Coating composition for preventing high temperature oxidation for electrodes.

摘要

The invention relates to a coating composition containing ceramic components, for preventing high temperature oxidation, which is to be applied especially for graphite electrodes employed in electric furnace steelmaking. This ceramic composition consists of the following components:
<UnorderedLists id="ula01" listStyle="none"><ListItem>(a) 40-75% by weight of silicon carbide as heat radiation component,</ListItem><ListItem>(b) 15-40% by weight of a binding and heat radiation promoting component consisting of 3-20 parts by weight of silicon nitride, 5-20 parts by weight of salt of phosphorus-containing acid, 2-10 parts by weight of chromium oxide, 2-10 parts by weight of tantalum carbide and 5-20 parts by weight of pulverous aluminium,</ListItem><ListItem>(c) 10-35% by weight of an additive for improving the adhesion to the graphite electrode and increasing the binding strength between the coated layers, consisting of
1-10 parts by weight of aluminium oxide, 3-15 parts by weight of glass powder, 3-15 parts by weight of zirconium oxide, 1-10 parts by weight of silicon dioxide, 1-10 parts by weight of magnesium oxide and 1-10 parts by weight of iron oxide.</ListItem><ListItem>(d) 5-20% by weight of metal powder consisting of 0-40 parts by weight of pulverous copper, 0-40 parts by weight of pulverous nickel, 0-40 parts by weight of pulverous stainless steel, 0-40 parts by weight of pulverous iron and 0-40 parts by weight of pulverous tin,</ListItem><ListItem>(e) 2-5% by weight of a sintering promotor mixture consisting of
10-30 parts by weight of silver carbonate and 30-50 parts by weight of copper sulfate and/or 30-50 parts by weight of iron sulfate, and</ListItem><ListItem>(f) 3-7% by weight of a melting point lowering component consisting of
30-60 parts by weight of iron fluoride and 40-70 parts by weight of copper fluoride, wherein the total of the above components (a)-(f) sums up to 100% by weight. This composition provides steelmaking graphite electrode with a burnt coated layer exhibiting a quite excellent adhesion and superior gas-tightness.</ListItem></UnorderedLists>