Sintering Process Suggestions
When we carry out the sintering process of zirconia, we would encounter the situation like the translucency and appearance color of the denture are not good.
Faced with this situation, how do we adjust the sintering process to achieve the best appearance and translucency for our denture?
First of all, after the sintering furnace has been used for many times or mixed with various brands of zirconium blocks to make dentures, the sintering furnace needs to use acticarbon to purify the furnace. You can get an acticarbon easily by online/offline shop. The acticarbon is the material commonly used in experiments to adsorb impurities and remove odors.
We pour 30-50 grams of activated carbon into the prepared burner tray before placing it on the stage. We use the heating system of activated carbon air burning at 5 degrees Celsius per minute, and then keep it at 650 degrees for one hour, which can achieve the effect of purifying the furnace. After an hour of heat preservation, we need to cool with water and milk, and then we can perform a high-temperature air-fire on the furnace to achieve the effect of completely purifying the furnace.
Meanwhile, when we are sintering we can use the Farrow® measuring ring with a detection temperature of 1,400 degrees to 1,700 degrees to monitor the temperature of our sintering.
For the empty sintering without any products, we choose the sintering temperature 20 degrees higher than our usual sintering temperature.
For example, we usually use 1,500 degrees for sintering, so this time we will use 1,520 degrees for sintering.
Note that the holding time of the empty sintering is 2 hours. Then the heating rate should be consistent with the temperature we usually use. The two crucibles are stacked on the furnace, and the purpose of placing two layers of crucibles is actually to protect the denture from being polluted by the furnace atmosphere when sintering.
After completion, lift the crucible into the furnace. Now let’s set his sintering curve. The system setting interface is like this. We can notice that the highest sintering temperature in the entire sintering curve is 1,480 degree.
We recommend that the maximum sintering temperature is 1,480 instead of 1,530, because the sintering temperature has a great impact on the product, including color and product translucency.
The major reason is that 3DPro is composed of a mixture of multiple powders. Its incisal part has high translucency because it is made of our UT powder, and the bottom is mixed ST Plus and ST powders.
The burning temperature of each powder is different; we can only take a compromised temperature to give him a whole burning temperature.
For the sintering temperature range of UT, we recommend 1,430 degrees to 1,480 degrees.
For the sintering temperature range of 3D, we recommend 1,480-1,500 degrees.
As you see, 1,530 degrees has exceeded the sintering temperature range of UT. Therefore, the 3D`s outlook all changed.
After sintering temperature over 1,530 degrees, we can see a clear difference in color and transparency between the sample on the left and the sample sintered at 1480 degrees on the right, even though they are made from the same zirconium block.
Our product will show the best color and transparency when it`s under 1,480 degree sintering.
Sintering at 1,530 degrees will make the color very light. For example, if we use A3 zirconium block sintering will make the color more like a color between a1 and a2. Therefore, we must strictly use the recommended sintering temperature of 1,480 degrees to sinter each time.