Steel restores itself and kills bacteria: how the simplest material has been invented

Steel restores itself and kills bacteria: how the simplest material has been invented

Steel that cures itself

In fantastic movies, robot damage is itself prolonged. Self-cuffing scratches on the body of a car are the dream of many car owners. The steel is already there. But it's difficult to produce, it's expensive, so it's still used mostly in construction -- for facade panels and roofing materials that won't rust; for example, when the roof of a warehouse where cargo with poor water contact is not allowed to be damaged.

Self-recovering coatings are special paints. They are based on microcapsules with special polymeric material. For any mechanical effect, e.g. scratching, the capsules are destroyed, and material is released that covers the injured area and a polymer layer is formed on the surface. It heals damage by reacting to the edges of the intact surface and forcing it to extend the scratch, as well as by isolating the area from the air, preventing corrosion of the metal.

The difficulty of producing steel with this coating lies both in creating paint with microcapsules and in putting it on.

Paint is a colloid solution of polymers, modifications, and microcapsules of several micrometres size. Modifiers, i.e. connecting elements, are needed to ensure that polymers are inside a microcapsule in a liquid state; the composition of the mixture itself is classified and only a few companies around the world are producing it, the technology is new and is still in the pilot phase.

Liquid compositions are applied to steel and then the connecting components are removed by means of a drying oven, leaving a complete polymer layer with microcapsules; it is important that the coatings are distributed evenly and the capsules themselves are not damaged, otherwise the properties of the steel will vary from site to site.

If the market evaluates the properties of the material, its production becomes larger and the price of the item drops, then it can be predicted that such steel will be widely distributed.

Bacterium steel killer

Anti-bacterial steel is used in medicine, and it is used to produce medical tools, and elements of hospitals such as rails or panels on walls where harmful micro-organisms usually accumulate, and many technology manufacturers, especially smartphones and laptops, have begun to make gadget shells during the pandemic.

There are several variations in the way steel acquires anti-bacterial properties; more of the material is covered with polymeric coating, which includes silver and copper ions; these metals are very effective in combating microbes: they destroy their casings when they come into contact, and 99% of microorganisms die.

But there are other developments: for example, if steel is loaded into the electrolyte solution and especially applied to the voltage, nanostructures are formed on the surface: microscopic pits, spikes and needles. Like metal ions, they damage and kill bacterial membranes, and the process that produces such steel does not differ from the material that is already used in the processing process, in a similar way the metal polishes or gives it anti-corrosive properties.

Both approaches are safe for cells of animals and plants: they are much larger than microbes and have nothing to fear.

Anti-bacterial steel applications now include ventilation and lining panels, such as interior trim in transport and space.

Super-strength steel - for super-powered machines

Metallurgicals are looking for ways to create both solid and light steel to make light parts, which will increase the speed and safety of cars, and when special equipment is produced, solid and light shells will reduce fuel consumption.

In order to reach the right parameters, metalworks form a structure of metal with a combination of different phases, some of which increase strength and others are responsible for maintaining plasticity.

In the steel industry there are several phases of steel: ferrit, followed by penite, sorbit, troostite, beinites and Marnesite. Ferrit is not strong enough, it is plastic and easily drawn; the further away from the ferrit is the phase, the higher the strength and the lower the plasticity.

If you add more solid phases to the plastic Ferritic matrix, you have a "pie" that is both plastic and solid, at the expense of each phase. It is more difficult to obtain steel consisting of a combination of different phases if they are far apart.

Ferrit-perlite steel has learned long ago, it is now one of the standard tasks of metallurgy: Ferrit-trostite- and Ferrit-Beinite steel is much more difficult to obtain, but the large steel companies have mastered it, but the solid Ferrit-Marencite is the result of a complex process that requires special equipment and a certain degree of technological mastery.

Steel hearts of electrical appliances

One of the applications of steel as electromagnetic material is the manufacture of transformers, generators, and electric motors. Iron is a unique material that can create its own magnetic field because of its atomic structure.

