A good aluminized layer is desired to be achieved by dipping clean steel in hot molten aluminum. For Al to adhere to steel it is found that that 10% Al is required at 0.002 inch below the surface. If the diffusion coefficient for Al in steel is 7.2x10-9 cm2/sec at the hot dipping temperature, determine the time required to achieve the required concentration at the required location below the surface of steel. Assume a maximum solubility of 100% at the dipping temperature into the steel and no Al is present in the steel to start with.