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Airplanes, which are mostly made of aluminum, are being reimagined from nose to tail, and aluminum is getting plenty of competition.
Small jet manufacturers were the first to make aircraft with composite fuselages and wings. In the large commercial passenger arena, Boeing delivered the first of its long-awaited “plastic dream machine” 787 last fall.
According to an article in Boeing’s Aero magazine, the 787 engineers were told to enter the design process with open minds, which “enabled Boeing engineers to specify the optimum material for specific applications throughout the airframe.”
The outcome is an airplane that is 50% advanced composites, 20% aluminum, 15% titanium, 10% steel and 5% other. Ceramic materials, presumably, fall into the final 5%.
Even though ceramic materials don’t contribute much to the volume or weight of an airplane, their contributions are critical, for example, as thermal barrier coatings on the engines. They also are finding their way onboard as lighting and in electronics, and the 787 passengers feature electrochromic windows instead of pull-down shades, probably thanks to an electrochromic oxide film.
For some aircraft, especially flying machines like DARPA’s hypersonic vehicles that blur the line between aircraft and spacecraft, ultra-high temperature ceramics are the key, critical materials. Without them, the aircraft disintegrates from heat and ablation.
John Tracy, a keynote speaker at ICC4, is leading the charge in new materials development in his role as Boeing’s chief technology officer and member of the company’s Executive Council. An engineer himself, he started his career as a stress analyst after a brief stint as a high school science teacher. Prior to becoming CTO, he was vice president of one of Boeing’s R&D unit, which included development of advanced materials and processes. Thus, his keynote talk, “Materials and Technical Achievement: An Aerospace Perspective,” should provide interesting insights into how materials are developed, evaluated and chosen for aircraft products. (See full abstract below.)
Tracy’s keynote sets the stage for the invited talks in the Aerospace track of ICC4. The invited speakers are international business and research leaders in aerospace and their talks will provide shape and form to the “big picture” issues that drive the industry and what it will mean for materials development in the future..
Rounding out the track, contributed posters focus on advances research on topics such as plasma spray-PVD of protective coatings, YSZ-reinforced porous YSZ composites, SiC-magnesium alloy composites, functionally graded UHTCs and more.
Here are the titles and abstracts of Tracy’s keynote talk and the invited talks.
Materials and Technical Achievement: An Aerospace Perspective
John Tracy, The Boeing Company
Aerospace technology achievements have amazed mankind. These accomplishments include speedy transcontinental and transoceanic crossings, instantaneous satellite communications, and human spaceflight.
Among the factors that have enabled aerospace companies to create products that provide breakthrough capabilities and captivate the general public is the development and implementation of materials engineered to meet a specific product’s mission requirements. In this presentation, John Tracy, chief technology officer and senior vice president of Engineering, Operations & Technology of The Boeing Company, the world’s largest aerospace company, will offer his perspective of the role that materials - including ceramics - have played in the technological advancement of the aerospace industry, especially with respect to today’s civil, defense and space markets.
Selected invited talks
Potential and limits of SiC chopped fiber-reinforced Ultra High Temperature Ceramics
Diletta Sciti, National Research Council
Borides and carbides of early transition metals are considered a class of promising materials for several applications, the most appealing ones being in the aerospace and energy sectors. The present work is focused on toughening of UHTCs, which is a crucial issue that needs to be addressed for application in aerospace engineering. Common strategies to increase the fracture toughness include either incorporation of elongated reinforcement (SiC chopped fibers, SiC whiskers) or in-situ development of SiC platelet-reinforced materials. Addition of fibers or whiskers allows toughness to be increased from 3-4 MPa.m1/2 (for unreinforced materials) to 5.0-6.3 MPa.m1/2. On the other hand, quite often, the improvement of fracture toughness is accompanied by a decrease of strength, due to a change of the defects population. The high temperature behavior of fiber-reinforced materials is investigated, including mechanical properties and oxidation behavior in conventional furnaces up to 1,700°C. Finally, the dynamic response to oxidation of sharp profile demonstrators is studied in plasma wind tunnel at temperatures around 1,800°C.