The iron atom has four unconfined 3d shells, and instead of ten electrons on it, there are only six. In the case of some elements of energy, it becomes profitable to fill two electrons of 4s shells farthest from the kernel than to complete 3d. So there are a few electrons that have orbital and spinal magnetic moments that are uncompensated, they rotate around the core and create their own magnetic field.

In some metals, electrons on the shell compensate each other, so materials do not create a magnetic field. There are many other metals with unconstructed d-shells that can magnetize, but only iron, nickel, and cobalt display these properties at room temperature, not just chilled.

Steel in electronics should be well magnetized in the external magnetic field and quickly re-exampled when it changes direction. For most industrial and household networks this occurs 50 times per second. The main requirement in this process is the ease of re-magnetization, which will ensure minimal energy costs during the operation of the finished product.

Iron as a material is a crystallistic structure in which atoms are located on the tops of ribs and in the center of cubes. It's almost like a lego design. It turns out that the individual magnetic fields of each atom are folded into a common field, at the expense of which parts made of iron can be over-exposed, drawn to magnets or act as magnets themselves.

Unique steel for transformers

Transformative steel is one of the subspecies of electrical steels, with a special structure where the crystal grate of each section has become equally oriented in space, thus achieving minimal energy losses during the operation of the electrical device.

Now, in simple terms, large volumes have become mixed -- they consist of small "grains" of metal, in which atoms form a cube crystal grate, and in conventional steel, different "seeds" can be oriented in different ways -- their magnetic fields, respectively, also have different directions.

In transformative steel, metalburgs achieve a deviation between the grates of different "grains" in just a couple of degrees. The result is a material that seeks to build a monocrystal, as if all material atoms were integrated into a single grid rather than separate "seeds." This is the construction of a metal in terms of classical Ferromagnetism is the most energy-friendly way, because the magnetic field passes through all the "grains" in the same direction and ensures the rapid re-magnification of the electrical system's core with minimal energy losses.

The technological cycle of transformer steel production is the most complex in the whole iron and steel industry. Steel is melted with a specific chemical composition, such as silicon, which increases the electrical resistance and the surface currents do not disrupt the magnetic field. Further, hot rolling, etching, cold rolling, dehydration, second cold rolling, protective coating, high temperature burning, electrical insulation and, in some cases, laser treatment of the surface.

A number of tasks are carried out at each technological shift, from obtaining the required band geometry to forming compounds in surface metal layers or across the strip.

Nano-structured steel, like rubber

Nano-structured is called a design steel that selects the chemical composition, adding manganese, carbon, and chrome, and the technological parameters of processing form a unique structure that provides a high degree of strength and plasticity.

In the past, steel with unstable structure had been melted to produce such material, which, when deformed, had shifted the various stages of the metal from one to another, changing its properties; in other words, steel had become stronger with mechanical effects.

And nanostructural steel is a material in which each "grains" has a doppelganger in the opposite direction. It produces a material that does not disintegrate when deformed, but is drawn out -- it is more like rubber. Nanostructed steel can extend to 50 per cent of its original length without breakage and can withstand 10 tons per square centimeter. By comparison, conventional steel is 2.5 times less solid and can only extend by 20 to 25 per cent.

This material, although produced only in test mode and in small volumes, has great prospects for autoprom and machine construction: nanostructured steel can provide solid parts of complex shape, but so long as production is not massive because of complexity and cost, the price of each sheet is too high; if the need for material grows, production will become completely different, and then the price of each sheet will become acceptable -- who knows, perhaps in the near future, all machines will start to be made of such steel.

The metal industry has moved forward in the last few decades: materials that were thought to be fantastic half a century ago can now be obtained on an industrial scale; many of them are not yet massive, but it is not known how the market will behave: perhaps very soon we will see new species of steel in smartphones, refrigerators and microwaves.