Description
Ceramic-glass is much more resistant than normal glass. In the molten state it is worked and shaped like any glass, but during cooling it undergoes a particular thermal treatment which leads to the separation of micro-crystals in the material. At the end of the cooling cycle the material is formed by a glass phase in which the micro-crystals are dispersed.
This material is used to make thermal shields which protect space-shuttles from damage and very high temperatures they encounter when going through the atmosphere.
Ceramic-glass is such a hard material that it can be worked on the lathe or used to make dental caps with a similar aesthetic effect than than obtained with traditional porcelain; it is harder than porcelain, resists dental plaque, has a translucent appearance similar to natural teeth. But ceramic-glass is also used for pots and transparent pans for fire-heating, for new kitchen counters, for the glassy layer on tiles for high-use floors.
There is an infinity of particular applications for special glass.
Micro-spheres of a special glass, filled with radioactive material, with a diameter smaller than that of a hair, are used to transport rays to a tumour-affected liver. They are introduced through a catheter positioned in an artery which takes blood to the liver. In so doing, the quantity of rays, which is up to five times more than traditional methods, is concentrated in the area of the tumour with greater effectiveness and less damage for the organism.
The micro-spheres completely exhaust their radioactivity in two or three weeks and remain in the liver as an inert and harmless material.
Glass as solvents
As its components have the ability to digest everything and in large quantities, glass is used to immobilize and make inert the radioactive waste in thermonuclear plants. The radioactive material which has exhausted its capacity to generate energy, but which will still remain dangerously radioactive for hundreds or thousands of years, is added to boron-silicate glass and melted. It is of course special glass, which can absorb radiation and resist water corrosion for hundreds of years.
This glass melts at a relatively low temperature, it has high chemical resistance and contains heavy elements like lead, barium and strontium which form a protective shield which stops, in the material, radiation emitted by the waste. The glass blocks are then placed in steel containers and buried in abandoned mines.
The same technique is used to treat many other toxic substances that are dangerous to man and the environment.
Asbestos, a carcinogenic crystal material, is vitrified to remove its carcinogenic property. The so-called heavy metals, like chrome, nickel, cadmium, which are found in the ash of thermoelectricity plants and urban waste incinerators, are extremely dangerous. If the ash is washed away, these elements are slowly dissolved and end up in the ground up to the water-bearing stratum which becomes polluted. By vitrifying the ash, this process is slowed down or eliminated.