Patent ID: 8893954

Claim:
A method of forming a surface layer on a substrate comprising: providing a stirring tool comprising a shoulder and a throat; providing a coating material, wherein at least a portion of the coating material is disposed within the throat of the stirring tool; wherein the throat has a cross-sectional area that is the same along the entire length of the stirring tool and a cross-sectional view of the coating material in the throat shows lengthwise contact between the throat and the coating material along the entire length of opposing sides of the portion of the coating material in the throat; orienting the stirring tool relative to the substrate such that a surface of the shoulder opposes an outer surface of the substrate; rotating the stirring tool and coating material together at a selected RPM; imposing relative lateral movement between the stirring tool and the substrate; depositing the coating material on the substrate to form a coating; and forming and shearing a surface of the coating by way of contact between the coating and the surface of the shoulder opposing the substrate, and frictional heating and compressive loading of the coating material against the substrate.