Help with spray weld issues

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Hi, new member here. Hoping I can get some help here from someone experienced with spray-welding, I am having some serious issues with flaking/cracking/peeling while attempting to spray this shaft. I took a couple of pics of the damage as I was turning the coating down to it's finished dimension in the lathe:This is my 2nd attempt after turning back down to bare metal, 1st attempt I could see spiderweb-like cracks in the coating before I ever took a tool to it. I should note I am not really a welder, was given a crash course with the exact same equipment I'm currently using and have been getting great results for years.Normally I don't get that deep brown color after a spray pass either, usually it is a light, almost white-gray after a spray pass like this:Sorry about the pic but I think you can see how much lighter the coating is in comparison to the 1st photo.Normally I use the following powder (This is what is on the label):Surface Engineering & Alloy Company2895 46th Ave N., St. Petersburg, FL 33714Alloy: 4472Size/Mesh: 140/400Description: Plasma Spray PowderHeat No.: SE-xxxxxThis time I was given basically the same stuff but Alloy 4470.Quick and dirty rundown of my spray procedure:- Undercut shaft to 1.960" (finish diameter is 2") and "rough" surface up with threading tool at 20-24 threads per inch and about .015" deep per side.- Setup spray gun on tool post and position nozzle about 4.5-5" from shaft.- Preheat shaft to about 200-250 degrees F.- Spray 1 pass (builds up to about 2") and allow shaft to cool to about 500F.- Spray final pass (builds up to about 2.040') and allow shaft to cool to 250-300F.- Turn coating down to finish diameter of 2" in a single pass with indexable carbide insert tool.This procedure has worked great on last 100+ shafts I've done, no issues and leaves a good smooth finish. Shafts are brand new when I start, the whole purpose for spraying is for wear resistance. I should also note that the shaft is made of 4150 steel and I am using "Flamex D" as fuel for the spray-weld gun. I have the fuel regulator set at 30 psi and O2 at 90. Airflow meter to spray gun reads "55" for both fuel and O2 when spraying. Quick pic of the spray gun itself if it helps:Was also told that I could spray this stuff directly onto the shaft without using a bonding spray weld coat. I plan on calling the company that sells the powder when they open Monday but was hoping someone maybe had some suggestions/tips on why I might be having trouble. Is it possible I have a bad batch of powder? Is the "Alloy 4470" stuff incompatible with the material or my methods? Should I be using some type of bonding coat? Any help appreciated!
Reply:That's a bonding issue maybe incompatible powder Shouldn't be any cracking at all when bondedI had a friend of mine modify some hydraulic rams for me using this method Hopefully  somebody can help youBacked my CATMA over your CARMA oops clusmy me  What would SATAN do ?? Miller Trailblazer 302 AirPakMiller Digital Elite  Optrel Welding HatArcair K4000Suitcase 12RC / 12 VSHypertherm PM-45Rage 3 sawRusty old Truck