The importance of materials in the chronicle of human development cannot be overemphasized. Mankind has been exploiting materials since prehistoric times. In fact, the three epochs of prehistory, the Stone Age, Bronze Age and Iron Age, are named after the materials and the related tool-making technologies that define them. Perhaps the earliest quantitative study of materials appeared in Galileo Galilei’s Discourses and Mathematical Demonstrations Relating to Two New Sciences (1638). The two sciences were the “strength of materials” and the “motion of objects” (kinematics). Materials science as a discipline has its roots in the study of metallurgy; only recently has it become the truly interdisciplinary science that it is today, merging metallurgy, ceramics and polymer science, and including aspects of chemistry and solid state physics.
History has shown us that a new material technology can change the world.1 As a result, innumerable technological advances owe their success to materials science. To illustrate this point, consider silicon. Silicon is the second most abundant element in the earth’s crust, but it rarely occurs in the elemental form. With the invention of the transistor, the need for high-purity forms of silicon led materials scientists to develop the Siemens Process, an economical method of refining metallurgical grade silicon, which enabled the emergence of the semiconductor industry. Today, silicon integrated circuits are ubiquitous, being directly or indirectly involved with virtually everything that we touch.
Material development and adoption challenges
The demand for stronger, lighter, greener yet less expensive materi als continues to outstrip availability, presenting many challenges as well as opportunities to the materials engineer. Unfortunately, the development of a new material and the related manufactur ing technology can be a lengthy process, taking much longer than we would like. In Technology Review, Thomas Eagar2 pointed out that it typically takes 20 years from the discovery of a new material to its commercialization. This proposition is underscored by many examples ranging from the vulcanization of rubber to diamond-like coatings. The reasons for this lag in materials technology insertion are many and varied. For example, too frequently product engineers want to use the new material in the same way that they used the previous material, rarely exploiting all of its favorable properties; hence, the promise of the new material is not immediately realized.
Initially, new materials are produced in small quantities, at least until the demand develops. An unfortunate result is that designers are reluctant to specify a new material that might not be available in the required quantities or may only be available from a single source. For aerospace applications, qualification of a new material can be a very costly and time-consuming endeavor, which can also be a significant barrier to adoption. For these reasons, a new material with superior performance, even at a lower cost, is frequently slow to be accepted. Nevertheless, as Eagar points out, industries like the aerospace industry are most likely to lead in the introduction of new material technologies. Here the value associated with a high level of performance (for example in advanced composites, the cost savings associated with a pound of saved weight) can be significantly larger than for many commercial, less demanding applications.
Cycle time acceleration initiatives
Several concerted efforts have been made to reduce this 20-year cycle time. For example, the Defense Advanced Research Projects Agency’s (DARPA) Accelerated Insertion of Materials program attempted to do this by creating a more rigorous materials development and qualification methodology, including a computational tool kit for use by designers. The purpose of the tool kit was to predict and control the statistical material properties through microstructure control (structure-property relations), thereby reducing insertion risk (Figure 1).
Since then, computational materials engineering (CME) has emerged as a powerful tool in contemporary materials science, and as the central theme in efforts to accelerate materials discovery and insertion of new materials technologies.
Still, the lag between new material discovery and insertion continues to be a challenge. Figure 2 illustrates the traditional materials development continuum. In June 2011, President Obama announced the launching of the Materials Genome Initiative, with the objective “to help business develop, discover and deploy new materials twice as fast.”3
In the words of John Holdren,4 Assistant to the President for Science and Technology and Director of the White House Office of Science and Technology Policy, “In much the same way that silicon in the 1970s led to the modern information technology industry, the development of advanced materials will fuel many of the emerging industries that will address challenges in energy, national security, healthcare and other areas. Yet the time it takes to move a newly discovered advanced material from the laboratory to the commercial marketplace remains far too long. Accelerating this process could significantly improve U.S. global competitiveness and ensure that the nation remains at the forefront of the advanced materials marketplace. This Materials Genome Initiative for Global Competitiveness aims to reduce development time by providing the infrastructure and training that American innovators need to discover, develop, manufacture and deploy advanced materials in a more expeditious and economical way.”
The Materials Genome Initiative will rely on CME advancements in conjunction with new experimental tools, and in particular, with coordinated and open data management systems that allow researchers to access and compare data; thereby facilitating far more collaboration than is currently available. The Initiative also considers the whole lifecycle of the material, including issues of recyclability and sustainability, which we will touch upon in this issue.
