February 18 is Harry Brearley’s birthday. Brearley was an English metallurgist who discovered “rustless steel” or stainless steel.
Brearley was searching for a new steel to use to minimize the corrosion of gun barrels but could still resist high temperatures and pressures associated with firing a gun. He discovered that if he added chromium to ordinary carbon steel, a thin layer of protection from rust appeared.
Stainless steel today is the name for steels containing at least 12% chromium. The chromium combines with the oxygen in the air to form a thin layer of chrome-containing oxide called a passive film. The sizes of these oxides are close enough to the same size as atomic chromium that they pack themselves close together on the surface of the steel a few atoms thick. If the layer is scratched, the film will self-repair as long as there is oxygen available.
Brearley marketed his discovery in his hometown of Sheffield, England by producing “rustless” knives, pots and other food-related products.
Notable Science History Events for February 18
1967 – J. Robert Oppenheimer died.
Oppenheimer was the American physicist who was the lead researcher for the Manhattan Project and is considered the ‘father of the atomic bomb’.
After the war, Oppenheimer served as the chairman of the General Advisory Committee of the new US Atomic Energy Commission. He used this platform to lobby against nuclear proliferation and control of nuclear power. This position did not stand well with the 1950s political scene. He was stripped of his security clearance and basically ended his public work.
1957 – Joseph Gilbert Hamilton died.
Hamilton was a medical physicist who pioneered the use of radioisotopes for treating and diagnosing diseases. He injected a radioactive sodium solution into a leukemia patient to treat the disease and showed radioactive iodine was useful for treating thyroid disease.
He was part of a series of human trials to determine the toxicity of plutonium. The teams injected unsuspecting patients with plutonium isotopes and waited for results.
Hamilton also experimented with radioactivity on himself. He died of leukemia believed to be a result of his work.
1957 – Henry Norris Russell died.
Russell was an American astrophysicist who is best known for the Hertzsprung-Russell diagram which shows the relationship between star brightness and spectral type. He developed a method to compute the distance to binary star systems and used the light from eclipsing binary stars to calculate their mass. He also described the coupling of electron angular momentum and spin quantum numbers known as Russell-Saunders coupling.
He also described the coupling of electron angular momentum and spin quantum numbers known as Russell-Saunders coupling. This coupling is also known as LS coupling since it combines the ℓ and s quantum numbers to form the j quantum value. This is done to account for the total angular momentum state of a particle.
1930 – Clyde Tombaugh discovers Pluto.
NASA
American astronomer Clyde Tombaugh discovered a planet outside the orbit of Neptune. He would load the images in a device called a blink comparator that rapidly switches the two photographs. This allowed Tombaugh to detect slight differences between the photographs which would suggest movement. He found a change from his late January plates and confirmed the discovery with another photograph.
1871 – Harry Brearley was born.
1838 – Ernst Mach was born.
Mach was an Austrian physicist who primarily researched how people perceive their surrounding through studies in acoustics and optics. His work with optical interference, shock waves, and the Doppler effect led to theories where measured phenomenon depended on the frame of reference of the observer and their relationship to the phenomenon. This would lead to much of Einstein’s theory of relativity. He is also known for the unit of speed known as the Mach number, the ratio of the speed of an object to the speed of sound.
1799 – Johann Hedwig died.
Hedwig was a German botanist who pioneered bryology, or the study of mosses. His work was compiled and published after his death in Species Muscorum Frondosorum. It was a comprehensive study of nearly all known mosses known at the time.
1745 – Alessandro Volta was born.
Volta was an Italian physicist who was a pioneering figure in early electricity research and invented the chemical electric battery. He introduced the concept of electromotive force, or the force required to separate positive and negative charges. His battery was similar to the citrus battery using zinc and copper electrodes separated by an acid.
1677 – Jacques Cassini was born.
Cassini II was a French astronomer who was the son of the Italian astronomer Giovanni Cassini. He compiled the first tables of the orbits of Jupiter and Saturn’s moons and succeeded his father as director of the Paris Observatory. He also proposed the theory that the Earth was shaped like an ellipsoid rather than just flattened at the poles.