Method and apparatus for depositing raised features at select locations on a substrate to produce a slip-resistant surface

1. A method for producing a slip-resistant surface on a substrate having a generally planar surface comprising the steps of:

a) providing a metallic substrate having a generally planar surface;

b) providing a radiant energy source selectively positionable adjacent to the surface, the energy source emitting a high energy beam and having a focusing device for varying the focal length of the beam, and a control device for managing the beam, the energy beam having an axis and a focal point, the axis aligned to intersect with the surface at an angle and the focal point being generally on the surface at a beam impingement point;

c) providing a powder supply apparatus having a supply of powder particles, and a powder feed tube with generally opposing first and second ends, the first end connected to the supply, the second end being open and generally directed toward the beam impingement point, the powder feed tube being disposed to convey the powder particles from the supply and discharge the particles generally toward the beam impingement point;

d) supplying, via the powder supply apparatus, substantially simultaneously with projection of the energy beam, a predetermined flow rate of powder particles generally toward the beam impingement point on the substrate;

e) intermittently projecting for a pre-selected duration and frequency, an energy beam from the radiant energy source generally toward the surface to the impingement point, the focal length of the energy beam coinciding with the separation between the energy source and the impingement point;

f) allowing partial melting of the substrate surface material proximate to the impingement point and of the powder particles to form an alloy of the two proximate to the impingement point, the partial melting of the substrate creating a fusion zone extending above and below the surface of the substrate, the fusion zone having a depth below the surface of the substrate; and

g) allowing additional powder particles to be melted and form a feature extending from the substrate surface and having a height approximately twice that of the fusion zone extending below the surface of the substrate.

2. The method of claim 1 , further comprising the steps:

h) causing relative movement between the radiant energy source and the substrate coordinated with the projection of the energy beam; and

i) repeating steps e) through g) thereby forming another feature on the substrate and creating a slip-resistant surface on the substrate.

3. The method of claim 2 , further comprising the step of selecting the energy beam intermittence projection duration and frequency between consecutive projections of the energy beam to establish the size of the feature on the substrate.

4. The method of claim 3 , further comprising the step of synchronizing the protection duration of the energy beam and the interval between consecutive projections of the energy beam with the relative movement between the radiant energy source and the substrate to manage the size and spacing of the features on the substrate.

5. The method of claim 4 , wherein the radiant energy source has a power ranging between about 400 watts and about 10,000 watts.

6. The method of claim 5 , wherein the radiant energy source is a laser.

7. The method of claim 6 , wherein the radiant energy source is a laser having an output wavelength less than or equal to 1.07 ×10 −6 microns.

8. The method of claim 4 , wherein said powder particles comprise a metallic material selected from the group comprising a nitride, carbide, silicide, boride, aluminide, ceramic, and mixtures thereof.

9. The method of claim 8 , wherein the powder particles comprise a metallic material selected from the group comprising tungsten, stainless steel, carbon steel, aluminum, titanium, nickel, copper, and mixtures thereof.

10. The method of claim 9 , further comprising the steps of:

providing a shroud gas supply apparatus; and

supplying an inerting gas via the shroud gas supply apparatus to the beam impingement point so as to enable the partial melting of the powder and substrate caused by the energy beam to occur in an inert atmosphere.

11. The method of claim 4 , wherein the fusion zone depth is at least 0.006 inches.

12. The method of claim 4 , wherein the fusion zone depth is within a range of 0.006 and 0.035 inches.

13. The method of claim 4 , wherein the radiant energy source has a power of at least about 400 watts.