Carbon-fiber reinforced plastics (CFRPs) are responsible for more than 50 percent of materials by weight in new aircraft such as the Boeing 787 Dreamliner and the Airbus A350. Yet polymer composites on average constitute less than 2 percent of an automobile's total weight. Kozarsky said:
It will take awhile before the average plane has as much carbon fiber as the 787 and the A350. The motivation now for using CFRP is more for long-distance flights. In larger volume, smaller planes for regional use, such as the B787, one trend to watch will be whether aircraft makers choose Alcoa's next-generation aluminum-lithium alloys, or go with CFRP for the skin.
Historically, carbon fiber has been well suited for an aircraft's flat skin, due to the nature of carbon's long fibers. But 3D components involve a more complicated, expensive molding technology. Kozarsky said:
Primary structures like fuselage and wings, and the landing gear and pylons, also have different structural requirements from each other. Secondary structures also have different requirements, further motivating why it's important to look at these structures on a component level while evaluating their ideal materials.
CFRPs are not only more expensive, but using them is also a step change difference, which is much greater than transitioning from using one metal to another metal. "When we talk to builders of wind turbines, automobiles, and aircraft, they're equally interested in advanced metals like aluminum, titanium, magnesium, and AHSS," said Kozarsky.
The lightest structural metal, magnesium, is not widely available, and has drawbacks in its material properties, including brittleness, susceptibility to corrosion, and sourcing difficulty. Despite these difficulties, automotive manufacturers are as interested in magnesium as they are in CFRP. Aircraft manufacturers are looking at titanium more because of its high strength-to-weight properties, but its high cost has limited its adoption outside of a few high-end applications. Some new processing technologies are emerging that may help to reduce costs.
@sjmonte: A joule is a unit of energy, not tensile strength. Tensile strengths are customarily given in units of pascals; one joule per cubic meter is equal to one pascal. However, since one pascal is very small, it's common to use the megapascal, i.e. million pascals, as the base unit.
Could you please give us the tensile strength in either megapascals or pounds per square inch?
In any case, the strength increases you report (more than 2x dry and more than 5x wet) are very impressive. If you have been producing these coupling agents since the 1970s, why haven't they been more widely adopted? I'd expect the composites industry to be extremely enthusiastic about something like this.
Ann: We have exhibited in the past few months at the following conferences and trade shows: ACMA 2012; SAMPE 2012; American Coatings Show 2012; ACS Rubber Division Energy Rubber Group Winter Conference; SPI NPE 2012; and SPE International Polyolefins 2012. So, it's just not fiberglass reinforced polyester. I am talking about all manner of inorganic and organic reinforcements used in thermosets and thermoplastics We manufacture since 1973 organometallic coupling agents based on titanium, zirconim, and aluminum chemistry - rather than silane chemistry. I have 29-U.S. Patents and 1 pending on their composition of matter and their application, and 375-ACS CAS abstracted works on the subject of the interface and their application in polymer compositions.
A class of neoalkoxy and coordinate titanates and zirconates can coordinate couple to any surface via its protons ever present on the inorganic/organic reinforcement - from carbon and aramid fiber to CaCO3 to PTFE - thus forming an impervious 1.5-nanometer chemical bridge between say the carbon fiber and epoxy. The fiber does not have to be pretreated, but can be coupled in-situ becase water of condensation is not needed as with silanes, which react with surface hydroxyls to form a silanol oligomer, which in turn condenses with the surface hydroxyl group to condense 3-moles of water, which must be removed.
The titanate or zirconate uses the resin phase to bring it to the interface and deposit 1.5-nanometer atomic monolayers thus bonding the resin to the reinforcement surface that subsequently resists aged deterioration under high pressure, high temperature, and severe environmental conditions such as 240-hr. water boil in 10% salt water. This mechanism works on all manner of carbonaceous substrates: carbon fiber; carbon black; carbon nano tubes; graphene; etc.
For example, carbon fiber reinforced methyl nadic anhydride cured epoxy composites produced by General Dynamics without zirconate will have a long-fiber tensile strength of 62 Joules, which will deteriorate to 21 Joules 240-hr. water boil in 10% salt water, while 4-parts per thousand of a zirconate [Ken-React(r) NZ(r) 97] added to the epoxy will yield 119 Joules Tensile initial and 113 Joules when similarly water boiled aged.
Actually, fabrication difficulty is mentioned several times in the article, both directly and indirectly, as moldability, disruptive technology vs non-disruptive technology, as "3D components involve a more complicated, expensive molding technology" and "CFRPs are not only more expensive, but using them is also a step change difference, which is much greater than transitioning from using one metal to another metal." Regarding recyclability, it's interesting to note that Boeing has invested in composite recycling: http://www.designnews.com/document.asp?doc_id=235280
I'm not sure what composites you're researching, but they sound like glass fiber. Carbon fiber is another story and answers your strength questions: the strength-to-weight ratio is higher for carbon fiber than steel and even higher than aluminum. Also, I'd bet that any carbon fiber materials you're likely to be able to purchase as a home user are not the ones you can get for building military or commercial aircraft.
The limitation of Carbon and Aramid and Glass reinforced materials - as well as nano-materials - is a lack of awareness of the ability to use zirconate and titanate and aluminate coupling agents to bond the interface of the fiber reinforcement to the polymer resin. Silanes - the material that made the Corvette possible (fiberglass reinforced peroxide cured unsaturated polyester) - have severe interfacial reaction and environmental aging issues due to the nature of their molecular bond formation.
Rob, good point. One of the "features" missing from the article is the fabrication difficulty. In aerospace and some high end applications, where the systems will last a long time, it is worth paying up front for more difficult fabrication. I think it was on this site that a new technique for welding titanium was discussed. This is just one example. Aluminum is also more difficult to weld than steel. Recall that most aircraft, which have used aluminum for a long time, are riveted. Jaguar started making the bodies of their high end XJs of aluminum. When they did that they save 500 pounds (on a 4,000+ pound vehicle). Many wondered if they would ever recover the cost of the production line changes that had to be made. As you mention, steel may end up getting better before price or process technology catches up for the other materials. In addition, steel and aluminum are eaisly recyclable.
As the 3D printing and overall additive manufacturing ecosystem grows, standards and guidelines from standards bodies and government organizations are increasing. Multiple players with multiple needs are also driving the role of 3DP and AM as enabling technologies for distributed manufacturing.
A growing though not-so-obvious role for 3D printing, 4D printing, and overall additive manufacturing is their use in fabricating new materials and enabling new or improved manufacturing and assembly processes. Individual engineers, OEMs, university labs, and others are reinventing the technology to suit their own needs.
For vehicles to meet the 2025 Corporate Average Fuel Economy (CAFE) standards, three things must happen: customers must look beyond the data sheet and engage materials supplier earlier, and new integrated multi-materials are needed to make step-change improvements.
3D printing, 4D printing, and various types of additive manufacturing (AM) will get even bigger in 2015. We're not talking about consumer use, which gets most of the attention, but processes and technologies that will affect how design engineers design products and how manufacturing engineers make them. For now, the biggest industries are still aerospace and medical, while automotive and architecture continue to grow.
More and more -- that's what we'll see from plastics and composites in 2015, more types of plastics and more ways they can be used. Two of the fastest-growing uses will be automotive parts, plus medical implants and devices. New types of plastics will include biodegradable materials, plastics that can be easily recycled, and some that do both.
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