Coated metal article and method of making the same

• US 3,867,166 A
• Filed: 07/10/1972
• Issued: 02/18/1975
• Est. Priority Date: 01/27/1969
• Status: Expired due to Term

• Current Assignee: James D. Sullivan
• Original Assignee: James D. Sullivan
• Inventors: Sullivan, James D.
• Primary Examiner(s): Van Horn, Charles E.
• Assistant Examiner(s): Ball, Michael W.
• Application Number:
  US05/270,528
• Time in Patent Office: 953 Days
• Field of Search: 117/135.1,129,75C,75B,169A,23,7A,7R,40 106/48,52,39.7,39.6,39DV 65/33 161/196
• US Class Current: 427/376.4
• CPC Class Codes: C03C 10/00 Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
• CPC Class Codes: C03C 4/00 Compositions for glass with special properties
• CPC Class Codes: C23D 5/02 by wet methods
• CPC Class Codes: C23D 5/04 by dry methods
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]

Abstract

A method of producing a mixed crystalline-glass coated metal article. A devitrifiable glass frit is initially heat treated to devitrify the frit and produce an amorphous glass matrix containing a multiplicity of devitrified silicate crystals. The devitrified frit is subsequently milled with a corrosion resistant glass frit and the mixture is applied to the metal article. The coated metal article is fired at an elevated temperature to fuse the glass to the metal, and during the firing, the amorphous glass matrix tends to dissolve in the corrosion resistant glass frit. The resulting coating, which is a mixture of glass and crystalline particles, has a high impact resistance and toughness as well as having excellent resistant to corrosive attack.

Claims

1. A COMPOSITE STRUCTURE TO BE SUBSEQUENTLY FIRED AT AN ELEVATED TEMPERATURE, COMPRISING A METAL BASE, AND A MIXED FRIT COMPOSITION DISPOSED ON A SURFACE OF THE BASE, SAID COMPOSITION COMPRISING A MIXTURE OF (A) A SUBSTANTIALLY FULLY DEVITRIFIED GLASS FRIT COMPOSED OF AN AMORPHOUS GLASS MATRIX ANDCONTAINING A SUBSTNTIALLY PORTION OF DEVITRIFIED CRYSTALLINE SILICATE PARTICLES AND BEING SUBSTANTIALLY FREE OF CRYSTOBALITE PARTICLES, AND (B) A CORROSION RESISTANT SUBSTNTIALLY NONDEVITRIFIABLE GLASS FRIT CONTAINING FROM 63% TO 80% BY WEIGHT OF SILICA, SAID MIXED FRIT COMPOSITION BEING SUBSEQUENTLY FIRED AT AN ELEVATED TEMPERATURE TO FUSE THE COMPOSITION TO THE METAL, SAID AMORPHOUS GLASS MATRIX TENDING TO DISSOLVE IN SAID CORROSION RESISTANT GLASS FRIT DURING SAID FIRING WHILE RETAINING THE IDENTITY OF THE DEVITRIFIED CRYSTLLINE PARTICLES TO PROVIDE A RESULTING CRYSTLLINE-GLASS COATING HAVING IMPROVED ABRASION RESISTANCE, IMPACT RESISTANCE, AND TOUGHNESS AND EXCELLENT CORROSION RESISTANCE.

2. The structure of claim 1, wherein said devitrified glass frit comprises up to 60% of said frit composition.

3. The structure of claim 1, wherein said devitrified particles comprise from 50% to 85% by weight of said devitrified glass frit.

