TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The amorphous colloidal silicate comprises an amorphous colloidal alkali metal silicate or alkaline earth metal silicate. The amorphous colloidal silicate further comprises colloidal silica. The colloidal amorphous silicate is selected from sodium silicate, potassium silicate, calcium silicate and magnesium silicate, preferably sodium silicate. The crystalline oxide particles are selected from silicon dioxide, aluminum oxide, titanium dioxide, magnesium oxide, calcium oxide, boron oxide, lithium oxide and zirconium oxide, preferably aluminum oxide. The coating comprises colloidal amorphous sodium silicate particles, colloidal silica and crystalline aluminum oxide. The emissivity agent is selected from silicon hexaboride, boron carbide, silicon tetraboride, silicon carbide, molybdenum disilicide, tungsten disilicide, zirconium diboride, cupric chromite and metallic oxides. The stabilizer agent is selected from bentonite, kaolin, magnesium alumina silica clay, tabular alumina and stabilized zirconium oxide, preferably bentonite. The protective layer comprises, based on the dry weight: 5-35 wt.% amorphous silicate; 23-79 wt.% crystalline oxide; 0-20 wt.% emissivity agent; 0-5 wt.% stabilizer/binding agent. The protective layer is non-porous and glassy.    TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The metal or metal containing alloy is nickel alloy, particularly nickel-steel alloy.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The heating or cooling method is selected from coal liquefaction, coal gasification, synthesis gas production (such as steam reforming), processing a synthesis gas (such as ammonia production, direct reduction and Fischer-Tropsch processes). The carbon monoxide and hydrogen in the reducing gas are reacted to form hydrocarbon. The heating or cooling unit is a tube, and the gas is passed through the tube and the protective layer is provided on the inner surface of the tube. The gas is heated to a temperature of 400-900 degrees C, preferably 500-800 degrees C. Preferred Composition: The coating composition comprises, based on dry weight of the composition: 5-35 wt.% colloidal amorphous silicate; 23-79 wt.% crystalline oxide particles; 0-20 wt.% emissivity agent; and 0-5 wt.% stabilizer/binding agent. Preferred Components: The reducing gas has a content of carbon monoxide of at least 1 vol.%, at least 2 vol.%, or at least 5 vol.%. The reducing gas comprises hydrogen (H2) and carbon monoxide (CO) as the major components. The reducing gas comprises 20-80 vol.% H2 and 5-50 vol.% CO. The reducing gas further comprises 1-15 vol.% CO2, 1-40 vol.% CH4 and/or 1-75 vol.% H2O. The reducing gas is a synthesis gas. The gas comprises a carbon compound selected from carbon monoxide, alkane, and carbon dioxide. The gas is essentially free of molecular oxygen. EXAMPLE - No suitable example given.