EFFECT OF COLD METAL SPRAYING PARAMETERS ON SPRAYED LAYERS ADHESION STRENGTHS

Document Type : Original Article

Authors

1 Prof. and Chairman of Prod. Eng. Dept., Fac. Eng., & Tech., Suez Canal University, Port Said, Egypt.

2 Ass. Prof. Machine Design Dept., Military Technical College, Cairo, Egypt.

3 Teacher Assistant, Prod., Eng., Dept., Fac. of Eng. & Tech., Suez Canal University, Port Said, Egypt.

Abstract

Cold spraying technique is applied employing austenitic alloy steel in coarse particles powder form sprayed by an oxy-acetylene spraying gun. The technique is carried out without preheating the sprayed surface. Fine bonding powder are employed to make adhesive substrate before spray-ing the basic powder which are sprayed in successive passes till reaching the required deposit thickness. Special disc specimens of st 42 are sprayed at different spraying parametei.s (normal least distance between the spraying nozzle and the sprayed surface, the rotating speed of the specimens, the transverse speed of the spraying gun and the deposit thicknesses). The adhesion strength of specimens are examined via special hard steel die placed on the tensile-compression testing machine of 125 KN capacity. That is done by shearing the deposited sprayed layer off the parent material. The adhesion strength of deposits mainly depend on the mechanical meshing among sprayed particles. Weak adhered sprayed deposits technique are not proper to carry shocks, concentrated loads and dynamic load except for bearing journals which are placed on soft bushes having the damping effect for shocks. Microstructure (metallography)examination has proved the above phenomenon. Recommended spraying para-meters are advised to give deposits with reasonable adhesion strengths sustaining the adequate bearing loads.

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