What does the diagram below have to do with automobiles? If you don’t recognize the pyramid, this is Abraham Maslow’s hierarchical diagram, a model that addresses human physical and psychological needs.
Our industrial society is built on a platform of core technologies that address these needs.
Physiological needs include food, shelter, warmth and health (the bottom tier). Safety and security needs appear on the second tier.
The core technologies to address these needs cover the following fields:
So much of the technology we create addresses our psychological and self-fulfillment requirements as humans. And that is fundamental to our love affair with the automobile from its invention to today. Much of our industrial infrastructure has been constructed to meet this love. Through automobiles we have experienced personal mobility, prestige, a feeling of accomplishment and self-fulfillment. We measure status through the automobiles we drive. To drive a Mercedes, BMW, Lexus, Lincoln, or Cadillac means a lot to a lot of humans.
With 2.5 billion automobiles in the forecast by the mid-21st century what will they look like and what will be their impact on our society and this planet? In this blog we will take a look at current and future materials as applied to the automobile.
The Search for Lighter, Energy and Eco-Friendly Materials
Automobile emissions contribute to greenhouse gases. Automobile production creates an enormous carbon footprint. Automobiles use materials that often are difficult to recycle or toxic when dumped into landfill.
Automobiles typically contain 3 basic materials:
- Metals and Alternatives – for the frame, body, engine, axles, wheel hubs and wiring
- Plastics, Polymers and Composites – for the tires, seats, dashboard and bumpers
- Ceramics – for the windows and lights
Metals and Alternative Main Structural Components
Until the last decades of the 20th century automobiles were primarily built of steel. I remember my first new car in 1972. It was a Mazda 618, a hatchback, two-door coupe that was bright orange, had a manual transmission, a 4-cylinder 1.8 liter high-performance engine, and a curb weight of 1,005 kilograms (greater than 1 ton). Most of that weight came from the steel used in its manufacture. If an automobile manufacturer were to replace the steel with carbon fiber, for example,the vehicle’s weight could be reduced by up to 40%, and CO2 by 30%.
Carbon fiber is just one of many materials in use or under consideration by the industry as a replacement for steel. Among these are duralumin and fiberglass. Duralumin is an aluminum alloy containing copper, manganese, magnesium, iron, and silicon. Duralumin resists corrosion caused by salt or acids. An automobile frame constructed of duralumin would weigh half that of one built using steel and would provide equal strength.
Ford introduced a prototype fiberglass automobile in 1938. In 1953, the Kaiser Darrin and Chevy Corvette were the first fiberglass-bodied production cars. Fiberglass when used in automobile bodywork is a composite primarily containing glass mat combined with resins. Fiberglass demonstrates shape versatility making it extremely popular among custom automobile designers. Automobile bodies made from fiberglass are much lighter than those made from steel. Depending on the composition of the resins (oil-based or biodegradable) fiberglass can be much more eco-friendly than either steel or duralumin.
Plastics, Polymers, and Biopolymers
Plastics usage in today’s automobiles provides an average weight saving of 180 kilograms (approximately 400 pounds). Plastics were first used to replace metal bumpers. Today’s cars use plastics throughout the automobile. Plastics combined with fiberglass can be found in many automotive body parts.
Shape memory polymers represent another class of materials for automobile manufacturing. Called “smart,” these materials have a memory and when subjected to an electric charge or heat change shape. Shape memory polymers can be self-sealing or self-healing when damaged making them ideal for automotive external and internal body parts. These materials have the ability to alter their colour in response to light and heat. Triple-shape memory materials consist of two different cross-linked polymers that soften at different set temperatures and experience three shape changes in response to heat and cold.
Although increasingly popular because of their strength, durability, ability to integrate colour to eliminate painting, and because of their friction and wear resistance, engineered resins are commonly used in car manufacturing today. But these engineered products have potential volatile and toxic characteristics. One of them, Bisphenol A , has been linked to numerous medical issues. Bisphenol is just one of many engineered resins which include Acrylonitrile Butadiene Styrene (ABS), Polybutylene Terephthalate (PBT), and Polycarbonate (PC).
Biopolymer compounds are biologically derived polymer resins combined with engineering thermoplastic resins. They are designed to be temperature resistant and impact absorbing making them ideally suited for automotive parts. What makes biopolymers attractive is their use of renewable carbon as opposed to fossil-fuel derived carbon. Japanese automotive manufacturers are committed to meeting a government mandate to include a minimum of 20% bio-derived polymers in their products by 2020. The most common biopolymers include Polylactic Acid (PLA) made from corn and Polyhydroxyalkanoates (PHAs). PLA reinforced with plant fibers is being used in a wide array of applications. Polyhydroxyalkanoates are bacterially synthesized, fully biodegradable, and nontoxic. They have high heat and cold tolerance and can replace synthetic plastics in a number of industrial applications reducing the industrial carbon footprint.
Ceramics have always been used in automobiles. Besides glass for windshields, side windows and lights, ceramics were introduced for use as spark plug insulators as early as the 1920s. Every car today contains ceramics within catalytic converters and oxygen sensors to improve combustion and reduce emissions. Ceramics are used in the electronics, computer controls and electrical motors that operate everything from windshield wipers to power windows, seats and locks. Ceramics are being used in braking systems to prolong brake life. And now new ceramics are being developed that have similar properties to metals making them highly temperature shock tolerant for many applications including the internal components of automobile engines.
In our next blog we will look at the motive power behind automobiles and the future of the internal combustion engine. As always, please feel free to ask questions or comment on this or any of the other blog articles appearing in 21st Century Tech.