No. Spray welding doesn't come close to the tight tolerances (1/7th of the width of a human hair) needed for spools in control valves.

Spray welding is a technique in which molten metal is sprayed onto a prepared surface.  Brass, cast-iron, stainless steel and other metals can be sprayed.  There is a possibility of chipping similar to chrome in this process.  After something is spray welded it will need to be machined in some way whether it is on a lathe or on a surface grinder.  The surface is not as nice as a finish as chrome, there seems to be some porosity in the spray welds.

The advantage is that spray welding is usually faster and cheaper than chrome.  It might be good for a quick fix on a cylinder rod but should not be considered anything more than a band-aid fix.