Coating Technology By Two – Phase (Cold gas – Solid particles) Flow

Abstract

The surface coating process which is known as a cold spray (CS) of solid particles is performed by acceleration the solid particles for a certain metal to supersonic speeds through nozzle gas flow , are subsequently deposited by impact onto surface . Also this paper presents an analytical model for (CS) process , by assuming one dimensional isentropic flow , to demonstrate the dynamics of dilute two – phase (powder particles plus carrier gas) flow . Furthermore the equations for particle model are introduced , when heat transfers between the solid particles and assumed gas.
 The velocity of the solid particles must be achieved to a critical value for carrying out an optimal deposition efficiency and a high coating quality , also several parameters , including gas condition such as stagnation pressure and temperature , the density of gas , in addition the particle characteristics and nozzle geometry affect on particle velocity then on the quality of coating .