Know that sickening feeling when you exit the grocery store and find your car has been banged up by a runaway shopping cart? It may one day be just a bad memory if auto body manufacturers make use of a new suite of tests developed by the National Institute of Standards and Technology (NIST) and three industry partners. Data from these tests could eventually help your vehicle’s exterior better defend itself against dings, dents, scratches, and things that go bump on the highway.
In a new paper in the journal Progress in Organic Coatings, researchers at four organizations—NIST and industry partners Eastman Chemical Co., the Hyundai America Technical Center and Anton Paar USA—describe three versions of a fast, reliable laboratory method for simulating scratching processes on automobile clearcoats (the uppermost, or surface, layer of an exterior polymer composite coating). The tests are designed to give manufacturers a better understanding of the mechanisms behind those processes so that future coating materials can be made more scratch resistant and resilient.
Stronger, more robust coatings are important to meet both consumer and industrial demands. For example, statistics show that: people are keeping their cars longer and want them to stay attractive (those owning cars for more than two years rose 41 percent from 2006 to 2015); nearly 600,000 drivers work for ride-sharing services in the United States that require them to maintain vehicle appearance; improved paint durability is consistently among the top three performance requirements for original equipment manufacturers; and 60 percent of all consumer complaints about autos are attributed to paint scratches and chip imperfections.
Currently, automobile coating manufacturers use two simple test methods to evaluate clearcoat scratch resistance and predict field performance: the crockmeter and the Amtech-Kistler car wash. The former is a device that uses a robotic ‘finger” moving back and forth with varying degrees of force to mimic damage from human contact and abrasive surfaces. The latter is a rotating wheel of brushes that simulate the impact of car washes on clearcoats.
“Unfortunately, both methods only assess clearcoat performance based on appearance, a qualitative measure where the results vary from test to test, and they don’t provide the quantitative data that scientifically helps us understand what happens to auto finishes in real life,” said NIST physicist Li Piin Sung, one of the authors of the new paper. “We demonstrated a test method that characterizes scratch mechanisms at the molecular level because that’s where the chemistry and physics happens … and where coatings can be engineered to be more resilient.”
Read more: New Tests Improve Auto Coatings
Image courtesy of nist.gov