Overview of Industry Producibility Roadmapping Efforts for Advanced Ceramics
Glen Mandigo, U.S. Advanced Ceramics Association
Changes in U.S. Government acquisition policy to emphasize Manufacturing Readiness Levels (MRL), along with concerns about U.S. military weapon system delivery and cost are shifting attention to production and cost risk for advanced ceramics, versus a focus on performance risk typical in U.S. federal funding for advanced ceramics over the past twenty years. Performance demonstrations alone are insufficient to expand the number of applications for CMCs and advanced ceramics. Future investments should focus on producibility. This presentation outlines MRLs as they would be applied to CMCs and other advanced ceramics, and provides an update on two important industry roadmapping efforts addressing producability and affordability of ceramic materials: the Ceramic Composite Affordability and Producibility roadmap that outlines a 10-year plan to reduce production and cost risk for CMCs, and a similar producibility roadmap effort started in 2011 for ceramic transparent armor materials.
Ceramic Innovations at Rolls-Royce
Jay Lane, Rolls-Royce Corporation
A turbine engine hot gas path presents a demanding environment that requires high performance materials. Due to increasing emphasis on reduced weight, lower emissions and specific fuel consumption and improved lifecycle and performance, ceramic matrix composites and thermal and environmental barrier ceramic coatings (TBCS and EBCs) are considered as enabling materials for next generation higher performance turbine engines. CMCs offer a cross-cutting technology with wide applicability to the combustion, turbine, and exhaust sections of a propulsion/energy engine due to their higher-temperature capability and low weight. EBCs will be required in conjunction with CMC components to protect the gas-washed surfaces against degradation due to high temperatures and water vapor exposure. CMC implementation will be phased in over time and will not replace all metal components within the hot gas path. Therefore, advanced TBCs continue to be developed to address the challenges of increasing gas path temperature and environmental contaminant attack. This presentation will review ceramic innovations at Rolls-Royce in the context of CMCs and coatings for next generation turbine engines.
Testing Developments for Ceramic Matrix Composites in Extreme Environments
John Koenig, Southern Research Institute
The severe environments that will be encountered in currently planned challenging aerospace applications require the use of advanced ceramic matrix composites in both structural and thermal protection systems. These composites exhibit complex mechanical, thermal, and degradation behavior that is highly dependent on the outside environment. Successful utilization of these materials in these challenging environments requires test developments to keep pace with the increasingly severe environments in which they are used. This paper will describe several significant advances made in the development of laboratory-based test methods for coupon and component level characterization Amongst the techniques being developed for application to ceramic matrix composite materials are mechanical strain visualization; high temperature (2,400°C), low pressure, oxidizing environment testing; high temperature interlaminar tensile testing of thin structures; permeability, and environment simulation subelement tests.
UBE’s Ceramic Strategy for Aerospace and Other Applications
Toshihiro Ishikawa, Ube Industries, Ltd.
Ube Industries have lots of excellent functional ceramics, for example, thermostructural ceramics (Tyranno fiber, MGC, Tyrannohex), highly pure ceramic-powders (Si3N4 powder), Mg-based powders, Ca-based powders), and precursor ceramics (SiC-based ceramics, SiO2-based ceramics), and so forth. Besides, Ube is the worldwide largest supplier of Mg-based ceramic powders (MgO, Mg(OH)2, and so on) produced from MgCl2 extracted from sea water. And Ube is also the largest supplier of Ca-based ceramic powders (CaO, CaCO3, CaNO3, and so on) in Japan. As you may know, near Ube city in Yamaguchi Prefectute, there are large limestone mountains. Using the limestone years ago, Ube established a cement industry. After that, Ube developed new functional ceramics that can be used for aerospace applications. For instance, Ube developed high heat-resistant SiC-based fibers and their derivitive. Of these, Tyranno SA fiber shows high strength and excellent heat resistance up to 2,000°C. And, thermally conductive, tough ceramic (SA-Tyrannohex) shows a relatively high strength up to 1,600°C in air along with an excellent thermal shock property. The raw material for producing both Tyranno SA fiber and SA-Tyrannohex is the almost same amorphous SiC-based fiber (Tyranno AG grade) containing small amount of aluminum. Fundamental, fine structure of both Tyranno SA fiber and SA-Tyrannohex is sintered SiC polycrystals. The aforementioned aluminum plays an important role for the sintering of the SiC polycrystals. It is very important that the aluminum exists as a solid solution in each SiC crystal. Absence of secondary phases composed of aluminum-based oxides at the boundary of SiC crystals is also very impotant for obtaining excellent high temperature properties. Today, I would like to introduce our company’s functional ceramics.