Zirconia going yellowish!

[Marcusthegladiator CDT]

 

[Mona Lobsey]

Hey guys, just wanna thank you all so much for your help! I have sent the photos to the company and they agreed that the heating elements need to be changed so they sent me new ones and the results now are just perfect! This forum is awesome

 

[Mona Lobsey]

And the company advised me to use a heating rate of >10°C per minute, even if the instruction from material supplier says for example 8°C per minute. Does that make sense to you?!

 

[RileyS]

Can anyone tell me what their opinion is of these heating elements? Are the little blemishes an issue? I'm getting the yellowing. Just did a cycle on empty to help get them "reglazed?" Going to cook some units to see if they are better. If not going to replace elements. Just want some insight to their current status.

 

[Axis Dental Milling]

Riley, it's Tyler Martin. When you run a cleaning cycle do not just run a empty chamber. Grab some old scrap zirconia and throw it in there with the tray and beads to help absorb any contamination. The elements need to rebuild the silica layer. Molybdenum disilicide based cermets MOSI2 heating elements withstand oxidation at very high temperatures. Their surface is protected by of a thin layer of silica glass that forms when they are exposed to oxygen at elevated temperatures.

 

[rich green]

Yellow crowns are often caused by a breakdown in the coating of the heating elements. The 1600 cycle is an attempt to "regrow" the coating. Examine your heating elements, you can use a mirror if the elements are still in the oven, and see if there are bare spots. The fast heating cycle and the 1600 should clear it up. good luck

 

[RileyS]

Riley, it's Tyler Martin. When you run a cleaning cycle do not just run a empty chamber. Grab some old scrap zirconia and throw it in there with the tray and beads to help absorb any contamination. The elements need to rebuild the silica layer. Molybdenum disilicide based cermets MOSI2 heating elements withstand oxidation at very high temperatures. Their surface is protected by of a thin layer of silica glass that forms when they are exposed to oxygen at elevated temperatures.

So...pretend I'm an idiot. Can you see any issues with the pictures I posted?

 

[Axis Dental Milling]

They are to glassed over and still have pockets where the silica needs to grow back. Run your cleaning cycle at 1600* and hold for two hours and put greenstate zirconia in it with the tray and beads.

 

[NicelyMKV]

Is that a *** oven Riley? If so, those elements do not like to get down to room temp.

 

[RileyS]

Unfortunately yes. I have it set to rest at 100C. THink I'll turn it up to...150?

 

[NicelyMKV]

Unfortunately yes. I have it set to rest at 100C. THink I'll turn it up to...150?

I had mine set to 300c before it caught fire...... Kept it from popping off and dis coloring my zr.

 

[Brent Harvey]

Mona,

It is true that when a oven is brand new you need to do a Break in cycle to help grow the silica layer on the elements to create that Glaze that you should always see on the Molybdenum disilicide heating elements (However) that is always done by the Manufacture. So if this is what is happening try to put a bunch of (Green State) milled pucks of Zirconia and break up the Old pucks and fill the tray as much as possible with that zirconia, Ramp your oven up from room temp to 1600deg C at a 10deg a min climb rate. Hold at that temp for 3 hours and natural cool. This may need to be repeated 3 to 4 times. This is the normal process that Manufactures do to there ovens before they are sent to the customer.

If you would like feel free to call me and i can further explain the process if needed.

Hope this helps...

 

[LeeV.]

Are there any Bleach shades available in Zirconia?

 

[Marcusthegladiator CDT]

Are there any Bleach shades available in Zirconia?

 

[GG - J]

Anyone have any working experience with
Pawa burnout oven
PA -1700TX

 

[FASTFNGR]

Does anyone have this problem before? I am using "Mihmvogt" Sintering furnace for about 2 months and never used Colored Zirconia in it, and i am experiencing a very bad yellowish color since the beginning on "DetalDirekt" Zirconia Crowns! I tried to sinter other brands than DentaDirekt and the results are just the same
I emailed the company but they said that is because the furnace still new! Does that make sense? All of my work is yellowish now and i am still waiting till the furnace will become old! Help please!!

Are you sintering in C or F degree? Under fire most of the time give that yellowish color, timing or lost of electrical current sometimes does the same thing.

 

[Davor RDT]

I am not sure what your purging scheduel is like but this sounds like contamination . After that a calibration and element inspection might be in order , not nessecarily in that order .