Corrosive glass-forming melts

The more common classification scheme is to divide the corrosive media into their state of aggregation, that is to subdivide into corrosion by solids, liquids and gases. While solid state corrosion is rarely dealt with, we have vast amount on literature on hot gas corrosion. The case of corrosion by liquids is commonly further subdivided into more specific cases, such as aqueous corrosion (e.g. acids and water), corrosion by glasses, metal melts and salt melts. The last case is for historic reasons known in the form of a rather misleading expression hot corrosion. A special case, which spans from the liquid into the gaseous state is given by the corrosion in hot water systems hydrothermal corrosion. 

We are not aware of hot corrosion testing of precursor-derived ceramics. A prediction rests upon the argument that for those which contain boron a top scale compositions in the Na-B-Si-O-system should form, that is a classical glass forming system with low melting points and viscosities [176]. Apart from the hot corrosion degradation by itself it is completely unknown whether this will induce crystallization of the amorphous precursor-derived ceramics. 

The physical properties of tantalum are similar to those of mild steel, with the exception that its melting point (2996°C) is much higher. It is ordinarily used in the pure form, and it is readily fabricated into many different shapes. The corrosion-resistance properties of tantalum resemble those of glass. The metal is attacked by hydrofluoric acid, by hot concentrated alkalies, and by materials containing free sulfur trioxide. It is resistant to all other acids and is often used for equipment involving contact with hydrochloric acid. 

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