Process for making wear-resistant coatings

A process for producing wear resistant coatings on the surface of a metal substrate, comprising the steps of:

• a. first, applying a layer of paint having a dispersion of hard particles onto the surface;
• b. then, placing over said paint layer a layer of braze alloy that in its molten state will wet the metal substrate and the hard particles;
• c. then, heating said substrate and hard-particle paint layer and braze alloy layer to a temperature above the liquidus of the braze alloy but below the solidus of the substrate;
• and then
• d. cooling the coated substrate to ambient temperature.

A process for producing wear resistant coatings on the surface of a metal substrate, comprising the steps of:

• a. first, applying a layer of paint having a dispersion of hard particles and braze particles onto the surface;
• b. then, heating said substrate and paint layer and braze alloy layer to a temperature above the liquidus of the braze alloy but below the solidus of the substrate;
• and then
• c. cooling the coated substrate to ambient temperature.

A process for producing wear resistant coatings on a concave surface, comprising the steps of:

• (a) applying a layer of wet adhesive to said concave surface,
• (b) applying dry hard particles onto said wet adhesive layer to embed the hard particles into the wet adhesive layer,
• (c) drying the adhesive with the imbedded hard particles,
• (d) applying another layer of wet adhesive over the dried layer of hard particles,
• (e) applying dry powdered braze alloy onto said other layer of wet adhesive to embed the braze alloy into the wet adhesive layer,
• (f) drying the adhesive with imbedded braze alloy particles;
• (g) heating said substrate with the layers of hard particles and the braze alloy to a temperature above the liquidus of the braze alloy but below the solidus of the substrate, and then
• (h) cooling the coated substrate to ambient temperature.

A process for producing coatings of hard particles on the surface of a substrate material, comprising the steps of:

• (a) wetting the surface of the substrate material with a basic compound selected from the group consisting of hydroxides of alkali and alkaline earth metals, amines, and ammonium hydroxide;
• (b) submerging the wetted substrate into in a paint comprising over 15 volume percent hard particles dispersed in a paint containing an acid-containing thickening agent that had been partially neutralized by adjusting its acidity to a pH of less than 7 for sufficient time to allow the basic compound to diffuse into the paint to substantially increase its viscosity;
• (c) removing the submerged substrate from the paint to form a layer of paint having a viscosity adjacent to the surface of the substrate substantially higher than the viscosity of the paint itself;
• and
• (d) drying the paint to form a coating of particles on the substrate.

A process for hardfacing metal surfaces, comprising the steps of:

• (a) first, wetting the surface of the substrate metal with a basic compound selected from the group consisting of hydroxides of alkali and alkaline earth metals, amines, and ammonium hydroxide;
• (b) then, submerging the wetted substrate into in a paint comprising over 15 volume percent of fusible metallic hardfacing particles dispersed in a paint containing an unneutralized acid-containing thickening agent, wherein the pH of the paint is less than pH 7, said fusible metallic hardfacing particles being selected from the group consisting of nickel, cobalt, or iron base hardfacing alloy, and mixtures of hard particles with braze alloys;
• (c) then, allowing the substrate to be submerged for sufficient time to allow the basic compound to diffuse into the paint to substantially increase the paint's viscosity;
• (d) then, removing the submerged substrate from the paint to form a layer of paint in which .the paint viscosity adjacent to the surface of the substrate is substantially higher than the viscosity of the paint alone;
• (e) then, drying the paint to form a coating of particles on the substrate;
• (f) then, heating the coated substrate in an inert atmosphere above the solidus of said hardfacing alloy or braze alloy to metallurgically bond the hardfacing particles to the metal substrate.

A process for hardfacing sheet steel, comprising the steps of:

• (a) moving a flat horizontal steel sheet beneath sprayers;
• (b) spraying a layer of adhesive onto said steel sheet
• (c) then spraying the desired amount of hard particle powder onto the layer of adhesive;
• (d) then spraying adhesive over the hard particle powder;
• (e) then spraying the desired amount of braze alloy powder over the adhesive;
• (f) then moving the sheet through an open-ended hydrogen sintering furnace that melts the braze, thus forming a metallurgically bonded composite of hard particles and braze on the top surface of a steel sheet.