Raytheon’s past material innovations
Raytheon has a long and successful history of materials discovery and innovation going back to the earliest days of the company. The Klixon Disk, a simple bi-metallic device invented by Al Spencer, launched the Spencer Thermostat Company and established the company’s founding fathers as successful entrepreneurs.5 Numerous successes followed, including the development of gallium arsenide-based microwave integrated circuits, then gallium nitride-based transmit/receive modules and panel arrays; each of which includes a multitude of underlying and critical supporting materials technologies. Chemically vapor deposited (CVD) zinc sulfide has become the standard long-wavelength-transparent electro-optical material for passive imaging at 8–12 micrometers wavelength in the infrared. Raytheon’s materials process innovation supplanted the competing hot-pressed material, Irtran-2. Raytheon produced thousands of electro-optic windows and domes, beginning in 1972 with the first CVD dome ever made.
Raytheon’s materials innovations today
Today, Raytheon continues to be actively involved in materials discovery, innovation and insertion at all points along the materials development continuum. With the advent of CME, in tandem with the ability to manipulate materials at the atomic level, Raytheon engineers are creating materials with properties that were simply not attainable before. In this edition of Technology Today, our first three articles discuss engineering of materials from the ground (nanoscale) up, one of which includes leveraging the remarkable properties of the carbon nanotube (CNT). Parenthetically, it has been 20 years since CNTs were first observed. One could conclude, based on Eagar’s thesis that wide-scale acceptance of CNTs is just around the corner.
Sometimes, materials discovery can be as straightforward as observing the world around us, as is the case with the bio-inspired optical shutters being developed at Raytheon for infrared imaging. Nature’s perfect material, diamond, is formed over millions of years within the earth’s crust at high temperatures and pressures. Since the 1960s, low-temperature processes have been developed to produce diamond in the laboratory environment. We will discuss Raytheon’s pioneering efforts in the chemical vapor deposition of diamond and its use as a superior conductor of heat, a critical characteristic for thermal management in high-power device applications. Finally, we will review progress in developing an exciting new form of “material” referred to as metamaterial. Metamaterials are engineered materials in the truest sense of the term, deriving their properties not from their constituent materials but from the periodic arrangement of these materials.
As we have seen, the processes of designing, optimizing and integrating materials into a product, component or subsystem occupy the center of the materials development continuum. Several articles on materials optimization and integration are included. New sensors that derive their unique capabilities from materials engineering are becoming important elements for ensuring our national defense and homeland security in the face of evolving threats. Examples in clude novel sonar transducer materials and a class of materials that give off light in the presence of nuclear radiation. Solutions to address energy security are discussed in a series of articles on materials technologies for large-scale energy storage.
Once a new material technology is integrated and deployed in a new system, the focus turns to sustainment. This is particularly true in aerospace and defense systems where very high importance is placed on reliability. Our remaining feature articles address the sustainment phase. This includes a discussion of regulations that control a material’s impact on the environment and Raytheon’s responsiveness to those regulations, as well as Raytheon’s response to the growing industry threat from counterfeit parts.
Our discussion of materials technology at Raytheon would not be complete without mentioning the role that manufacturing plays in the materials development continuum. In our Eye on Technology section, we introduce our latest technology network — the Manufacturing Technology Network, a companywide association of experts established to better integrate manufacturing technologies and strategies with new materials development in order to accelerate deployment.
1. Robert Friedel, Materials That Changed History, Nova (2010). http://www.pbs.org/wgbh/nova/tech/materials-changed-history.html
2. Thomas W. Eagar, Bringing New Materials to Market, Technology Review, February/March (1995). Pg. 43.
3. Ceramic Tech Today, ACerS Ceramic Materials, Applications & Business Blog, Eileen De Guire, editor, June 30, 2011. http://ceramics.org/ceramictechtoday/2011/06/30/materials-genome-initiative/.
4. Materials Genome Initiative for Global Competitiveness, National Science and Technology Council, June 24, 2011. http://www.whitehouse.gov/sites/default/files/microsites/ostp/materials_genome_initiative-final.pdf
5. Alan R. Earls and Robert E. Edwards, Raytheon Company, The First Sixty Years, Arcadia Publishing (2005).