TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Materials: The binder comprises a nano-composite of nano-particles in an organically-modified inorganic polycondensate (especially a modified polysiloxane) or precursor thereof. The nano-particles are metal oxide particles, preferably SiO2, TiO2, ZrO2, Al2O3, AlOOH, Y2O3, CeO2, SnO2, iron oxide and/or Ta2O5 (especially SiO2), or precursors thereof which are converted into nano-particles by a sol-gel process. The nano-particles are modified with a surface modifier with a mol. wt. of less than 1500 containing an anhydride, acid amide, amino or SiOH group, hydrolysable silane residue and/or beta-dicarbonyl group. The nano-composite is obtained by a sol-gel process involving reaction of nano-scale particles with silane(s) of formula RxSiA4-x in whichA = OH or hydrolysable groups;R = non-hydrolysable groups;x = 0, 1, 2 or 3, with the proviso that x is at least 1 in at least 50 wt% of the silane, and the binder is formed by reaction of the same silanes in a sol-gel process. Preferred Substrates: Quartz, graphite, ceramic, fused silica or iron alloys, especially crucibles with a quartz, graphite or ceramic substrate for melting corrosive non-ferrous metals, and feed pipes with a fused silica or iron alloy substrate for aluminum metallurgy. EXAMPLE - A dispersion of 60 wt% silicon nitride (SiN) powder in anhydrous ethanol was mixed with the same amount of binder (inosil S-38 (RTM)) to give a sprayable suspension containing 30 wt% SiN. The suspension was sprayed onto a clean, dust-free, dry crucible to give a coating with a thickness of 40 microns (several coats, wet-on-wet), dried in air and then stoved for 30 minutes at 500degreesC. When used for melt-processing, the coated crucible gave silicon ingots with no defects, which were demoulded with no problems. If the SiN particles were applied as a suspension in water with no other additives and then stoved at 1000-1100degreesC, the coating was susceptible to damage by pieces of solid silicon when filling the crucible and melting the charge.