Solutes with very high melting points

[rppearso]

Does anyone know of any solutes (such as sodium chloride) that have VERY high melting points (preferably 1800C or higher)? They don't have to be water soluable but they need a solvent that can disolve them.

 

[oz93666]

if you put "melting points of compounds" in search , you get some helpful links ... http://www.gcsescience.com/imeltcomplease.htm ... nothing soluble , except by dissolving in weak acid ... zinc oxide 1975C

 

[Nidum]

Have you looked at metal oxides ? Alumina in particular has a very high melting point and can be made into colloidal suspensions and dissolved by acids ?

 

[rppearso]

very awesome, thank you. Trying to machine a substance to form another molten material around and then be able to disolve it away so I can make complex internal structures that would be incredibly expensive to machine.

 

[Nidum]

You need ceramic core materials for that . These are commercially available as either cement like materials which can be moulded or as solid blocks which can be machined . They will dissolve away in special etchant mixes . Different etchant mixes are made so that depending on which metal you are casting the core will etch away preferentially to the metal .

These ceramic core materials are essentially the same ones as are used for the moulds when casting components like Nimonic turbine blades by the lost wax process .