Nanotechnology promises to benefit many different aspects of industry. The automotive industry is certainly no exception. Nano-enhanced materials are already beginning to improve the performance and cost-effectiveness of vehicles, and this effect will only increase in the coming years, as harder, stronger, lighter nanomaterials become commercially available.
The industry's overarching development goals are to improve fuel consumption, environmental impact, safety, and comfort, as continually growing car use conflicts with environmental pressures and infrastructure limits. Nanotechnology will undoubtedly play a huge role in the way automotive manufacturers deal these changes.
Scratch-Resistant and Dirt-Resistant Paints
For several years, nanotechnology research has been working towards coatings and paints which are highly scratch resistant, self-healing and dirt repellant. These technologies would allow automotive paint to last for the lifetime of the vehicle without aging, and require cleaning much less often.
These technologies are now becoming commercial. Some after-market products are available which use hard, water-repelling polymer nanocomposites or quartz nanoparticles - this enables the coatings to remain clean themselves and protect against scratches and chips, and reduce corrosion, without altering the appearance of the paint underneath.
Paints are also available which can alter their heat-reflecting properties depending on the intensity of the incident sunlight. This helps to regulate the temperature of the vehicle, making the job of the air conditioning system easier and therefore saving fuel.
Developing technologies in this field which are not yet commercially available include coatings which are not just more scratch-resistant, but actually heal any minor damage which they do sustain. This is achieved by embedding ceramic nanoparticles in a flexible polymer, which can flow over itself to heal cracks and scratches whilst remaining robust.
Nanoparticle coatings for vehicles can self-clean - they surface is made super-hydrophobic, causing water to form beads on the surface and run easily off, collecting and removing dirt in the process. Cleaning is therefore much easier, and required less frequently. Image re-drawn from Nanovere Technologies.
Nanotechnology is also already playing an important part in automotive manufacturing. Since the 1990s, strong adhesives have been used to enhance welded joints and mechanical fasteners.
Recently, adhesives which have been enhanced with iron oxide nanoparticles, or, in some cases, carbon nanotubes, can in some cases replace and outperform welds altogether. They can also allows metal to be bonded strongly to plastic or composite panels, which can save a great deal of weight and cost compared steel or aluminium bodywork.
Nanoparticle Fillers for Tyres
Nanoparticles of carbon or silica have been used as fillers for tyre rubber for many years, helping to enhance tyre performance and durability. Silica, which does not naturally mix well with rubber, is now often used in conjunction with organosilanes, which can bind well to both components, creating a more stable material.
This video from Deutsche Welle gives an overview of the ways nanotechnology is being used int he automotive industry, with commentary from some of the companies at the forefront of the field.
Windows and Wipers
The approach to dirt-resistant paints for cars, which uses nanoparticles to create a hydrophobic (water-resistant) surface has also been applied to glass for vehicle windows.
The beading effect for water on the surface means that water runs off much more easily, and does not impair visibility during heavy rain or spray. This also reduces wear on windscreen wipers, which are hardly required at all - at most road speeds the air flow past the car would be sufficient to clear the beaded water droplets from the glass.
Nano-coatings on the inside of the glass can use a similar approach to prevent water vapour from condensing on the glass in humid conditions.
Nanotechnology is also making polycarbonate glazing a reality. Polycarbonate (PC) is much lighter than standard glass, is safer, and is a more flexible material to design with, but physical limitations such as its poor scratch resistance and low UV shielding have prevented its widespread use. Addition of a transparent, scratch-resistant coating containing silica nanoparticles alleviates many of these issues. This will allow more rapid adoption of PC windows and windscreens over the next few years - it is predicted that by 2020, around 20% of all vehicle glazing will be made from nano-enhanced PC.
Nano-Treatments for Automotive Textiles
Textiles are used extensively in cars - from seat coverings and seatbelts to air filters and tyre cord. There is a general trend in automotive design towards replacing more and more hard surfaces inside the vehicle with fabrics, as they are an easy way to reduce weight, and improve overall recyclability.
Conventional fabrics are highly susceptible to wear and tear, collection of dust and dirt, and can be a fire hazard if untreated. A wide array of nanotechnologies can be applied to textiles to improve their performance and lifetime, some of which are already in use, and some of which are still several years away from commercial application.
Table 1. A selection of current and forthcoming nano-treatments for automotive textiles
|Hydrophilic TiO2 nanoparticle coating
||Effective moisture wicking
||Dirt and liquid stain resistance
||Commercially available - e.g. Vauxhall/Opel Insignia
||Too costly for commercial use
||Commercially available for automotive applications
|Modified clay nanocomposites
||Too costly for commercial use, despite higher performance and improved environmental profile compared to existing technologies
|SiO2, Al2O3, ZnO nanoparticles, CNT
||Wear and tear resistance, UV protection