Yes these blades were only hardfaced on the bottom from factory which as you say, is probably to encourage some sort of self sharpening action.
If it was rough, its was far more likely something like an arc spray coating tbh (or, as you say, something like PTA), HVOF & plasma spray by their very nature tend to go down very smooth. Masking of either to a fine stop is no problem though.....
It's an italian made remote controlled job. Biggest one they make i believe. Barbieieri i think.
God knows, cubitron linisher and cubitron flap wheel isnt touching it.
if it helps, we've had some good sucess with some zirconia products for intermediate finishing, on things like stellite etc, which the cubitron stuff just bounces off..... If i remember, ill have a look in the abrasives cupboard and see what they *actually* are (i know theyre lime green, but thats not really much help!!).
Stellite is a very hard material and can be difficult to machine with any type of abrasive. I think Zirconium is a softer material than Cubitron, but it is still hard enough to remove material from Stellite
Cubitron is ceramic - it could be that its so hard it is skating over the tungsten carbide. Whereas the zirconium is possibly breaking down and constantly exposing new cutting edges.
I would say he has got that way too hot to be honest.
Neither are materials i know much about im afraid, more Peters thing, (and he's already replied, so i very much default to him!) but tbh, theres v few materials i can think of that id trust at that sort of thickness on a critical repair, generally, we would normally say that 2mm is about the limit for most of the coatings (With a few being a LOT less). That being said, if youre going to risk it on anything, an shaft like that, with the coating inlaid is always going to be the best option available.
Who do you get your diamond grinding discs from Pete? I use ATS but be interested in a back up supplier.
Pferd do a good one. Sit down when you get the price.
It depends on the application. For machinable alloys you can easily go to 2mm. For hard deposits (eg tungsten carbide) I prefer to pre-apply in layers - usually 4 - 6 even passes normally rate at 100mm per second with torch to job distance around 125mm. Then fuse. This process can be repeated to build up thickness. 2mm is achievable but be careful near edges - stresses in the coating can cause flaking/chipping. In reality a single application of 4 - 6 passes is usually enough to give a good wear performance and save on material costs. In reality there isn't a right or wrong, each application will need it's own treatment. If working on an edge grind a 3mm-4mm chamfer and bead along that.
The ATS ones I use are around £50. https://www.atsdiamondtools.co.uk/product/cut-n-grind-vacuum-brazed-diamond-wheel/
