Ceramic Mug Group, When we are shopping for ceramic mugs, occasionally we will see ceramic mugs inside or outside will have part of the mug body showing black gray, feel as if it was burned by the fire left behind the smoldering color. Do you know that such a coffee mug can be used normally? What is the cause of this?
Ceramic coffee mug partially or completely black and gray phenomenon is called smoky. This defect is because the billet oxidation is incomplete or reduction too early, so that the billet in the body of carbonaceous organic matter and low-temperature carbon deposits can not be burned out of time, the glaze layer is closed.
By the glaze layer is closed, the surface of the ceramic mug is black and gray, with the shape of smoke. According to
ceramic manufacturer more than 20 years of experience in the production of coffee mugs know that the factors affecting the smoke are.
1. In the oxidation stage of burning small and medium fire insulation, oxidation is incomplete, part of the carbon residue in the body of the billet, so that the billet section was gray-black, especially when the billet contains a large amount of carbon in the use of clay, such as gangue, etc., it should be more in the glaze layer before the melting of the billet in the body of the full oxidation of the carbon. For the billet does not contain carbon products should also be in the fire insulation stage to strengthen the oxidation of coal-fired batch kiln and thick tire products, should pay special attention. This is because the batch kiln, ignition kiln temperature is low, more water vapor, plus this time the flue gas temperature is low, the chimney pumping force is weak, in the coal and pry furnace in a short period of time, the nature of the flame in the kiln is a reducing gas, at this time not only the carbon inside the body of the carbon can not be excluded, but also make the body of the billet deposition of carbon, especially when the kiln billet moisture content is high, it is easier to make the products produce water black. Therefore, the fire insulation stage (generally between 1000 ~ 1100 ℃), to maintain a strong oxidizing gas, and there is enough insulation time. That is to say, in the kiln operation, should control the grate on the ash layer, fire layer, the thickness of the coal layer, to ensure good ventilation, excess air coefficient is large, the fire layer of the combustion room clear Bright, each time you add the coal should be burned through, in order to make the billet get fully oxidized. Otherwise, the amount of coal added at this time is too much, the ash layer is too thick, poor ventilation under the stove bar, combustion does not penetrate, the combustion chamber produced by the free carbonaceous flue gas, long time to store in the kiln, and this stage, the billet stomata Rate and the largest billet, strong adsorption, it is easy to adsorb the smoke, resulting in carbon deposition, that is, we see the black and gray smoke pattern on the mug.
2. Reduction stage later, the reduction gas is too thick, that is, when the glaze has been melted, the kiln still maintains a strong reduction gas, but not in time to turn into a weak reduction gas or neutral gas, the product is still in the reduction gas, then the CO in the flue gas decomposition occurs at high temperatures resulting in the area of the material carbon, especially when using calcium glaze, it is easy to adsorb the smoke, thus causing carbon deposition, which is the black and gray smoke pattern we see on the cups. Calcium glaze, because CaO carbon absorption phenomenon is more serious, the most likely to form glaze smoky.
3. Ceramic mug black also need to analyze the billet glaze formula is reasonable. Such as the use of excessive CaO or other flux, so that the billet glaze prematurely produce liquid phase and melt, glass range is too narrow, so that the deposition of carbon can not be burned out in time, or too large a temperature difference between the kiln to ensure that the product gas changes, so that part of the product is in a chaotic gas. So that part of the product is in the chaos of the gas or fuel containing too much sulfur, its sulfur gas in the kiln to stay too long, then the sulfur will take the oxygen in the flue gas, so that the reduction gas becomes thick, easy to produce smoky defects.
In summary, these are the 3 reasons for ceramic mug smoking. This can be drawn in the production stage, how to avoid producing
smoked ceramic mug. Then, such a ceramic cup whether it affects the use, can buy it? Theoretical conditions, the smoke is produced inside the mug, the cup Outside the glaze to cover it inside, is not to affect the use. However, its aesthetics are not consistent with other ceramic mugs.
