how to increase hardness of CrC-NiCr

[Bler]

Hi ,everyone !
How to increase the hardness of CrC-NiCr. My main parameter are as following:

Gun:SM-F100
Ar :40-65
H2 :4
rate:20
distance :60
turn speed :90 rpm

The requirement is >HR83N, but my result is always 81-83.
I try many times ,but still can not achieve the requirement.
HELP

[Gordon]

Hi Bler

Are these the recommended parameters for the powder product that you are using?

Make sure you are hardness testing on sufficient coating thickness. Is it HR 15 N you are using?

[Bler]

Thank you for you attention ,Gordon.

The start parameter :
current :400
Ar:40
H2:4
Distance :80

I think my parameter is better than the start parameter,

Yes ,HR15N. In the latest test ,the thickness is about 0.3mm,the hardness is 82.5,still cannot meet the requirement .
I have already tried about 40 batches, but the result is bad .

Does the carrier gas can have some influence to the hardness?

[joanwang]

Thank you for you attention ,Gordon.

The start parameter :
current :400
Ar:40
H2:4
Distance :80

I think my parameter is better than the start parameter,

Yes ,HR15N. In the latest test ,the thickness is about 0.3mm,the hardness is 82.5,still cannot meet the requirement .
I have already tried about 40 batches, but the result is bad .

Does the carrier gas can have some influence to the hardness?

Hi, Bler
The powder is supposed to be Metco81VF_NS,right? Very Fine powder. If the powder wasn't dry and be stired enough it will block the powder line during spray and the spray stream would be uncontinuously.

The carries gas shoud be adjusted to propell the powder to the center of the stream for good melting.

I suggest you start the spray with feeding powder and monitor the stream to check if the powder is at the center of the plasma stream. or you can optimize your parameter to generate more kinetic energy of the stream.

[Bler]

Thank you for you attention ,Gordon.

The start parameter :
current :400
Ar:40
H2:4
Distance :80

I think my parameter is better than the start parameter,

Yes ,HR15N. In the latest test ,the thickness is about 0.3mm,the hardness is 82.5,still cannot meet the requirement .
I have already tried about 40 batches, but the result is bad .

Does the carrier gas can have some influence to the hardness?

Hi, Bler
The powder is supposed to be Metco81VF_NS,right? Very Fine powder. If the powder wasn't dry and be stired enough it will block the powder line during spray and the spray stream would be uncontinuously.

The carries gas shoud be adjusted to propell the powder to the center of the stream for good melting.

I suggest you start the spray with feeding powder and monitor the stream to check if the powder is at the center of the plasma stream. or you can optimize your parameter to generate more kinetic energy of the stream.

Thank you for your reply!
I tried to increase Ar and adjust spray distance ,the hardness is enhanced slight ,but still less than 83. I find that the coating has some unmelted ,and I consider that the speed of the particles are enough,so I will take some measure to enhance the melting degree of the particles next step.

[Bler]

I change my gun ,now the hardness is about 15N 85.Thank you for attention!

[Jaydev]

Hope you are doing it with HVOF/HVOLF gun then only higher hardness can be achieved in comparision to plasma or any other process.

[Bler]

Hope you are doing it with HVOF/HVOLF gun then only higher hardness can be achieved in comparision to plasma or any other process.

I change the inner gun to F4 gun,now it is ok.The power of ineer gun is too low,it will never achieve the hardness.

[Jaydev]

Hope you are doing it with HVOF/HVOLF gun then only higher hardness can be achieved in comparision to plasma or any other process.

I change the inner gun to F4 gun,now it is ok.The power of ineer gun is too low,it will never achieve the hardness.

what I understand is for applying carbide coating - HVOF/HVOLF equipment is best suitable in terms of achieving higher hardness and better surface finish with lower porosity.

If you are doing it with Plasma spray then it is interesting to know why plasma has been selected for this coating?

[Bler]

Hope you are doing it with HVOF/HVOLF gun then only higher hardness can be achieved in comparision to plasma or any other process.

I change the inner gun to F4 gun,now it is ok.The power of ineer gun is too low,it will never achieve the hardness.

what I understand is for applying carbide coating - HVOF/HVOLF equipment is best suitable in terms of achieving higher hardness and better surface finish with lower porosity.

If you are doing it with Plasma spray then it is interesting to know why plasma has been selected for this coating?

I spray the inner bore of the part.And i only have 3 guns. SM-F100,F4 HBS,DJ 2600. I tried inner gun at first ,as only this gun could get into the inner bore,but the result is not good .Then I make a fixture of F4 ,it can get into now. The reason I didnot choose DJ2600 gun,just because it cannot get into the part .

[loriolo]

Hi Bler
you did well, I used for aero industries application, an F4 HBS gun (which has gas, current/watter cables perpendicular to spray direction), and it is very short, and you can enter in a 200 mm hole without any problem, you must build a special support.