Though some homers work You may have given up daily shaving in the past few months. Who doesn’t want a longer-lasting razor? Multi-bladed cartridges usually only last a week or two before they begin to grip the skin and are then tossed in the trash. But what if someone could invent a razor that would stay sharp for six months or even a year?
That’s the idea behind a recent experiment by researchers at the Massachusetts Institute of Technology who wanted to find out why steel razor blades dull so quickly, especially when they only cut soft human hair. By observing and recording the cutting process under a scanning electron microscope, the team found that the hairs formed small chips in the surface of the blade. According to Cem Tasan, professor of materials science at MIT and author of the study published today in the journal, these microscopic chips interfere with the blade̵
“We want to develop new materials that are better and last longer,” says Tasan. “This problem with the blade is an excellent example. We’re so used to it that you don’t even think about it. You use the razor for a few weeks and then move on. “
According to Tasan, razor blades are made from martensitic steels, some of the toughest materials known to mankind. Martenistic steel (named after a 19th century German metallurgist) is a super-hard alloy that is ground by heat and tempering and is used in commercial razors, surgical instruments, ball bearings, and bicycle disc brakes. Tasan and his colleagues found that, despite this strength, the blades tired rather quickly after several shaves.
Tasan and graduate student Gianluca Roscioli developed an experiment to examine the wear and tear of a blade after each shave. After examining several different commercially available razors, the team found that they were all made from a similar hardened steel carbide alloy. Because the materials were similar, the experiment only used one brand of razor.
Roscioli shaved with the same razor every three days for a month and then took it to the Cambridge lab. The researchers set up a device that allows the leaves to be viewed under a microscope. An electron beam is reflected from the surface in order to obtain information about the molecular structure of the leaves.
“Our first thought was that this was a wear problem, that material was being removed from the razor,” says Tasan. “We expected the blade to get rounder and rounder over time. We didn’t see it. “
Instead, he continues, “We saw the blade that makes this C-shaped crack broken and chipped.”
This video shows how the tiny chips form in the surface blade after they are cut through human hair.
According to Tasan, commercial disposable razors that are sold to both men and women usually use the same grade of steel but have different coatings and numbers of blades in the cartridge. (Razors that are sold to men and women are similar except for the handle design and number of blades. Single-blade razors, which are often sold to women, don’t stay as sharp as multi-blade razors, says Tasan.)