4. The structure of claim 1, wherein said metal base is a ferrous metal.

5. The structure of claim 3, wherein said crystalline particles have a size less than 10 microns.

6. A composite structure to be subsequently fired at an elevated temperature, comprising a steel base, and a mixed frit composition disposed on a surface of the base, said composiTion comprising a mixture of (a) a substantially fully devitrified glass frit composed of an amorphous glass matrix and containing a substantial portion of devitrified crystalline silicate particles, said silicate particles comprising from 50% to 85% by weight of said devitrified glass frit and said devitrified glass frit being free of crystobalite particles, and (b) a corrosion resistant substantially non-devitrifiable glass frit containing from 63% to 80% by weight of silica, said devitrified frit comprising from 20% to 50% by weight of said mixed frit composition and the balance being said corrosion resistant glass frit, said mixed frit composition being subsequently fired at an elevated temperature to fuse the composition to the metal, said amorphous glass matrix tending to dissolve in said corrosion resistant glass frit during said firing while retaining the identity of the devitirifed crystalline particles to provide a resulting crystalline-glass coating having improved abrasion resistance, impact resistance, and toughness and excellent corrosion resistance.

7. A METHOD OF COATING A METAL ARTICLE, COMPRISING THE STEP OF SUBSTANTIALLY FULLY DEVITRIFYING A DEVITRIFIABLE GLASS FRIT TO PRODUCE A DEVITRIFIED FRIT COMPOSED OF AN AMORPHOUS GLAS MATRIX AND A PLURALITY OF DEVITRIFIED CRYSTLLINE SILICATE PARTICLES DISPERSED WITHIN SAID MATRIX, SAID DEVITRIFIED GLASS BEING SUBSTANTIALLY FREE OF CRYSTOBALITE PARTICLES, MIXING SAID DEVI TRIFIED GLASS FRIT WITH A CORROSION RESISTANT SUBSTANTIALLY NONDEVITRIFIABLE GLASS FRIT TO PROVIDE A MIXTURE, APPLYING SAID MIXTURE TO THE METAL ARTICLE AS A COATING, AND FIRING SAID ARTIC-CLE AT A TEMPERATURE SUFFICIENTLY HIGH TO FUSE SAID MIXTURE TO SAID METAL ARTICLE, SAID AMORPHOUS GLASS MATRIX TENDING TO DISSOLVE IN SAID CORROSION RESISTANT GLASS FRIT DURING FIRING.

8. A method of coating a metal article, comprising the step of substantially fully devitrifying a devitrifiable glass frit to produce a devitrified frit composed of an amorphous glass matrix and a plurality of devitrified crystalline silicate particles dispersed within said matrix, said devitrified glass frit being substantially free of crystobalite particles, mixing said devitrified glass frit with a corrosion resistant substantially non-devitrifiable glass frit containing from 63% to 80% by weight of silica to provide a mixture, applying said mixture to the metal article, and firing said article at a temperature sufficiently high to fuse said mixture to said metal article, and for a time sufficient to dissolve at least a substantial portion of said amorphous glass matrix in said corrosion resistant glass frit while retaining the identify of the devitrified crystalline particles to provide a strystalline-glass coating.

9. The method of claim 8, wherein said devitrifiable glass frit is devitrified by heating said frit to a temperature ofo 1,000*F to 1,600*F.

10. The method of claim 8, wherein said mixing is accomplished by milling said frits together, the milled mixture having a particle size such that at least 85% of said particles pass through a 200 mesh sieve.

11. The method of claim 8, wherein said metal article is fired at a temperature in the range of 1,400*F to 1,700*F.

12. A method of coating a steel base, comprising the steps of heating a devitrifiable glass frit to a temperature sufficiently high to substantially fully devitrify the frit, the devitirifed frit comprising an amorphous glass matrix having dispersed therein a plurality of devitrified silicate crystals and being substantially free of crystobalite particles, said crystals comprising at least 50% by weight of said devitrified frit, mixing the devitirifed frit with a corrosion resistant substantially non-devitrifiable frit with said devitrified frit comprising up to 60% by weight of the mixture, applying the mixture to the steel base, and firing the steel base at a temperature in the raNge of 1,400*F to 1,700*F for a period of time sufficient to dissolve at least a substantial portion of said amorphous glass matrix in said corrosion resistant glass while retaining the identity of the devitrified crystalline particles to produce a resulting mixed crystalline-amorphous glass coating having improved abrasion resistance, shock resistance and toughness, and excellent resistance to corrosive attack.