Hard Chrome Application

"Joe AutoDrill" fired this volley in news:Clnqo.14635$ snipped-for-privacy@newsfe08.iad:

Joe, you can pretty much hard chrome anything, what with all the electro- less plating options available for a base layer.

But regardless of how hard it is, the chrome will be subject to easy damage if the substrate it's on isn't solid.

So, yes; you could hard chrome a marshmallow, but it would crack like an eggshell under any impact.

LLoyd

Depending on your application there are several processes that are currently being used to replace hard chrome. I am not that familiar with them other than the information that is sent me over the internet and by mail. Armoloy is one system of hard finishing, the other is a type of spray welding that will deposit any surface hardness you want. I have a customer that spray welds large valve seats for wear and corrosion resistance. What type of application are you looking to do?

John

So, who wants to volunteer to do _this_ demo? ;-)

Cheers! Rich

John,

No particular new application. Just trying to learn more about the process.

...Although I would like to see the marshmallow done. :)

Regards, Joe Agro, Jr. (800) 871-5022

01.908.542.0244 Automatic / Pneumatic Drills: Spindle Drills: Tapping: Site: V8013-R

One problem with electroplating is that you get hydrogen embrittlement unless the parts are post-processed by heat-treating. Unless the plating is done just right, you can get blistering and peeling later, a good plater with a decent lab is in order. Folks frequently try to use it in place of proper material selection, hard chrome is just not the same as hard facing or proper alloy selection. The plating layer may be hard, but it's only as solid as the substrate. What it's good for is building up mildly worn machine parts to be finished by grinding to size, there was quite a business plating worn radial engine cylinders at one time. What with EPA regs and the heavy metals and corrosive chemicals involved, there's a lot fewer platers around than there once was. Electroless nickel sticks better and has about the same appearance, which is what a lot of folks are looking for with the hard chrome. Hard chrome used to be used a lot on custom pistols, electroless nickel has kind of taken that niche over, it's not quite as fussy to apply, doesn't build up on the corners like electroplating and can be done without a whole lot of fume hoods and such. Still involves toxic chemicals, though. No post-treatment for getting rid of the hydrogen, either. There are a number of plating and coatings handbooks out there, should you want to look into it further.

Stan

Carbon plate something (dust) and then electro-plate on top and the carbon drops out or goes into solution as the copper is plated. Then Chrome for red chrome.

But the quality look is nickle plate, copper plate, then the chrome layer. Nickle by itself makes a blue chrome. Moody pistol color.

The reflection through atomic layers... Really.

The copper kills off he blue from the Nickle making it warmer looking chrome when it is applied.

Mart>> What type of application are you looking to do?

One of the popular model airplane engine piston/sleeve setups is a hyper-eutectic aluminum piston running in a hard chromed aluminum or brass cylinder sleeve. The cylinder expands more than the piston when hot, which tends to keep the engine safe if you accidentally overheat the thing, while the chrome is durable and slicker than snot.

So there's two non-ferrous metals that I know of it being used on.

For some applications Hamilton-Standard used to nickel-plate entire aluminum aircraft propeller blades. The procedure was to first plate them with conductive rubber (yeah, they were using an electroplating process to deposit _rubber_--don't ask me about the chemistry of it--it was a trade secret and I didn't have a need-to-know) then put the nickel on top, on the principle that the rubber would prevent a crack in the nickel from propagating into the blade.