Open pack heat treatment of metal sheet material using sized particles as spacing means

Claim 2

The composite article of claim 1 wherein the adhesive composition comprises a halide of iron.

Claim 3

The composite article of claim 1 wherein the adhesive composition comprises at least one substance selected from the group consisting of ferrous chloride, ferric chloride and the hydrates thereof.

Claim 4

The composite article of claim 1 wherein the spacing particles comprise a halogen-containing energizer.

Claim 5

The composite article of claim 1 wherein the spacing particles comprise a halogen-containing energizer selected from the group consisting of ferrous chloride, ferric chloride and the hydrates thereof.

Claim 6

The composite article of claim 1 wherein the spacing particles have a size of about one thirty-second to about one-fourth inch.

Claim 7

The composite article of claim 1 wherein the spacing particles have a size of about one-sixteenth to about three-sixteenths inch.

Claim 8

The composite article of claim 1 wherein the coated ferrous metal sheet material is in the form of a coil of continuous strip and contiguous convolutions in the coil constitute the layers.

Claim 9

The composite article of claim 9 wherein a halogen-containing energizer is present between contiguous convolutions in the coil, and the contiguous convolutions in the coil have a spacing of about one thirty-second to about one-fourth inch.

Claim 10

The composite article of claim 1 wherein outermost portions of the adhered spacing particles extend outwardly from the sheet material surface beyond outermost surfaces of the portion of the said adhesive composition acting to cause the spacing particles to adhere to the coated sheet material and the adhered particles of the source of chromium.

Claim 11

The composite article of claim 11 wherein the sheet material is ferrous metal strip, substantially the entire surface area of at least one side of the strip is coated with the adhesive composition, and the spacing particles are substantially uniformly dispersed across the width of the strip and over the surface area of said adhesive coated side.

Claim 12

The composite article of claim 12 wherein the spacing particles have a size from about one thirty-second inch to about one-fourth inch, and from about 12 to about 144 of the spacing particles are applied per square foot of surface area.

Claim 13

A process for preparing chromized ferrous metal sheet material comprising applying on at least a portion of the surface area of at least one side of ferrous metal sheet material a. adhesive composition, b. a substantially uniform coating of particles of a source of chromium having a particle size not greater than about minus 5 mesh (Tyler Screen), and c. a plurality of dispersed sheet material spacing particles having a particle size of at least one thirty-second inch, the spacing particles being of substantially larger size than the particles of the source of chromium, the steps (a), (b) and (c) being carried out in any desired order or with any two or more of said steps being carried out simultaneously, the steps (b) and (c) applying to the same or different sides of the ferrous metal sheet material or to both sides thereof, step (a) applying to any side or sides to which steps (b) and (c) applies, the step (c) being carried out without compaction, the sheet material spacing particles being substantially uniform in size, the adhesive composition having an adhesive characteristic under the conditions of step (b) whereby an adherent particulate coating of the chromium source is formed, the adhesive composition having an adhesive characteristic under the conditions of step (c) whereby the spacing particles are caused to adhere to the coated sheet material, thereafter assembling a plurality of layers of the coated ferrous metal sheet material having the adherent coating of particles of the source of chromium and the adherent spacing particles thereon into a pack for chromizing the surface thereof, the contiguous Layers of the coated sheet material in the pack having at least one adherent coating of particles of the source of chromium and having adherent spacing particles therebetween, the spacing particles having a size whereby they are in contact with and act to space contiguous layers of the coated sheet material in the chromizing pack assembled therefrom, the spacing particles being substantially uniformly dispersed on the coated surface area of the sheet material, the number and relative spacings of the spacing particles being such that an open pack satisfactory for chromizing at a chromizing temperature of at least 1,550* F is formed without deforming or marring the ferrous sheet material, and subjecting the pack to an elevated chromizing temperature of at least 1,550*F to chromize the surfaces of the sheet material, the pack being in a protective atmosphere and a halogen-containing energizer being present therein while the sheet material is being chromized.

Claim 14

The process of claim 14 wherein the adhesive composition comprises a halogen-containing energizer.

Claim 15

The process of claim 14 wherein the adhesive composition comprises a halide of iron.

Claim 16

The process of claim 14 wherein the adhesive composition comprises at least one substance selected from the group consisting of ferrous chloride, ferric chloride and the hydrates thereof.

Claim 17

The process of claim 14 wherein the spacing particles comprise a halogen-containing energizer.

Claim 18

The process of claim 14 wherein the spacing particles comprise at least one substance selected from the group consisting of ferrous chloride, ferric chloride and the hydrates thereof.

Claim 19

The process of claim 14 wherein the spacing particles have a size of about one thirty-second to about one-fourth inch.

Claim 20

The process of claim 14 wherein the spacing particles have a size of about one-sixteenth to about three-sixteenths inch.

Claim 21

The process of claim 14 wherein the ferrous metal sheet material is in the form of continuous strip, the coated strip is coiled to form a chromizing pack therefrom, and contiguous convolutions in the coil constitute the layers.

Claim 22

The process of claim 22 wherein a halogen-containing energizer is applied on the surface of at least one side of the ferrous metal sheet material and is present between contiguous convolutions in the coil, and contiguous convolutions in the coil have a spacing of about one thirty-second to about one-fourth inch.

Claim 23

The process of claim 14 wherein the outermost portions of the adhered spacing particles extend outwardly from the sheet material surface beyond outermost surfaces of the portion of the said adhesive composition causing the spacing particles to adhere to the coated sheet material and the adhered particles of the source of chromium whereby gases can pass between the spaced contiquous layers of the coated sheet material in the chromizing pack.

Claim 24

The process of claim 24 wherein the sheet material is ferrous metal strip, substantially the entire surface area of at least one side of the strip is coated with the adhesive composition, and the spacing particles are substantially uniformly dispersed across the width of the strip and over the surface area of said adhesive coated side.

Claim 25

The process of claim 25 wherein the spacing particles have a size from about one thirty-second inch to about one-fourth inch, and from about 12 to about 144 of the spacing particles are applied per square foot of surface area.