relationship between powder feed rate and carrier gas flow rate in plasma spray??????

[fahad03092]

For Plasma spray, if we increase powder feed rate should we need to increase or decrease carrier gas flow rate?

Can anyone help me about this.

Is carrier gas flow rate has any effect on powder feed rate?

[Metallurgy_eng]

The carrier gas flow rate is proportional to the particle velocity and deposition affect. You can not change powder feeding rate with carrier gas flow rate. But if you increase carrier gas too much your Deposition effect falls. You have to change powder feeding For a thicker coating at a time.

Best regard

[LEN WOOD]

(10-26-2011 05:36 PM)fahad03092 Wrote:  For Plasma spray, if we increase powder feed rate should we need to increase or decrease carrier gas flow rate?

Increasing powder feed rate usually requires an increase of carrier gas to inject greater volume of powder into the 'sweet spot' of the plasma. The thermal dynamics of the spray stream need to be optimised in order to obtain desired coating qualities and stability of process. Too low a carrier can result in wasted material, unmelts and build up on injector/ powder port, etc. Too high and overheated, cooled particles and poor quality coating, etc can occur.

(10-26-2011 05:36 PM)fahad03092 Wrote:  Is carrier gas flow rate has any effect on powder feed rate?

Depends on the powder feed system used - what system?

[joanwang]

(10-26-2011 09:16 PM)LEN WOOD Wrote:  

(10-26-2011 05:36 PM)fahad03092 Wrote:  For Plasma spray, if we increase powder feed rate should we need to increase or decrease carrier gas flow rate?

Increasing powder feed rate usually requires an increase of carrier gas to inject greater volume of powder into the 'sweet spot' of the plasma. The thermal dynamics of the spray stream need to be optimised in order to obtain desired coating qualities and stability of process. Too low a carrier can result in wasted material, unmelts and build up on injector/ powder port, etc. Too high and overheated, cooled particles and poor quality coating, etc can occur.

(10-26-2011 05:36 PM)fahad03092 Wrote:  Is carrier gas flow rate has any effect on powder feed rate?

Depends on the powder feed system used - what system?

It's essential to make sure the plasma powder goes into the center of the plasma stream during spray. So if powder feed rate changed,it's better to adjust the carrier gas flow.

[ServiceTech]

(10-26-2011 05:36 PM)fahad03092 Wrote:  For Plasma spray, if we increase powder feed rate should we need to increase or decrease carrier gas flow rate?

Can anyone help me about this.

Is carrier gas flow rate has any effect on powder feed rate?

Usually not but it depends on the powder feeder. What system do you have? Sulzer Metco 4MP and 9MP types utilize pressure differential and require hopper pressure adjustments when carrier gas flows are varied.