An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

A powder boronizing composition comprising: a. 0.5 to 4.5 wt % of a boron source selected from B.sub.4C, amorphous boron, calcium hexaboride, borax or mixtures thereof; b. 45.5 to 88.5 wt % of a diluent selected from SiC, alumina or mixtures thereof; c. 1.0 to 20.0 wt % of an activator selected from KBF.sub.4, ammonia chloride, cryolite or mixtures thereof; and d. 10.0 to 30.0 wt % of a sintering reduction agent selected from carbon black, graphite or mixtures thereof.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4; from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69, from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3, from 12 to 20 wt. % of Cr.sub.2O.sub.3, from 4 to 20 wt. % of CuFe.sub.5O.sub.8, and less than 5 wt. % of one or more compounds chosen from FeO(OH), Cr+3O(OH), CrMn, Si and SO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

Provided is an apparatus and a method of spray-coating solid powder on a substrate disposed in a coating chamber which is in a vacuum state, and more particularly, to an apparatus and a method for coating solid powder, which are configured such that a gas sucked from an atmospheric pressure gas, together with a gas supplied from a gas supply unit, can be used as a carrier gas for transporting the solid powder.

Provided is an apparatus and a method of spray-coating solid powder on a substrate disposed in a coating chamber which is in a vacuum state, and more particularly, to an apparatus and a method for coating solid powder, which are configured such that a gas sucked from an atmospheric pressure gas, together with a gas supplied from a gas supply unit, can be used as a carrier gas for transporting the solid powder.

In a ferritic stainless steel sheet, the arithmetic average roughness Ra is 0.2 m or more and 1.2 m or less. In addition, the dull pattern transfer rate on the steel sheet surface is 15% or more and 70% or less. Furthermore, micropits with a depth of 0.5 m or more and an open area of 10 m.sup.2 or more which are formed on the steel sheet surface have an existing density of 10.0 or less per 0.01 mm.sup.2 and an open area ratio of 1.0% or less. In addition, a film formed on the steel sheet surface is constituted from an oxide containing SiO.sub.2 as a main constituent, which oxide contains at least Si, N, Al, Mn, Cr, Fe, Nb, Ti and O as film-forming elements other than C, wherein the Si content is 10 at % or more, and the N content is 10 at % or less.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.