Are you tired of replacing your shaving blades? It seems that no matter how sharp our razors start as, they all get dull with use, a bit too quickly. Scientists have little idea how something as soft and flexible as hair can wear out stainless steel razors, until recently.
To understand what happens, a research team from MIT's Department of Materials Science and Engineering zeroed in on the act of shaving: they simulated the interaction between blades and faux hair, and examined the whole progress under a scanning electron microscope (SEM).
Human hair, a filament structure, is made of primarily fibrous proteins such as alpha-keratin. On the other hand, shaving tools such as modern-day razors are made from stainless steel. In theory, the toughness of the two isn't comparable.
Previous investigations pointed to metallurgic issues including blade edge rounding and cracks on the blades' coating as the main culprits behind the loss of sharpness. But according to the MIT researchers, the microstructure of hair shaving devices, which has not been questioned before, is where the wear-and-tear really happens.
The microscopic structure of a material dictates many of its properties, such as strength, toughness, corrosion resistance, thermally induced behaviors, and wear resistance.
In situ SEM single-hair cutting-force measurement (MIT)
In their early stage of exploration, a team member repeatedly shaved his facial hair with a disposable razor and examined the edge of his razor with a scanning electron microscope (SEM), in order to evaluate the progress of dulling with continuous use.
Through their in-depth investigations, the team concluded that the deformation of a blade is quite a "tricky" process. For it to happen, a trifecta of conditions would need to apply - out-of-plane bending, microstructural heterogeneity, and asperities. Asperities are microscopic unevenness that appear in all seemingly smooth surfaces. The coincidence of the trio during shaving could lead to a crack in a blades' microstructure. The shear amount of hair and repeated uses increase the odds and sizes of fractures, which eventually dulls the edge of a razor.
By finding the causes behind the dulling of the blades, the group hopes that they can use the knowledge to identify "a new processing path", which can make shaving blades more wear-resistant.
This latest research is published in the journal Science.
Source: MIT News