How soft hair deforms the sharpest steel blades

August 06, 2020

Why do the edges of a steel razor dull from cutting far softer materials? The micromechanical conditions that lead to this phenomenon have been revealed through a series of "realistic shaving" experiments, the findings of which suggest ways for current blade technology to be improved, toward lengthening the lifetimes of commercial disposable razors and thus lessening their environmental burden. It's an everyday observation: The sharpest steel razor dulls quickly after a few short shaves. The tempered edge of the most finely honed chef's knife can become practically unusable after cutting tomatoes and potatoes. However, how steel loses it edge upon cutting significantly softer materials like hair - despite being more than 50 times harder - remains poorly understood. While it's generally been assumed that the degradation of a sharpened edge is due to basic wear mechanisms like edge rounding or cracking of a steel blade's brittle and hard coating, such explanations do not account for the underlying structural complexity of the interaction between the steel and the material it's meant to cut, nor for the dynamics of their co-deformation. Using martensitic stainless-steel blades - those typical of standard commercial disposable safety razor cartridges - and human hair, Gianluca Roscioli and colleagues performed a series of cutting experiments and ­in situ­ electron microscopy to observe the evolution of blade wear during realistic shaving conditions. Roscioli et al. found that differences in cutting angle due to hair bending, microstructural variation in the blades edge, and the location of these variations relative to the hair as it was being cut all worked in concert to cause a blade's edge to fail. The findings suggest that the design of cutting blades could be improved by implementing more homogeneous microstructures at the cutting edge, which could be realized using nanostructured alloys, for example.
-end-


American Association for the Advancement of Science

Related Electron Microscopy Articles from Brightsurf:

Ultracompact metalens microscopy breaks FOV constraints
As reported in Advanced Photonics, their metalens-integrated imaging device (MIID) exhibits an ultracompact architecture with a working imaging distance in the hundreds of micrometers.

Attosecond boost for electron microscopy
A team of physicists from the University of Konstanz and Ludwig-Maximilians-Universität München in Germany have achieved attosecond time resolution in a transmission electron microscope by combining it with a continuous-wave laser -- new insights into light-matter interactions.

Microscopy beyond the resolution limit
The Polish-Israeli team from the Faculty of Physics of the University of Warsaw and the Weizmann Institute of Science has made another significant achievement in fluorescent microscopy.

Electron cryo-microscopy: Using inexpensive technology to produce high-resolution images
Biochemists at Martin Luther University Halle-Wittenberg (MLU) have used a standard electron cryo-microscope to achieve surprisingly good images that are on par with those taken by far more sophisticated equipment.

Limitations of super-resolution microscopy overcome
The smallest cell structures can now be imaged even better: The combination of two microscopy methods makes fluorescence imaging with molecular resolution possible for the first time.

High-end microscopy refined
New details are known about an important cell structure: For the first time, two Würzburg research groups have been able to map the synaptonemal complex three-dimensionally with a resolution of 20 to 30 nanometres.

Developing new techniques to improve atomic force microscopy
Researchers from the University of Illinois at Urbana-Champaign have developed a new method to improve the noise associated with nanoscale chemical imaging using atomic force microscopy.

New discovery advances optical microscopy
New Illinois ECE research is advancing the field of optical microscopy, giving the field a critical new tool to solve challenging problems across many fields of science and engineering including semiconductor wafer inspection, nanoparticle sensing, material characterization, biosensing, virus counting, and microfluidic monitoring.

A pigment from ancient Egypt to modern microscopy
Egyptian blue is one of the oldest manmade colour pigments.

Ball-and-chain inactivation of ion channels visualized by cryo-electron microscopy
Ion channels, which allow potassium and sodium ions to flow in and out of cells, are crucial in neuronal 'firing' in the central nervous system and for brain and heart function.

Read More: Electron Microscopy News and Electron Microscopy Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.