The ratio of oxygen to fuel of Jet kote III

[wangqun72]

Hi everyone ,I am a user of Jet kote III HVOF system in China, the suggested paramete for WC/12Co powder by Deloro Stellite Co. Inc is as fellow :the flux of C3H6 is 133SCFH , flux of oxygen is 1010 SCFH and the carry gas of Ar is 57 SCFH.The JK112 coating deposited by using the suggseted paramete was crack, Can you tell me the reasons for occurrence of this cracking phenomenon. What's more, as you know ,C3H6+4.5O2=3CO2+3H2O,the oxygen to fuel is 1010/(133*4.5)=1.6786, why the oxygen is set to so high level.

[Gordon]

Hi wangqun72

to the Surface Engineering Forum.

Quote:Can you tell me the reasons for occurrence of this cracking phenomenon.

There could be many. We would need much more information about your process set-up, the nature of the cracks and when they occur to really get an idea of your problem.

Quote:What’s more, as you know ,C3H6+4.5O2=3CO2+3H2O,the oxygen to fuel is 1010/(133*4.5)=1.6786, why the oxygen is set to so high level.

No direct experience with Jet kote III HVOF system. But with SM Diamond jet with propylene for WC/Co type coatings the figure is more like 0.80 (oxygen for complete combustion). This equates roughly to the maximum flame temperature. So, I too feel your oxygen level is high.

[derek]

I have experence on JP5000 and K2 gun, the Keronsene and O2 ratio we use is 1.1-1.3, never use 1.6 defore.

[wangqun72]

(06-04-2010 01:19 PM)derek Wrote:  I have experence on JP5000 and K2 gun, the Keronsene and O2 ratio we use is 1.1-1.3, never use 1.6 defore.

Hi ,derek,I have experence on JP5000 too,mostly the parameters I usually used were :keronsene flux :6.5GPH,Oxygen flux:1950SCFH,spray distance:330mm and the feed rate : 76 g/min for WC/Co(15~45um) powder,the good coating can be obtained.According to this,the fuel/oxygen is about 0.9.

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Dear Gordon ,Thanks for your reply,by the way, could give me your E-mail,I can send photo of detail results to you, including spray parameter microhardness and microstructure.My e-mail:wangqun72@163.com

[Gordon]

Hi Wangqun72

If you click on the username of a member you should find contact information.

Any problems uploading images/attachments, please just email them to me and I will attach them to your post.

I tend to prefer to keep discussions open on the forum. Once they go private, they are obviously only of use to the individual/company and in this scenario should be treated in professional business terms.

[wangqun72]

Thanks for all the replies!
The most suitable ratio of O2 and C3H6 for Jet kote III is about 7.5 which is not like the DJ 2700 and other spraying gun.

Wang qun