Spray-coated combustion cylinders

Another technique for finishing combustion cylinders is to spray the bored surface with liquid metal to eliminate the formation of pores when the surfaces are honed. This technique has its own problems, however, since the spray nozzle that deposits the liquid metal could leave solidified drops of metal on the surface of the cylinder or cause cratering of the surface if drops of metal splatter on the surface during spraying.

Figure 1 shows an image of a surface that has been coated by a rotating nozzle. Figure 2 is a scan of a cylinder showing solidified droplets and surface craters caused by the bombardment of small drops of metal. Dark spots on the image of Figure 2 are solidified drops of metal that protrude above the surface. Light colored regions are craters produced by metal droplets bombarding the surface.

Figure 1. Cylinder surface coated with a metal spray from a rotating head

Figure 2. Sprayed surface with droplets and craters