prototype engineering tasks without requiring physical articles. In the commercial sector, Airbus Industrie also employs a host of U.S. and European commercial software products. Airbus Industrie is reported to have moved from physical prototype design process to a full paperless design process with its A330 and A340 aircraft.
Europe is behind the United States in hot structure airframe designs and materials for components for the extreme thermal, mechanical, and acoustic loads in many projected applications. Despite some impressive growth in the past five years, recent economic pressures have slowed or stopped several key programs. The European Space Agency's (ESA) and its membership continue to look for piecemeal applications of individual sub-technologies of the troubled HERMES space plane Program. Most European hypersonic flight vehicle programs have been drastically reduced or stopped. Examples include the financially troubled ESA FESTIP study and the now defunct German Hypersonic Technology Program (formerly Sanger Program). Overall, the Europeans apparently are trying to maintain hot structure technology programs while attempting to find new applications to sustain advanced development.
Japan is also behind the United States in hot structure design, test, and production. Japan has closely studied and attempted to duplicate or commercially acquire many aspects of the hot structure production process. Their National Aeronautics and Space Development Agency (NASDA) and the National Aerospace Laboratory (NAL) have managed government- funded programs in single-stage and two-stage space transportation concept development and associated design and materials development. These efforts will impact future high-speed civil aircraft and hypersonic aircraft initiatives under study. Japanese funding to establish and improve indigenous capabilities in advanced material processing, lightweight thermal structure manufacturing and test facility infrastructure have been well reported. Although their general capabilities in hot structures have grown recently, Japanese firms still lag the United States in critical engineering and technology areas, including aerothermal and structural analysis codes, test facilities, and materials development.
The United States has a substantial lead in actively cooled structures. Europe is still generally conducting fundamental research on structural materials, coolant design and function, and thermal-aerodynamic cooling phenomena characterization. The European leader, France, does have some near-term applications of actively-cooled structures, primarily because of its military-funded requirements in hypersonic flight vehicles (i.e., aircraft and missiles). The French have done extensive work in computational models for hypersonic flow condition and boundary layer interface. This effort could help an actively-cooled structure designer to evaluate this concept before expensive prototype development and tests occur. Some work has also been done by Germany, but future activities may cease with the official demise of the national hypersonic program. Japan's actively cooled structures technology also remains behind that in the United States. The bright spot is the amount of funding still potentially available to develop actively cooled structure in applied high-speed flight vehicles. Some aircraft and space plane programs being managed by NAL include structure concepts that will require the levels of thermal-mechanical performance that actively cooled structures are best suited to perform. NASDA's HOPE vehicle does not drive structure requirements to include actively cooled structures. This explains why Japanese research and development efforts have not aggressively attacked this area yet. Further maturation of NAL's single-stage space plane or a hypersonic passenger aircraft could accelerate the current pace of development.